Folic acid, the B vitamin known to prevent neurological problems in fetuses, also may help fight colon cancer.

But just what dose would be the right amount continues to puzzle scientists.

"Clearly, taking 400 micrograms a day, which is more than most Americans take in daily, seems to convey more protection," says Dr. Joel Mason, a researcher at the Human Nutrition Research Center on Aging at Tufts University who's spent the past decade working on this issue. "We have 20 large epidemiologic studies, which included tens of thousands of people, that tell us this. But epidemiologic studies can only establish an association, not a cause-and-effect relationship."

"We also have animal studies that show that varying the amount of folate in the diet can modulate the development of colon cancer," says Mason, who presented a summary of research on folic acid earlier this month at a conference in Las Vegas of the American College of Nutrition.

But Connie Diekman, a registered dietician at Washington University in St. Louis and a spokeswoman for the American Dietetic Association, says research also has shown there's a good and a bad side to taking folic acid.

"Experts say there is benefit from taking folic acid, but they also say [in the October issue of Cancer Research,] that it's a problem if you take too much," Diekman says.

For instance, she says, "doses of folic acid greater than 1,000 micrograms can mask vitamin B12 deficiency."

"The optimal timing and dose of folic acid still needs to be determined," Diekman says.

About three years ago, the federal government set standards for fortifying most grain products with folic acid to protect against neurological problems in developing fetuses, Diekman says. A recent South Carolina study shows that neurological birth defects in that state have decreased since fortification became mandatory, she says.

When the experts finally do decide on the right dose of folic acid to help fight colon cancer, it's likely you'll be taking it in pill form. Getting enough in the diet is difficult because the foods that contain folic acid -- liver, kidney beans, lentils, cooked spinach -- aren't on the favorites list of most Americans.

Colon cancer is the second leading cause of cancer-related deaths in the United States for men and women combined, according to the Cancer Research Foundation of America. But if everyone followed the guidelines for screening, experts say, there could be 30,000 fewer deaths a year from this disease.

Mason says he currently is conducting a large-scale, long-term study that should indicate how much folic acid we need daily to "really prevent colon cancer."

"I've primarily been studying the relationship between folate and colon cancer, but it also may be effective in preventing cervical cancer, breast cancer, stomach and esophagus cancer," Mason says. "But clearly the most compelling evidence is in colon cancer."

(From HealthScout)