reported in humans, high dosages have caused liver damage in rats.Deficiencies and Toxicity of Vitamin B6 (Pyridoxine)Vitamin B6, or pyridoxine, has an effect on over 60 proteins in the body, importantly, those that play a role in the nervous system, in red and white blood cell production, and in heart disease. Food sources of B6 are meats, oily fish, poultry, whole grains, dried fortified cereals, soybeans, avocados, baked potatoes with skins, watermelon, plantains, bananas, peanuts, and brewer's yeast. Current DRI recommendations are 2 mg in all adults, although for heart protection some experts recommend 3 to 6 mg. Deficiencies are very uncommon but can cause skin problems and nervous system disorders, including impaired memory and concentration. They may also increase the risk for kidney stones. In rare cases, infants are born unable to metabolize pyridoxine; in such cases seizures or convulsions can occur, and vitamin B6 must be administered. Deficiency is associated with increased levels of the chemical homocysteine, which is turn has been associated with heart disease, birth defects, and possibly Alzheimer's disease and dementia. (It is not known if reducing homocysteine levels will have any protective effect.) A diet rich in fruits and vegetables may reduce homocysteine levels. Very high doses (2,000 mg per day) can cause nerve damage with symptoms of instability and numbness in the feet and hands, which may be permanent in some cases. In some cases, the damage may be permanent. Pyridoxine also reduces the effects of L-dopa, the drug used for Parkinson's disease.Deficiencies and Toxicity of Vitamin B12 (Cobalamin)Vitamin B12 is essential for the production of blood cells, manufacturing genetic material, and for healthy functioning of the nervous system. The only natural dietary sources of B12 are animal products, meats, dairy products, eggs, and fish (clams and oily fish are very high in B12); like other B vitamins, however, B12...
