Cardiovascular disease vitamin

Vitamin E can also act as an antioxidant (qv) in animals and humans alone or in combination with vitamin C (qv). Both are good free-radical scavengers with the vitamin C acting to preserve the levels of vitamin E (35). Vitamin E in turn can preserve the levels of vitamin A in animals (13). It has been shown that vitamin E reduces the incidence of cardiovascular disease (36—39). This most likely results from the antioxidant property of the vitamin which inhibits the oxidation of low density Hpoproteins (LDLs) (40—42). The formation of the oxidized LDLs is considered important in decreasing the incidence of cardiovascular disease (43). 

So far, it is not possible to give any recommendations concerning the vitamin C intake required for the prevention of osteoporosis, cataracts, cancer, or cardiovascular disease. 

Low levels of vitamin E have been associated with increased incidence of coronary artery disease. Observational studies have therefore suggested that supplemental a-tocopherol might have value in the treatment of cardiovascular disease. Clinical studies demonstrated contradicting results regarding the benefits of vitamin E in the prevention of cardiovascular disease. Four... 

Pham DQ, Plakogiannis R (2005) Vitamin E supplementation in cardiovascular disease and cancer prevention Part 1. Ann Pharmacother 39 1870-1878... 

Globally, undernutrition is widespread, leading to impaired growth, defective immune systems, and reduced work capacity. By contrast, in developed countries, there is often excessive food consumption (especially of fat), leading to obesity and to the development of cardiovascular disease and some forms of cancer. Deficiencies of vitamin A, iron, and iodine pose major health concerns in many countries, and deficiencies of other vitamins and minerals are a major cause of iU health. In developed countries, nutrient deficiency is rare, though there are vulnerable sections of the population at risk. Intakes of minerals and vitamins that are adequate to prevent deficiency may be inadequate to promote optimum health and longevity. 

The a-tocopherol, P-carotene (ATBC) Cancer Prevention study was a randomised-controlled trial that tested the effects of daily doses of either 50 mg (50 lU) vitamin E (all-racemic a-tocopherol acetate), or 20 mg of P-carotene, or both with that of a placebo, in a population of more than 29,000 male smokers for 5-8 years. No reduction in lung cancer or major coronary events was observed with any of the treatments. What was more startling was the unexpected increases in risk of death from lung cancer and ischemic heart disease with P-carotene supplementation (ATBC Cancer Prevention Study Group, 1994). Increases in the risk of both lung cancer and cardiovascular disease mortality were also observed in the P-carotene and Retinol Efficacy Trial (CARET), which tested the effects of combined treatment with 30 mg/d P-carotene and retinyl pahnitate (25,000 lU/d) in 18,000 men and women with a history of cigarette smoking or occupational exposure to asbestos (Hennekens et al, 1996). 

OMENN G S, GOODMAN G E, THORNQUIST M D, BALMES J, CULLEN M R, GLASS A, KEOGH J P, MEYSKENS F L, VALANIS B, WILLIAMS J H, BARNHART S and HAMMAR S (1996) Effects of a combination of beta-carotene and vitamin A on lung cancer and cardiovascular disease. N EnglJ Med 1150-1155. 

The above scientific information on rice bran phytochemicals indicates that a multitude of mechanisms are operating at the cellular level to bring about specific health effects. Several health benefits of rice bran appear to be the result of the synergistic function of the many phytochemicals, antioxidants, vitamins and minerals which operates through a specific immune response. Their role in the biochemical mechanisms at the cellular level which result in major health effects is shown in Fig. 17.1. A short overview summarizing the effect of the various phytochemicals on major health issues such as cancer, immune function, cardiovascular disease, diabetes, altered liver function and gastrointestinal and colon disease will be given below. 

In animals, the major function of carotenoids is as a precursor to the formation of vitamin A. Carotenoids with provitamin A activity are essential components of the human diet, and there is considerable evidence that they are absorbed through the diet and often metabohzed into other compounds. Beyond their important role as a source of vitamin A for humans, dietary carotenoids, including those that are not provitamin A carotenoids, have been implicated as protecting against certain forms of cancer and cardiovascular disease. ... 

Many epidemiological studies have analyzed the correlations between different carotenoids and the various forms of cancer and a lot of conclusions converge toward protective effects of carotenoids. Many studies were carried out with (i-carotene. The SUVIMAX study, a primary intervention trial of the health effects of antioxidant vitamins and minerals, revealed that a supplementation of p-carotene (6 mg/day) was inversely correlated with total cancer risk. Intervention studies investigating the association between carotenoids and different types of cancers and cardiovascular diseases are reported in Table 3.1.2 and Table 3.1.3. 

In the Unites States, the daily intake of 3-carotene is around 2 mg/day Several epidemiological studies have reported that consumption of carotenoid-rich foods is associated with reduced risks of certain chronic diseases such as cancers, cardiovascular disease, and age-related macular degeneration. These preventive effects of carotenoids may be related to their major function as vitamin A precursors and/or their actions as antioxidants, modulators of the immune response, and inducers of gap-junction communications. Not all carotenoids exert similar protective effects against specific diseases. By reason of the potential use of carotenoids as natural food colorants and/or for their health-promoting effects, research has focused on better understanding how they are absorbed by and metabolized in the human body. 

Vitamin E consists of a family of related compounds, the tocopherols. The most abundant in the American diet is 7-tocopherol and, although it is potentially superior in the detoxification of nitrogen dioxide, the biochemistry of a-tocopherol is considered more relevant to cardiovascular disease (Kayden and Traber, 1993). Vitamin E undoubtedly has several modes of action in vim. The most clearly understood of these, at the chemical level, is the role of a-tocopherol as an antioxidant. 

Elevated homocysteine concentrations have been associated with an increased risk for cardiovascular disease in both epidemiologic and clinical studies.43 Several studies have evaluated the benefit of lowering homocysteine levels with folic acid supplementation. One study reported a reduction in major cardiac events with the combination of folic acid, vitamin B12, and vitamin B6 following PCI.44 However, a more recent study found an increased risk of instent restenosis and the need for target-vessel revascularization with folate supplementation following coronary stent placement.45 The role of folate in the management of IHD is currently unclear. 

Omenn, GS, 1996. Antioxidant vitamins, cancer, and cardiovascular disease. N Engl J Med 335, 1067-1068. 

Carotenoids are of physiological interest because some of them are precursors of vitamin A. They have been in the news recently because many exhibit radical or single oxygen trapping ability and as such have potential antioxidant activity in vivo. They may reduce the risk of cardiovascular disease, lung cancer, cervical... 

Most medical researchers agree that people with diets rich in fruits and vegetables have a lower incidence of cardiovascular disease, certain cancers, and cataracts. Although fruits and vegetables are high in antioxidants, they also contain fibre and many different vitamins... 

The clinical problems that arise in the menopause are hot flushes, sweating, depression, decreased libido, increased risk of cardiovascular disease and osteoporosis. The latter results in increased incidence of hip, radial and vertebral fractures. Oestrogen is one factor controlling synthesis of active vitamin D and osteoporosis is in part due to a deficiency of vitamin D. Not surprisingly, to reduce these problems, administration of oestrogen is recommended (known as hormone replacement therapy or HRT). HRT reduces some of the risk factors for coronary artery disease since it reduces blood pressure and decreases the blood level of LDL-cholesterol and increases that of HDL-cholesterol. However, there is considerable debate about whether HRT increases the risk of breast or endometrial cancer. 

Vitamin E in the diet is known to provide valuable antioxidant properties for humans, preventing the destruction of cellular materials, e.g. unsaturated fatty acids in biological membranes, and also helping to prevent heart disease. Other materials are similarly known to have beneficial antioxidant properties, and we are encouraged to incorporate sufficient levels of antioxidant-rich foods into our diets to minimize the risks of cardiovascular disease, cell degradation, and cancer. 

Carotenoids are isoprenoid compounds that are biosynthesized only by plants and microorganisms. Some carotenoids (a- and p-carotene, p-cryptoxanthine) can be cleaved into vitamin A (retinol) by an enzyme in the small intestine. Carotenoids have been reported to present some effects in the prevention of cardiovascular diseases [410] and in the prevention of some kind of cancers [411]. Furthermore, antioxidant activity has been widely reported [411-414] but a switch to pro-oxidant activity can occur as a function of oxygen concentration [415,416]. 

Asplund K. Antioxidant vitamins in the prevention of cardiovascular disease a systematic review. J Intern Med 2002 251(5) 372-92. 

Clarke R, Armitage J. Antioxidant vitamins and risk of cardiovascular disease. Review of large-scale randomised trials. Cardiovasc Dmgs Ther 2002 16(5) 411-5. 

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. 

Vitamins B12 and B6 have preventive effects against age-related chronic diseases, including cardiovascular disease (CVD), stroke, and cognitive decline... 

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