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The application of multiple omics technologies in biomedical cohorts has the potential to reveal patient-level disease characteristics and individualized response to treatment. However, the scale and heterogeneous nature of multi-modal data makes integration and inference a non-trivial task. We developed a deep-learning-based framework, multi-omics variational autoencoders (MOVE), to integrate such data and applied it to a cohort of 789 people with newly diagnosed type 2 diabetes with deep multi-omics phenotyping from the DIRECT consortium. Using in silico perturbations, we identified drug-omics associations across the multi-modal datasets for the 20 most prevalent drugs given to people with type 2 diabetes with substantially higher sensitivity than univariate statistical tests. From these, we among others, identified novel associations between metformin and the gut microbiota as well as opposite molecular responses for the two statins, simvastatin and atorvastatin. We used the associations to quantify drug-drug similarities, assess the degree of polypharmacy and conclude that drug effects are distributed across the multi-omics modalities.

In our recent dietary assessment field studies on passive dietary monitoring in Ghana, we have collected over 250k in-the-wild images. The dataset is an ongoing effort to facilitate accurate measurement of individual food and nutrient intake in low and middle income countries with passive monitoring camera technologies. The current dataset involves 20 households (74 subjects) from both the rural and urban regions of Ghana, and two different types of wearable cameras were used in the studies. Once initiated, wearable cameras continuously capture subjects' activities, which yield massive amounts of data to be cleaned and annotated before analysis is conducted. To ease the data post-processing and annotation tasks, we propose a novel self-supervised learning framework to cluster the large volume of egocentric images into separate events. Each event consists of a sequence of temporally continuous and contextually similar images. By clustering images into separate events, annotators and dietitians can examine and analyze the data more efficiently and facilitate the subsequent dietary assessment processes. Validated on a held-out test set with ground truth labels, the proposed framework outperforms baselines in terms of clustering quality and classification accuracy., Comment: accepted to BHI 2022

Additional file 1. Detectable difference in secondary study outcomes after one year of follow-up.

Malnutrition is a major public health concern in low-and-middle-income countries (LMICs). Understanding food and nutrient intake across communities, households and individuals is critical to the development of health policies and interventions. To ease the procedure in conducting large-scale dietary assessments, we propose to implement an intelligent passive food intake assessment system via egocentric cameras particular for households in Ghana and Uganda. Algorithms are first designed to remove redundant images for minimising the storage memory. At run time, deep learning-based semantic segmentation is applied to recognise multi-food types and newly-designed handcrafted features are extracted for further consumed food weight monitoring. Comprehensive experiments are conducted to validate our methods on an in-the-wild dataset captured under the settings which simulate the unique LMIC conditions with participants of Ghanaian and Kenyan origin eating common Ghanaian/Kenyan dishes. To demonstrate the efficacy, experienced dietitians are involved in this research to perform the visual portion size estimation, and their predictions are compared to our proposed method. The promising results have shown that our method is able to reliably monitor food intake and give feedback on users' eating behaviour which provides guidance for dietitians in regular dietary assessment., Comment: 11 pages, 14 figures, submitted for publication

Additional file 1: Supplementary Table 1. Univariable summary statistics of all factors considered. Supplementary Table 2. Risk score calculation. Supplementary Table 3. Description of clusters.

AIMS/HYPOTHESIS: It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435). METHODS: We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively. RESULTS: The TC and TC-PA models showed better fit than null models (TC: χ2 = 242, p = 0.004 and χ2 = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ2 = 180, p = 0.041 and χ2 = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle. CONCLUSIONS/INTERPRETATION: These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.

Altres ajuts: This work was also financially supported by the Centre for the Development of Industrial Technology (CDTI) of the Spanish Ministry of Science and Innovation under the grant agreement: TECNOMIFOOD project. CER-20191010. L.M-G is supported by the NIHR Imperial Biomedical Research Centre (BRC). There is extensive information of the beneficial effects of virgin olive oil (VOO), especially on cardiovascular diseases. Some VOO healthy properties have been attributed to their phenolic-compounds (PCs). The aim of this review is to present updated data on the effects of olive oil (OO) PCs on the gut microbiota, lipid metabolism, immune system, and obesity, as well as on the crosstalk among them. We summarize experiments and clinical trials which assessed the specific effects of the olive oil phenolic-compounds (OOPCs) without the synergy with OO-fats. Several studies have demonstrated that OOPC consumption increases Bacteroidetes and/or reduces the Firmicutes/Bacteroidetes ratio, which have both been related to atheroprotection. OOPCs also increase certain beneficial bacteria and gut-bacteria diversity which can be therapeutic for lipid-immune disorders and obesity. Furthermore, some of the mechanisms implicated in the crosstalk between OOPCs and these disorders include antimicrobial-activity, cholesterol microbial metabolism, and metabolites produced by bacteria. Specifically, OOPCs modulate short-chain fatty-acids produced by gut-microbiota, which can affect cholesterol metabolism and the immune system, and may play a role in weight gain through promoting satiety. Since data in humans are scarce, there is a necessity for more clinical trials designed to assess the specific role of the OOPCs in this crosstalk.

Table S1. Measurement error structure for protein, potassium, sodium and total sugar intake and density as assessed by myfood24 and interviewer-based 24-h recall. Table S2. Attenuation factors and correlation between dietary assessment tool and true intake for protein, potassium, sodium and total sugar intake as assessed by myfood24 for different numbers of repeat administrations of the tool. Table S3. Attenuation factors and correlation between dietary assessment tool and true intake for protein, potassium, sodium and total sugar intake and density as assessed by myfood24 and interviewer-based 24-h recall by sex. Table S4. Attenuation factors and correlation between dietary assessment tool and true intake for protein, potassium, sodium and total sugar intake and density as assessed by myfood24 and interviewer-based 24-h recall by age group. (DOCX 27 kb)

This work is licensed under a Creative Commons Attribution 3.0 Unported License.-- et al., Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation., The Department is funded by grants from the Medical Research Council (MRC), Biotechnology and Biological Sciences Research Council (BBSRC), National Institute for Health Research (NIHR) all from the UK, an Integrative Mammalian Biology (IMB) Capacity Building Award, an FP7- HEALTH- 2009- 241592 EurOCHIP grant and funding from the NIHR Imperial Biomedical Research Centre Funding Scheme. G.F. is supported by an NIHR senior investigator award, A.V. is supported by an NHMRC overseas-based clinical research fellowship (535976) and a FP7-People-2009-256365 reintegration grant. S.C. and B.L. were supported by grants SAF2011-23622, S/BMD 2349 2010, IPT-2012-1331-060000 and fellowship BES-2009-027615, respectively

Funder: Henning och Johan Throne-Holsts, Funder: Hans Werthén, Funder: Swedish Foundation for Strategic Research, Funder: NIHR clinical senior lecturer fellowship, Funder: Wellcome Trust Senior Investigator, Funder: NIHR Exeter Clinical Research Facility, Funder: Science for Life Laboratory (Plasma Profiling Facility), Funder: Knut and Alice Wallenberg Foundation (Human Protein Atlas), Funder: Erling-Persson Foundation (KTH Centre for Precision Medicine), Background: Non-alcoholic fatty liver disease (NAFLD) is highly prevalent and causes serious health complications in individuals with and without type 2 diabetes (T2D). Early diagnosis of NAFLD is important, as this can help prevent irreversible damage to the liver and, ultimately, hepatocellular carcinomas. We sought to expand etiological understanding and develop a diagnostic tool for NAFLD using machine learning. Methods and findings: We utilized the baseline data from IMI DIRECT, a multicenter prospective cohort study of 3,029 European-ancestry adults recently diagnosed with T2D (n = 795) or at high risk of developing the disease (n = 2,234). Multi-omics (genetic, transcriptomic, proteomic, and metabolomic) and clinical (liver enzymes and other serological biomarkers, anthropometry, measures of beta-cell function, insulin sensitivity, and lifestyle) data comprised the key input variables. The models were trained on MRI-image-derived liver fat content (

Supplementary material. (DOCX 87Â kb)

AIMS/HYPOTHESIS: Here, we describe the characteristics of the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) epidemiological cohorts at baseline and follow-up examinations (18, 36 and 48 months of follow-up). METHODS: From a sampling frame of 24,682 adults of European ancestry enrolled in population-based cohorts across Europe, participants at varying risk of glycaemic deterioration were identified using a risk prediction algorithm (based on age, BMI, waist circumference, use of antihypertensive medication, smoking status and parental history of type 2 diabetes) and enrolled into a prospective cohort study (n = 2127) (cohort 1, prediabetes risk). We also recruited people from clinical registries with type 2 diabetes diagnosed 6-24 months previously (n = 789) into a second cohort study (cohort 2, diabetes). Follow-up examinations took place at ~18 months (both cohorts) and at ~48 months (cohort 1) or ~36 months (cohort 2) after baseline examinations. The cohorts were studied in parallel using matched protocols across seven clinical centres in northern Europe. RESULTS: Using ADA 2011 glycaemic categories, 33% (n = 693) of cohort 1 (prediabetes risk) had normal glucose regulation and 67% (n = 1419) had impaired glucose regulation. Seventy-six per cent of participants in cohort 1 was male. Cohort 1 participants had the following characteristics (mean ± SD) at baseline: age 62 (6.2) years; BMI 27.9 (4.0) kg/m2; fasting glucose 5.7 (0.6) mmol/l; 2 h glucose 5.9 (1.6) mmol/l. At the final follow-up examination the participants' clinical characteristics were as follows: fasting glucose 6.0 (0.6) mmol/l; 2 h OGTT glucose 6.5 (2.0) mmol/l. In cohort 2 (diabetes), 66% (n = 517) were treated by lifestyle modification and 34% (n = 272) were treated with metformin plus lifestyle modification at enrolment. Fifty-eight per cent of participants in cohort 2 was male. Cohort 2 participants had the following characteristics at baseline: age 62 (8.1) years; BMI 30.5 (5.0) kg/m2; fasting glucose 7.2 (1.4) mmol/l; 2 h glucose 8.6 (2.8) mmol/l. At the final follow-up examination, the participants' clinical characteristics were as follows: fasting glucose 7.9 (2.0) mmol/l; 2 h mixed-meal tolerance test glucose 9.9 (3.4) mmol/l. CONCLUSIONS/INTERPRETATION: The IMI DIRECT cohorts are intensely characterised, with a wide-variety of metabolically relevant measures assessed prospectively. We anticipate that the cohorts, made available through managed access, will provide a powerful resource for biomarker discovery, multivariate aetiological analyses and reclassification of patients for the prevention and treatment of type 2 diabetes.

AIMS/HYPOTHESIS: It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435). METHODS: We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively. RESULTS: The TC and TC-PA models showed better fit than null models (TC: χ2 = 242, p = 0.004 and χ2 = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ2 = 180, p = 0.041 and χ2 = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle. CONCLUSIONS/INTERPRETATION: These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.

Supplementary material. (DOCX 87Â kb)

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is highly prevalent and causes serious health complications in individuals with and without type 2 diabetes (T2D). Early diagnosis of NAFLD is important, as this can help prevent irreversible damage to the liver and, ultimately, hepatocellular carcinomas. We sought to expand etiological understanding and develop a diagnostic tool for NAFLD using machine learning. METHODS AND FINDINGS: We utilized the baseline data from IMI DIRECT, a multicenter prospective cohort study of 3,029 European-ancestry adults recently diagnosed with T2D (n = 795) or at high risk of developing the disease (n = 2,234). Multi-omics (genetic, transcriptomic, proteomic, and metabolomic) and clinical (liver enzymes and other serological biomarkers, anthropometry, measures of beta-cell function, insulin sensitivity, and lifestyle) data comprised the key input variables. The models were trained on MRI-image-derived liver fat content (

Aims/hypothesis: It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435). Methods: We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively. Results: The TC and TC-PA models showed better fit than null models (TC: χ2 = 242, p = 0.004 and χ2 = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ2 = 180, p = 0.041 and χ2 = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle. Conclusions/interpretation: These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.

Aims/hypothesis: It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435). Methods: We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively. Results: The TC and TC-PA models showed better fit than null models (TC: χ2 = 242, p = 0.004 and χ2 = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ2 = 180, p = 0.041 and χ2 = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle. Conclusions/interpretation: These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.

Aims/hypothesis: Here, we describe the characteristics of the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) epidemiological cohorts at baseline and follow-up examinations (18, 36 and 48 months of follow-up). Methods: From a sampling frame of 24,682 adults of European ancestry enrolled in population-based cohorts across Europe, participants at varying risk of glycaemic deterioration were identified using a risk prediction algorithm (based on age, BMI, waist circumference, use of antihypertensive medication, smoking status and parental history of type 2 diabetes) and enrolled into a prospective cohort study (n = 2127) (cohort 1, prediabetes risk). We also recruited people from clinical registries with type 2 diabetes diagnosed 6–24 months previously (n = 789) into a second cohort study (cohort 2, diabetes). Follow-up examinations took place at ~18 months (both cohorts) and at ~48 months (cohort 1) or ~36 months (cohort 2) after baseline examinations. The cohorts were studied in parallel using matched protocols across seven clinical centres in northern Europe. Results: Using ADA 2011 glycaemic categories, 33% (n = 693) of cohort 1 (prediabetes risk) had normal glucose regulation and 67% (n = 1419) had impaired glucose regulation. Seventy-six per cent of participants in cohort 1 was male. Cohort 1 participants had the following characteristics (mean ± SD) at baseline: age 62 (6.2) years; BMI 27.9 (4.0) kg/m2; fasting glucose 5.7 (0.6) mmol/l; 2 h glucose 5.9 (1.6) mmol/l. At the final follow-up examination the participants’ clinical characteristics were as follows: fasting glucose 6.0 (0.6) mmol/l; 2 h OGTT glucose 6.5 (2.0) mmol/l. In cohort 2 (diabetes), 66% (n = 517) were treated by lifestyle modification and 34% (n = 272) were treated with metformin plus lifestyle modification at enrolment. Fifty-eight per cent of participants in cohort 2 was male. Cohort 2 participants had the following characteristics at baseline: age 62 (8.1) years; BMI 30.5 (5.0) kg/m2; fasting glucose 7.2 (1.4) mmol/l; 2 h glucose 8.6 (2.8) mmol/l. At the final follow-up examination, the participants’ clinical characteristics were as follows: fasting glucose 7.9 (2.0) mmol/l; 2 h mixed-meal tolerance test glucose 9.9 (3.4) mmol/l. Conclusions/interpretation: The IMI DIRECT cohorts are intensely characterised, with a wide-variety of metabolically relevant measures assessed prospectively. We anticipate that the cohorts, made available through managed access, will provide a powerful resource for biomarker discovery, multivariate aetiological analyses and reclassification of patients for the prevention and treatment of type 2 diabetes.

Type 2 diabetes (T2D) is a disease with a high prevalence in south Asian countries. Diet is the cornerstone strategy for the management of T2D. South Asians may have increased postprandial blood glucose responses following the same dietary challenge compared to white Europeans. Dietary fibre and protein play a role in regulating blood glucose and appetite via a myriad of mechanisms such as gut microbiota fermentation to short-chain fatty acids. Mycoprotein is a food ingredient high in both fibre and protein which has a positive effect on blood glucose and appetite in humans. Likewise, guar gum is a fibre-rich ingredient that decreases blood glucose and appetite in people with T2D. The aim of this thesis is to determine the effect of mycoprotein on glycaemia and energy intake in humans and the mechanisms underpinning these. In Study 1, the associations between mycoprotein-based food consumers and non-consumers with non-communicable disease markers such as blood glucose, energy intake and diet quality are studied in the UK free-living population using the National Diet and Nutrition Survey. The results showed that there is a positive association between mycoprotein consumers and healthy diet scores, fibre, fasting glucose and glycated haemoglobin. In Study 2, a systematic review of the effects of mycoprotein on glycaemic control and appetite in humans is performed. The results showed that the acute effects of mycoprotein on glycaemia are unclear, there is a consistent decrease in insulinaemia and energy intake in healthy humans. In Study 3, the acute effect of mycoprotein and guar gum in glycaemic control and appetite in people with T2D of South Asian and European ethnicity is investigated via a randomised controlled trial. The results showed that mycoprotein decreases postprandial blood glucose and that enriching chapati with guar gum induces a decreased blood glucose response. South Asians, however, had an increased postprandial glucose response compared to white Europeans. In Study 4, the effects of mycoprotein fermentation by the healthy gut microbiota is investigated using in vitro batch fermentation cultures. The results on breath hydrogen, pH, SCFAs, and bacterial communities, showed that mycoprotein may not be fermented. Open Access

The association between alcohol consumption and cardiometabolic disease risk has been described as a J or U-shaped curve attributed to a combination of harmful and beneficial effects varying with volume of intake. Diet is an established risk factor for cardiometabolic disease and related traits However, few studies examining this association adequately control for residual confounding by dietary intake. Therefore, the aim of this thesis was to investigate the relationship between alcohol consumption and markers of cardiometabolic health independent of dietary intake. Cross sectional analyses were conducted using data from the Airwave Health Monitoring Study – a British occupational cohort (n = 9,581). Alcohol consumption behaviour was determined from questionnaire and 7-day diet record data. Diet quality was determined by measuring adherence to the Dietary Approaches to Stop Hypertension (DASH) diet using data from the 7-day diet records. Markers of cardiometabolic health included: adiposity (body mass index and waist circumference), blood pressure, cholesterol, HbA1c and C-reactive protein. All analyses were replicated in an independent UK cohort using UK Biobank data (n =146,888). As part of this thesis, genetic analyses were conducted to investigate whether genes implicated in the regulation of HDL-c may facilitate some of the cardioprotective effects attributed to alcohol intake. Heavy alcohol consumption is associated with a deterioration in cardiometabolic health. The risk of cardiometabolic disease as indicated by a cardiometabolic risk score was lowest amongst moderate drinkers and highest amongst never, and heavy drinkers. Increasing alcohol intake was associated with a deterioration in diet quality and had an additive effect of total energy intake. Diet quality did not modify the relationship between moderate alcohol intake and cardiometabolic risk. Alcohol intake did not alter the effect of genes implicated in the regulation of HDL-c. These findings were validated in a sub-sample of the UK Biobank cohort. To conclude, the findings from this thesis show that alcohol consumption plays a key role in determining diet quality and cardiometabolic risk. Specifically, risk of developing obesity. Open Access

The beneficial effects of resistant starch on appetite regulation and body weight is well established in the literature; however, the underlying mechanism is not fully understood. Cell walls are the main source of resistant starch in human diets. Changes in dietary patterns over the recent years are dominantly characterised by highly-processed food, which commonly lack their cell-wall structure intact. Industrial processing can cause damage to the native structure of the cell wall, affecting nutrient bioavailability rate and appetitive responses. This thesis aimed to investigate the literature on food structure definition and its effect on energy intake and appetite regulation. Firstly, a systematic review of the effect of food structure on subjective appetite sensations and energy intake was conducted. It has been shown that there is a gap in the current literature on food structure definition. There are only four clinical trials found in the literature that investigated the effect of cellular wall integrity on appetite and energy intake. Secondly, cross-sectional analyses were conducted on two cohort studies to investigate the effect of food structure on energy intake; the National Diet and Nutrition Survey and the Airwave Health Monitoring Study. Lastly, a human clinical study was conducted to investigate the acute effect of different cell-wall structure meals on a subsequent open-buffet meal, and subjective appetite ratings. The work presented in this thesis suggest that there is an inverse association between the intake of minimally-processed (intact cell-wall) food and energy intake on the long-term, however more work is required to investigate the mechanism and acute effect of food structure. Open Access

Background: Previous research has demonstrated that acute propionate supplementation in humans can have favourable effects on energy metabolism by raising energy expenditure and lipid oxidation. Moreover, acute propionate supplementation in humans has shown to affect subjective appetite by increasing nausea and triggering the release of the anorectic hormone glucagon-like peptide 1 (GLP-1). Studies investigating the acute effects of propionate administration on glucose homeostasis in humans report conflicting outcomes. However, previous research has generally only investigated the acute impact of propionate supplementation in the overnight fasted state and for relatively short observation periods (

Childhood Crohn’s disease is associated with growth failure, weight loss and malnutrition. The aetiology of which is multifactorial; chronic inflammation, therapy induced and reduced calorific intake. These factors contribute to alterations in metabolism and body composition. Visceral adipose tissue is the adipose compartment, most strongly associated with chronic inflammation. Intestinal adipose tissue expansion described as ‘creeping fat’ is well recognized from surgical specimens as a hallmark of Crohn’s disease. Expansion of visceral adipose tissue is associated with cardiometabolic risk factors which have been reported in adults and children with inflammatory bowel disease. I performed a systematic review, to understand gaps in the literature in the context of body composition in children with inflammatory bowel disease. 22 studies were included, reporting on body composition in a total of 1477 children with inflammatory bowel disease . Lean mass deficits were more pronounced in children with Crohn’s ; 93.6% of Crohn’s and 47.7% of ulcerative colitis. Fat related compartment findings were inconsistent, and no clear conclusions could be drawn. Given that children with Crohn’s disease had more pronounced deficits in body composition, and intestinal fat expansion is a hallmark of disease, but there is a paucity of data regarding body fat measures; my main aim was to quantify visceral adipose tissue volumes and liver ectopic fat using magnetic resonance imaging (MRI) and Magnetic Resonance Spectrometry (MRS), in this cohort. My secondary aim was to examine relationship of visceral adipose tissue and ectopic liver fat in children with Crohn’s disease, disease specific and, metabolic parameters and plasma adipokines. I tested a null hypothesis in that no difference would be observed in abdominal adipose tissue or ectopic liver fat between children with Crohn’s disease and healthy children. A prospective cohort of children (7–17 years) with CD and healthy children, were recruited. Visceral adipose tissue , abdominal subcutaneous adipose tissue, abdominal muscle volumes (expressed in litres), and intrahepatocellular lipid (IHCL), was determined using MRS. Blood was analysed for CRP, ESR, albumin, fasting insulin, fasting glucose, lipid profile, adipokines (adiponectin, leptin, visfatin and resistin). Multiple regression analysis was used to identify factors associated with the dependent variable (compartment volume) significance was set at p

Background: Innovation adoption and diffusion (IAD) in healthcare refers to the essential process of integrating novel practices into systems’ critical functions. IAD is often slow and unsuccessful, leading to patients not receiving optimal care in a timely manner. IAD research has been dominated by descriptive or prescriptive theories with limited benefit to practice applications; these theories are often simplistic and assume IAD to follow a linear and predictable pathway despite emerging evidence portraying healthcare organisations as complex adaptive systems. Therefore, contemporary IAD research is increasingly shifting in favour of complexity theory replacing linear theories. Nonetheless, nursing research in the field is still trailing behind other disciplines on this shift. Aim: This study applied complexity theory to evaluate the process of innovation adoption and diffusion in frontline nursing practice. Objectives: The study explored why some nursing units succeed in innovation adoption and diffusion while others, within the same organisation, fail. Methodology: Drawing on constructivism, this study applied a theoretical framework built on complexity theory as the grand theory, complex adaptive system (CAS) as the middle-range theory, and Atun’s framework at the micro level. The theoretical framework requires a systems thinking approach capable of exploring the system as a whole rather than a collection of isolated, separate individual components. Design: A Comparative case study design was adopted, forming a 2x2 matrix incorporating two cases with four units of investigation. The two cases were two innovations selected as representatives for the phenomenon of IAD in frontline nursing: WHO 5 Moments for Hand Hygiene (5MHH) and Intentional Nursing Rounding (INR). Each innovation (case) was evaluated through its adoption and diffusion into two comparable units of investigation (wards); a ward of successful adoption and diffusion and an unsuccessful comparator ward. The study deployed multiple data collection methods incorporating non-participatory observation for thirty hours in each unit, and semi-structured interviews with nurses across the nursing hierarchy. Results: The study was able to identify several manifestations of complexity in frontline nursing and demonstrate how these impact adoption and diffusion behaviours. Manifestations of complexity were identified in attributing clinical outcomes to staff compliance; in the discrepancy between evidence, policy, performed, practice, and records; and through the disparity in staff values and priorities across the hierarchy. Existing organisational arrangements of clinical governance (policy design, dissemination, monitoring and clinical documentation) did not facilitate IAD at the frontline. Conclusion: Complexity offers an explanation for the variation in frontline innovation behaviours. Future strategies are recommended to improve IAD in frontline nursing through enhancing the adaptability of the innovation, engaging the informal social communication network, recognising frontline priorities, acknowledging staged and gradual improvement in compliance over time, and maintaining patient interest at the core of all frontline practice innovations. Open Access

Evidence suggests that the ileum is an important player in appetite regulation. The ileum contains a high density of L-cells that secrete appetite suppressing hormones Glucagon Like Peptide-1 and Peptide YY (PYY) in response to luminal nutrients and bacterial fermentation products, short chain fatty acid (SCFAs). Processing of foods may change their structures and reduce the amount of carbohydrates reaching the ileum, which may reduce appetite hormone release. However, access to the human ileum is difficult and little is known about the interplay between food, ileum environment and appetite hormone release. This thesis aimed to understand the impact of food structures on the levels of carbohydrate reaching the ileum and their effect on SCFA production and appetite hormone release. A nasoenteric tube was placed in the distal ileum of healthy participants (n=10) who consumed one of the three intervention diets for four days: High fibre, intact structures (I-HF) High fibre, disrupted structures (D-HF) or Low fibre, disrupted structures (LF). Blood and ileal samples were collected on day 4 in fasted and fed states (hourly for 8h). Disrupting the food structures of a high fibre diet (D-HF) reduced the amount of reducing sugars and bile acids, but not starch, in the ileal space compared to a high fibre intact diet (IHF). The numbers of bacteria and the concentrations of SCFAs in the ileum dramatically dropped from fasted to postprandial states, and this effect was not different between the groups. Postprandial PYY release was higher in D-HF in comparison to LF. Metabolomic analysis of ileal contents identified dynamic changes in several metabolites which were different between groups, including aspartate which was higher in D-HF compared to I-HF and LF. In addition, D-HF had higher serum SCFAs compared to I-HF and LF groups. Therefore a difference in ileal metabolites and/or colonic fermentation may be playing a part in the observed PYY difference. Further studies are needed to better understand the role of food structures and ileal metabolites in appetite hormone release. Open Access

Our gut harbours a biosphere of microorganisms constantly responding to the environmental cues we provide for them. From what we eat to how we behave and when we get sick so can our gut microbiome. However, this is not a one-way communication, these microorganisms also work for us in regulating many aspects of our body’s biochemical, physiological and immune functions. The gut microbiome lives in different compartments of varying nutrient availabilities, chemical and physiological conditions. The highly fluctuant environment of the small intestine (SI) and the presence bile acids and oxygen render this compartment inhabitable by most species. However, Streptococcus spp. thrive in the SI because they are highly efficient at metabolising simple carbohydrates for energy. Chapter 3 showed certain strains Streptococcus spp. may be in competition with one another for the availability of nutrients in the SI. Inside the colon, these facultative anaerobes were replaced by a diverse community of obligate anaerobes capable for fermenting complex carbohydrates, proteins and even mucin glycans. These microbial communities are resilient and adaptable to short-term Western diet intervention although carbohydrate fermentation activity of the colonic microbiota was decreased as Chapter 3 showed. In Chapter 4, significant alterations in the community structure and metabolic capacity of the colonic microbiota were observed in patients with irritable bowel syndrome (IBS). Lower carbohydrate fermentation and increased protein fermentation were evident in patients with constipation-predominant IBS. Diarrhoea-predominant IBS patients excreted more primary bile acids. Using multi-omics integration, a novel host-microbial co-metabolic pathway involving purine salvage was identified. Chapter 5 showed the passage of short chain fatty acids (SCFA) from the lumen to the mucosa was interrupted by the presence of a mucus layer. A diffusion dynamic for the trans- compartmental passage of SCFA was subsequently hypothesised. This thesis presents a compartmentalised view of the gut microbiome, demonstrating its unique adaptations to dietary change and that disturbances in its community structure and functional capacity underlie the pathophysiology of functional gastrointestinal disorders. Open Access

Cardiovascular diseases (CVD) continue to be the leading cause of death worldwide. Hypercholesterolemia (HC) is a modifiable risk factor in the development of CVD. Diet-based therapies, such as dietary fibres (DF) are first-line treatment options to be used solely or in conjunction with pharmacological options for cholesterol management. DF have been shown to reduce HC, but underlying mechanisms are unknown. Existing literature suggest that the hypocholesterolemic effect may be as a result of an interplay of diet, host metabolism, and gut microbiota (GM) which leads to the increased faecal excretion of bile acids (BA). Faecal BA excretion (FBAE) leads to a reduction of circulating cholesterol via a cascade of reactions, therefore increasing FBAE may be a cardioprotective mechanism. A novel mechanism was thus hypothesised. DF may modulate GM to promote the polymerisation of secondary BA deoxycholic acid (DCA) to polydeoxycholic acid (PDC). PDC cannot be reabsorbed; it is subsequently excreted, triggering compensatory reactions that lead to reduced plasma cholesterol and its associated CVD risk. This PhD project explored the mechanisms involved in and the effects of diet on PDC production in humans using a combination of cutting edge metabolomic and metagenomic tools. An ultra-performance liquid chromatography-based method was developed for high throughput and sensitive detection and quantification of PDC. PDC was reliably detected in human faeces (up to 90% of total faecal DCA) and was found to correlate with anti-inflammatory butyrate producing GM and established beneficial GM like Bifidobacteria, and also with a high fibre high protein diet. More investigations are warranted to further elucidate the role of PDC in host physiology. Current indications suggest a beneficial role for PDC. Abbreviations: CVD cardiovascular diseases; HC Hypercholesterolemia; DF dietary fibres; BA bile acids; GM gut microbiota, FBAE faecal bile acid excretion, DCA deoxycholic acid; PDC polydeoxycholic acid. Open Access

Current dietary interventions in the treatment of obesity are struggling to prevent its increasing global prevalence and detrimental side-effects, including non-alcoholic fatty liver disease (NAFLD). Many studies addressing the macronutrient content of the human diet have shown that manipulation of the macronutrient makeup of the diet may have beneficial effects on weight loss, appetite regulation, body composition and metabolic health. However, obesity and nutrition research are flawed by the limitations of current dietary recording methodologies, as there is an inverse relationship between accuracy of reporting of energy intake by all current nutritional methodologies and body weight. This work aimed to determine the effects of specific individual nutrients (a high-protein, hypo-caloric diet, and long chain n3-polyunsaturated fatty acids (n3-PUFA) supplementation with a hypocaloric diet) on weight, adiposity and appetite in overweight participants. In addition to this a pilot study explored the use of a novel lightweight wearable micro-camera in improving the accuracy of dietary intake assessment. Anthropometric measurements were taken using weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), bioelectrical impedance (BIA), and the gold standard for measuring body composition, magnetic resonance imaging (MRI). Energy intake and appetite was measuring using a 3- or 7-day food diary, an ad-libitum meal, visual analogue scale and, for the n3-PUFA study, fMRI was also employed to assess changes in food reward through measuring changes in blood oxygen level dependent (BOLD) signal in response to food images. The results suggest that any changes in body composition, biochemistry and appetite induced by a 12-week hypocaloric diet appear to be independent of protein content (body weight change of -4.06±0.85kg body weight with normal protein vs -4.42±0.85kg with high protein diet), whilst n3 PUFA supplementation during a calorie restricted diet may improve weight loss (-2.53kg±0.59kg, p

Obesity has become a global health issue, and type-2 diabetes (T2DM) is one of its most common comorbidities. The Roux-en-Y gastric bypass (RYGB) is the most effective surgical procedure for treating obesity, resulting in significant and sustainable weight loss. One proposed mechanism for how RYGB achieves successful weight-loss is based on profound changes in the secretion of gastrointestinal hormones that follow surgery, including increases in Glucagon-Like Peptide-1, Oxyntomodulin and Peptide YY (GOP). Surgically induced changes in physiology are also associated with specific behavioural factors and psychological characteristics, both of which are recognised as important contributors to successful postoperative outcome. This study hypothesised that patients with obesity and T2DM following RYGB have a healthier eating behaviour profile, mediating the long-term sustainable weight loss than Very-Low-Calorie diet (VLCD) or GOP infusion. Eating behaviour, food reward, psychological status, health-related quality of life and food intake were assessed at baseline and following each intervention using a set of validated questionnaires and a 4-day food-diary before and after each intervention. The RYGB showed a reduction in the reward drive to eat at three-month which was maintained up to one-year post-surgery. There were also reductions in external-eating, disinhibition and weight and shape concerns which were not observed following VLCD or GOP, suggesting that calorie-restriction or gut-hormone alone maybe not be responsible for changes in eating behaviour following RYGB. Meanwhile, there were similarities between the RYGB and GOP groups in terms of the increase in the flexible dietary restraint measured by the Dutch Eating Behaviour questionnaire. Moreover, the GOP group did not show any changes in the taste perception as were observed following RYGB. Understanding the behavioural mechanisms that account for such variations could help the development of personalised therapeutic approaches based on the need to improve treatment outcomes and dietary advice offered to patients with obesity. Open Access

Severe anaemia (Hb

Asthma is a chronic inflammatory disease characterized by decline in lung function, goblet cell metaplasia and tissue remodeling. Recent years have demonstrated the interplay between the airways and the gut microbiota, showcasing the dampening of airway inflammation by gut-microbial metabolites short-chain fatty acids (SCFAs) in rodent models. No studies have investigated the presence and effect of SCFAs in the airways of asthmatics and limited studies have investigated the metabolic profile of asthmatics and the effect of fibre supplementation. We demonstrate the presence of SCFAs (mainly acetate and propionate) in the airways of healthy controls and asthmatics, with an increase in acetate in asthmatics. The levels of SCFAs detected in the airways exceeded what has previously been described in peripheral blood. SCFA concentrations in asthmatic airway were correlated with specific airway microbial genera, suggesting a possible production of SCFAs by the airway microbiota. This was further confirmed by in vitro batch culture, where airway bacterial species produced higher amount of SCFAs in the presence of mucin, indicating proteolytic activity by the airway microbiota. In order to determine the direct effect, which local SCFA level could have on the airway epithelium, the effect of acetate and propionate were investigated on primary airway epithelium. Both SCFAs promoted a modulation of cytokine gene response upon, stimulation on both apical and basolateral side, which was further enhanced by IL-13 treatment. These results suggest that the microbial-airway-derived SCFAs promote a local change in the inflammatory response in vitro, which is different to the response seen with gut-microbial-derived SCFAs in preclinical data. Furthermore, the metabolic profile of asthmatics was investigate using 1H NMR spectroscopy and UPLC-MS, in order to identify potential urinary biomarkers that would aid in the diagnosis of asthma and sub-populations of asthma. Several urinary biomarkers were found to be either elevated or decreased in asthmatics belonging to purine, polyamine and fatty acid metabolism. Interestingly, a panel of carnitines were able to distinguish between sub-population of severe asthmatics. Lastly, investigating the effect of prebiotic supplementation to individuals with exercise-induced asthma, did not generate any statistically significant effect on SCFAs concentrations nor lung function, possibly due to the low levels of prebiotic supplementation. Open Access

Obesity is a fast-growing epidemic that poses a major challenge to the public health. There is a current lack of safe and effective anti-obesity treatment options, therefore an improved treatment option is critical. Short chain fatty acids (SCFAs), produced in the colon via fermentation of non-digestible carbohydrates by gut microbiota, activates FFA2 and FFA3, G-protein coupled receptors (GPCRs) that stimulate the release of anorectic gut hormones GLP-1 and PYY. However, the underlying molecular mechanisms stimulating their release are poorly understood. A fundamental mechanism controlling the signalling capacity of GPCRs is via receptor trafficking to diverse cellular compartments such as early endosomes (EE), or very early endosomes (VEE). A subpopulation of VEEs contains the adaptor protein APPL1, essential for driving receptor recycling from the VEE and regulating endosomal G protein signalling. I therefore characterised the signalling pathways exerted by SCFAs in intestinal enteroendocrine cells and colonic organoids and elucidated the trafficking properties of FFA2 that regulate anorectic gut hormone release. In enteroendocrine cells, SCFAs are unable to elicit Gαq/11-signalling but robustly activates Gαi/o signalling which is important for propionate induced GLP-1 secretion. FFA2 undergoes both constitutive and ligand induced internalisation. Following ligand-induced internalisation, FFA2 traffics to the VEE to activate Gαi endosomal signalling that is regulated by APPL1. In addition, by employing high resolution single vesicle imaging, I unveiled propionate-induced FFA2 recycling is APPL1 dependent. I also examined the dependence of receptor internalisation and found that receptor internalisation is critical only for propionate induced- Gαi/o signalling, p38 activation and GLP-1 release, while Gαq/11 signalling occurs from the plasma membrane. Together these findings suggest an important spatial requirement for propionate-mediated activity and uncovers novel mechanisms regulating the release of anorectic gut hormone, GLP-1. Open Access

The structural elements within a food, known as food structure, are thought to play a critical role in appetite regulation and energy homeostasis. Food structure can refer to the spatial arrangement of cellular structural elements, such as starch granules, or the physical form of a food. Manipulating the starch structure within a food system, such as in peas, can limit starch digestibility and thus improve the quality of the starch eaten. Bypassing upper gastrointestinal (GI) tract digestion can increase microbiota fermentation activity, which is responsible for the beneficial effects associated with resistant starch consumption. Short-chain fatty acids, fermentation by-products, have previously been reported to regulate glucose homeostasis, reduce energy intake and increase peripheral anorexigenic gut hormone concentrations in humans. A large part of this thesis aimed to investigate the acute effects of manipulating the starch structure within peas by inactivating the starch-branching enzyme of the pea seeds (SBE-deficient peas) on appetite regulation and energy homeostasis in humans. The first study presented in this thesis investigated the effect of food structure within peas on gastric emptying rates using a 13C breath test. The data suggest that manipulating the structure of the peas improves glycaemic response without affecting the gastric emptying rate. The second study presented in this thesis investigated the effect of upper GI digestion on different pea structures. SBE-deficient pea seeds were less available at the small intestinal level to be broken down into glucose. The third study presented in this thesis investigated the effects of lower gut fermentation on different pea structures. SBE-deficient pea seeds produced more short chain fatty acids (SCFAs) as a result of fermentation. However, these pea studies did not cause a change in subjective appetite or in appetite-regulating hormones. Propionate, one of the main SCFAs produced from microbial fermentation, is thought to play a crucial role in appetite regulation and energy homeostasis. Supplementation with inulin-propionate ester (IPE), which selectively enriches colonic propionate, has been reported to increase peripheral anorexigenic gut hormone concentrations and reduce energy intake acutely in humans. Long-term IPE supplementation prevented weight gain and reduced intra-hepatocellular lipid content. Another part of this thesis aimed to investigate the effects of colonic 4 propionate on appetite regulation and energy homeostasis in humans following a lower energy diet through IPE supplementation over a 12-week period. IPE reduced subjective appetite and led to significant weight loss compared to baseline. However, these effects were independent of changes in anorexigenic gut hormones. The majority of the work presented in this thesis supports a role of fermentation in energy and appetite homeostasis. However, the exact underlying mechanisms remain unclear. Open Access

Obesity is a major global health issue. As high-protein and high-fibre diets are associated with increased satiety and weight loss, uncovering the mechanisms by which dietary protein- and fibre-derived metabolites are sensed in the gut and regulate appetite may reveal targets for anti-obesity therapies. The work presented in this thesis sought to further this endeavour with a two-pronged approach, in vitro and in vivo. The in vitro intestinal organoid model recapitulates the major features of the in vivo intestinal epithelium. I cultured intestinal organoids from mouse duodenum, jejunum and ileum, and demonstrated that basal GLP-1 content increased distally along the small intestine, in line with the in vivo L-cell density pattern. Research within our group had identified that the amino acid L-Phenylalanine has anorectic properties and highlighted the calcium-sensing receptor as a potential target through which L-Phenylalanine mediates GLP-1 release. My work built on this by showing that L-Phenylalanine significantly stimulates GLP-1 release in mouse ileal organoids, an effect significantly attenuated by a calcium-sensing receptor antagonist. Investigation of the underlying signalling mechanisms indicated that L-Phenylalanine-induced GLP-1 secretion may not be mediated via a Gi/o-coupled pathway, and that Ca2+ influx through L-type calcium channels may be required. The in vivo dietary intervention study I concurrently ran in healthy humans led to observations that a high-protein, high-fibre test meal stimulated GLP-1 and PYY release that remained above fasting levels for the 6-hour sampling period. Furthermore, acute repeated exposure of the gut to a protein- and fibre-enriched diet may have beneficial effects in terms of sustaining post-prandial plasma PYY responses and modulating glucose homeostasis. Gastrointestinal contents from the terminal ileum and proximal colon were obtained from participants via a specialised nasoenteric sampling tube, and microbial profiling of these together with stool samples revealed region-specific differences within the distal gut, indicating that stool may not be an accurate proxy for either microbial diversity or composition of the terminal ileum or proximal colon. Additionally, acute temporal shifts in microbial composition, perhaps due to dietary intervention, were identified in the gut contents samples. The work in this thesis has contributed to our knowledge of how ingested protein and fibre affect anorectic gut hormone release, glucose homeostasis and appetite, and has shed light on how differences in microbial diversity and composition can exist in different regions of the distal gut. It has also enhanced our understanding of the mechanisms that sense L-Phenylalanine in the gut. Further investigations are required to determine the therapeutic potential of protein- and fibre-derived metabolites as appetite-suppressing agents, with an end-goal of developing novel strategies to prevent and treat obesity. Open Access

Nutrient sensing is the process by which cells detect and respond to dynamic metabolite fluctuations. In gastrointestinal enteroendocrine cells (EECs), this process facilitates the post-prandial secretion of anorectic gut hormones. As these elicit diverse impacts on physiology, appetite and metabolism, they present potential targets for anti-obesity therapeutics. Short chain fatty acids (SCFAs) are produced as by-products of the fermentation of non-digestible carbohydrates by the gut microbiota, predominantly in the colon. SCFAs induce EECs to release anorectic hormones GLP-1 and PYY by acting as ligands at G protein-coupled receptors (GPCRs) FFAR2 and FFAR3. Thus far, it has been confirmed that FFAR2 and FFAR3 couple to Gαi/o but FFAR2 alone activates Gαq/11 calcium mobilisation. However, FFAR2 is seemingly only able to induce calcium signals in EECs when activated by synthetic FFAR2 ligands, not SCFAs. It is plausible that crosstalk between FFAR2 and FFAR3 could be preventing FFAR2 coupling to Gαq in response to SCFAs. This has been assessed by combining genome editing and functional signalling assays. Conversely, the results demonstrate that co-expression of FFAR2 and FFAR3 in heterologous systems enhances propionate-mediated calcium mobilisation. Futhermore, functional knockout of FFAR3 has no impact on propionate signalling in EECs. Interestingly, crosstalk with FFAR4 may represent a mechanism for the lack of SCFA-induced Gαq signalling in EECs. The impact of SCFAs on the expression of other GPCR signalling machinery remains poorly characterised. This project has, to date, demonstrated propionate and butyrate robustly upregulate transcripts encoding the umami taste receptor, via a Gαi/o independent mechanism. We show that overnight exposure of EECs to butyrate enhances the calcium mobilisation in response to L-Alanine when IMP is present. Therefore, I propose an alternative, indirect mechanism by which SCFAs enhance gut hormone release; namely, by inducing a hypersensitivity of EECs to L-amino acids by promoting expression of taste signalling components. Open Access

Undernutrition is a predictor of morbidity and mortality in older adults and those living with conditions of accelerated aging such as COPD. Nutritional screening is recommended to identify at-risk individuals but there are concerns that this initial step in a pathway of nutritional care is not always completed or communicated. In addition, there is little research in community-dwelling older populations regarding how best to organise care at the hospital-community interface. Exploring existing pathways of nutritional care experienced by community dwelling older adults will help us to understand potential determinants of undernutrition that may influence their trajectory of recovery and highlight any gaps in care. The aim of this thesis was to examine nutritional risk, physical function and quality of life in a cohort of community-dwelling older adults. An observational prospective cohort study of community-dwelling, older adults demonstrated that individuals at medium and high risk of undernutrition were at higher risk of mortality and suffered a worse trajectory of recovery following hospital admission compared to their counterparts at low nutritional risk. However, cross-sectional analyses using data from a large cohort of COPD patients attending pulmonary rehabilitation between August 2009 and January 2015 showed that whilst medium/high nutritional risk was associated with worse strength and function prior to a period of respiratory rehabilitation, it did not influence performance, with similar benefits observed in low and medium/high nutrition risk groups. This thesis suggests that irrespective of nutritional status, older adults recently discharged from hospital or attending outpatient rehabilitation programmes exhibited reduced ability to perform activities of daily living, however, that individuals at nutritional risk experience a reduced rate of recovery, suggesting that worse nutritional status may compound adverse effects on physical function and quality of life following hospital admission. However, nutritional support may have the potential to reduce further deterioration in at risk participants. Open Access

Type 2 diabetes mellitus (T2D) and obesity are two of the key health challenges of modern society. With an ageing population and increasing life expectancy, advanced T2D, including those treated with insulin, is now frequent within clinical practice. Effective treatment of glycaemic control in those treated with insulin relies at present on insulin intensification, that although effective at managing blood glucose, is associated with weight gain and an increased risk of cardiovascular disease (CVD) mortality. Bariatric surgery has been shown to be one of the most effective treatments for obesity and T2D. One key mechanism by which bariatric surgery aids diabetes control is through energy restriction. The use of formula low energy diet (LED) to replicate this and attendant significant weight loss has been observed to bring about T2D remission in those with recently diagnosed T2D patients. However, evidence for the use of these formula diets is lacking in those T2D patients concurrently treated with insulin. The work presented in this thesis aimed to investigate the role of formula low energy diets in obese type 2 diabetes patients concurrently treated with insulin. Investigation 1 studied the effect of a formula LED, over a 24-week period, on weight loss insulin usage, and glycaemic control in obese T2D patients treated with insulin compared with gold standard clinical care (GSC). The presented data demonstrates that those on an LED had greater weight loss, improvement in HbA1c, and reduction in insulin usage compared to GSC. Investigation 2 studied the effect of weight loss induced by an LED on surrogate markers of CVD. Compared with GSC, there were key reductions in triglycerides, diastolic blood pressure and high sensitivity C-reactive protein. Based on CVD risk algorithms, there may be a CVD benefit of weight loss through LED, at least in the short term. The work presented in the thesis helps to support the use of formula LED as a therapeutic treatment for complex T2D patients. The exact mechanisms by which the LED brings about the observed improvements in glycaemic control and reduction in insulin usage remains be determined. Open Access

Propionate, a product of microbial fermentation, is thought to play a key role in appetite regulation and energy homeostasis. Supplementation with inulin-propionate ester (IPE), which selectively increases colonic propionate production, has previously been reported to reduce energy intake and increase peripheral anorexigenic gut hormone concentrations acutely in humans. Furthermore, long-term IPE-supplementation prevented weight gain and reduced intrahepatocellular lipid content. This thesis aimed to further investigate the effect of colonic propionate on appetite regulation and energy homeostasis in humans. Study 1 investigated the effect of L-rhamnose, a propiogenic non-digestible carbohydrate, on gut transit rates using a dual 13C breath test combined with breath H2. The presented data suggest that L-rhamnose delays gastric emptying rates, increases circulating propionate concentrations and is fermented in the small intestine despite it previously being considered to reach the colon intact. Study 2 investigated the effect of IPE on brain responses to food picture stimuli during an fMRI food picture evaluation task. IPE reduced brain responses to food picture stimuli in the striatum, a brain region involved in reward processing, and reduced their subjective appeal, and reduced energy intake. Study 3 investigated the effect of IPE following a 7-day supplementation period with food products containing IPE (IPE-FP). IPE-FP reduced energy intake. IPE-FP also significantly increased fasting and post-prandial energy expenditure. However, this effect was lost after correcting for lean mass. There was also a reduction in fasting non-esterified fatty acid concentrations following IPE-FP. Finally, study 4 investigated the effect of propionate on liver fat accumulation in two human hepatocyte cell lines. Propionate did not reduce liver fat accumulation in vitro, which suggests the effects observed in vivo may be indirect. The majority of work presented in this thesis supports a role for propionate in energy homeostasis. However, the exact underlying mechanisms remain to be elucidated. Open Access

Fermentable carbohydrates have been shown to exert beneficial effects on dysregulated metabolic conditions such as obesity and diabetes by improving insulin sensitivity and glucose homeostasis, independent of weight loss. Short-chain fatty acids produced by the fermentation of these carbohydrates are considered the primary mediators of these beneficial effects. This thesis aims to evaluate the effect of fermentable carbohydrates on metabolic profiles of pre-diabetic individuals at high risk of developing diabetes and the effect of colonic propionate on glucose and lipid homeostasis in obese individuals. The work presented in this thesis comprises of two axes. The first one is centered on the development and validation of an analytical approach of quantifying SCFAs in human plasma, serum and urine. The applicability of the assay in nutritional studies is also assessed in the second aim. The second part explores the metabolic profiles of pre-diabetic and obese individuals with the employment of 1H nuclear magnetic spectroscopy and mass spectrometry analysis. Concentrations of SCFAs and alteration of the lipid profile were also assessed. The responses to dietary interventions were compared using multivariate statistics. The fermentable carbohydrate inulin increased the production of postprandial SCFAs in pre-diabetic individuals but did not exhibit a significant effect on the overall metabolic profile. Colonic propionate improved the postprandial lipaemia in obese individuals and exerted higher microbial derived metabolites suggesting a role for propionate in the lipid homeostasis in obesity. Propionate levels in the circulation were not affected but systemic acetate significantly increased during the meal test. Finally, the controlled intervention with the non-fermentable carbohydrate cellulose improved lipid profiles in pre-diabetic and obese individuals. Open Access

There is a high prevalence of T2DM and CHD in South Asians who have migrated to developed countries including UK, compared to their Caucasian counterparts. Studies investigating genetics, obesity, and physical activity have not been able to explain the prevalence of metabolic disorders in South Asians. Dietary intake might play a role in the development of metabolic diseases suggested by published work showing contradictory result. We hypothesized that detailed dietary assessment will lead to understanding the high prevalence of metabolic disorders in South Asians. The data of a sub-cohort from LOLIPOP was used to re-examine the dietary intake and metabolic disorders in groups without and with CHD in South Asians versus Caucasians. Initially the estimated dietary records were analysed which revealed higher carbohydrate but lower SFA and alcohol intakes in both South Asian groups, a dietary profile which is not associated with metabolic disorders. It is possible that food components which are not shown in traditional dietary assessment play a role in metabolic diseases. Thus, I undertook metabolomics profiling method for serum and duplicate diet samples with the intention to get further insight in the relationship between dietary intake and metabolic disorders. ¹HNMR technique was applied for both samples. The analysis for serum and food samples showed no difference between South Asians and Caucasians in the UK. But the comparison between South Asians in the UK versus India revealed higher levels of valine, citrate, and glucose but, lower dimethylglycine and phenylalanine. Food analysis revealed higher levels of citrate, glucose, alanine, and glycerol whereas, fumarate and phenylalanine were lower in South Asians in UK. Most of the identified compounds play a role in energy metabolism which raises the possibility of the effect of diet composition on metabolic disorders. Further investigation is required applying a targeted metabolomics study to identify specific pathways. Open Access

Background: Cardiovascular disease (CVD) is one of the leading causes of death worldwide, driven by various metabolic risk factors and diabetes. Diet is a key modifiable component in the development of these risk factors. This study aimed to investigate cardio-metabolic risk factors associated with diet. Secondly, dietary interaction with genetic risk of diabetes. Methods: A cross-sectional analysis was conducted on 5,864 participants’ baseline data from the Airwave Health Monitoring Study. Participants completed a 7-day food diary and a health screening including blood sample, blood pressure and anthropometrics. Diet quality was assessed according to UK Dietary Reference Values (DRV) using the novel DRV index and the established UK nutrient profile model. The nutritional genomic association with diabetes and HbA1c% was studied using a polygenetic risk score (GRS). Results: A higher DRV score was associated with a lower waist circumference ( -0.56 p16g/day) modified the genetic effect on HbA1c ( 1.22, p=0.002). Obesity (BMI >30kg/m2) increased the effect on HbA1c by =1.90 pinteraction =0.0006. Conclusion: Individuals consuming a high quality diet (high in complex carbohydrates, fibre, fruit and vegetables and wholegrain) aligned with the UK guidelines were associated with fewer metabolic risk factors for CVD and diabetes. A high quality diet also reduced the genetic effect on HbA1c and diabetes in high-risk individuals. These findings support the importance of encouraging a healthy diet, along with moderate alcohol consumption, as part of public health advice for a lower risk of CVD and diabetes, especially in high genetic risk groups.

Propionate is a short chain fatty acid produced in the colon via fermentation of undigested foods. Elegant in vitro and in vivo studies have shown that increased production of propionate in the gut can reduce body weight and energy intake, and improve glucose homeostasis. These positive effects have been attributed to increased levels of the gut hormones, PYY and GLP-1, increased energy expenditure and improved beta-cell function. Furthermore, bariatric surgery increases levels of colonic propionate and this likely contributes to the huge weight loss seen with this treatment. Additionally, other short chain fatty acids and the consumption of fermentable carbohydrates to increase levels of short chain fatty acids can delay gastric emptying and affect the central regulation of appetite. Taken together, these findings suggest propionate could have several beneficial health effects in humans. Inulin-propionate ester was developed to deliver propionate to the colon. Effects of acute delivery of propionate to the colon with a single dose of inulin-propionate ester was investigated in healthy human volunteers on energy intake, subjective ratings of appetite and satiety and plasma glucose and insulin levels. Potential mechanisms for any effects were explored by assessing plasma levels of PYY and GLP-1, gastric emptying using 13C-octanoic acid, energy expenditure using indirect calorimetry, and central effects using fMRI. In addition, encapsulated sodium propionate was used to assess delivery to the small intestine on appetite and glucose and insulin levels. Acutely increasing colonic levels of propionate significantly reduced energy intake, increased satiety, increased levels of PYY and GLP-1, and reduced anticipatory food behaviour in humans. No effects were observed on gastric emptying, plasma levels of glucose and insulin and energy expenditure. In addition, delivery of propionate to the small intestine did not affect appetite or plasma levels of glucose and insulin. Colonic propionate significantly reduced energy intake and reduced appetite likely through increasing levels of GLP-1 and PYY and reducing anticipatory food behaviour. In addition, propionate does not affect appetite or glucose and insulin levels via the small intestine. As obesity is a growing epidemic, it is likely that interventions that increase colonic propionate levels could prevent weight gain or drive weight loss by regulating energy homeostasis. Open Access

The current treatment for cancer is focused on chemotherapeutic treatments which can lead to many side effects including nausea, vomiting and chemoresistance. Combating chemoresistance is a key target in cancer therapy, along with enhancing the effects of current chemotherapy treatments. One progressive novel approach being investigated is pre-treating (“priming”) cells prior to chemotherapeutic treatment. Evidence has shown that “priming” of cancer cells can sensitizes the mitochondria to respond better to chemotherapy and hence reduce severity of treatment and side effects. In this thesis, I aim to define the mechanism by which “priming” enhances cell death through the mitochondria. Firstly, cannabidiol (CBD), a phytocannabinoid that has shown to have beneficial properties in inflammation, pain relief and in reducing cancer cell progression was examined for a potential “priming” agent. Secondly, the effect of the chemotherapy agent, cisplatin, was fully defined for its role in mitochondrial function along with a combination therapy of CBD and cisplatin. And finally, “priming” with CBD was assessed for any potential benefit to cancer treatment. I have demonstrated here that “priming” with CBD can enhance the killing effect of cisplatin in cancer cells and not in control cells. More specifically, the underlying mechanism for “priming” by CBD was shown to be through the modulation of mitochondrial function by means of the high stress two-phase system p53/Nrf2 together with voltage dependant anion channel 1 (VDAC1) receptor activation. From this body of work, “priming” has been shown to have a potential in enhancing current chemotherapeutic treatment. Open Access

Background Epidemiologic evidence is sparse on the role of dietary patterns that may be important drivers of high blood pressure (BP) and body mass index (BMI) levels. Additionally, dietary fibre intake in association with BP and BMI yielded inconsistent results. Objective Investigate the relationships of eating frequency, dietary energy density, diet quality, evening energy intake, GI, GL, and dietary fibre to BP, BMI using cross-sectional data from the INTERnational study on MAcro/micronutrients and blood Pressure (INTERMAP) of 4680 men and women aged 40–59 y from Japan, China, the United Kingdom, and the United States of America. Methods During 4 visits, eight BP, four weight and height measures, four 24-hour dietary recalls, and two 24-hour urine samples were collected. Consumption of all solid foods was aggregated into eating occasions. Nutrient density is expressed using the Nutrient Rich Food index. Multivariable adjusted linear regression models were used to estimate BP and BMI differences per 2SD higher intakes of eating occasions, dietary energy density, Nutrient Rich Food index, evening energy intake, GI, GL, and dietary fibre. Results Compared to participants with

Intestinal microbiota play an important role in determining susceptibility to obesity. Their ability to ferment non-digestible carbohydrates, to produce short-chain fatty acids (SCFAs), is thought to be important in influencing host metabolism. However, the underlying mechanisms are poorly understood. Using mice that lack the short-chain fatty acid receptor; free fatty acid receptor 2 (FFAR2), it was found that this receptor is essential for transducing the effects of fermentable carbohydrate to reduce food intake and prevent body weight gain. These beneficial metabolic effects were associated with an increase in the anorectic gut hormone peptide YY (PYY) due to an FFAR2-dependent increase in the density of PYY-expressing cells within the proximal colon. Inulin supplementation also increased GLP-1 cell density in the proximal colon, resulting in increased circulating GLP-1 concentrations. However, this was not dependent on expression of FFAR2. Further investigation revealed that the increase in PYY cell density was associated with increased expression of the paired-box transcription factor Pax4 known to function in terminal differentiation of PYY cells. It is, therefore, apparent that SCFAs, produced by microbial fermentation of inulin, act via FFAR2 to increase Pax4 expression and thereby enhance PYY cell proliferation. The ability of SCFAs to influence enteroendocrine cell fate and potentiate anorectic gut-brain signalling represents a paradigm shift in the understanding of nutrient sensing and highlights the potential for cellular engineering approaches for the treatment obesity. Open Access

Subjects with prediabetes are at much higher risk of developing diabetes than healthy subjects. Weight loss helps reduce the risk of developing diabetes in these subjects, but long-term weight loss is difficult to achieve due to increases in appetite. Consumption of fermentable carbohydrate has been shown to reduce food intake and body weight, and also improve insulin sensitivity independent of weight loss. Therefore, fermentable carbohydrates may help prevent the development of diabetes in subjects with prediabetes via a two-pronged effect. This thesis comprises three investigations which examine the effects of inulin compared to cellulose control on 1) appetite and food intake, 2) measures of glucose homeostasis and 3) a long-term randomised control trial examining the effect of inulin on weight loss maintenance. In each investigation, subjects take 30g/inulin a day following a 4-week dose-escalation period. In investigations 1 and 2 all subjects take both inulin and cellulose supplements for a 6-week period each, separated by a 4-week wash-out phase. Investigation 3 is a randomised control trial comprising a 9-week weight loss phase, during which participants aim to reach a 5% weight loss at 9 weeks, and a 9-week weight maintenance phase during which subjects are asked to maintain the weight they have lost. In this body of work I demonstrate that inulin reduces appetite, food intake and weight in subjects with prediabetes. I also demonstrate that inulin was significantly associated with an increase in early insulin secretion and GLP-1, potentially due to an improvement in the incretin effect. Inulin also appears to improve insulin sensitivity in subjects with a specific subtype of prediabetes only. Finally, I demonstrate that inulin supplementation results in significantly greater weight loss maintenance, alongside changes in body composition likely to be beneficial long-term. Open Access

Accumulation of ectopic fat in liver and pancreas are seen as key indicators of the metabolic syndrome affecting over a third of the population in the western world. Deposition of these ectopic fat depots is linked to insulin resistance, a major risk factor in the development of type 2 diabetes. Quantifying ectopic fat deposition, without the use of biopsy, has always been a challenge. Magnetic resonance (MR) techniques have emerged as the gold-standard for estimating overall fat deposition. However, little is known on the regional variation of fat deposition in liver and pancreas in human subjects. The aim of this project was to determine, using an in vivo Multi-Echo MR imaging technique, regional variations in ectopic fat deposition in liver and pancreas and assess the potential impact of environmental factors, including BMI, age, and gender. The overall ranges in liver and pancreas fat ranged from 0.69- 32.27 % and 0.40 - 24.18% respectively. There was a strong correlation between liver fat, body weight, waist-to-hip ratio and waist circumferences. A significant correlation between pancreatic fat and waist-to-hip ratio, particularly in men, was also observed. The relationship between liver and pancreatic fat was surprisingly weak, suggesting different mechanism of accumulation. Regional variations in liver and pancreatic fat were assessed by using surgical segmentations as anatomical markers, resulting in 8 anatomical segments for the liver and 3 for the pancreas. Intra-abdominal adipose tissue and age had the largest effect on liver and pancreatic fat deposition. Relative physical activity influenced the overall levels of liver ectopic fat content but did not significantly affect regional distribution in the pancreas. No gender differences in fat distribution in the liver were detected but a strong correlation with pancreas and men was detected. Life-style interventions, such as weight loss programs, showed significant reduction in overall liver and pancreatic fat content. As for bariatric interventions, more significant reduction of overall ectopic fat in liver was seen with an increase in total and regional pancreas fat content. In conclusion, I have shown, utilising an anatomical compartmentalisation of the liver and pancreas, that there are significant heterogeneity in fat deposition in the pancreas, and that different regions respond variably to lifestyle interventions. There is a more homogeneous fat deposition in the liver, which is more consistently modulated in response to lifestyle changes. Open Access

The link between early life and development of metabolic disorders and obesity in later life has been the focus of many studies over the past decades. Fetal life and early infancy are two of the most critical periods of physiological and metabolic development and plasticity, and thus, are periods whereby a stimulus can cause long term consequences on the health of an individual (developmental programming). Accelerated weight gain during early life per se or in combination with extreme birth weights (low/high birth weight) have been postulated as factors that can affect the development of individuals with later consequences in health. However, there is not a clear understanding of the specific contribution at different ages to impaired health neither of the mechanisms involved in these alterations. In this thesis, I used an isogenic murine model with natural birth weight variation within a normal range to investigate the effects of extreme birth weights on body composition and appetite regulation at different stages of life. I compared low and high birth weights phenotypes during lactation, at the time of weaning, and a young adulthood as well as early matured age. Mice were challenged to a moderate high fat diet for 12 weeks after weaning in order to assess the effects of both birth weight and a hypercaloric feed on body composition and hypothalamic neural activity. At weaning, adiposity was positively related to birth weight and weight gain but negatively related to growth rate. Low birth weight male mice (LBWm) had a lower plasma glucose concentration but similar levels of insulin to High birth weight male mice (HBWm), indicating a degree of hyperinsulinemia. Low birth weight females (LBWf) were hyperinsulinemic and hyperglycemic compared to High birth weight females (HBWf). There was an upregulation in the expression of genes related to insulin signaling, adipogenesis/lipid metabolism and thermoregulation in Subcutaneous Adipose Tissue (SAT) of LBWm mice compared to HBWm mice but the contrary was seen in LBWf mice in respect to their counterpart. LBWm mice caught up in weight with HBWm mice at younger age than the equivalent catch up in female mice. Birth weight and diet impacted body fat patterning and appetite regulation differently in both young males and females. However, at week 51 of age (early matured age), diet seemed to override the effects of birth weight on total body fat. LBWm mice tended to have smaller adipocytes than young and matured HBWm mice, especially when fed a HF diet, and this pattern was independent of fat mass. In conclusion, the current study suggests that extreme birth weights in an isogenic mouse model (within natural birth weight variation), as well as postnatal nutrition influenced growth, glucose / lipid metabolism, body fat patterning and appetite regulation in an age-gender dependent manner. Open Access