Folate findings prompt new attention to proper amounts
■ Avoiding too much of a good thing is important for some older people when determining the correct amount of this vitamin.
By Susan J. Landers — Posted Jan. 29, 2007
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Washington -- Folate has maintained a relatively low profile since 1998 when it was added, in folic acid, to the nation's grain supply. Now, thanks to the publication of new studies, this nutrient is re-entering the limelight.
Findings suggest that this B vitamin could play a role in slowing cognitive impairment and, teamed with vitamin B-6, might decrease the risk of Alzheimer's disease by lowering homocysteine levels.
Meanwhile, the Centers for Disease Control and Prevention raised concerns with a report that the folate status of women of childbearing age is declining despite long-standing evidence that adequate doses of this vitamin in the diets of newly pregnant women can help prevent neural tube defects in their infants.
These studies are generating new discussions on just how much folate is required for good health and on the risks of taking too much or too little.
The findings mean different things for patients of different ages. Older people are likely to be attracted by the news of folic acid's potential for improving cognition, but they need to be warned that too much folic acid can result, indirectly, in cognitive impairment. And young women may need to be reminded to take a supplement for the health of future offspring.
"I think it's very appropriate that we are paying a lot of attention to this vitamin these days," said Joel Mason, MD, director of the vitamins and carcinogenesis laboratory at the USDA Nutrition Research Center on Aging at Tufts University in Boston. "I think we are finding that it does have an impact on a lot of aspects of our health that we were not formerly aware of."
When grains were newly fortified, the message of their positive impact on infant health was apparently heard and heeded. An examination of data from the 1999 to 2000 National Health and Nutrition Examination Survey found that median serum folate in nonpregnant women of childbearing age had increased substantially over pre-fortification days, the CDC said.
But the agency's more recent analysis, published in the Jan. 5 Morbidity and Mortality Weekly Report, found that serum folate concentrations had dropped by 16% between 1999-2000 and 2003-04.
As a result, physicians should continue to urge young women patients to take a supplement that contains 400 micrograms of folic acid, said Lynn B. Bailey, PhD, professor of food science and human nutrition at the University of Florida's Institute of Food and Agricultural Sciences, in Gainesville.
The CDC finding also has reignited a debate over how much of the supplement should be added to grain.
The March of Dimes would like to see the amount doubled to help prevent birth defects. The CDC finding was disturbing, said Jennifer L. Howse, PhD, the group's president, in a statement. "Folic acid is the most important vitamin that women can take to help prevent serious birth defects of the brain and spine, it's most important that they start consuming it before they get pregnant and continue into early pregnancy."
But when it comes to older people and folic acid, the situation becomes murkier. A study in the January Archives of Neurology, for instance, found that older people with a higher level of folate from diet and supplements may have a reduced risk of developing Alzheimer's disease. Another, though, this one in the Jan. 1 American Journal of Clinical Nutrition, found that low vitamin B-12 status and high serum folate were associated with anemia and cognitive impairment in people 60 and older.
Dr. Mason offered his take on the latter study's implications. "If you have low B-12 levels and are taking a lot of folate, it might actually be to your detriment in terms of cognitive capacity." He estimates that 10% to 15% of the elderly are in the low B-12 range and could feasibly be adversely affected by excessive doses of folate.
"In fact," said Dr. Mason, who was not involved in the study, "when mandatory folic acid fortification was being debated, that factor was considered when choosing the level of folate."
Dr. Bailey recommends that physicians determine whether a patient has normal vitamin B-12 status to avoid problems. "As we age, our B-12 levels tend to go down because there is a high level of malabsorption," she noted. "We lose hydrochloric acid in our stomachs which is needed to digest these vitamins."
The National Institutes of Health also warns of potential interactions with proton pump inhibitors. These medications can interfere with vitamin B-12 absorption by slowing the release of hydrochloric acid into the stomach.
Researchers also are exploring folate's role in preventing chronic disease, including some cancers and heart disease. But it's too early to make predictions there, said Dr. Mason, who is working on folate's role in the prevention of certain cancers.
"We are in the midst of a rapidly changing field," he said. "Doctors need to stay tuned for advances over the next couple of years. What I conclude right now is not necessarily what the truth will be two years from now."