Detailed information on vitamin B6, uses of vitamin B6, signs and symptoms of vitamin B6 deficiency, and vitamin B6 supplements.
Dietary Supplement Fact Sheet: Vitamin B6
Table of Contents
- Vitamin B6: What is it?
- What foods provide vitamin B6?
- What is the Recommended Dietary Allowance for vitamin B6 for adults?
- When can a vitamin B6 deficiency occur?
- What are some current issues and controversies about vitamin B6?
- What is the relationship between vitamin B6, homocysteine, and heart disease?
- What is the health risk of too much vitamin B6?
- Selected Food Sources of vitamin B6
Vitamin B6 is a water-soluble vitamin that exists in three major chemical forms: pyridoxine, pyridoxal, and pyridoxamine [1,2]. It performs a wide variety of functions in your body and is essential for your good health. For example, vitamin B6 is needed for more than 100 enzymes involved in protein metabolism. It is also essential for red blood cell metabolism. The nervous and immune systems need vitamin B6 to function efficiently, [3-6] and it is also needed for the conversion of tryptophan (an amino acid) to niacin (a vitamin) [1,7].
Hemoglobin within red blood cells carries oxygen to tissues. Your body needs vitamin B6 to make hemoglobin. Vitamin B6 also helps increase the amount of oxygen carried by hemoglobin. A vitamin B6 deficiency can result in a form of anemia  that is similar to iron deficiency anemia.
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An immune response is a broad term that describes a variety of biochemical changes that occur in an effort to fight off infections. Calories, protein, vitamins, and minerals are important to your immune defenses because they promote the growth of white blood cells that directly fight infections. Vitamin B6, through its involvement in protein metabolism and cellular growth, is important to the immune system. It helps maintain the health of lymphoid organs (thymus, spleen, and lymph nodes) that make your white blood cells. Animal studies show that a vitamin B6 deficiency can decrease your antibody production and suppress your immune response [1,5].
Vitamin B6 also helps maintain your blood glucose (sugar) within a normal range. When caloric intake is low your body needs vitamin B6 to help convert stored carbohydrate or other nutrients to glucose to maintain normal blood sugar levels. While a shortage of vitamin B6 will limit these functions, supplements of this vitamin do not enhance them in well-nourished individuals [1,8-10].
Vitamin B6 is found in a wide variety of foods including fortified cereals, beans, meat, poultry, fish, and some fruits and vegetables [1,11]. The table of selected food sources of vitamin B6 suggests many dietary sources of B6.
The Recommended Dietary Allowance (RDA) is the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97 to 98 percent) healthy individuals in each life-stage and gender group .
The 1998 RDAs for vitamin B6  for adults, in milligrams, are:
|Ages 19-50||1.3 mg||1.3 mg|
|Ages 51+||1.7 mg||1.5 mg|
|All Ages||1.9 mg||2.0 mg|
|Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III 1988-94) [12,13] and the Continuing Survey of Food Intakes by Individuals (1994-96 CSFII) , indicated that diets of most Americans meet current intake recommendations for vitamin B6 .|