Too much folate unhealthy for some seniors: study

By Anne Harding

NEW YORK (Reuters Health) - Older people who are deficient in vitamin B12 may run the risk of developing anemia and cognitive impairment if they're getting too much folate, a new study shows.

Studies have suggested that excess folate can mask or worsen vitamin B-12 deficiency, which is common among older people. Given that the US has been fortifying all enriched cereal-grain products with folate since 1998 in order to prevent pregnant women from having children with neural tube birth defects, it's possible that many people may be getting too much of the nutrient, researchers say.

To investigate the interaction between folate and vitamin B-12 in older people, Dr. Martha Savaria Morris of Tufts University in Boston and colleagues looked at blood levels of the nutrients and risk of anemia and cognitive impairment in nearly 1,500 people participating in a national survey on nutrition. About one-quarter of the men and women in the study had low blood levels of vitamin B-12.

Subjects with low serum vitamin B-12 and high serum folate were 2.6 times more likely to have cognitive impairment and 3.1 times more likely to have anemia, the researchers found. However, among people with normal B-12 levels, high levels of folate were protective against cognitive impairment.

It is extremely difficult for a person to know whether or not he or she has adequate levels of B-12, Morris told Reuters Health, given that there's no real "gold standard" test. People must consume adequate amounts of the nutrient, which is contained in animal proteins, but a substance called intrinsic factor must be present in the stomach in order for people to absorb B-12 properly.

The best approach, Morris added, is for seniors to keep an eye on their folate intake. "It's hard not to get enough folate at this point, and if you're eating a lot of fortified foods and combining that with vitamin use then you're probably increasing the chance of being in a high folate category," she said.

She advises seniors to look at the folate content of the enriched foods they're eating, for example breakfast cereals. "If you're already get 1200 percent of your required folate from your breakfast cereal, a multivitamin is questionable."

Older people should not take a supplement with folic acid unless their doctor recommends it, Morris said. The only younger people who need to be concerned about getting too much folate, she added, are vegetarians who are not taking B-12 supplements.

SOURCE: American Journal of Clinical Nutrition, January 2007.