Vitamin B6

Vitamin B6 is a water-soluble compound (so-called because the human body cannot synthesize it naturally, and must obtain it from diet) that performs a wide variety of functions, and is essential for good health. B6 is involved in the metabolism of protein and red blood cells; the function of the nervous and immune systems, and the conversion of the amino acid tryptophan into the vitamin niacin.

A wide variety of foods serve as sources for B6, including fortified cereals, beans, meat, poultry and some fruits and vegetables. Among the best sources are:

Food                                                                  Milligrams per serving                       %DV (Daily Value)*

________________________________________________________________________

¾ cup ready-to-eat cereal, 100% fortified         2.00                                                        100

Baked potato, flesh and skin, 1 medium            .70                                                            35

Raw Banana, 1 medium                                     .68                                                            34

Garbanzo beans, canned, ½ cup                         .57                                                            30

Chicken breast, meat only, ¼ breast cooked      .52                                                            25

Rainbow trout, cooked, 3 ounces                       .29                                                            15

Avocado, raw, sliced ½ cup                               .20                                                            10

Walnuts, English/Persian, 1 ounce                     .15                                                              8

*DV=Daily Value: reference number based on the Recommended Dietary Allowance. This form of measurement was developed to help consumers determine how much of a specific nutrient is present in a food item. The DV for Vitamin B6 is 2.0 milligrams. The percentage tells you how much of it is provided in a single serving. Percent DVs are based on a 2,000-calorie diet.

Two recent national health surveys indicate that most Americans are getting sufficient B6 in their diets. Men and women ages 19 and older need between 1.3 and 1.5 mg of B6 per day, with pregnant and nursing women needing slightly more (2.0 mg/day).  When deficiencies are seen, they tend to occur in older Americans; symptoms occur during later states of deficiency, when there has been a prolonged lack of B6 intake. Symptoms include dermatitis, depression, confusion and convulsions. A B6 deficiency can decrease the production of antibodies, thus suppressing the immune response and also result in a form of anemia, similar to iron deficiency.

An overdose of B6 can cause nerve damage in the arms and legs. This neuropathy is usually caused by excess intake from supplements, not from food, and is reversible when the dosage is stopped. The Food and Nutrition Board of the Institute of Medicine has established an upper tolerance level for adults of 100 mg per day for all adults.).

References:

National Institutes of Health, Office of Dietary Supplements Factsheets 2007

Modern Nutrition in Health and Disease, 9 th Edition, Baltimore, Williams and Wilkins, 1999

Institute of Medicine, Food and Nutrition Board, Dietary Reference Intakes, National Academy Press, 1998