Some experts believe that a high daily dose of folic acid can reduce the risk for pre-eclampsia, the dangerous high blood pressure that can occur during pregnancy. A randomized trial has found that it does not work.
Folic acid in small doses is proven to reduce the risk for the serious birth defects of the brain or spinal cord called neural tube defects, so prenatal vitamins contain the nutrient. But some epidemiological evidence has suggested that the more folic acid taken, the lower the risk for pre-eclampsia.
Researchers tested that hypothesis with a group of 2,464 women who had at least one risk factor for pre-eclampsia, such as high blood pressure or diabetes. Half received 4.0 milligrams of folic acid a day, and half got daily placebo tablets along with 1.1 milligrams of folic acid. The study is in BMJ.
There was no difference between the groups in incidence of pre-eclampsia or any other negative outcome, such as stillbirth, they tracked.
Why not take the larger dose, just in case? The senior author, Dr. Mark C. Walker, chairman of obstetrics and gynecology at the University of Ottawa, said we do not know what the long-term effects are. “There are so many times in medicine where things go from panacea to prescription to poison. I’m advising people to take a regular multivitamin, and that’s it.”