(Reuters Health) - Folic acid fortification not only protects developing babies against certain birth defects but also supports healthy brain development through the teenage years, researchers report.

“It’s been known for more than 20 years that prenatal exposure to folic acid protects the fetus against spina bifida and other neural tube defects,” said senior study author Dr. Joshua L. Roffman from Massachusetts General Hospital in Charlestown.

“But our findings are among the first to link prenatal folic acid exposure to improved brain health outcomes in young people,” and to show the effect is due to specific changes in brain development, he told Reuters Health in an email.

The researchers evaluated associations between prenatal folic acid exposure, maturation of the brain’s cortex, and the risk of psychiatric disorders in youths 8 to 18 years of age born before, during, and after full implementation of folic acid fortification of grain products between 1996 and 1998.

Brain cortex thickness was greatest in youth born after full implementation of folic acid fortification, intermediate in those born during the rollout and lowest in those born before folic acid fortification, according to the report in JAMA Psychiatry.

After the brain reaches its full thickness, the cortex begins to thin in a selective pruning process. Delayed thinning has been associated with higher intelligence, whereas accelerated thinning has been associated with schizophrenia and autism, the researchers note.

In this study, folic acid fortification was associated with slower thinning of the brain cortex, and this delayed thinning was associated with lower odds of developing psychotic disorders like schizophrenia.

“Despite longstanding recommendations that women of child-bearing age take folic acid to protect against neural tube defects, especially in the event of unplanned pregnancy, most women who are capable of pregnancy do not take prenatal folic acid supplements (e.g., prenatal vitamins), and less than half of the world’s population lives in countries that require folic acid fortification of grain products,” Roffman said.

The results demonstrate that prenatal folic acid may confer additional protective, long-lasting effects on brain health, beyond its effects on neural tube defect prevention, he added.

“Even if such benefit ultimately proves to be small or limited to a certain population, given that folic acid during pregnancy is safe for both mother and fetus, inexpensive, and readily available, these findings may help compel its wider use,” Roffman said.

“This study provides additional evidence in support of the National Academy of Sciences, Engineering, and Medicine’s recommendation that all women of childbearing age consume 0.4 mg (400 micrograms) of folic acid daily,” said Dr. Patrick J. Stover from Texas A&M University in College Station, who wasn’t involved in the research.

“This study provides additional evidence that all countries should use folic acid fortification or other effective approaches to ensure women have adequate levels of folic acid intake during pregnancy,” he said.

SOURCE: bit.ly/2IQonuB JAMA Psychiatry, online July 3, 2018.