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Vitamin B6, Vitamin B12, and Folic Acid

July 1st, 2005

One of the advances that changed the way we look at vitamins was the discovery that too little folic acid, one of the eight B vitamins, is linked to birth defects such as spina bifida and anencephaly. Fifty years ago, no one knew what caused these birth defects, which occur when the early development of tissues that eventually become the spinal cord, the tissues that surround it, or the brain goes awry. Twenty five years ago, British researchers found that mothers of children with spina bifida had low vitamin levels. Eventually, two large trials in which women were randomly assigned to take folic acid or a placebo showed that getting too little folic acid increased a woman’s chances of having a baby with spina bifida or anencephaly and that getting enough folic acid could prevent these birth defects.

Enough folic acid, at least 400 micrograms a day, isn’t always easy to get from food. That’s why women of childbearing age are urged to take extra folic acid. It’s also why the US Food and Drug Administration now requires that folic acid be added to most enriched breads, flour, cornmeal, pastas, rice, and other grain products, along with the iron and other micronutrients that have been added for years.

The other exciting discovery about folic acid and two other B vitamins is that they may help fight heart disease and some types of cancer. It’s too early to tell if there’s merely an association between increased intake of folic acid and other B vitamins and heart disease or cancer, or if high intakes prevent these chronic diseases.

Folic Acid: The current recommended intake for folic acid is 400 micrograms per day. There are many excellent sources of folic acid, including prepared breakfast cereals, beans, and fortified grains.

Vitamin B6: A healthy diet should include 1.3 to 1.7 milligrams of vitamin B6. Higher doses have been tested as a treatment for conditions ranging from premenstrual syndrome to attention deficit disorder and carpal tunnel syndrome. To date, there is little evidence that it works.

Vitamin B12: The current recommended intake for vitamin B12 is 6 micrograms per day. Vitamin B12 deficiency can be caused by pernicious anemia, due to a lack of “intrinsic factor” (a substance secreted by gastric cells that binds to vitamin B12 and enables its absorption). A more common cause of deficiency is often diagnosed in older people who have difficulty absorbing vitamin B12 from unfortified foods; such people can typically absorb vitamin B12 from fortified foods or supplements, however, providing yet another reason to take a multivitamin. Symptoms of B12 deficiency include memory loss, disorientation, hallucinations, and tingling in the arms and legs. Some people diagnosed with dementia or Alzheimer’s disease are actually suffering from the more reversible vitamin B12 deficiency.

Entry Filed under: Vitamins & Minerals

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