The investigation, led by University of Wisconsin-Madison Dr. Bermans Iskandar, an associate professor of neurosurgery, showed the nerve regeneration in the rats was triggered by a change in DNA.
The researchers said the healing effects of the vitamin increased with the dosage, until regrowth of the damaged tissue reached a maximum level, after which it declined progressively with increasing doses until it reached the level seen in the absence of the vitamin.
The scientists said they discovered folate stimulated a process known as DNA methylation -- a biochemical process in which chemical compounds known as methyl groups are attached to DNA.
"The ability to change gene function through DNA methylation suggests exciting new prospects for understanding the origins of disease and for developing new treatments," Iskandar said. "Our study showed that folate, a commonly available dietary supplement known to change gene functioning, did so in a way that fosters nervous system repair."
Folate occurs naturally in leafy green vegetables and other foods. The synthetic form, folic acid, is used to supplement cereal grains in the United States. The NIH said the vitamin is important for the formation of the brain and spinal cord in the early embryo.
The research is reported in the Journal of Clinical Investigation.