Pyridoxine, or Vitamin B6, is an extremely important B vitamin involved in the formation of body proteins and other compounds, chemical transmitters in the nervous system, red blood cells and prostaglandines (compounds regulating heart and kidney functions, blood pressure, and allergic response). It is critical in maintaining hormonal balance and proper immune functions.
Vitamin B6 deficiency is charcterized by depression, seizures (especially in infants and young children), glucose intolerance, migraine, chronic pain, depression and impaired nerve function. Studies show that numerious health conditions including asthma, depression, premenstrual syndrome (PMS), morning sickness, and kidney stones respond well to B6 supplementaion.
Good Sources of Vitamin B6
Good sources of vitamin B6 include whole grains, legumes, bananas, seeds and nuts, potatoes, Brussels sprouts, and cauliflower (see below about the bioavailability of B6 from plant foods). Keep in mind that the level of vitamin B6 in your body is linked to the magnesium content of your diet. The RDA for vitamin B6 is 2.0 milligrams for men and 1.6 milligrams for women.
What May Cause Vitamin B6 Deficiency?
1. Poor nutrition - People who get most of their calories from sugar and fat are at greater risk to develop thiamine deficiency. Many adult Americans do not consume the RDA of 1.5-2.0 milligrams and are at greater risk of pyridoxine deficiency-releated health problems.
Vitamin B6 Quick Calculator
So, what daily foods can supply the recommended daily allowance of vitamin B6 and give you that blissful peace of mind and a great feeling of being full of energy? Here is a selection of some foods that can be substituted for similar products in the same category:
- chicken breast, roasted (1/2, app. 3 oz) - 26% of RDA
- beef top round steak, broiled (3oz) - 24% of RDA
- banana (1) - 35% of RDA
- turkey white meat, roasted (3 oz) - 23% of RDA
- fresh tuna, cooked (3 oz) - 23% of RDA
- potato, baked (7 oz) - 35% of RDA
2. Artificial Colorings and Dyes - Some artificial food additives and dyes destroy vitamin B6 or make it inactive. Among most aggressive vitamin B6 antagonists are:
- FD&C Yellow #5 (tartarazine) food color
- drugs such as isoniazid, hydralazine, dopamine, penicillamine; oral contraceptives
Vitamin B6 and Asthma
Clinical studies have shown that some patients with asthma benefit from vitamin B6 supplementaion. Oral supplementation with 50 mg of vitamin B6 twice daily resulted in a dramatic decrease in frequency and severity of wheezing and asthmatic attacks.
Vitamin B6 and Depression
B6 levels are typically quite low in depressed patients, especially women taking birth control or estrogens (Premarin). Depressed individuals with low B6 levels usually respond well to supplementation.
Vitamin B6 and Mental Abilities
Vitamin B6 comprises three chemically distinct compounds pyridoxal, pyridoxamine, and pyridoxine. It is involved in regulating the blood homocysteine levels. High levels of homocysteine in the blood have been suggested as a cause or mechanism in the development of Alzheimer's disease and other forms of dementia. Supplementation with B vitamins including vitamin B6 has been shown to reduce blood homocysteine levels and improve mental function and mood in older people.
Vitamin B6 and Coronary Heart Disease
Recent studies suggest that women who regularly take folic acid and vitamin B6 above the current recommended dietary allowance (RDA) may be at lower risk of developing CHD. Low vitamin B6 levels are also associated with an increased risk of thromboembolism. Thromboembolism is a condition characterized by obstruction of a blood vessel by a blood clot. Supplementation with B vitamins including vitamin B6 may reduce blood homocysteine levels and decrease risk of developing thromboembolism.
It has been noted that vegetarians in general have lower than recommended level of vitamin B6 inspite of the high total intake. This is where the issue of bioavailability comes in. Bioavailability is the fraction of the ingested nutrient that is utilised by the body. The major factors that affect bioavailability of vitamin B-6 are formation of reaction products during food processing and presence of other substances. The bioavailability of vitamin B-6 from animal products is quite high, reaching 100% for many foods. In general the bioavailability from plant foods is lower. The presence of fiber reduces the bioavailability by 5-10% whereas the presence of pyridoxine glucoside reduces the bioavailability by 75-80%. This glucoside is found in a variety of plant foods, with the highest content occurring in the crucifers (broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, Hanover salad, kale,
kohlrabi, mustard, radish, rutabaga, and turnip). Vegetarians therefore should take vitamin B6 supplements.
Pyridoxine deficiency in the diet causes disorders in protein metabolism, for
example in hemoglobin synthesis. Pyridoxine deficiency causes accumulation of
hydroxykynurenic and xanthurenic acids, since conversion of tryptophan to
nicotinic acid is interrupted.
Although its toxicity is low, vitamin B6 is one of the vitamins
about which there is still a dispute on the question of the safety margin. Doses
in the range of 600 mg-6 g a day on chronic administration cause a reversible