Friday, April 5, 2013
Article # 451. Daily Requirements of Vitamin B
Daily Requirements of Vitamin B
The B-vitamin group consists of eight compounds that all play important roles in cellular metabolism. The B vitamins have distinct roles within the body, although they often co-exist together in the same foods, such as organ meats, green leafy vegetables, fish and legumes. B vitamins are water-soluble, dispersed throughout the body and excreted in the urine when in excess, making it necessary to replenish them regularly. The daily requirements of B vitamins vary dramatically.
Vitamin B1, or thiamine, is needed for the catabolism of sugars and amino acids. Daily requirements of thiamine, which is referred to as Recommended Dietary Allowances (RDA), ranges from 0.2mcg for infants under 6 months old to 2.8mcg for lactating females, according to the National Academy of Sciences. Deficiency leads to beriberi, which causes emotional disturbances, impaired sensory perception and pain in the limbs.
Vitamin B2, or riboflavin, is needed for the metabolism of fats, ketone bodies, carbohydrates and proteins. The RDA for riboflavin ranges from 0.3mg for infants under 6 months old to 1.6mg for lactating females. The RDA is the minimum daily amount of a nutrient to prevent acute deficiency symptoms in 97 to 98 percent of individuals. Deficiency causes ariboflavinosis, which manifests as cracked lips, inflammation of the tongue and sensitivity to light.
Vitamin B3, or niacin, is needed for DNA repair and the production of steroid hormones. The RDA for niacin ranges from 2mg in infants under 6 months old, to 17mg for lactating females. Deficiency leads to pellagra, which causes aggression, dermatitis, weakness, mental confusion and diarrhea. Too much niacin can lead to "flushing," or vasodilation of the skin, which includes redness, itching and mild burning.
Vitamin B5, or pantothenic acid, is needed to synthesize coenzyme-A, proteins, carbohydrates and fats. The RDA for pantothenic acid ranges from 1.7mg in infants under 6 months old to 7mg for lactating females. Deficiency, although rare, can result in acne and numbness in the limbs.
Vitamin B6, or pyridoxine, is needed for amino acid metabolism and to govern the release of glucose from glycogen. The RDA for pyridoxine ranges from 0.1mg in infants under 6 months old to 2mg for lactating females. Deficiency leads to microcytic anemia, depression and hypertension.
Vitamin B7, or biotin, is necessary for cell growth, the production of fatty acids and the metabolism of amino acids. The RDA for biotin ranges from 5mcg in infants under 6 months old to 35mcg for lactating females. Deficiency does not usually cause symptoms in adults, but it may lead to neurological disorders in infants.
Vitamin B9, or folic acid, is needed to synthesize and repair DNA, which is crucial during periods of rapid cell division and growth. The RDA for folate ranges from 150mcg in infants under 6 months old to 600mcg for pregnant females. Deficiency in adults results in macrocytic anemia, whereas deficiency in pregnant women can lead to birth defects.
Vitamin B12, or cobalamin, is needed to make DNA and to help maintain healthy nerve and red blood cells. The RDA for cobalamin ranges from 0.4mcg in infants under six months old, to 2.8mcg for lactating females. Deficiency results in macrocytic anemia, peripheral neuropathy, memory loss and other cognitive deficits.