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Optimizing Folate Intake

By Alexander Gelfand

"Folate is good stuff," says Xiaobin Wang, MD, ScD, MPH. Just how good, however, has been a matter of some debate-until now.

When mothers consume it through fortified foods and folic acid supplements, prenatal folate prevents neural tube defects such as anencephaly and spina bifida. Folate and other B vitamins, such as B6 and B12, also regulate blood levels of homocysteine, an amino acid that promotes atherosclerosis and increases the risk of heart attack and stroke when produced in excess. But for many years, clinical studies failed to show that reducing elevated homocysteine levels through folic acid supplementation improved patient outcomes.

Wang and her colleagues have produced a series of papers (including one published in The Lancet) demonstrating that those disappointing results arose from studies conducted in the U.S. and Canada, where mandatory fortification of grains and cereals with folic acid ensures that most people already get enough of the stuff.

By contrast, studies conducted in China-a country where there is no national fortification program, genetic mutations tied to elevated homocysteine levels are common, and rates of hypertension and stroke are 
high-paint a different picture. There, folic acid supplements have indeed been shown to slow the progress of atherosclerosis and reduce the risk of cardiovascular disease. For Wang, the takeaway is simple: Folate is a useful tool, but "it's only good when people need it."

Most recently, Wang, who is director of the Center on the Early Life Origins of Disease and the Zanvyl Krieger Professor in Child Health, found that optimal folate status at preconception is not only important in itself but may also counteract the adverse effect of DDT on early pregnancy loss in a Chinese preconception cohort. She also discovered high rates of elevated homocysteine levels in Chinese children 
and adolescents.

Wang believes these results argue for B vitamin supplementation across the lifespan to improve pregnancy outcomes and head off adult diseases in populations that lack fortification. Ultimately, Wang hopes that her work will encourage national fortification programs abroad.

"Additional research is needed to determine optimal dosage and combination of B-vitamin intake that is tailored to individual life stage and health needs and avoids potential adverse health effects of excessive B-vitamin intake," Wang says.