So it makes sense to eat foods rich in folic acid and to take a daily multivitamin-mineral pill, which commonly contains 400mcg of folic acid, the amount experts recommend to help protect arteries and prevent birth defects. If you're over 50, it's also wise to take 500mcg of B12 daily. Folic acid: vital to your vitality 9 out of 10 Americans don't get enough of this extraordinary nutrient

GOOD REASONS TO GET MORE

Heart: If you get too little folic acid (at least 400mcg daily is generally recommended), an amino acid called homocysteine can accumulate in your blood. Homocysteine, a recently identified villain in heart disease, attacks arteries and encourages clotting and plaque. Excessive homocysteine triples your odds of a heart attack, say Harvard University investigators. The good news: B vitamins, chiefly folic acid, suppress hazardous homocysteine. Taking 400 micrograms (mcg) daily of folic acid in a supplement controls homocysteine in most people, according to new tests by M. Rene Malinow at Oregon Health Sciences University. He says 400mcg work as well as 1,000 or 2,000mcg. University of Washington researchers recently concluded that inadequate folic acid causes 56,000 heart disease deaths yearly. B6 and B12 also help suppress homocysteine.

Brain, mind and mood: Folic acid may help save you from a stroke. Tufts University investigators found that older men and women with high homocysteine and low folic acid had double the risk of narrowed carotid (neck) arteries, which increases susceptibility to strokes. Low folic acid levels also have been linked to serious depression, dementia, memory loss and low mental acuity, even in young people. When deficiencies were corrected, these conditions improved. One theory: The body needs folic acid to manufacture neurotransmitters, chemicals that transmit messages through the brain.

Cancer: Too little folic acid may raise your odds of colon, lung or cervical cancer. In a Harvard study, those who ate the most folic acid were a third less apt to have polyps that can lead to colon cancer than those who ate the least folic acid. In other research, high folic acid intakes are linked to a 40-70 percent reduction in colon cancer. The lung tissue of lung cancer victims is typically deficient in folic acid, report University of Alabama researchers. They also say women with low folic acid are five times more likely to develop precancerous changes in the cervix than are women high in folic acid. Why? Folic acid helps prevent a cancer-causing gene from being switched on, according to Harvard's Edward Giovannucci.

Birth defects: Adequate folic acid intake could prevent 3,000 neural tube birth defects every year, says Godfrey Oakley of the Centers for Disease Control and Prevention. A recent California study showed that women taking a vitamin with folic acid in the three months before conception cut the odds of such birth defects 65 percent. Low folic acid intake also can double the risk of premature births. Oakley urges all women who are or could get pregnant to take a 400mcg supplement of folic acid every day. The cost: a mere $5 a year.