Folate antioxidant vitamins

Evidence that a diet rich in fruits and vegetables may protect against coronary heart disease is accumulating. It is unclear exactly which substances in fruits and vegetables are responsible for the observed inverse association with cardiovascular disease. The inverse association may be attributed to folate, antioxidant vitamins, or other constituents such as fiber, potassium, fla-vonoids, or other phytochemicals. The protective effect of folate may be attributed to its role as a cosubstrate in homocysteine metabolism (Eichholzer et al., 2001). 

The observed associations between folate, antioxidant vitamins, and cardiovascular disease may be confounded by other substances in fruits and vegetables, as the following examples of studies show Flavonoids (see Chapter 31) are naturally occurring, water-soluble antioxidants found widely distributed in vegetables, fruits, tea, and wine. There is an inverse relationship between flavonoids and decreased risk of coronary heart disease. Lycopene, the key antioxidant in tomatoes, shows an inverse association with myocardial infarctions. There is an inverse association between folate and cardiovascular disease. 

Eichholzer, M. et al., The role of folate, antioxidant vitamins and other constituents in fruit and vegetables in the prevention of cardiovascular disease the epidemiological evidence, Int. J. Vitam. Nutr. Res., 71, 5-17, 2001. 

Figure 22.6 How various factors increase the risk of atherosclerosis, thrombosis and myocardial infarction. The diagram provides suggestions as to how various factors increase the risk of development of the trio of cardiovascular problems. The factors include an excessive intake of total fat, which increases activity of clotting factors, especially factor VIII an excessive intake of saturated or trans fatty acids that change the structure of the plasma membrane of cells, such as endothelial cells, which increases the risk of platelet aggregation or susceptibility of the membrane to injury excessive intake of salt - which increases blood pressure, as does smoking and low physical activity a high intake of fat or cholesterol or a low intake of antioxidants, vitamin 6 2 and folic acid, which can lead either to direct chemical damage (e.g. oxidation) to the structure of LDL or an increase in the serum level of LDL, which also increases the risk of chemical damage to LDL. A low intake of folate and vitamin B12 also decreases metabolism of homocysteine, so that the plasma concentration increases, which can damage the endothelial membrane due to formation of thiolactone.

Like folate and vitamin C, vitamin B6 (pyroxidine) is water soluble and like folate has several vitamers. Vitamin B6 may be involved in more bodily functions than any other nutrient (Tambasco-Studart et al., 2005), is a cofactor for many enzymes, especially those involved in protein metabolism, and is also a cofactor for folate metabolism. Vitamin B6 has anticancer activity (Theodoratou et al., 2008), is a strong antioxidant (Denslow et al., 2005), is involved in hemoglobin biosynthesis, lipid and glucose metabolism and immune and nervous system function. Possible consequences of deficiency include anemia, impaired immune function, depression, confusion, and dermatitis (Spinneker et al., 2007). Vitamin B6 deficiency is generally not a problem in the developed world, but there could be as yet poorly defined consequences of suboptimal intake particularly for the elderly. 

Data suggest that many nutrients in fruits and vegetables (e.g., dietary fiber, folate, potassium, flavonoids, and antioxidant vitamins) are associated with reduced risk of CVD. These findings are consistent with smdies showing an association between decreased risk of CVD and total intake of fruits and vegetables (Figure 9.1). Knekt... 

Nuts are another food group promoted for preventing CVD and commonly consumed as part of the MeD. In particular, cardiovascular benefits of moderate nut intake have been observed lowering risk factors in trials and reducing CVD risk in prospective cohort studies/ Nuts contain several macro- and micronutrients which could be responsible for the aforementioned effects. These include unsaturated fatty acids, plant proteins, folate, fiber and antioxidant vitamins and phytochemicals. 

Folate is a relatively unstable nutrient processing and storage conditions that promote oxidation are of particular concern since some of the forms of folate found in foods are easily oxidized. The reduced forms of folate (dihydro- and tetrahydrofolate) are oxidized to p-aminobenzoylglutamic acid and pterin-6-carboxylic acid, with a concomitant loss in vitamin activity. 5-Methyl-H4 folate can also be oxidized. Antioxidants (particularly ascorbic acid in the context of milk) can protect folate against destruction. The rate of the oxidative degradation of folate in foods depends on the derivative present and the food itself, particularly its pH, buffering capacity and concentration of catalytic trace elements and antioxidants. 

Possibly beneficial effects of intakes more than adequate to meet requirements the promotion of optimumhealth and life expectancy. There is evidence that relatively high intakes of vitamin E and possibly other antioxidant nutrients (Section 4.6.2) may reduce the risk of developing cardiovascular disease and some forms of cancer. High intake of folate during early pregnancy reduces the risk of neural tube defects in the fetus (Section 10.9.4). 

Food additives can enhance the safety and nutritional quality of a food or vice versa. By preventing oxidation of fat and easily oxidized vitamins, antioxidants ensure that safety is enhanced and the intended nutritional value of the food is delivered. Antibrowning agents such as sulfite retain phytochemicals and vitamins A and C but lower the amount of thiamine, folate, and pyridoxal. Sorbic acid can prevent... 

Seaweeds are generally a good source of some B group vitamins (Bi, E2, B12). Other vitamins of B-complex are present too, but only in low or trace amounts (niacin, Bg, biotin, folates). Certain seaweeds contain great quantities of vitamins with antioxidant activity, vitamins C and E, and the provitamin forms of vitamin A, carotenoids. 

Jain MG, Hislop GT, Howe GR, Ghadirian P (1999) Plant foods, antioxidants, and prostate cancer risk findings from case, control studies in Canada. Nutr Cancer 34 173-184 Beilby J, Ambrosini GL, Rossi E, De Klerk NH, Musk AW (2010) Serum levels of folate, lycopene, P-carotene, retinol and vitamin e and prostate cancer risk. Eur J Clin Nutr 64 1235-1238... 

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