A. Vitamin B6 - a water-soluble B complex vitamin, as we just explained — comes in three chemically related forms. The most common form, pyridoxine, is used in vitamin supplements and food fortification.
Q. Exactly what role does vitamin B6 play in the body?
A. Like most of the other B complex vitamins, B6 plays a part in the biochemical processes which result in the release of energy from food, part of the process of metabolism. It helps to convert the calories we take in as carbohydrates into usable energy, through complex chemical reactions involving oxygen. Without a dietary source of B6, the carbohydrates we eat are incompletely metabolized, allowing compounds to build up to toxic levels in the blood. It is these toxic compounds which are thought to be a significant cause of vitamin-deficiency symptoms.
Vitamin B6, like all the B vitamins, is a coenzyme and is required for the proper functioning of more than 60 enzymes. It is converted in the liver, the red blood cells and other tissues into biochemicals necessary for metabolism. It is also essential for the body's manufacture of nucleic acids, the genetic building blocks for all cells.
Vitamin B6 plays a role in cell multiplication, including the red blood cells and cells of the immune system. Deficiencies can cause anemia and lowered resistance to infection,
Does B6 play any role in cancer prevention?
It may, both through its effects on immune function and proper cell replication. Low blood levels of B6 have been found in people with breast cancer and Hodgkin's disease (a cancer of the lymph nodes). And animals deprived of B6 seem to be more vulnerable to virus deprived of B6 seem to be more vulnerable to virus-induced malignant tumors.
Q Does it have any other important functions?
A Vitamin B6 also influences the nervous system, through its effect on minerals and neurotransmitters — the messengers of the central nervous system. B6 is necessary for the body to convert tryptophan, a constituent of protein, to serotonin, an important brain neuro-transmitter with many physiological functions. Concentrations of B6 are up to 25 to 50 times higher in the brain than in the blood.
Q What does vitamin B6 have to do with fighting infection?
A Both animals and humans with B6 deficiencies have severely depressed immune responses, more so than with deficiencies of any other B vitamins. Many different aspects of the immune response are affected, including the number of infection-fighting white blood cells and their ability to identify a particular type of disease-causing invader and launch an attack. Many researchers believe that getting adequate amounts of vitamin B6 can improve immune response.
Researchers at the American Human Nutrition Research Center on Ageing have shown that B6 supplements can boost immunity in older healthy people, reversing what was considered to be an age-related slowing down of the immune system which puts them at risk of infection and, possibly, cancer.
Q. You said that B6 is essential for certain brain chemicals. Is vitamin B6 ever used to treat mental disorders?
A. Yes. Vitamin B6 has been used for a variety of mental symptoms, although its use is considered controversial. Researchers at Tufts University have reported that B vitamin supplements, including B6, improved symptoms of depression and mental performance in men aged 70 To 79. In the study, all the men were given an antidepressant medication, and half also took a supplement containing 10 mg each of B, B2 and B6.
Q. Isn't vitamin B6 sometimes also recommended to women who have premenstrual syndrome?
A. Yes. In two small studies, doses of 500 mg of vitamin B6 did seem to provide some relief from symptoms of breast tenderness, headaches, fluid retention, irritability and nausea associated with premenstrual syndrome. We should add that this dosage could be dangerous and that trials of this kind, where subjective factors are involved, are often suspect. The placebo effect can be more powerful than most people appreciate.
Q.What else is vitamin B6 used for?
A. Daily doses are said to protect people from the 'Chinese restaurant syndrome' - headaches, flushing, rapid heartbeat and tightening around the temples and neck, which some people develop when they eat monosodium glutamate (MSG — an ingredient often used in Chinese food). However, people who have this problem would be well advised to avoid Chinese food. Vitamin B6 has been used for years to treat morning Vitamin B6 has been used for years to treat morning sickness, and a study by researchers at the University Of Iowa College Of Medicine found it really works. Pregnant women who took 25 rng every 8 hours for 72 hours experienced significant relief from severe nausea and vomiting, compared with a group taking placebos, or harmless 'blank' pills. It appeared to have no effect on mild nausea, however.
Q.Anything else it's good for?
A. Some research also suggests that vitamin B6 deficiency may play a role in the development of some kinds of kidney stones, in raising the risk of heart disease, in worsening some types of seizure disorders, and in the development of diabetes-associated cataracts. Some doctors use supplements of vitamin B6 and other B vitamins to help recovering alcoholics regain normal neurological and psychological function.
VITAMIN B6
QUICK-REFERENCE GUIDE
RNI
Men: 2 mg Women: 1.6 mg
Sources
Vitamin B6 is widely distributed in foods. The richest sources are chicken, fish, liver, kidney, pork and eggs. Other good sources include brown rice, soybeans, oats, whole-wheat products, peanuts and walnuts.
Signs of Deficiency
Deficiency rarely occurs alone, and is most commonly seen in people who are deficient in several B complex vitamins. Signs of deficiency include weakness; sleeplessness, nerve problem in the hands and feet, inflamed lips, tongue and mouth and reduced resistance to infection.
Possible toxicity Problems
Taken in large amounts for a long period of time vitamin B6 can cause walking and severe sensory neuropathy loss of sensation in the feet and hands.
Toxicity has been observed although rarely with cloths 100 and 200 mg. most problems however observed in men and women have occurred at doses higher than 500 mg a day.
