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Coronary Heart Disease (CHD) is a major cause of death in Western countries. Mediterranean and Asian populations have a lower risk of death from CHD compared to Westernised population, as do vegetarian versus omnivorous populations. Dietary constituents of traditional diets consumed by these populations are thought to influence both the classical risk factors for CHD, and the more recently identified risk factors, such as oxidative modification of low density lipoprotein (LDL), LDL particle size, arterial compliance and haemostatic factors. The aim of this thesis was to examine the effects of several food components, particularly soybean and monounsaturated fat (MUFA), on CHD risk factors through 3 carefully controlled dietary interventions, and a cross-sectional study. A randomised crossover dietary intervention study was conducted in 42 healthy males to investigate the effect on CHD risk factors of replacing lean meat with tofu, a soybean product regularly consumed by Asian populations, while controlling all other dietary factors. The tofu diet resulted in significantly lower total cholesterol and triacylglycerol levels compared to the lean meat diet, and LDL particles that were more resistant to in vitro oxidative modification. However, insulin, fibrinogen, factor VII, and lipoprotein (a) were not significantly different on the 2 diets. A postprandial study was subsequently conducted to investigate any acute effects of a tofu test meal on the oxidative modification of LDL in 16 male subjects. There was no significant difference between the susceptibility of LDL to oxidative modification before and after the tofu meal. Twenty eight healthy subjects completed a separate randomised crossover dietary intervention comparing a high MUFA fat diet, using an Australian high oleic sunflower oil, with a low fat, high carbohydrate diet on CHD risk factors. The high MUFA oil diet significantly increased high density lipoprotein cholesterol compared to the low fat diet as well as producing LDL that were more resistant to oxidative modification. Neither the size of the LDL particle nor arterial compliance were significantly different on the 2 diets. Twelve matched pairs of vegetations and omnivores were also studies to compare the habitual diet of a low and higher risk population group, to compare their risk factors and identify dietary constituents that may explain the differences. The vegetarians consumed less saturated fat (SFA) and dietary cholesterol while consuming more polyunsaturated fat, dietary fibre and vitamin E compared to omnivores. The vegetarians had lower total cholesterol, LDL cholesterol and triacylglycerol levels compared to the omnivores and had LDL particles that were more resistant to in vitro oxidation. These findings contribute to our knowledge about the dietary constituents that can alter some CHD risk factors in healthy subjects, and which could reduce the risk of developing CHD. Investigations in high risk groups might reveal even more benefits.

<p>Chronic diseases pose public health concerns globally with an increasing trend in developing countries. The development of interventions to minimize or prevent the burden associated with chronic diseases has therefore become a necessity. In 2002 the School of Public Health of the University of the Western Cape developed a health club intervention in Khayelitsha. This intervention focused on promoting healthy lifestyles, particularly improved diet and physical activity. The objectives of this study was to determine whether members were more physically active than non-members and to determine whether members made healthier dietary choices than non-members.</p>

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The effects of maternal dietary glucose restriction on reproductive performance were investigated by feeding pregnant rats isocaloric diets containing graded levels of dietary glucose (0, 12, 24 and 60%) during pregnancy and during pregnancy and lactation, and by measuring the effects of glucose restriction on (1) maternal, fetal and neonatal metabolism, on (2) growth and composition of the mammary glands and placentas, and (3) on milk composition. Carbohydrate restriction induced maternal metabolic adaptations that were proportional to the severity of the glucose restriction. Placental growth and composition as well as mammary gland composition were not affected by dietary glucose restriction, whereas fetal growth and development and milk composition were significantly impaired when glucose was limited in the maternal diet. This suggests that the effects of dietary glucose on the fetus and on milk composition were not mediated by changes in placenta and mammary gland DNA, protein or glycogen concentrations. Complete dietary glucose restriction significantly depressed fetal liver, lung and heart glycogen concentrations; repletion of the maternal diets with 12 and 24% glucose restored cardiac glycogen to normal but not fetal lung glycogen and liver glycogen. Pups born to dams fed a glucose-free diet failed to survive longer than 24 h postpartum and that was associated with the low levels of tissue glycogen at birth in these pups. At birth, lung and liver glycogen concentration of pups of the 12 and 24% glucose diets was similar to pups of the control diet despite the fact that these reserves were depressed in utero; and these pups efficiently corrected the transient hypoglycemia observed following parturition. The effects of glucose restriction on fetal liver glycogen were not reflected by similar changes in fetal plasma insulin, glucagon and glucose levels or in glycogen synthase and phosphorylase activities. Maternal dietary glucose was an important determinant

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A dextran sulphate (DS) model of ulcerative colitis was used to examine the effects of macronutrient restriction with (MR+PRO) and without (MR) probiotic supplementation (VSL#3RTM) on protein metabolism and growth. MR and MR+PRO decreased weight and chest circumference gain, but had no effect on linear growth of piglets. MR decreased the protein fractional synthesis rate (FSR) of liver, masseter, longissimus dorsi, colon, as well as plasma albumin, measured by stable isotope tracer L-[ring-2H 5]phenylalanine. MR+PRO increased the FSR of hepatic proteins by greater than 70% and increased both the FSR and absolute synthesis rate (ASR) of the total plasma protein pool, albumin and fibrinogen. Over 11 days, MR+PRO piglets showed a smaller decrease in plasma total protein concentrations than WN piglets, and maintained higher albumin levels than either WN or MR piglets. These findings highlight the importance of adequate nutrition during gastrointestinal inflammation and show that when food intake is decreased, probiotics stimulate liver protein synthesis and increase the acute phase protein response, similar to the well-nourished state.

We developed a methodology to measure plasma hepatic glutathione (GSH) turnover and we tested it in rats treated with an inhibitor of GSH synthesis. Our goal was to determine whether protein intakes above NRC recommendations maximize hepatic GSH stores and turnover in vivo. We also wished to learn if plasma GSH, cysteine, or methionine concentrations or plasma GSH turnover could be used as noninvasive predictors of liver GSH status. Rats were fed purified diets containing 0, 5, 10, 20 or 40% casein for one week. The 0 and 5% casein diets were considered inadequate in protein, 10% marginal, 20% adequate and 40% excessive. Liver GSH content (mmol/liver) of rats fed 0 and 5% casein diets was 12.29 $ pm$ 1.11 and 16.43 $ pm$ 0.95, respectively, and increased to 23.62 $ pm$ 1.82 in the 10% group. Liver GSH content did not differ between the 20 and 40% groups. As dietary casein increased from 0-20%, free plasma GSH and cysteine concentrations and plasma GSH turnover increased, but did not increase further with the 40% diet. A sigmoidal relationship between plasma GSH turnover and hepatic GSH content was demonstrated. The best predictor of liver GSH content was not free plasma GSH concentration nor plasma GSH turnover, but the free plasma cysteine concentration.

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