ications.General Toxicity of Vitamin BBecause the B vitamins are water-soluble and eliminated in the urine, toxic reactions from oral administration of most of them are extremely rare. (Exceptions are niacin and B6.) (For specific adverse reactions from deficiencies or high dosage levels, see individual discussions of B vitamins, below). It should be noted that substances known as B15 (pangamic acid) and B17 (laetrile) are neither vitamins nor nutrients; both chemicals are highly dangerous and have no proven nutritional or other value.Deficiencies and Toxicity of Vitamin B1 (Thiamin)Thiamin is essential for converting blood sugar into energy and is involved in metabolic activities in nerves, heart, and muscles and in the production of red blood cells. Thiamin is found in almost all foods, but the best source is pork and good sources are dried fortified cereals, oatmeal, corn, nuts, cauliflower, and sunflower seeds. Recommended RDA is 1.2 mg per day for men and 1.1 mg for women. Supplements for people with normal diets and health are unnecessary. Severe vitamin B1 deficiency, known as beriberi, is rare in the U.S., but can occur in alcoholics, in severely malnourished people, or in those receiving long-term dialysis or intravenous feeding. Symptoms may include visual disturbances, paralysis, staggering, loss of sensation in the legs and feet, psychosis, and congestive heart failure. No toxic effects have been reported for thiamin.Deficiencies and Toxicity of Vitamin B2 (Riboflavin)Like thiamin, riboflavin is important in the production of energy. Some dietary sources are liver, dried fortified cereals, and low fat yogurt. Recommended DRI is 1.7 mg. Supplements for people with normal diets and health are unnecessary. Deficiencies affect the skin and mucous membranes and can cause cracks on the lips or corners of the mouth, eczema of the face and genitals, a burning sensation on the tongue, or eye irritation. Previously, no toxic effects h...
