Search

Background A key feature of metabolic health is the ability to adapt upon dietary perturbations. Recently, it was shown that metabolic challenge tests in combination with the new generation biomarkers allow the simultaneous quantification of major metabolic health processes. Currently, applied challenge tests are largely non-standardized. A systematic review defined an optimal nutritional challenge test, the “PhenFlex test” (PFT). This study aimed to prove that PFT modulates all relevant processes governing metabolic health thereby allowing to distinguish subjects with different metabolic health status. Therefore, 20 healthy and 20 type 2 diabetic (T2D) male subjects were challenged both by PFT and oral glucose tolerance test (OGTT). During the 8-h response time course, 132 parameters were quantified that report on 26 metabolic processes distributed over 7 organs (gut, liver, adipose, pancreas, vasculature, muscle, kidney) and systemic stress. Results In healthy subjects, 110 of the 132 parameters showed a time course response. Patients with T2D showed 18 parameters to be significantly different after overnight fasting compared to healthy subjects, while 58 parameters were different in the post-challenge time course after the PFT. This demonstrates the added value of PFT in distinguishing subjects with different health status. The OGTT and PFT response was highly comparable for glucose metabolism as identical amounts of glucose were present in both challenge tests. Yet the PFT reports on additional processes, including vasculature, systemic stress, and metabolic flexibility. Conclusion The PFT enables the quantification of all relevant metabolic processes involved in maintaining or regaining homeostasis of metabolic health. Studying both healthy subjects and subjects with impaired metabolic health showed that the PFT revealed new processes laying underneath health. This study provides the first evidence towards adopting the PFT as gold standard in nutrition research. Electronic supplementary material The online version of this article (10.1186/s12263-017-0570-6) contains supplementary material, which is available to authorized users.

Background: Low-grade chronic inflammation in overweight subjects is thought to play an important role in disease development. Objective: It was hypothesized that specific dietary components are able to reduce low-grade inflammation as well as metabolic and oxidative stress. Design: Dietary products [resveratrol, green tea extract, α-tocopherol, vitamin C, n-3 (omega-3) polyunsaturated fatty acids, and tomato extract] selected for their evidence-based antiinflammatory properties were combined and given as supplements to 36 healthy overweight men with mildly elevated plasma C-reactive protein concentrations in a double-blind, placebo-controlled, crossover study with treatment periods of 5 wk. Inflammatory and oxidative stress defense markers were quantified in plasma and urine. Furthermore, 120 plasma proteins, 274 plasma metabolites (lipids, free fatty acids, and polar compounds), and the transcriptomes of peripheral blood mononuclear cells and adipose tissue were quantified. Results: Plasma adiponectin concentrations increased by 7%, whereas C-reactive protein (principal inflammation marker) was unchanged. However, a multitude of subtle changes were detected by an integrated analysis of the "omics" data, which indicated modulated inflammation of adipose tissue, improved endothelial function, affected oxidative stress, and increased liver fatty acid oxidation. Conclusion: An intervention with selected dietary products affected inflammatory processes, oxidative stress, and metabolism in humans, as shown by large-scale profiling of genes, proteins, and metabolites in plasma, urine, and adipose tissue. This trial was registered at clinical trials.gov as NCT00655798. © 2010 American Society for Nutrition.

In pigs and humans, the nutrients starch, protein, fat and some minerals need to be digested prior to the terminal ileum for optimal use of these nutrients. In contrast, the non-starch polysaccharides (NSP) are mainly fermented by microbes in the hindgut. Results of experiments in pigs showed that NSP negatively affected apparent digestion of protein, fat and some minerals. In addition, large amounts of fermented NSP increased the empty weight of the hindgut. Because tissue of organs like the intestinal tract are metabolically very active, it may have required more energy for maintenance, hence leaving less energy for growth. Despite all the negative effects as mentioned above, including NSP-rich ingredients in pig diets also has quite a lot of advantages. Their energy supply can cover the energy requirements for maintenance. In addition, positive effects on the well-being and health of pigs, and on the excretion of ammonia are claimed. In conclusion, in future pig diet formulation not only the nutritional aspects of NSP-rich ingredients should be taken into account, but also their non-nutritional aspects. This might be realized by developing nutrient based feed evaluation systems, rather than the energy based systems which are presently used.

In a factorial design, animal fat was added incrementally (0, 35, 70 and 105 g/kg) to maize starch (M) or to two sources of fermentable carbohydrates (260 g purified cellulose (C) per kg or 270 g soya-bean hulls (S) per kg). The 12 experimental diets were formulated by replacing maize starch in the control diet with fat, cellulose and soya-bean hulls of equivalent estimated net energy. Ninety-six castrated males were given these diets according to net energy. Apparent digestibilities of crude protein, crude lipid, crude fibre and nitrogen-free extract were measured and were compared with those expected from the separate ingredients. Net energy conversion ratio (nECR) was also measured. Results showed that in the C and the S diets prediction of the apparent digestibility of nutrients was worse than in the M diets (significant effect of source of carbohydrate). Prediction of apparent digestibility of crude protein and crude lipid improved as the added fat increased (significant effect of amount of fat), except in the C and S diets where for digestible crude lipid the 70 g added fat per kg gave the worst prediction (significant effect of the interaction). The net energy calculated from the experimental data on apparent digestibility was proportionately between 0·83 and 0·98 of that calculated from the expected data. The pigs on the C and S treatments showed a significant lower nECR when calculated from the expected apparent digestibility coefficients, but not when calculated from those which were measured. At the highest fat addition, the nECR was poorest. It is concluded that the amounts of digestible components in compound foods cannot always be obtained from those in the separate ingredients.

We introduce the metabolomics and proteomics based Postprandial Challenge Test (PCT) to quantify the postprandial response of multiple metabolic processes in humans in a standardized manner. The PCT comprised consumption of a standardized 500 ml dairy shake containing respectively 59, 30 and 12 energy percent lipids, carbohydrates and protein. During a 6 h time course after PCT 145 plasma metabolites, 79 proteins and 7 clinical chemistry parameters were quantified. Multiple processes related to metabolism, oxidation and inflammation reacted to the PCT, as demonstrated by changes of 106 metabolites, 31 proteins and 5 clinical chemistry parameters. The PCT was applied in a dietary intervention study to evaluate if the PCT would reveal additional metabolic changes compared to non-perturbed conditions. The study consisted of a 5-week intervention with a supplement mix of anti-inflammatory compounds in a crossover design with 36 overweight subjects. Of the 231 quantified parameters, 31 had different responses over time between treated and control groups, revealing differences in amino acid metabolism, oxidative stress, inflammation and endocrine metabolism. The results showed that the acute, short term metabolic responses to the PCT were different in subjects on the supplement mix compared to the controls. The PCT provided additional metabolic changes related to the dietary intervention not observed in non-perturbed conditions. Thus, a metabolomics based quantification of a standardized perturbation of metabolic homeostasis is more informative on metabolic status and subtle health effects induced by (dietary) interventions than quantification of the homeostatic situation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-011-0320-5) contains supplementary material, which is available to authorized users.

The present study examined differences in faecal digestibilities of organic matter (dOM) and crude protein (dXP), between growing pigs housed either in pens as groups or individually in metabolism cages. In addition, a study was made of the influence of dietary composition on these observed differences. Four experimental diets were composed by iso-energetic exchange of maize starch in the control diet with purified cellulose (260 g kg-1), toasted soyabean hulls (280 g kg-1) or renderers fat (67 g kg-1), respectively. Both in pens and in metabolism cages, dOM and dXP were measured, using both chromic oxide (Cr2O3) and acid-insoluble ash (AIA) as markers. In metabolism cages, the results of the marker method were compared to those of the classical method, where dOM and dXP were measured by collecting faeces quantitatively. Recoveries of both markers were measured, after a period of 10 and 3 days. With Cr2O3 as marker, pen-housing resulted in a dOM which was on average 2.5 (1.7–4.5) units lower and a dXP averaging 4.5 (3.0–5.8) units lower than measured in the metabolism cages (P≤0.001). No significant interactions were demonstrated between housing system and dietary composition. In contrast, with AIA as marker significantly higher digestibility values were observed for pigs in pens, when fed the cellulose diet. With this diets, the dOM was on average 14.7 units higher and the dXP was on average 10.9 units higher for the penned pigs. For the pigs fed one of the other three diets, the dOM was on average 1.5 (0.1–2.7) units lower and the dXP was on average 3.7 (1.9–5.7) units lower. Thus, with AIA as a marker, the effect of housing system on digestibility interacted with the type of diet (P≤0.05 on dOM and P≤0.01 on dXP). Comparison between the marker method with the classical method, showed that Cr2O3 provided similar results. In contrast, AIA displayed significantly higher dOM and dXP, except with the cellulose diet. This could be explained by differences in the recoveries of both markers. For Cr2O3 this was close to 100% and for AIA it varied from 97% on the cellulose diet to 183% on the control diet. The analytical procedure for AIA requires more research. Shortening the measuring period from 10 to 3 days did not prove to be significant, but increased the standard deviations. It was concluded that for practical application, faecal digestibilities should be measured with penned pigs. According to the findings, under such conditions Cr2O3 is a good marker. AIA was found to be unsuitable.

An experiment was conducted to study the effect of feeding level and semen collection frequency on semen quantity and quality of 62 Yorkshire boars at two artificial insemination centres during 10 successive periods of 2 weeks. The experiment had a 2 × 2 factorial design with two feeding levels (2·75 and 3·5 kg/day) and two semen collection frequencies (three and five times in 2 weeks).In the first 2-week period boars on the high frequency semen collection scheme produced 94 × 109 sperm cells more than boars on the low scheme. In periods 2 to 10 the mean difference was only 18 × 109 sperm cells. Boars on the high feeding level produced 32 × 109 sperm cells more per 2-week period than the boars on the low feeding level (P < 0·05). Boars at the high collection frequency and the high feeding level tended to produce a higher number of sperm cells during periods 2 to 10 than the boars on the high semen collection frequency and the low feeding level (P > 0·05). No effects of food intake or semen collection frequency on semen quality were found.

A number of studies have shown that tea catechins can inhibit intestinal iron absorption, mostly iron in the nonhaem form. This randomized, double-blind, placebo-controlled, 3-periods cross-over study examined the degree of inhibition of nonhaem iron absorption by pure crystalline epigallocatechin gallate (EGCG). The study was designed to show the maximum inhibitory action of EGCG by selecting 30 healthy women with low iron stores. Treatments were 150 mg, 300 mg EGCG and placebo each for 8 consecutive study days with a wash-out period of 14 days between treatments. Iron incorporation was assessed by supplying 57Fe orally and 58Fe intravenously. Differences in fractional nonhaem iron absorption between the treatments were evaluated by using two-sided ANOVA. Results showed a relative nonhaem iron absorption reduction of 14% with 150 mg EGCG and 27% for 300 mg EGCG treatment compared to placebo. Differences were statistically significant (p≤0.05) between the placebo and the 300 mg EGCG treatments and between the 150 and 300 mg EGCG treatments. The inverse relation between EGCG dose and fractional nonhaem iron absorption was linear (p=0.0002). In this study the magnitude of the inhibitory action of EGCG on nonhaem iron absorption was found to be much lower than that reported in the literature for black tea and similar compounds. The doses of EGCG in supplements, which will be lower than those used in this study, are not expected to have any health relevant effects on iron absorption in subjects with normal iron stores. © 2005 Elsevier GmbH. All rights reserved.

An experiment was designed to study the effect of dietary protein source on feed intake and on small intestinal morphology in newly weaned piglets. In total, 108 piglets were used, without access to creep feed during the suckling period. Piglets were weaned at 27 days of age. They were fed ad libitum one of two iso-nitrogenous experimental diets, which differed in their protein composition and contained either skim milk powder (SMP) or hydrolysed feather meal (FM), the latter component having low ileal protein digestibility. Diets contained equal amounts of indispensable amino acids. On day 4 postweaning, 18 piglets with a similar high feed intake were selected within each dietary treatment and sampled for small intestinal morphology on days 4, 7, or 14 postweaning. The dietary protein source did not affect feed intake during the first three days after weaning. From days 0 (day of weaning) to 2, the mean feed intake increased from 28.9 (S.D. 45.2) to 202.1 (S.D. 129.9) g day -1 piglet-1. In the second week, the feed intake of the selected piglets receiving the SMP diet was higher (P

In the Netherlands ammonia emission should be reduced considerably to prevent detrimental effects on the environment. Ammonia is mainly formed by enzymatic conversion of urea and other N-compounds in urine. In traditional fattening pig houses approximately 13% of the N taken in by the feed is emitted as ammonia. Different nutritional factors are influencing ammonia emission. Of these the protein content, the acid-base balance and the carbohydrate composition are the most important. In different experiments the sole effects of these factors on ammonia emission have been investigated. The objective of this study was to determine whether the effects of these factors are additive.

We investigated the effects of dietary carbohydrates on the composition and pH of fecal material and on the ammonia emission from the slurry of growing pigs. Thirty-four barrows (BW approximately 40 kg) were randomly allotted to 1 of 10 diets. A basal diet was formulated to meet all requirements for protein, amino acids, minerals, and vitamins. The control diet was composed of the basal diet plus heat-treated cornstarch. In the other diets, the cornstarch in the control diet was replaced with three levels of either coconut expeller, soybean hulls, or dried sugar beet pulp. Feces were collected separately from urine in a balance experiment. Feces were mixed with a standardized urine (ratio of 1:2.5, wt/wt) to form a slurry. A sample of this slurry was placed in an in vitro system to determine the pH and the ammonia emission for 16 d at 20 degrees C. The fecal and slurry DM contents decreased (P < .001) and the total VFA concentrations increased (P < .001) when the level of dietary carbohydrates increased. The pH and the ammonia emission decreased as the level of carbohydrates increased (P < .001). The addition of soybean hulls to the diet had the greatest effect on reducing the pH and ammonia emission (P < .001), and the effects of sugar beet pulp and coconut expeller were approximately the same. A linear relationship was found between the intake of dietary nonstarch polysaccharides (NSP) and the ammonia emission (P < .001). For each 100-g increase in the intake of dietary NSP, the slurry pH decreased by approximately .12 unit and the ammonia emission from slurry decreased by 5.4%. We conclude that replacing cornstarch in the diet with components that have a high concentration of fermentable carbohydrates increases the VFA concentration of feces and slurry and reduces the pH and ammonia emission from the slurry of growing pigs.

Net portal-drained viscera (PDV) flux of glucose, VFA, ammonia, and urea was determined in pigs fed diets with or without resistant starch. Diets consisted of 65% cornstarch (diet CS), 32.5% cornstarch and 32.5% raw potato starch (diet CPS), or 65% raw potato starch (diet PS); the remaining 35% supplied all amino acids, fat, fiber, minerals, and vitamins. The diets contained twice the maintenance requirement for energy and were fed twice daily to four barrows (initial BW 56 kg) in three periods in a crossover design. The pigs were fitted with catheters in a mesenteric vein, a mesenteric-artery, and the portal vein, and net PDV flux was calculated by multiplying portal-arterial concentration differences and corresponding portal vein flow. Net PDV flux of glucose was significantly less after feeding diets CPS and PS, and portal absorption of ileally digested glucose was 89, 66, and 41% for diets CS, CPS, and PS, respectively. Net PDV flux of VFA was lowest after feeding diet CS and three to four times higher after feeding diets CPS and PS. Net PDV flux of ammonia was highest for diet CS and almost halved after feeding diets CPS and PS. There was a small negative net PDV flux of urea for diets CS and CPS, which significantly increased after feeding diet PS. These results suggest that excretion of nitrogen is shifted from urine to feces primarily by reduction of the net PDV flux of ammonia when resistant starch is fed.

The objective of this study were a) to compare the apparent total tract digestibility (TD) between non-cannulated (intact) and cannulated (steered ileo-cecal valve technique, SICV) pigs fed diets differing in energy density (Exp. 1) and b) to compare the direct vs marker (Cr2O3) methods for estimation of the TD and apparent ileal digestibility (ID) in SICV-cannulated pigs (Exp. 2). In Exp. 1, 24 intact and 18 SICV-cannulated castrates of approximately 40 kg initial BW were randomly assigned to six treatments in a 2 x 3 x 2 factorial arrangement (two pig types, three carbohydrate sources, and two fat levels). In Exp. 2, the same SICV-cannulated pigs from Exp. 1 were given those treatments in a 2 x 3 x 2 factorial arrangement (two methods of digestibility estimation, three carbohydrates sources, and two fat levels). In both experiments either cornstarch, soybean hulls, or pure cellulose, without or with fat, were incorporated into a barely-soybean meal based diet to alter energy density. Daily diets were isoenergetic (based on NEf), and water supply was .33 L/MJ of NEf. In Exp. 1, the pig type effect on the TD of DM, OM, CP, and the pig type x carbohydrate interactions for the TD of DM, OM, and crude fiber (CF) were significant (P < .05), merely due to a larger difference found for the diet enriched with cellulose. In Exp. 2, the TD and ID evaluated with the marker method were significantly lower (except for the TD of CF) than with the direct method, mainly because Cr recovery was below 100%. Overall, the marker method seems to be superior because the TD means obtained from Cr ratios were closer to the TD obtained from intact pigs. In general, the SICV technique seems to be suitable for long-term digestibility studies to measure the TD and ID in the same pig fed low-or high-fiber diets.

Fermentable nonstarch polysaccharides (dietary fiber) affect energy retention in group-housed growing pigs by reducing physical activity. This study assessed the effects of fermentation and bulkiness of dietary carbohydrates on physical activity in relation to energy metabolism. Eight clusters of 14 pigs were fed one of four diets in a 2 × 2 factorial arrangement. Factors included 1) gastrointestinal fermentation and 2) dietary bulkiness. Contrasts in fermentation were created by exchanging gelatinized maize starch with raw potato starch on a volume basis. Bulkiness was altered by adding 15% milled wheat straw to the diets. Apart from these differences, amounts of other dietary ingredients fed to the pigs were similar. Pigs were housed in groups. Nitrogen and energy balances were measured per cluster during a 14-d period. Dietary bulkiness did not affect ME intake, heat production, or energy retention. Metabolizability decreased when maize starch was replaced with raw potato starch (P < .01), resulting in a lower energy retention on the potato starch diets (P < .01). However, the lower ME intake on the potato diets was partially compensated by a reduced energy expenditure on physical activity (P < .01), which was 17.6% lower than that of pigs fed the maize starch diets. Dietary bulkiness did not affect physical activity. The effect of fiber-rich diets (non-starch polysaccharides) on activity in growing group-housed pigs seems to be related to fermentation in the gastrointestinal tract, and not to bulkiness (volume).