Vitamins antioxidant

There are numerous reports of the effects of antioxidant vitamins on transformation. Vitamin C suppresses x-ray-induced transformation when CSHlOTy cells are treated daily for one week following irradiation (97), suppresses transformation by y-rays or neutrons, and prevents the promotion of radiation-induced transformation by 12-0-tetradecanoylphorbol 13-acetate (TPA), but has no effect on cell survival (98). In these studies, the continuous presence of vitamin C for a critical period appears to be necessary for suppression of transformation. Vitamin C may act on the promotion stage of... 

No unequivocal unique function for vitamin E has been defined. However, it does act as a hpid-soluble antioxidant in cell membranes, where many of its functions can be provided by synthetic antioxidants. Vitamin E is the generic descriptor for two famihes of compounds, the tocopherols and the tocotrienols (Figure 45—5). The different vitamers (compounds having similar vitamin activity) have different biologic potencies the most active is D-a-tocopherol, and it is usual to express vitamin E intake in milhgrams of D-a-tocoph-erol equivalents. Synthetic DL-a-tocopherol does not have the same biologic potency as the namrally occurring compound. 

Nutrient analysis of stabilized rice bran and its derivatives indicates that it is a good source of protein, dietary fiber and carbohydrates, in addition to several valuable phytonutrients, antioxidants, vitamins and minerals (Table 17.1). SRB and its water-soluble and water-insoluble derivatives contain all the nutrients at different levels. They are gluten and lactose free and do not give rise to any food allergy. 

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. 

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. 

Hercberg, S. et al.. The SU.VI.MAX Study a randomized, placebo-controlled trial of the health effects of antioxidant vitamins and minerals. Arch. Intern. Med., 164, 2335, 2004. 

Heart Protection Study Collaborative Group, MRC/BHF Heart Protection Smdy of antioxidant vitamin supplementation in 20,536 high-risk individuals a randomised placebo-controlled trial. Lancet, 360, 23, 2002. 

Snodderly, D.M., Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Am. J. Clin. Nutr, 62, 1448S, 1995. 

Results obtained in in vivo and ex vivo experiments are of various types. Some studies have found positive effects of the consumption of carotenoids or foods containing carotenoids on the markers of in vivo oxidative stress, even in smokers. Other studies demonstrated no effects of carotenoid ingestion on oxidative stress biomarkers of lipid peroxidation. " It should be noted that for studies using food, the activity observed may also be partly due to other antioxidant molecules in the food (phenols, antioxidant vitamins) or to the combination of actions of all the antioxidants in the food. 

Abushita, A.A., Daood, H.G., and Biacs, P.A., Change in carotenoids and antioxidant vitamins in tomato as a function of varietal and technological factors, J. Agric. Food Chem., 48, 2075, 2000. 

Steinberg, D. (1993). Antioxidant vitamins and coronary heart disease. N. Engl. J. Med. 328, 1487-1489. 

Singh, V.S. and Gaby, S.K. (1991). Premalignant lesions role of antioxidant vitamins and /3-carotene in risk reduction and prevention of malignant transformation. Am. J. Clin. Nutr. 53, 386S-390S. 

Epidemiological studies in Europe reveal an inverse relationship between plasma vitamin E levels and the incidence of ischaemic heart disease (Gey and Puska 1989), and the risk of angina pectoris appears to increase with low plasma levels of vitamins E, A and C (Rie-mersma et al., 1991). These interesting observations require further population-based controlled intervention trials with specific supplements of antioxidant vitamins (Gey etal., 1991). 

Routine antioxidant vitamin supplementation, e.g. with vitamins C and/or E, of the diabetic diet should be considered. Vitamin C depletion is present in all diabetics irrespective of the presence of vascular disease. A recent study demonstrated no significant difference between the dietary intake of vitamin C (the main determinant of plasma ascorbate) in patients with diabetes and age-matched controls, confirming the view that ascorbate depletion is secondary to the diabetic process and su esting that diabetic patients require additional intakes of the vitamin to maintain optimal levels (Sinclair et /., 1994). Antioxidant supplementation may have additive beneficial effects on a wide variety of processes involved in diabetic vascular damage including blood pressure, immune function, inflammatory reactions. 

Within the gut, oxidative damage may be prevented by phytic acid, obtained from cereals and vegetables (Graf et al., 1987), and by soluble non-starch polysaccharides like pectin (Kohen et al., 1993). The use of antioxidant vitamins in the treatment of inflammatory bowel disease has also been su ested (Evans et al., 1990). 

Oxidization of LDL-cholesterol is believed to play a significant role in the atherosclerotic process. The antioxidant vitamins, vitamin E and vitamin C, protect LDL cholesterol from oxidation. Evidence from observational and animal studies suggested that increased intake of antioxidant vitamins might inhibit the formation of atherosclerotic lesions and decrease the risk for cardiovascular events.40 However, several large, randomized, prospective studies found no beneficial effect of vitamin E or other antioxidants on cardiovascular outcomes in patients with IHD or IHD risk factors.41,42 Based on this evidence, current guidelines do not recommend supplementation with vitamin E or other antioxidants for the sole purpose of preventing cardiovascular events. 

Other dietary factors implicated in prostate cancer include retinol, carotenoids, lycopene, and vitamin D consumption.5,6 Retinol, or vitamin A, intake, especially in men older than age 70, is correlated with an increased risk of prostate cancer, whereas intake of its precursor, [3-carotene, has a protective or neutral effect. Lycopene, obtained primarily from tomatoes, decreases the risk of prostate cancer in small cohort studies. The antioxidant vitamin E also may decrease the risk of prostate cancer. Men who developed prostate cancer in one cohort study had lower levels of l,25(OH)2-vitamin D than matched controls, although a prospective study did not support this.2 Clearly, dietary risk factors require further evaluation, but because fat and vitamins are modifiable risk factors, dietary intervention may be promising in prostate cancer prevention. 

Carotenoids are one of the most abundant groups of pigments found in nature. Every year more than 100 million tonnes of them are being synthesized in the biosphere. Nearly 600 molecular species of carotenoids are currently identified (Del Campo et al., 2007). As powerful antioxidants, vitamin precursors, natural colorants, and odorants they became a serious global market commodity accounting for almost 1 billion dollars of the yearly trade (BCC research, 2007). 

Evans, JR, 2006. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev 19(2) CD000254. 

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

Butler, G., Nielsen, J.H., Slots, T., Sanderson, R.A., Eyre, M.D. and Leifert, C. (2007b), Effect of low input dairy management systems on milk composition - II. Fat soluble antioxidants/vitamins . Journal of Dairy Science, submitted. 

Daood HG, Vinkler M, Markus F, Hebshi EA and Biacs PA. 1996. Antioxidant vitamin content of spice red pepper (paprika) as affected by technological and varietal factors. Food Chem 55 365—372. 

Keli SO, Hertog MG, Feskens EJ, Kromhout D. 1996. Dietary flavonoids, antioxidant vitamins, and incidence of stroke the Zutphen Study. Arch Intern Med 156 637-642. 

Abushita AA, Hebshi EA, Daood HG and Biacs PA. 1997. Determination of antioxidant vitamins in tomatoes. 

Barth MM and Zhuang H. 1996. Packaging design affects antioxidant vitamin retention and quality of broccoli florets during postharvest storage. Postharv Biol Technol 9 141—150. 

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