Vitamins lipid-lowering effects

Recently, ingestion of purple juice for 14 days has been shown to improve endothelial function, as measured by flow-induced vasodilation, in patients with coronary artery disease [78]. The authors attributed this effect to the flavonoidic content of the purple juice. These benefits were observed despite use of antioxidant vitamins, lipid lowering medications and small increases in total cholesterol and triglycerides levels. 

Lipid-lowering drugs. Fibrates, and some statins, enhance anticoagulant effect. Colestyramine is best avoided for it may impair the absorption of both warfarin and vitamin K. 

However large RCTs, such as VISP (Toole et al. 2004) or VITATOPS (Anonymous 2010) have failed to document any significant effects of B vitamins on stroke prevention. Post hoc analyses, such as that of HOPE-2 (Saposnik et al. 2009) have suggested that folate, Bg and B12 could reduce stroke risk in patients with known CVD, mainly if patients were younger than 70 years, recruited from regions without folic acid food fortification, with higher baseline cholesterol and Hey levels, and not under antiplatelet or lipid-lowering... 

Niacin is a water-soluble vitamin that has been available as a lipid-lowering medication and in prevention of atherosclerosis for half a century (Ganji et al. 2003 Olsson 2010). Numerous studies have documented its beneficial effects on reducing cardiovascular disease (CVD) (Olsson 2010). Clinically, the most well-known effect of niacin deficiency is pellagra which, as noted above, is manifested by dermatitis, diarrhoea and dementia (Bodor and Offermanns 2008 Ganji, et al. 2003). In this chapter we look at the effects of niacin on human physiology and its consequent effects on disease states. 

Esterbauer et al. (1991) have demonstrated that /3-carotene becomes an effective antioxidant after the depletion of vitamin E. Our studies of LDL isolated from matched rheumatoid serum and synovial fluid demonstrate a depletion of /8-carotene (Section 2.2.2.2). Oncley et al. (1952) stated that the progressive changes in the absorption spectra of LDL were correlated with the autooxidation of constituent fatty acids, the auto-oxidation being the most likely cause of carotenoid degradation. The observation that /3-carotene levels in synovial fluid LDL are lower than those of matched plasma LDL (Section 2.2.2) is interesting in that /3-carotene functions as the most effective antioxidant under conditions of low fOi (Burton and Traber, 1990). As discussed above (Section 2.1.3), the rheumatoid joint is both hypoxic and acidotic. We have also found that the concentration of vitamin E is markedly diminished in synovial fluid from inflamed joints when compared to matched plasma samples (Fairburn etal., 1992). This difference could not be accounted for by the lower concentrations of lipids and lipoproteins within synovial fluid. The low levels of both vitamin E and /3-carotene in rheumatoid synovial fluid are consistent with the consumption of lipid-soluble antioxidants within the arthritic joint due to their role in terminating the process of lipid peroxidation (Fairburn et al., 1992). 

The role of the antioxidant properties of vitamins C, E, and p-carotene in the prevention of cardiovascular disease has been the focus of several recent studies. Antioxidants reduce the oxidation of low-density lipoproteins, which may play a role in the prevention of atherosclerosis. However, an inverse relationship between the intake or plasma levels of these vitamins and the incidence of coronary heart disease has been found in only a few epidemiological studies. One study showed that antioxidants lowered the level of high-density lipoprotein 2 and interfered with the effects of lipid-altering therapies given at the same time. While many groups recommend a varied diet rich in fruits and vegetables for the prevention of coronary artery disease, empirical data do not exist to recommend antioxidant supplementation for the prevention of coronary disease. 

Hyperoxia was found to encourage the accumulation of primary and end-products of lipid peroxidation together with a significant lowering of the vitamin E content of rat brain tissue [152]. The consequence of hyperoxia was epileptiform seizures, which were prevented by vitamin E or synthetic antioxidant pre-injection. Other workers [153] have found that protection against hyperoxia is directly related to the level of vitamin E or selenium supplementation. However, some [ 154] have indicated no beneficial effects for vitamin E in reducing oxygen toxicity. 

Chemiluminescence has been used to investigate lipid peroxidation on the brains of rats. Cerebral hypoxia was induced by arterial hypoxaemia fP p2 17-22 mmHg) with normocapnia (/%°2 28-38 mmHg) and normotension (MABP 100-140 mmHg). Mixed gas (02/N2, 4/96%) was used as a replacement for obtaining lowered E 2. The chemiluminescence findings indicate that vitamin E and betamethasone act on the breakdown of lipid hydroperoxide and that mannitol acts on hydroxy radicals in lipid peroxidation [183-185], A recent study has found that phenytoin is superior to vitamin E as a protectant in a mouse cerebral infarction model [ 186] and that this effect is enhanced by combination with mannitol and vitamin E. 

The observation of a lower incidence of coronary heart disease (CHD) and certain types of cancers in the Mediterranean area led to the hypothesis that a diet rich in grain, legumes, fresh fruits and vegetables, wine in moderate amounts, and olive oil was beneficial to human health. To date, this effect has been mainly attributed to the low saturated fat intake of the Mediterranean diet and its high proportion of monounsaturates, which indeed may favorably affect the plasma lipid and lipoprotein profiles. Nevertheless, other components of the diet, such as fiber, vitamins, flavonoids, and phenols, may play an important role in disease prevention, acting on different cardiovascular variables. 

Thus, in vitamin E deficiency, selenium has a beneficial effect in lowering the concentrations of alkylperoxyl radicals, and conversely, in selenium deficiency, vitamin E has a protective effect in reducing the radicals. When selenium is adequate, but vitamin E is deficient, tissues with low activity of glutathione peroxidase [e.g., the central nervous system and (rat) placenta] are especially susceptible to lipid peroxidation, whereas tissues with high activity of glutathione peroxidase are not. Conversely, with adequate vitamin E and inadequate selenium, membrane lipid peroxidation will be inhibited, but tissues with high peroxide production and low catalase activity will still be at risk from peroxidative damage, especially to sulfhydryl proteins. 

A concern has been raised that phytosterol doses that are effective for cholesterol reduction may impair the absorption and lower blood concentrations of fat-soluble vitamins and antioxidants. A number of studies showed that phytosterols had no effect on plasma concentrations of vitamin D, retinol, or plasma-lipid-standardized alpha-tocopherol. Moreover, the reports of the effect of phytosterols on concentrations of blood carotenoids (lutein, lycopene, and alpha-carotene) are controversial. There seems to be general agreement that phytosterol doses >1 g/d significantly decrease LDL-C standardized beta-carotene concentrations however, it remains to be determined whether a reported 15-20% reduction in beta-carotene due to phytosterol supplementation is associated with adverse health effects. Noakes et al. found that consumption of one or more carotenoid-rich vegetable or fruit servings a day was sufficient to prevent lowering of plasma carotenoid concentrations in 46 subjects with hypercholesterolemia treated with 2.3 g of either sterol or stanol esters. 

Water, saccharides, lipids, proteins, and minerals — the main components — form the structure of and are responsible for the sensory and nutritional properties of foods. Other constituents, present in lower quantities, especially colorants, flavor compounds, vitamins, probiotics, and additives, also contribute to different aspects of food quality. The catabolysis that takes place in raw materials postharvest, as well as chemical and biochemical changes and interactions of components during storage and processing, affect all aspects of food quality. These processes can be effectively controlled by the food processor who knows food chemistry. 

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