Vitamin B6 — Pyridoxine

Vitamin B6 (Pyridoxine) is a very important B vitamin, especially for women. It seems to
be connected somehow to hormone balance and water shifts in women. Vitamin B6 is actually three related compounds, all of which are found in food–pyridoxine, pyridoxal, and pyridoxamine. Pyridoxal is the predominant biologically active form; however, in vitamin supplements, pyridoxine is the form used because it is the least expensive to produce commercially. Vitamin B6 is stable in acid, somewhat less stable in alkali, and is fairly easily destroyed with ultraviolet light, such as sunlight, and during the processing of food. It is also lost in cooking or with improper food storage.

Pyridoxine is absorbed readily from the small intestine and used throughout the body in a multitude of functions. Fasting and reducing diets usually deplete the vitamin B6 supply unless it is supplemented. Usually within eight hours, much of the excess is excreted through the urine; some B6 is stored in muscle. It is also produced by the intestinal bacteria.

Sources: Vitamin B6 in its several forms is widely available in nature, though not many
foods have very high amounts. Since it is lost in cooking and in the refining or processing of foods, it is not the easiest B vitamin to obtain in sufficient amounts from the diet, especially if we eat much processed food, as it is not one of the vitamins replaced in
“enriched” flour products such as cereals and pastries.

The best sources of vitamin B6 are meats, particularly organ meats, such as liver, and the whole grains, especially wheat. Wheat germ is one of the richest sources. Besides meat, good protein sources of B6 include fish, poultry, egg yolk, soybeans and other dried beans, peanuts, and walnuts. Vegetable and fruit sources include bananas, prunes, potatoes, cauliflower, cabbage, and avocados. As examples of how easily vitamin B6 is lost in the processing of food, raw sugar cane has a good amount, while refined sugar has none; whole wheat flour contains nearly 0.5 mg. of pyridoxine (wheat germ and wheat flakes have much more), while refined wheat flour has almost none, and even whole wheat bread has lost nearly all of its vitamin B6.

Functions: Pyridoxine and its coenzyme form, pyridoxal-5-phosphate, have a wide
variety of metabolic functions in the body, especially in amino acid metabolism and in the central nervous system, where it supports production of gamma-aminobutyric acid (GABA). Many reactions, including the conversion of tryptophan to niacin and arachidonic acid to prostaglandin E2 require vitamin B6. The pyridoxal group is important in the utilization of all food sources for energy and in facilitating the release of glycogen (stored energy) from the liver and muscles. It helps as well in antibody and red blood cell production (hemoglobin synthesis) and in the synthesis and functioning of both DNA and RNA. By helping maintain the balance of sodium and potassium in the body, vitamin B6 aids fluid balance regulation and the electrical functioning of the nerves, heart, and musculoskeletal system; B6 is needed to help maintain a normal intracellular magnesium level, which is also important for these functions. The neurotransmitters norepinephrine and acetylcholine and the allergy regulator histamine are all very important body chemicals that depend on pyridoxal-5-phosphate in their metabolism. Also, the brain needs it to convert tryptophan to serotonin, another important antidepressant neurotransmitter.

Pyridoxine is especially important in regard to protein metabolism. Many amino acid reactions depend on vitamin B6 to help in the transport of amino acids across the intestinal mucosa into the blood and from the blood into cells. By itself and with other enzymes,
pyridoxal-5-phosphate helps build amino acids, break them down, and change one to another and is especially related to the production and metabolism of choline, methionine, serine, cysteine, tryptophan, and niacin.

The body has a high requirement for vitamin B6 during pregnancy. It is important for maintaining hormonal and fluid balance of the mother and for the developing nervous system of the baby. Pyridoxine may somehow be related to the development and health of
the myelin covering of the nerves, which allows them to conduct impulses properly.

Uses: With its many functions, there is also a wide range of clinical uses of vitamin B6,
clearly being most helpful when symptoms and diseases are related to a pyridoxine/pyridoxal-5-phosphate depletion or deficiency. Recently there has been widespread use of higher doses of B6, usually from 50-200 mg. per day (though some studies use 500 mg. per day of pyridoxine in time-release form) for premenstrual symptoms, especially water retention, which can lead to breast soreness and emotional tension. Pyridoxine has been very helpful in this role, probably because of its diuretic effect through its influence on sodium-potassium balance and its mysterious influence on the hormonal system. Vitamin B6 also helps with the acne that often develops premenstrually, as well as with dysmenorrhea, or menstrual pain; magnesium is usually used as well in all of these menstrual-related problems. In pregnancy, B6 has been helpful in many women for controlling the nausea and vomiting of morning sickness, which some authorities feel is highly related to vitamin B6 deficiency.

It seems that whenever there are increased levels of estrogen in the body, more B6 is required. This occurs not only in pregnancy but also for women who take birth control pills and those postmenopausal women on estrogen treatment as well. It is likely that some of the emotional symptoms experienced by many women on the pill, such as fatigue, mood swings, depression, and loss of sex drive, may be related to a deficiency of B6 and thereby helped by supplementation.

Vitamin B6 is used for people with stress conditions, fatigue, headaches, nervous disorders, anemia, and low blood sugar or diabetes, and in men for prostatitis, low sex drive, or hair loss. Pyridoxal-5-phosphate (P5P) is occasionally used in formulas or as an individual supplement for certain conditions. As the active coenzyme of pyridoxine, P5P can go more directly into the metabolic cycles and does not have to be converted; thus, it may be more helpful than pyridoxine alone in such problems as fatigue, allergies, viral disease, chemical sensitivities, mental illness, and cancer. Pyridoxine supplementation is also used for a variety of skin problems–dandruff, eczema, dermatitis, and psoriasis. In regard to the nervous system, vitamin B6 has been supportive in cases of epilepsy, Parkinson’s disease, multiple sclerosis, and neuritis. Vitamin B6 therapy, from 100-300 mg. daily for 8-12 weeks, appears to reduce carpal tunnel syndrome and increase the ability to use the hands in most patients.

Pyridoxine is a natural diuretic and is often helpful not only for the previously mentioned premenstrual problems but also in overweight and fluid-retaining people and as an adjunct to blood pressure control. Vitamin B6 (along with magnesium) has received some note in regard to preventing the formation of kidney stones or the recurrence of stones in those who have had them. In his book Nutrition and Vitamin Therapy (Grove Press, 1980), Michael Lesser, M.D., states that in a study reported in 1974 by the Journal of Urology, 10 mg. of vitamin B6 and 300 mg. of magnesium oxide prevented recurrence in about 80 percent of patients with a long history of kidney and urinary tract stone formation. Dr. Lesser also noted that the B6-magnesium combination helps in some hyperactive kids and those with fits or problems of autism. He states that pyridoxine in fairly large doses will stimulate dream activity as well as reduce the potential toxicity of barbiturate drugs, carbon monoxide and some other chemical exposures, and irradiation. Vitamin B6 works best when taken with magnesium, zinc, riboflavin, and brewer’s yeast or the other B vitamins.

Pyridoxine, probably more than the other B vitamins except folic acid, is supportive of healthy immune function. B6 deficiency can produce immune weakness, and B6 treatment may be helpful against infections and cancer. Recent studies have shown that pyridoxine can inhibit the growth of some cancer cells, specifically mice and human melanoma cells. Further research with B6 will likely find an even wider range of uses.

Deficiency and toxicity: There is basically no toxicity with pyridoxine at reasonable daily
dosages, though there has been some recent concern about this. Regular oral intake of 200 mg. and intravenous doses of 200 mg. have shown no side effects. Usually, the toxic doses are much higher, between 2Ð5 grams. Some recent reports in the medical literature show that regular usage of over 2,000 mg. per day, which some women especially have been taking, are correlated with episodes of peripheral neuritis. Although the experience of weakness or tingling of arms or legs has been transient and mostly correctable by decreasing the B6 dosage, this does warrant some concern about excessive use of B6, especially long-term use. Since part of the neuropathy problem comes from the liver’s inability to convert all of the pyridoxine to active P5P, this concern can be lessened by supplementing some of the B6 as pyridoxal-5-phosphate (as I have done in many of my programs), especially when the dose of vitamin B6 exceeds 200 mg. per day. In addition, using increased amounts of magnesium with the higher levels of vitamin B6 will reduce the occurrence of the peripheral neuritis.

Deficiency, as usual, is a bigger concern with vitamin B6, as it is with all the B vitamins. So many functions are performed by pyridoxine that its deficiency affects the whole body. Most of these deficiency symptoms are fairly vague. Muscle weakness, nervousness, irritability, and depression are not uncommon. Many of the symptoms are similar to those of both niacin and riboflavin deficiencies; depression is common in all of them.

Metabolically, pyridoxine deficiency has a dramatic effect on amino acid metabolism, with a decreased synthesis of niacin from
tryptophan, a decrease in neurotransmitter chemicals, and a decrease in hemoglobin production. Fatigue, nervous system symptoms, and anemia are all influenced by deficiency. Further nerve-related problems include paraesthesia, incoordination, confusion, insomnia, hyperactivity, and, more severely, neuritis, electroencephalogram (EEG) changes, and convulsions. Other problems include dermatitis or cracks and sores at the corners of the mouth and eyes and visual disturbances.

There is special concern about deficiency during pregnancy, when vitamin B6 needs are higher, as it may cause water retention and the nausea and vomiting of morning sickness and has been correlated with a higher incidence of common problems of later pregnancy, such as toxemia (preeclampsia, high blood pressure, edema, and hyper-reflexes) and eclampsia (those same symptoms plus seizures). B6 deficiency in later pregnancy can be associated with birthing difficulties. There is also an increased likelihood of diabetic and blood sugar problems in pregnancy when vitamin B6 is deficient.

Overall, vitamin B6 deficiency can cause a variety of nervous symptoms, skin problems, and amino acid/protein metabolic abnormalities. These can lead to the more common expressions–headache, dizziness, inability to concentrate, irritability and epileptic-type activity, labile depression, and weakness. Water retention is common. Nausea, vomiting, and dry skin, especially extensive dandruff and a cracked sore mouth and tongue are also more likely with vitamin B6 deficiency.

Requirements: Vitamin B6 intake, though based on many factors, is determined primarily
by protein intake, because it is so important to protein metabolism. The RDA for adults is a minimum of 2 mg. of B6 per 100 grams of protein consumed. In children, it ranges from 0.6-1.2 mg. per 100 grams of protein.

However, the need for vitamin B6 increases in a variety of situations. During pregnancy and lactation and with birth control pill or estrogen use, higher levels are required. For those who eat a high-sugar or processed-food diet or a high-protein diet, requirements for B6 are greater and deficiencies or depletion are more common. When there is impairment of the digestive system, cardiac failure, or radiation use, or even just the aging process, needs for vitamin B6 are increased.

Drugs that influence needs for B6 are oral contraceptives, isoniazid (for tuberculosis), hydralazine (for high blood pressure), amphetamines, reserpine (for high blood pressure), and some antibiotics. More B6 is utilized with an increased intake of the amino acid methionine. Adequate magnesium in the body is important to the functions of vitamin B6.

A safe, basic intake for vitamin B6 is probably 10-15 mg. per day, though much higher daily amounts are easily tolerated. B6 should also be taken along with other B vitamins to prevent metabolic imbalance. For therapeutic purposes, amounts between 50-100 mg. (this is the quantity pyridoxal-5-phosphate usually comes in) are most common, and up to 200-500 mg. per day in time-release forms is used for some conditions, such as premenstrual problems and depression. With the current questions about neurologic side effects associated with megadoses of vitamin B6, particularly as pyridoxine hydrochloride, I suggest limiting regular daily intake to 500 mg. daily or 1,000 mg. for a short course of treatment, such as one to two weeks; also, take some additional magnesium, 200-300 mg, which may help reduce any neurologic concerns.