The study, scheduled to be published in the April 8 edition of the journal Circulation, finds the vitamin blunted the damage from heart attack in animal studies.

"We want to emphasize that it is premature for people to begin taking high doses of folic acid," senior study investigator Dr. David Kass, of The Johns Hopkins University School of Medicine in Baltimore says in a statement. "But if human studies prove equally effective, then high-dose folate could be given to high-risk groups to guard against possible heart attack or to people while they are having one."

"We do not know how much or how little of it is needed to be effective," Kass cautions. A large amount could yield unpredictable side effects and studies have linked folic acid supplements to increased rates of colon and prostate cancer, Kass says.

Folate -- naturally found in leafy green vegetables, beans and nuts -- is sometimes used as a general term to include folic acid -- the form of vitamin B9 put in supplements and added to foods, especially grain products.