Vitamin B6: What is it?

Vitamin B₆ is a water-soluble vitamin that exists in three major chemical forms: pyridoxine, pyridoxal, and pyridoxamine. 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, and it is also needed for the conversion of tryptophan (an amino acid) to niacin (a vitamin).

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.

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.

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.

What foods provide vitamin B6?

Vitamin B₆ is found in a wide variety of foods including fortified cereals, beans, meat, poultry, fish, and some fruits and vegetables. The table of selected food sources of vitamin B₆ suggests many dietary sources of B₆.

Table of Food Sources of Vitamin B₆

Food	Milligrams (mg) per serving	% DV*
Ready-to-eat cereal, 100% fortified, ¾ c	2.00	100
Potato, Baked, flesh and skin, 1 medium	0.70	35
Banana, raw, 1 medium	0.68	34
Garbanzo beans, canned, ½ c	0.57	30
Chicken breast, meat only, cooked, ½ breast	0.52	25
Ready-to-eat cereal, 25% fortified, ¾ c	0.50	25
Oatmeal, instant, fortified, 1 packet	0.42	20
Pork loin, lean only, cooked, 3 oz	0.42	20
Roast beef, eye of round, lean only, cooked, 3 oz	0.32	15
Trout, rainbow, cooked, 3 oz	0.29	15
Sunflower seeds, kernels, dry roasted, 1 oz	0.23	10
Spinach, frozen, cooked, ½ c	0.14	8
Tomato juice, canned, 6 oz	0.20	10
Avocado, raw, sliced, ½ cup	0.20	10
Salmon, Sockeye, cooked, 3 oz	0.19	10
Tuna, canned in water, drained solids, 3 oz	0.18	10
Wheat bran, crude or unprocessed, ¼ c	0.18	10
Peanut butter, smooth, 2 Tbs.	0.15	8
Walnuts, English/Persian, 1 oz	0.15	8
Soybeans, green, boiled, drained, ½ c	0.05	2
Lima beans, frozen, cooked, drained, ½ c	0.10	6
* DV = Daily Value. DVs are reference numbers based on the Recommended Dietary Allowance (RDA). They were developed to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for vitamin B6 is 2.0 milligrams (mg). The percent DV (%DV) listed on the nutrition facts panel of food labels tells you what percentage of the DV is provided in one serving. Percent DVs are based on a 2,000 calorie diet. Your Daily Values may be higher or lower depending on your calorie needs. Foods that provide lower percentages of the DV also contribute to a healthful diet.

What is the Recommended Dietary Allowance for vitamin B6 for adults?

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:

Life-Stage	Men	Women	Pregnancy	Lactation
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) 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 .

When can a vitamin B6 deficiency occur?

Clinical signs of vitamin B₆ deficiency are rarely seen in the United States. Many older Americans, however, have low blood levels of vitamin B₆, which may suggest a marginal or sub-optimal vitamin B₆ nutritional status. Vitamin B₆ deficiency can occur in individuals with poor quality diets that are deficient in many nutrients. Symptoms occur during later stages of deficiency, when intake has been very low for an extended time. Signs of vitamin B₆ deficiency include dermatitis (skin inflammation), glossitis (a sore tongue), depression, confusion, and convulsions . Vitamin B₆ deficiency also can cause anemia. Some of these symptoms can also result from a variety of medical conditions other than vitamin B₆ deficiency. It is important to have a physician evaluate these symptoms so that appropriate medical care can be given.

Who may need extra vitamin B₆ to prevent a deficiency?
Individuals with a poor quality diet or an inadequate B₆ intake for an extended period may benefit from taking a vitamin B₆ supplement if they are unable to increase their dietary intake of vitamin B₆ . Alcoholics and older adults are more likely to have inadequate vitamin B₆ intakes than other segments of the population because they may have limited variety in their diet. Alcohol also promotes the destruction and loss of vitamin B₆ from the body.

Asthmatic children treated with the medicine theophylline may need to take a vitamin B₆ supplement. Theophylline decreases body stores of vitamin B₆ , and theophylline-induced seizures have been linked to low body stores of the vitamin. A physician should be consulted about the need for a vitamin B₆ supplement when theophylline is prescribed.