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Dietary antinutritional factors have been reported to adversely affect the digestibility of protein, bioavailability of amino acids and protein quality of foods. Published data on these negative effects of major dietary antinutritional factors are summarized in this manuscript. Digestibility and the quality of mixed diets in developing countries are considerably lower than of those in developed regions. For example, the digestibility of protein in traditional diets from developing countries such as India, Guatemala and Brazil is considerably lower compared to that of protein in typical North American diets (54–78 versus 88–94 %). Poor digestibility of protein in the diets of developing countries, which are based on less refined cereals and grain legumes as major sources of protein, is due to the presence of less digestible protein fractions, high levels of insoluble fibre, and/or high concentrations of antinutritional factors present endogenously or formed during processing. Examples of naturally occurring antinutritional factors include glucosinolates in mustard and canola protein products, trypsin inhibitors and haemagglutinins in legumes, tannins in legumes and cereals, gossypol in cottonseed protein products, and uricogenic nucleobases in yeast protein products. Heat/alkaline treatments of protein products may yield Maillard reaction compounds, oxidized forms of sulphur amino acids, D-amino acids and lysinoalanine (LAL, an unnatural nephrotoxic amino acid derivative). Among common food and feed protein products, soyabeans are the most concentrated source of trypsin inhibitors. The presence of high levels of dietary trypsin inhibitors from soyabeans, kidney beans or other grain legumes have been reported to cause substantial reductions in protein and amino acid digestibility (up to 50 %) and protein quality (up to 100 %) in rats and/or pigs. Similarly, the presence of high levels of tannins in sorghum and other cereals, fababean and other grain legumes can cause significant reductions (up to 23 %) in protein and amino acid digestibility in rats, poultry, and pigs. Normally encountered levels of phytates in cereals and legumes can reduce protein and amino acid digestibility by up to 10 %. D-amino acids and LAL formed during alkaline/heat treatment of lactalbumin, casein, soya protein or wheat protein are poorly digestible (less than 40 %), and their presence can reduce protein digestibility by up to 28 % in rats and pigs, and can cause a drastic reduction (100 %) in protein quality, as measured by rat growth methods. The adverse effects of antinutritional factors on protein digestibility and protein quality have been reported to be more pronounced in elderly rats (20-months old) compared to young (5-weeks old) rats, suggesting the use of old rats as a model for assessing the protein digestibility of products intended for the elderly.

We measured non-haem Fe absorption with and without added Ca in a short-term feeding study, in thirteen women with marginal Fe status, by the use of a double stable isotope technique. Supplementing 500 mg Ca as calcium carbonate significantly (P = 0·0009) reduced Fe absorption from a single meal from 10·2 % (range 2·2–40·6) to 4·8 % (range 0·7–18·9). A significant inverse correlation in the absence ( − 0·67, P = 0·010) and presence ( − 0·58, P = 0·037) of Ca, respectively, was found between Fe absorption and Fe stores measured by serum ferritin (SF). Wide variation in Fe absorption was observed between individuals in the absence and in the presence of Ca, despite pre-selection of participants within a relatively narrow range of iron stores (SF concentrations). Correction of Fe absorption data based on group mean SF was not found to be useful in reducing the inter-individual variability in iron absorption. It appears that selecting a study group with a narrow initial range of Fe stores does not necessarily reduce the inter-individual variability in Fe bioavailability measurements. These results support the hypothesis that body Fe stores, although an important determinant of dietary Fe absorption, are not the main factor that determines Fe absorption under conditions of identical dietary intake in subjects with low Fe stores.

Johanne Poirier1, Kevin A. Cockell1,2,3, W.M. Nimal Ratnayake2, Kylie A. Scoggan2,3, Nick Hidiroglou2, Claude Gagnon2, Hélène Rocheleau2, Heidi Gruber2, Philip Griffin2, René Madère2, Keith Trick2 and Stan Kubow11School of Dietetics and Human Nutrition, Macdonald Campus of Mcgill University, Ste-Anne-de-Bellevue, Quebec, Canada h9X 3V9. 2Nutrition Research Division, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada K1A 0K9. 3Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1h 8M5. AbstractHypercholesterolemic diets are associated with oxidative stress that may contribute to hypercholesterolemia by adversely affecting enzymatically-generated oxysterols involved in cholesterol homeostasis. An experiment was conducted to examine whether the cholesterol-lowering effects of the antioxidants selenium and α-tocopherol were related to hepatic oxysterol concentrations. Four groups of male Syrian hamsters (n = 7-8) were fed high cholesterol and saturated fat (0.46% cholesterol, 14.3% fat) hypercholesterolemic semi-purified diets: 1) Control; 2) Control + α-tocopherol (67 IU all-racemic-α-tocopheryl-acetate/kg diet); 3) Control + selenium (3.4 mg selenate/kg diet); and 4) Control + α-tocopherol + selenium. Antioxidant supplementation was associated with lowered plasma cholesterol concentrations, decreased tissue lipid peroxidation and higher hepatic oxysterol concentrations. A second experiment examined the effect of graded selenium doses (0.15, 0.85, 1.7 and 3.4 mg selenate/kg diet) on mRNA expression of the oxysterol-generating enzyme, hepatic 27-hydroxylase (CYP27A1, EC 1.14.13.15), in hamsters (n = 8-9) fed the hypercholesterolemic diets. Supplementation of selenium at 3.4 mg selenate/kg diet was not associated with increased hepatic 27-hydroxylase mRNA. In conclusion, the cholesterol lowering effects of selenium and α-tocopherol were associated with increased hepatic enzymatically generated oxysterol concentrations, which appears to be mediated via improved antioxidant status rather than increased enzymatic production.

The aim of the present study was to elucidate possible cholesterol-lowering mechanism(s) of high-dose supplemental Se in the form of selenite, a known hypocholesterolaemic agent. Male Syrian hamsters (four groups, ten per group) were fed semi-purified diets for 4 weeks containing 0·1 % cholesterol and 15 % saturated fat with selenite corresponding to varying levels of Se: (1) Se 0·15 parts per million (ppm), control diet; (2) Se 0·85 ppm; (3) Se 1·7 ppm; (4) Se 3·4 ppm. Lipids were measured in the bile, faeces, liver and plasma. The mRNA expression of several known regulators of cholesterol homeostasis (ATP-binding cassette transporters g5 ( Abcg5 ) and g8 ( Abcg8 ), 7-hydroxylase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, LDL receptor ( LdLr) and Nieman-Pick C1-like 1 protein ( Npc1l1 )) were measured in the liver and/or jejunum. Oxysterols including 24-( S )-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol (27-OHC) were measured in the liver. Significantly lower total plasma cholesterol concentrations were observed in hamsters consuming the low (0·85 ppm) and high (3·4 ppm) Se doses. The two highest doses of Se resulted in decreased plasma LDL-cholesterol concentrations and increased mRNA levels of hepatic Abcg8 , Ldlr and jejunal Ldlr. Higher hepatic 27-OHC and TAG concentrations and lower levels of jejunal Npc1l1 mRNA expression were noted in the 1·7 and 3·4 ppm Se-treated hamsters. Overall, Se-induced tissue changes in mRNA expression including increased hepatic Abcg8 and Ldlr , increased jejunal Ldlr and decreased jejunal Npc1l1 , provide further elucidation regarding the hypocholesterolaemic mechanisms of action of Se in the form of selenite.

Objectives: Excessive sodium (Na) intakes and insufficient potassium (K) intakes are known contributors to hypertension. In July 2010, the Health Canada-led multi-stakeholder Sodium Working Group issued recommendations to lower Na intakes of Canadians. Baseline data and ongoing monitoring are needed. Methods: Na and K content based on recently analyzed food composite samples from the Canadian marketplace were matched with over 35,000 dietary recalls from the Canadian Community Health Survey (CCHS 2.2). The distributions of usual intakes for Na and K were constructed using SIDE software and estimates by age and sex for the 5th, 10th, 25th, mean, median, 75th, 90th and 95th percentiles were determined. Results: Based on recent analyses of Canadian foods, the majority of Canadians exceeded the Tolerable Upper Intake Level (UL) for Na for their age and sex group, including infants, children, adolescents and adults. In sharp contrast, few had Adequate Intakes (AI) of K. Conclusion: Canadians of all ages need to decrease Na intakes below the UL. At the same time, increased consumption of dairy products, fruits and vegetables must be promoted to increase K intakes to current recommendations. Both dietary interventions are required to help lower hypertension in the Canadian population. We provide the first report based on direct analyses of Canadian foods, confirming the high Na and low K intakes of the Canadian population. With its annual sampling program of foods commonly consumed in Canada, the Total Diet Study provides an important sentinel system for monitoring these dietary risk factors for hypertension. Objectifs : Des apports excessifs en sodium (Na) et insuffisants en potassium (K) sont deux facteurs contribuant à l'hypertension. En juillet 2010, le Groupe de travail multi-intervenants sur le sodium, dirigé par Santé Canada, a publié la Stratégie de réduction du sodium pour le Canada. Des données de base et un suivi permanent sont requis. Méthode : Les contenus en Na et en K basés sur des analyses récentes d'échantillons composites d'aliments vendus sur le marché canadien ont été appariés avec plus de 35 000 « rappels alimentaires » [feuilles de rappels des aliments ingérés] de l'Enquête sur la santé dans les collectivités canadiennes, cycle 2.2, volet nutrition (ESCC 2.2). Les distributions des apports typiques en Na et en K ont été établies en utilisant le logiciel SIDE, et les estimations par âge et par sexe pour les 5e, 10e, 25e, 75e, 90e et 95e centiles, ainsi que pour la moyenne et la médiane, ont été déterminées. Résultats : D'après des analyses récentes d'aliments canadiens, les apports en Na de la majorité des Canadiens (nourrissons, enfants, adolescents et adultes) excèdent l'apport maximal tolérable (AMT) pour leur groupe d'âge et leur sexe. Par contre, peu de Canadiens ont des apports suffisants (AS) en K. Conclusion : Les Canadiens de tous les âges ont besoin de réduire leurs apports en Na en dessous de l'AMT. Parallèlement, la consommation accrue de produits laitiers, de fruits et de légumes doit être promue afin d'augmenter les apports en K jusqu'aux niveaux recommandés. Ces deux interventions sont requises afin de réduire l'hypertension au Canada. Notre rapport est le premier à être fondé directement sur des analyses d'aliments canadiens; il confirme les apports excessifs en Na et insuffisants en K des Canadiens. Grâce à son programme d'échantillonnage annuel des aliments habituellement consommés au Canada, l'étude de la diète totale fournit un système sentinelle important pour le suivi de ces facteurs de risque d'hypertension d'origine alimentaire.

This study tested the hypothesis that protein source is a factor determining the impact of the diet on lipid metabolism in hamsters. Twenty-eight hamsters of similar body weight were assigned for a period of 8 weeks to one of the following four diets (seven per group) containing either 20 % (w/w) casein (CAS), beef protein (BF), wheat gluten (WG) or soya protein (SOY). The fat composition of the diet was the same (15·5 % w/w) in all groups and provided SFA, MUFA and PUFA representative of the average Canadian diet. After an overnight fast, blood and liver were collected for the measurement of serum lipids, fatty acid composition of liver phospholipids and mRNA levels of selected genes involved in lipid metabolism. WG resulted in lower total cholesterol, HDL-cholesterol and non-HDL-cholesterol but, along with SOY, in higher mRNA levels of cholesterol 7 α-hydroxylase and LDL receptor. Furthermore, both WG and SOY resulted in lower 18 : 3n-3, 20 : 4n-6, total n-6 PUFA, 18 : 1n-9 and total MUFA, but higher 22 : 6n-3, total n-3 PUFA, 22 : 6n-3/18 : 3n-3 and 22 : 5n-3/18 : 3n-3 ratios in liver phospholipids, and higher hepatic Δ6-desaturase mRNA levels. These results show that the impact of dietary protein on lipid metabolism is source-dependent and associated with changes in mRNA abundances of key hepatic enzymes and receptors.

Overview: Iron is an essential nutrient, playing a central role in oxygen transport and cellular energy metabolism. The importance of ensuring adequate bioavailable dietary iron stems from the severe consequences associated with iron deficiency (ID) and anemia, including reduced immune function and resistance to infection, developmental delays and irreversible cognitive deficits in young children, impaired physical work performance, and adverse pregnancy outcomes. Specific populations: Poor dietary iron intake and ID exist in Canada, particularly in women of reproductive age. Data from the provincial nutrition surveys suggest that the prevalence of inadequate iron intakes (and low intakes of absorbable iron) among women under 50 years of age is over 10%, which may reflect poor iron status. Teenage girls are at risk for low iron stores because of the adolescent growth spurt and the onset of menstruation; those who are vegetarian are at even greater risk. Conclusions: The Canadian diet has changed so that grain products are now the main source of dietary iron for all age groups. The public must be educated to ensure the consumption of adequate quantities of bioavailable iron and enhancing factors such as vitamin C. Industry, government, and health professionals must work together to promote healthy eating patterns and the selection of appropriate foods.

For many nutrients, a systematic determination of the effects of high intakes over extended periods of time has not been conducted. Governments and scientific bodies have just begun to establish the methodology for, and to conduct, nutrient risk assessments for setting ‘tolerable upper levels of intake’ (UL) for nutrients. Nutrient risk assessment provides the framework for using available information to evaluate the safety of nutrients when added to foods or when consumed as supplements, in order to minimize the risks from over-consumption. When intakes are inadequate, food fortification may be the appropriate choice for some nutrients, while in other situations, when requirements are markedly higher for some population subgroups than for the general population, supplements may be the most appropriate intervention. The present paper will present some examples of how to use the UL along with food consumption data to assess the appropriateness of food fortification v. supplementation strategies and to assess their impact on nutrient intakes of the population. The important steps to be followed when evaluating which approach is best are: (a) establishing need, i.e. assessing the gap between current and desired intakes; (b) assessing safety, i.e. consider the margin of safety between requirement and UL as well as the severity and reversibility of the adverse effect that was used to establish the UL; (c) estimating exposure through statistical modelling, in which population-based estimates of intakes before and after the intervention are compared; (d) monitoring the impact of the intervention to ensure that the desired benefits are achieved and that excessive intakes are minimized. This approach can optimize the public health benefits of food fortification or supplement use while minimizing the risks due to excessive intakes.