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N-acylethanolamines (NAEs) are endogenous lipid-signaling molecules involved in satiety and energetics; however, how diet impacts circulating NAE concentrations and their downstream metabolic actions in humans remains unknown. Objectives were to examine effects of diets enriched with high-oleic canola oil (HOCO) or HOCO blended with flaxseed oil (FXCO), compared with a Western diet (WD), on plasma NAE levels and the association with energy expenditure and substrate oxidation. Using a randomized controlled crossover design, 36 hypercholesterolemic participants consumed three isoenergetic diets for 28 days, each containing 36% energy from fat, of which 70% was HOCO, FXCO, or WD. Ultra-performance liquid chromatography-MS/MS was used to measure plasma NAE levels and indirect calorimetry to assess energy expenditure and substrate oxidation. After 28 days, compared with WD, plasma oleoylethanolamide (OEA) and alpha-linolenoyl ethanolamide (ALEA) levels were significantly increased in response to HOCO and FXCO (P= 0.002, P< 0.001), respectively. Correlation analysis demonstrated an inverse association between plasma OEA levels and percent body fat (r= −0.21, P= 0.04), and a positive association was observed between the plasma arachidonoyl ethanolamide (AEA)/OEA ratio and android:gynoid fat (r= 0.23, P= 0.02), respectively. Results suggest that plasma NAE levels are upregulated via their dietary lipid substrates and may modulate regional and total fat mass through lipid-signaling mechanisms.

More than 200 clinical trial reports and several meta-analyses have demonstrated that phytosterols (PSs), natural components of plants, induce clinically relevant reductions in blood low-density lipoprotein cholesterol levels. Here we review data regarding the biochemical effects and potential cardiovascular benefit of PSs as part of the dietary management of dyslipidemia. In addition to discussing the efficacy, effectiveness, and safety of PSs as hypocholesterolemic agents, this review provides an overview of PSs as an adjunctive therapy to cholesterol-lowering pharmaceuticals. Given this lack of evidence regarding the benefits of PSs for reducing cardiovascular end points, this review also discusses the present knowledge that exists about the ability for therapeutic dosages of PSs to confer protection from cardiovascular-related mortality and morbidity. Finally, this review summarizes the factors that affect PS efficacy and the Canadian regulations that govern the use of PSs as cholesterol-lowering agents in foods and supplements.

Advances in the use of stable isotopes in tracer methodology have clearly improved our capacity to investigate in vivo lipid metabolism in humans. The introduction of the isotope ratio mass spectrometry (IRMS) provides higher precision of measurement of isotopic enrichment to track shifts in diet on the flux of tracers through metabolic pathways. Novel applications using stable isotopes including 2H, 13C, and 18O have allowed important discoveries to be made in areas of fat and cholesterol metabolism in ways that have assisted in understanding diet‐disease relationships.

Noncholesterol sterols (NCSs) in plasma encompass endogenous cholesterol precursors and exogenous phytosterols and cholesterol metabolites, which are used as surrogate measures of cholesterol synthesis and cholesterol absorption, respectively. The ratios of cholesterol synthesis to cholesterol absorption surrogates are also utilized to assess the overall balance of cholesterol metabolism, with higher values representing more synthesis and lower values more absorption. The objective of this review is to focus on recent findings using plasma NCSs and their potential in customizing dietary and pharmacological hypolipidemic therapies.

Background: The relationship between plant sterol (PS) absorption and circulatory concentrations with cholesterol absorption and biosynthesis during PS consumption has yet to be clearly elucidated in humans. It is therefore essential to examine campesterol, β-sitosterol, and cholesterol absorption and cholesterol fractional synthesis rate (FSR) following PS consumption in individuals with high versus low basal circulatory PS concentrations.Design: A randomized, crossover trial was conducted in 82 hypercholesterolemic men consuming spreads with or without 2 g/d of PS for two 4-week periods, each separated by a 4-week washout. Endpoint tracer enrichments after ingestion of 2H-labeled campesterol or β-sitosterol and 13C-labeled cholesterol were determined by isotope ratio mass spectrometry.Results: For both phases of dietary intervention, the endpoint cholesterol absorption index was positively correlated with campesterol (r= 0.5864, p< 0.0001) and β-sitosterol (r= 0.4676, p< 0.0001) absorption indices; inversely, endpoint cholesterol FSR correlated negatively with the absorption indices of campesterol (r= −0.5004, p< 0.0009), β-sitosterol (r= −0.4154, p< 0.05), and cholesterol (r= −0.4056, p< 0.0001). PS intervention reduced absorption indices of campesterol, β-sitosterol, and cholesterol by 36.5% ± 2.7%, 39.3% ± 2.9%, and 34.3% ± 1.9%, respectively, but increased cholesterol FSR by 33.0% ± 3.3% relative to control. Endpoint circulatory PS levels (cholesterol adjusted) were positively associated with endpoint absorption indices of campesterol (r= 0.5586, p< 0.0001, for placebo; r= 0.6530, p< 0.0001, for PS intake) and cholesterol (r= 0.3683, p< 0.001 for placebo; r= 0.3469, p< 0.002, for PS intake) and were negatively associated with cholesterol FSR (r= −0.3551, p< 0.002, for placebo; r= −0.3643, p< 0.001, for PS intake). The cholesterol-lowering effect of PS was most pronounced among individuals falling within the 50th–75th percentiles of basal PS concentrations.Conclusion: These data suggest that basal PS concentrations indicate not only sterol absorption efficiency but also the extent of PS-induced cholesterol reduction and thus might be clinically useful to predict the extent of cholesterol response to PS intervention within a given individual.

Background: Dietary conjugated linoleic acid (CLA) represents a group of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid. The effects of dietary CLA on blood lipids and body composition in humans remain controversial.Objective: To examine whether consumption of milk enriched naturally or synthetically with cis9, trans11 (c-9, t-11) and trans10, cis12 (t-10, c-12) CLA isomers alters blood lipid indices, including concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triacyglycerol; indices of liver function including plasma alanine transaminase and total bilirubin; C-reactive protein; tumor necrosis factor-alpha; and body weight and composition in moderately overweight, borderline hyperlipidemic humans.Design: A randomized, 3-phase, crossover, single-blind clinical trial was carried out in moderately overweight, borderline hyperlipidemic individuals who consumed (1) milk naturally enriched in CLA (4.2%) containing c-9, t-11 only providing 1.3 g/d of CLA; (2) milk enriched with a 4.2% synthetic mixture of t-10, c-12 and c-9, t-11 CLA isomers providing 1.3 g/d of CLA; or (3) untreated milk as a control providing 0.2 g/d CLA. Dietary phases were each 8 weeks in duration and were separated by 4-week washout periods. Plasma lipid levels were measured in blood samples collected at the beginning and end of each dietary phase. Magnetic resonance imaging was carried out at the beginning and end of each dietary phase to assess any changes in regional body fat composition.Results: Compared with the control intervention, consumption of the two CLA-enriched milks failed to alter plasma total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triacyglycerol concentrations; body weight; or fat composition. CLA consumption did not significantly affect plasma alanine transaminase, total bilirubin, C-reactive protein, or tumor necrosis factor-alpha concentrations.Conclusion: Results from this study fail to support the role of milk enriched naturally with CLA containing c-9, t-11 or synthetically with c-9, t-11 and t-10, c-12 CLA isomers in modulation of lipid profiles or body composition in moderately overweight, borderline hyperlipidemic individuals.

Deficient cholesterol and/or excessive 7-dehydrocholesterol (7-DHC) may be responsible for the pathology of Smith-Lemli-Opitz syndrome (SLOS). Both high-cholesterol diets given to ameliorate cholesterol deficiency while decreasing 7-DHC and cholesterol-enriched diets plus simvastatin to further decrease sterol synthesis have been used as potential therapies. However, the effect of dietary cholesterol and simvastatin on cholesterol synthesis in SLOS has not been reported. Twelve subjects with SLOS enrolled in the study: Nine had received a high cholesterol diet (HI) for 3 y and three were studied after 4 wk on a low cholesterol diet (LO). Cholesterol fractional synthesis rate (FSR) was measured after oral administration of deuterium oxide, using gas chromatography isotope ratio mass spectrometry. FSR was lower in HI compared with LO (HI: 1.46 ± 0.62%/d; LO: 4.77 ± 0.95%/d; p< 0.001). Three HI subjects were retested after 0.8 y taking simvastatin (HI ST). Simvastatin tended to reduce FSR and significantly decreased (p< 0.01) plasma 7-DHC compared with cholesterol supplementation alone. The study demonstrates the utility of the deuterium incorporation method to understand the effect of therapeutic interventions in SLOS. The data suggest that dietary cholesterol supplementation reduces cholesterol synthesis in SLOS and further support the rationale for the combined treatment of SLOS with a cholesterol-enriched diet and simvastatin.

Objective:Plant sterols (PS) consumed as a snack may not have the same cholesterol-lowering potential as when consumed with a meal due to poor solubilization. It was hypothesized that the consumption of a single dose, low-fat yogurt rich in PS (1.6 g/d) with a meal over an afternoon snack will lead to favourable changes in plasma lipids, plasma PS concentrations, and cholesterol synthesis without negatively affecting α-tocopherol or carotenoids levels.Methods:Twenty-six hyperlipidemic males and females completed the randomized trial of three phases (control, single PS dose consumed with a meal, or single PS dose as an afternoon snack) while consuming controlled, low-fat diets. Plasma lipids, cholesterol synthesis rates, plasma PS and serum fat-soluble antioxidants were measured at baseline and after 4 weeks.Results:Endpoint total cholesterol (TC) levels after the PS snack phase were decreased (p= 0.04) (5.30 ± 0.2 mmol/L) compared to the control phase (5.53 ± 0.2 mmol/L). However, endpoints for TC (5.37 ± 0.2 mmol/L) for PS dose with a meal were comparable to control phase. Low-density lipoprotein-cholesterol tended to be different (p= 0.06) at the end of the intervention phases (3.51 ± 0.1, 3.43 ± 0.1, and 3.33 ± 0.1 mmol/L; control, meal and snack, respectively). Cholesterol fractional synthesis rates were higher (p= 0.007) by 25.8% and 19.5% at the end of the snack and meal phases, respectively, compared with the control phase. Plasma campesterol and β-sitosterol concentrations, adjusted for TC, were higher (p< 0.01) in the snack phase (2.30 ± 0.3 and 0.54 ± 0.1 μmol/mmol, respectively) and in the meal phase (2.00 ± 0.3 and 0.51 ± 0.1 μmol/mmol, respectively) when compared to the control phase (1.81 ± 0.3 and 0.40 ± 0.1 μmol/mmol, respectively). No changes in α-tocopherol or carotenoids levels were detected after adjusting for TC, for all phases.Conclusion:These results indicate that a single dose of PS in low-fat yogurt, provided as a snack, lowers cholesterol levels but does not alter fat-soluble vitamin or carotenoid concentrations in hyperlipidemic participants.

The purpose of this study was to examine whether changes in cholesterol metabolism after weight loss were affected by single nucleotide polymorphisms (SNPs) in ABCG5 and ABCG8 genes. Thirty-five hypercholesterolemic women lost 11.7 ± 2.5 kg (P< 0.001). Cholesterol kinetics were assessed using stable isotope techniques. TaqMan PCR was used to detect SNPs in ABCG5/G8. Homozygous Q604E variants in ABCG5 had larger (P< 0.05) reductions in cholesterol absorption and greater increases (P< 0.05) in synthesis in contrast to heterozygous and homozygous wild-type carriers. Heterozygous C54Y carriers had smaller declines (P= 0.047) in synthesis compared with homozygous variant individuals. The presence of at least one Y54 variant was associated with higher (P= 0.042) post-weight-loss synthesis compared with carriers of the C54 genotype. The direction of the results is consistent with cross-sectional studies on the effects of Q604E and C54Y polymorphisms on plasma cholesterol. SNPs in ABCG5/G8 were found to be associated with the response of cholesterol metabolism to weight loss. The evidence for associations between SNPs in ABCG5/G8 and various parameters of cholesterol metabolism indicates the potential effectiveness of establishing genetic screening tools to determine optimal lipid-lowering treatment routes for individuals during weight reduction.

Objective:The objectives of this study were to determine 1) whether the extent of weight loss is predictive of the degree of changes in hormone and lipid levels; 2) the interactions between energy regulating hormones after weight loss through an energy deficit/exercise protocol diet and exercise; 3) whether initial metabolic parameters are indicative of the extent of weight loss.Methods:Thirty-five hyperlipidemic females (BMI 28–39 kg/m2) 35–60 years old participated in a six month weight loss trial. Weight loss resulted from a diet and exercise program that when combined produced a 30% energy deficit. Fasting plasma taken during 2 wk stabilization periods at the beginning and end of the study was analysed for lipids, hormone and glucose levels.Results:Average weight loss was 11.7 ± 2.5 kg (p< 0.0001). TC, LDL-C, and triacylglycerols decreased 9.3 ± 9.5% (p< 0.0001), 7.4 ± 12.2% (p< 0.001), and 26.8 ± 19.6% (p< 0.05), respectively, while HDL-C increased (p< 0.05) by 8.2 ± 16.3%. Leptin levels declined (p< 0.001) 48.9 ± 16.0% and ghrelin levels rose (p< 0.001) 21.2 ± 26.7%. While overall levels of adiponectin did not differ, individual values changed such that weight loss predicted increases in adiponectin levels. Though initial weight did not predict weight loss, baseline lipid and insulin levels positively predicted weight loss.Conclusion:Initial metabolic parameters may be predictors of weight loss. Beneficial effects of weight loss as achieved through diet and exercise on measured parameters indicate moderate weight loss reduces key risk factors of cardiovascular disease in overweight individuals.

Dietary phytosterols have been shown to reduce plasma cholesterol concentrations when consumed in different food matrices, but their effectiveness in nonfat or low-fat beverages has not been established. The objective of this study was to examine whether phytosterols alter plasma lipid levels when incorporated into nonfat or low-fat beverages. Fifteen moderately hypercholesterolemic men and women consumed three precisely controlled diets for periods of 21 days each in random order. Diets contained either a nonfat placebo beverage (NF), a beverage that is nonfat with added phytosterols (NFPS), or a beverage that is low in fat with added phytosterols (LFPS). Total cholesterol concentrations were not different between groups at endpoint, decreasing (P< 0.05) equally by 8.5%, 11.6%, and 10.1% with NF, NFPS, and LFPS consumption, respectively. There was no effect of dietary treatment on LDL cholesterol concentrations, which decreased over time (P< 0.05) by 5%, 10.4%, and 8.5% with NF, NFPS, and LFPS, respectively. HDL cholesterol and triacylglycerol concentrations were unaffected by the diets. Provision of phytosterols as part of nonfat and low-fat beverages did not exert any greater hypocholesterolemic effect than a nonfat placebo beverage.

Medium chain triacylglycerols (MCT) have been suggested as efficacious in weight management because they possess greater thermogenic qualities relative to long chain triacylglycerols; however, MCT may also increase circulating lipid concentrations, possibly increasing risk of cardiovascular disease (CVD). The present objective was to examine the effect of a diet supplemented with a functional oil (FctO) composed of energy expenditure-enhancing MCT (50% of fat), cholesterol-lowering phytosterols (22 mg/kg body weight), and triacylglycerol-suppressing n-3 fatty acids (5% of fat), versus a beef tallow-based diet (BT), on plasma lipid and aminothiol concentrations. In a randomized, single-blind, crossover design, partially-inpatient trial, 17 overweight women consumed each oil as part of a controlled, supervised, targeted energy balance diet for 27 days, with 4 or 8 weeks of washout between phases. Mean plasma total cholesterol concentration was lower (P< .0001), by 9.1%, on FctO (4.37 ± 0.20 mmol/L) versus BT (4.80 ± 0.20 mmol/L). Mean plasma low-density lipoprotein (LDL) cholesterol was also lower (P< .0001) following FctO (2.39 ± 0.15 mmol/L) versus BT (2.86 ± 0.16 mmol/L), representing a 16.0% difference between diets. High-density lipoprotein (HDL) cholesterol and circulating triacylglycerol concentrations remained unaffected by treatment. Ratios of HDL:LDL and HDL:total cholesterol were higher (P< .01) by 22.0% and 11.0%, respectively, on FctO versus BT. Plasma total homocysteine remained unchanged with FctO, but decreased (P< .05) with control, hence higher (P< .05) end points were observed with FctO (6.95 ± 0.33 μmol/L) versus BT (6.27 ± 0.28 μmol/L). Plasma glutathione increased (P< .05) by 0.44 μmol/L with FctO supplementation. In conclusion, despite equivocal effects on homocysteine levels, consumption of a functional oil composed of MCT, phytosterols, and n-3 fatty acids for 27 days improves the overall cardiovascular risk profile of overweight women.

Objective: The objectives of this study were to compare the effects of diets rich in medium‐chain triglycerides (MCTs) or long‐chain triglycerides (LCTs) on body composition, energy expenditure, substrate oxidation, subjective appetite, and ad libitum energy intake in overweight men. Research Methods and Procedures: Twenty‐four healthy, overweight men with body mass indexes between 25 and 31 kg/m2consumed diets rich in MCT or LCT for 28 days each in a crossover randomized controlled trial. At baseline and after 4 weeks of each dietary intervention, energy expenditure was measured using indirect calorimetry, and body composition was analyzed using magnetic resonance imaging. Results: Upper body adipose tissue (AT) decreased to a greater extent (p< 0.05) with functional oil (FctO) compared with olive oil (OL) consumption (−0.67 ± 0.26 kg and −0.02 ± 0.19 kg, respectively). There was a trend toward greater loss of whole‐body subcutaneous AT volume (p= 0.087) with FctO compared with OL consumption. Average energy expenditure was 0.04 ± 0.02 kcal/min greater (p< 0.05) on day 2 and 0.03 ± 0.02 kcal/min (not significant) on day 28 with FctO compared with OL consumption. Similarly, average fat oxidation was greater (p= 0.052) with FctO compared with OL intake on day 2 but not day 28. Discussion: Consumption of a diet rich in MCTs results in greater loss of AT compared with LCTs, perhaps due to increased energy expenditure and fat oxidation observed with MCT intake. Thus, MCTs may be considered as agents that aid in the prevention of obesity or potentially stimulate weight loss.

De novo endogenous cholesterol synthesis is an integral component of developing human infant adaptive mechanisms that regulate cholesterol homeostasis. Smaller central pools of cholesterol later in life may contribute to reduced low-density lipoprotein-cholesterol (LDL-C) concentrations in the plasma and thus reduce the risk of cardiovascular disease. Early infant adaptive mechanisms may theortically result in altered central pools of cholesterol in later life. To examine the response of cholesterol homeostasis to long-term dietary cholesterol supplementation, endogenous cholesterol synthesis was studied in 81 full-term healthy neonates at 4 months or at 11 and 12 months of age. Thirty-two infants were breast-fed (BF) (6 males, 7 females), fed regular cows milk protein-based formula (RF) (6 males, 3 females) 0.85 mmol cholesterol/L (33 mg cholesterol/L), or fed regular cow milk protein-based formula with the addition of cholesterol (RF+cholesterol) (5 males, 5 females) 3.44 mmol cholesterol/L (133 mg cholesterol/L). Effects of cholesterol supplementation on cholesterol synthesis rates were evaluated at 4 months of age. Forty-nine other infants, BF (11 males, 6 females) fed RF (7 males, 12 females), or RF+cholesterol (6 males, 7 females) until 6 months of age were studied to test the hypothesis of imprinting using a cross-over design study with a 1-month 250 mg cholesterol/day challenge at 11 months of age. The incorporation rate of deuterium in body water into erythrocyte-free cholesterol over 48 hours was used as an index of cholesterol fractional synthetic rate (FSR) at 4, 11, and 12 months of age. Both plasma total- and LDL-C were higher (P[lt ] .04) in BF compared with RF+cholesterol and RF formula-fed groups at 4 months of age. Plasma cholesterol concentrations for all 3 groups were similar at 11 and 12 months of age. FSR (pools/d) was 4-fold higher (P[lt ] .0001) in both RF and RF+cholesterol compared with BF groups, but not different between RF and RF+cholesterol formula-fed groups. No differences in FSR before and after cholesterol challenge were observed within the 3 feeding groups at 11 and 12 months of age. However, synthesis rates from 4 months to 12 months increased (P[lt ] .03) in BF infants and decreased in both RF+cholesterol (P[lt ] .0001) and RF (P[lt ] .0001) fed groups. These results demonstrate relative insensitivity of synthesis rates and serum cholesterol concentrations to cholesterol challenge, irrespective of early dietary cholesterol intake in formula-fed and BF infants. These findings support the notion that early dietary cholesterol causes minimal changes in cholesterol metabolism about 6 months after dietary exposure in young infants.

To determine whether hydrogenated fat consumption alters triglyceride metabolism and cholesterol esterification rates, 14 women (65–71 years of age) were provided with each of four diets for 5-week periods according to a randomized cross-over design. The experimental diets contained either soybean oil (SO), low transsqueeze (SQM), medium transtub (TM), or high transstick (SM) margarines. Triglyceride uptake by adipose tissue was determined by measuring plasma acylation-stimulating protein (ASP), FFA, glucose, and insulin levels, while rates of transfer and esterification rate of newly synthesized cholesterol (ER) were derived by using plasma CETP levels and the deuterium incorporation methodology. Plasma ASP levels were lowest (P< 0.05) in subjects on the SM diet (33.4 ± 12.7 nM) compared with the SO (48.7 ± 17.0 nM) and SQM (50.7 ± 15.7 nM) diets. Conversely, FFA were highest (P< 0.05) on the SM diet (0.86 ± 0.45 mM) relative to all the other diets. No differences were observed in plasma glucose and insulin levels among diets. A trend toward higher CETP levels after consumption of the SM diet was observed. However, the ER was lowest (P< 0.05) after the SM (0.111 ± 0.062 g·day−1) diet and highest after consumption of the SQM (0.216 ± 0.123 g·day−1) diet. In addition, ASP levels were negatively correlated with FFA (r= −0.63, P< 0.05), LDL cholesterol (r= −0.56, P< 0.05), and TG (r= −0.41, P< 0.05), whereas FFA was positively correlated with apolipoprotein B-containing lipoproteins (r= 0.58 and 0.47, for VLDL and LDL cholesterol, P< 0.05), and negatively correlated with HDL cholesterol (r= −0.51, P< 0.05). The ER was found to positively correlate with HDL cholesterol and HDL2subfraction (r= 0.53 and 0.45, respectively, P< 0.05). Taken together, these data demonstrate that the alterations in circulating lipid levels, commonly observed with consumption of hydrogenated fat-rich diets, can be explained in part by changes in ASP activity as well as newly synthesized cholesterol ER.

Since the discovery of leptin in 1994, a considerable amount of research has focused on leptin as a central regulator of body weight. In the animal model, research has demonstrated leptin action through hypothalamic centres altering both satiety and energy expenditure. In contrast to animal studies, it is unlikely that leptin functioning in the human system exerts such a profound role in body weight regulation. Human studies suggest that leptin levels are strongly correlated with both percentage fat mass and body mass index, in accordance with the proposed ‘lipostatic theory’. Current research suggests the existence of a unique inter-relationship between dietary fat, leptin expression and leptin action within the peripheral system. More specifically, it has been demonstrated that polyunsaturated fatty acid (PUFA) intake influences adipose tissue expression of leptin, and of several lipogenic enzymes and transcription factors. In addition, leptin stimulates triglyceride depletion in white adipose tissue without increasing free fatty acid release, thus favouring fatty acids versus glucose as a fuel source. Recent studies suggest that the reduction in adipose hypertrophy observed with n-3 PUFA-containing fish oil feeding might involve a leptin-specific process. A large amount of evidence supports direct functioning of leptin in peripheral lipid metabolism in vivoand in vitro. It is possible that PUFAs will maintain an efficient level of circulating leptin, thus preventing leptin insensitivity and weight gain. There has been much recent progress in clinical leptin research, from energy expenditure to leptin analogue efficacy; the purpose of the present review is to summarize our current understanding of leptin functioning.

Doubly labeled water (DLW) is an accurate, portable method for measuring free‐living energy expenditure. However, under certain conditions shifts in baseline abundance of deuterium and oxygen‐18 tracers used in the method may produce errors in derivation of both turnover (k) rates and calculated energy expenditure. Present objectives were to examine during what experimental situations baseline errors arise and to address means of correcting for such baseline shifts so that consequent errors in energy expenditure calculations are minimized. Under conditions where shifts in baseline abundance for deuterium and oxygen‐18 parallel abundances corresponding to the natural meteoric water ratio, self‐compensating changes in k values for both deuterium and oxygen will result in minimal error to the DLW energy expenditure calculations, provided that the dose ratio of isotopes also mimics the meteoric water line. However, in situations where relative shifts in abundance of each isotope across the measurement period are not in parallel relative to the natural meteoric water line, then the potential for larger DLW errors exists. Optimally, subjects should equilibrate with the new water source. Failing this, correction for shifting baseline can be accomplished by measuring isotopic abundance changes in a control group of subjects not given the DLW dose, but performing similar tasks and consuming the same diet as the group given DLW. Alternatively, theoretically based correction values can be calculated given knowledge of the abundances of the final drinking water and the interval time that subjects consumed the new fluid.

Fats and their component fatty acids provide important attributes of texture and flavour which are central to the perceived sensory properties of food. Fats have important roles in the intestinal absorption of fat soluble vitamins A, D, E and K and also produce satiety signals that regulate meal size. Fats, however, are likely best known for representing the greatest source of calories in the diet (e.g. approximately 9 kcal per gram for fat compared to 4 kcal per gram for protein and carbohydrates). Regulatory recommendations state that a maximum of 30% of calories derived from fat should be consumed by adults in the North American diet to assist in the prevention of chronic diseases (e.g. coronary heart disease and cancer). A growing body of evidence suggests that metabolic utilization of dietary fats is influenced by the overall composition of fatty acid comprising the fat; more specifically the size, isomeric configuration, degree of unsaturation and the esterified position on the glycerol molecule. Thus, qualitative factors of fat consumption in addition to the amount consumed may be a regulator of caloric balance. Various factors influencing the digestion, absorption and partitioning of dietary fat for energy utilization and synthesis of triacylglycerides are reviewed, with particular emphasis given to the methodology of evaluating the partition of fat for oxidation versus storage.

BackgroundThe Mediterranean-style diet (MedDiet) is an established healthy-eating behavior that has consistently been shown to favorably impact cardiovascular health, thus likely improving quality of life and reducing costs associated with cardiovascular disease (CVD). Data on the economic benefits of MedDiet intakes are, however, scarce.ObjectiveThe objective of this study was to estimate the annual healthcare and societal cost savings that would accrue to the Canadian and American public, independently, as a result of a reduction in the incidence of CVD following adherence to a MedDiet.DesignA variation in cost-of-illness analysis entailing three stages of estimations was developed to 1) identify the proportion of individuals who are likely to adopt a MedDiet in North America, 2) assess the impact of the MedDiet intake on CVD incidence reduction, and 3) impute the potential savings in costs associated with healthcare and productivity following the estimated CVD reduction. To account for the uncertainty factor, a sensitivity analysis of four scenarios, including ideal, optimistic, pessimistic, and very-pessimistic assumptions, was implemented within each of these stages.ResultsSignificant improvements in CVD-related costs were evident with varying MedDiet adoption and CVD reduction rates. Specifically, CAD $41.9 million to 2.5 billion in Canada and US $1.0–62.8 billion in the United States were estimated to accrue as total annual savings in economic costs, given the ‘very-pessimistic’ through ‘ideal’ scenarios.ConclusionsCloser adherence to dietary behaviors that are consistent with the principles of the MedDiet is expected to contribute to a reduction in the monetary burdens of CVD in Canada, the United States, and possibly other parts of the world.