For an Immune System Boost, Folic Acid Supplements?

Fri, 4 Nov. 2011 - 9:22 p.m. MT
Credit: ARA Staff - American Running Association

Folic acid is the synthetic form of folate, a B vitamin that occurs naturally in some foods, including vegetables, fruits, beans, and peas. Folate is vital for the production and maintenance of our bodies’ cells, especially during rapid periods of growth—infancy, adolescence, and pregnancy in particular. Folate is needed to make DNA and RNA, the genetic material that dictates cell functions, and there is plenty of evidence that it helps prevent changes to DNA that may lead to cancer.

Since folate helps make and repair DNA, it makes sense that a deficiency of the vitamin could hamper immunity. What does the science say about taking extra folic acid to boost the immune system? As Harvard Women’s Health Watch editor Celeste Robb-Nicholson, MD, points out, in some animal experiments, severe folate deficiency has been found to impair immunity. However, this finding has yet to be duplicated in human studies. The fact is, even in animals, the health impact remains unclear.

For most healthy adults, the Recommended Dietary Allowance (RDA) of folate—from natural as well as fortified foods and vitamin supplements—is 400 micrograms (mcg) a day. Pregnant women should take more, about 600 mcg a day. This reduces the risk of neural tube defects such as spina bifida.

For the rest of us, taking higher than recommended doses of folate or folic acid to prevent disease or improve overall health is not necessarily toxic, but not presently recommended either. The evidence from clinical trials is conflicting. The Tolerable Upper Intake Level for folic acid from supplements or fortified foods is 1,000 mcg a day. Folic acid is water-soluble and any excess is excreted in the urine, so the risk of toxicity is small even if you exceed that limit. However, experts are uncertain about the long-term health effects of excess folic acid supplementation.

Naturally occurring folate from foods is not associated with any health risk, so get as much of your daily requirement as you can from a healthy diet. If that’s not possible, take a multivitamin that contains 400 mcg of folic acid.

Others who may need more than the RDA include people with intestinal disorders that interfere with absorption of nutrients, as well as people who take certain medications. Anticonvulsants such as phenytoin (Dilantin) interact in complex ways with folic acid; tell your doctor and pharmacist what medication you are taking before beginning a folic acid supplement.

In general, the evidence favors a folic acid supplement for epileptic women prior to pregnancy to reduce the risk of fetal abnormality. One study found that preconceptional folic acid supplementation is effective in preventing major congenital malformations in the newborns of women with epilepsy taking antiepileptic drugs. The authors report that “[s]upplementing with at least 0.4 mg of folic acid before pregnancy may be considered.”

However, remember that folic acid pills are typically used to treat or prevent dietary folic acid deficiency. Folate is a B-complex vitamin needed by the body to manufacture red blood cells, and a deficiency of this vitamin causes certain types of anemia.

If you are taking folic acid to treat a deficiency, you probably will feel better quickly, often within 24 hours. Still, do not stop taking the drug until your doctor tells you to do so. In the long haul, your doctor may tell you to eat more liver, as well as foods prepared from dried yeast, fruit, and fresh leafy green vegetables to increase the folic acid in your diet naturally. Smart food choices will always better serve dietary needs than pill supplements.

NCBI U.S. National Library of Medicine, National Institutes of Health, PubMed Health, September 2008, “Folic Acid,” http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000723

Harvard Health Newsletter, February 2011, “Does Folic Acid Improve Immunity?” http://view.mail.health.harvard.edu/?j=fe5816757d6d07787016&m=febb15747d630d7a&ls=fde71c78706d0d7b71137075&l=fe57157677630c7b7217&s=fe2e157574600775771776&jb=ffcf14&ju=fe1e16797d65037b7c1576&r=0

Epilepsia, 2009 May;50(5):1247-55, http://www.ncbi.nlm.nih.gov/pubmed/19507305

(RUNNING & FITNEWS^® January / February 2011 • Volume 29, Number 1)