Folic Acid, B12 Combo Reduces Risk of Vascular Disease

DUBLIN, Ireland--Joe McPartlin, Ph.D., and colleagues from St. James's Hospital discovered that folic acid in combination with vitamin B12 lowers plasma total homocysteine (a risk factor for vascular disease) more effectively than folic acid alone. McPartlin and his colleagues published a study in the Jan. 19 issue of the Lancet (359: 227-28, 2002) (www.thelancet.com) as basis for their suggestion that the proposed grain fortification program for the United Kingdom be amended to include vitamin B12 in addition to folic acid.

The researchers investigated the correlation between homocysteine levels and folate and vitamin B12 status before and after folic acid supplementation. The 30 male and 23 female participants were instructed to avoid supplements and foods fortified with folic acid and B vitamins before and during the 36-week study. For 26 weeks, the men were given folic acid at increasing doses, from 100 mcg/d to 400 mcg/d, while the women received 500 mcg/d of folic acid. The supplementation period was followed by a 10-week washout period.

In both groups, homocysteine levels were found to be directly related to serum folate concentrations, with more positive levels occurring with folic acid supplementation. However, as the dose of folic acid increased, homocysteine levels became more dependent on B12 for proper metabolism. Researchers suggested that while homocysteine concentration depends on folate status, supplementing with folic acid shifts the body's dependence to vitamin B12 for regulating homocysteine levels; however, this dependence reverts when folic acid supplementation ceases.

Owing to this finding, researchers concluded that if the mandatory folic acid grain fortification were initiated, this would cause the UK population to become dependent on vitamin B12 for maintaining normal homocysteine metabolism. Another side effect of folic acid supplementation is the masking of vitamin B12 deficiency. Researchers recommended that greater cardio-protective benefits would be had if the mandatory grain fortification program were to include folic acid and vitamin B12.

Phil Harvey, Ph.D., director of science and quality for the National Nutritional Foods Association, noted that the United States' grain fortification program has been dramatically successful in reducing the numbers of neural tube defects in the country. However, he concurred with the study's authors that adding vitamin B12 would only enhance the health benefits. "Folate is very important directly, but it works hand-in-hand with vitamin B12, as well as with vitamin B6 and other nutrients. ... Adding B12 would be a good combination."

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