VITAMINS AND MINERALS
Vitamins are organic molecules needed in very small amounts for normal body functioning. Some vitamins are coenzymes; that is, they are necessary for the functioning of certain enzymes. Others are antioxi-dant vitamins, including vitamins C, E, and beta-carotene (a precursor for vitamin A). Antioxidants prevent damage from free radicals, which are mole-cules that contain an unpaired electron and are highly reactive. The reactions of free radicals can damage DNA, cell membranes, and the cell organelles. Free radicals are formed during some normal body reac-tions, but smoking and exposure to pollution will increase their formation. Antioxidant vitamins com-bine with free radicals before they can react with cel-lular components. Plant foods are good sources of these vitamins. Table 17–5 summarizes some impor-tant metabolic and nutritional aspects of the vitamins we need.
Deficiencies of vitamins often result in disease: vitamin C deficiency and scurvy, for example. Other deficiency diseases that have been known for decades include pellagra (lack of niacin), beri-beri (riboflavin), pernicious anemia (B12), and rickets (D). More recently the importance of folic acid (folacin) for the development of the fetal central nervous sys-tem has been recognized. Adequate folic acid during pregnancy can significantly decrease the chance of spina bifida (open spinal column) and anencephaly (absence of the cerebrum, always fatal) in a fetus. All women should be aware of the need for extra (400 micrograms) folic acid during pregnancy.
Minerals are simple inorganic chemicals and have a variety of functions, many of which you are already familiar with. Table 17–6 lists some important aspects of minerals.
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