While women are encouraged to supplement their diets with folic acid during pregnancy to prevent the risk of neural tube defects, excess amounts of the nutrient may predispose their daughters to obesity and diabetes when they are older. Researchers who made this finding, published in Journal of Endocrinology‘s article “Excess Perigestational Folic Acid Exposure Induces Metabolic Dysfunction in Post-Natal Life,” recommend the establishment of a safe upper level of folic acid supplementation for pregnant women to prevent these risks while still protecting women’s unborn children.
“While taking a minimum of 0.4 mg of folic acid per day is essential when pregnant, our study shows that it is possible to have too much of a good thing,” said Dr. Elisa Keating, lead author of the study at Faculty of Medicine of the University of Porto in Portugal, in a news report. “Considering the increasing amount of folic acid consumed during pregnancy through fortified foods, multivitamin pills and supplements, the search for a safe upper dose of folic acid is urgently needed.”
It should be noted that the researchers conducted their studies in rats and administered 20 times the recommended daily intake of folic acid. Excess supplementation was continued from the time of mating rats through to lactation. Offspring were monitored at three and 13 months of age for signs of metabolic disease and compared to offspring of rats given the recommended level of folic acid.
Excessive folic acid led to overweight offspring who grew to become insulin resistant in adulthood. This may have been a result of an adiponectin deficiency, as this is a hormone that protects against diabetes and obesity, as well as an irregular eating behavior.
The ill effects were most noticeable in female offspring, leading the researchers to predict that daughters of women consuming too much folic acid may be at a higher risk of developing obesity or diabetes than sons. No offspring from rats given the recommended amount of folic acid suffered from metabolic disease.
The World Health Organization established the current recommendations for folic acid supplementation: 0.4 mg per day for women with a normal health history record and 5 mg per day for women with a family history of neural tube defects. Studying the line between adequate supplementation and excess supplementation is an area of interest for the researchers in the future.
“Our study clarifies the potential effects of excess folic acid exposure and may play an important role on rethinking current public health policies surrounding folic acid supplementation,” said Dr. Keating.