Should you take folic acid?

New studies suggest that getting too much folic acid might fuel certain cancers in some people.

And with the vitamin showing up in ready-to-eat cereals, bread, snack bars and multivitamins, some experts fear it's easy to exceed the recommended daily intake of 400 micrograms. There is an urgent need, some say, to figure out how much folic acid is enough but not too much for different segments of the population.

Getting enough folate also may protect against anemia, premature birth and congenital heart defects, and keeps hair, skin and nails healthy.

But scientists also know that excess folic acid can cover up a shortage of the vitamin B12, a common condition in older people that can cause dementia if unaddressed.

Then there's cancer. The vitamin can help prevent development of certain cancers, particularly in the colon, where cells replicate especially fast. Studies show that people who get plenty of folic acid reduce their risk of developing colorectal cancer and precancerous polyps by 40 percent to 60 percent.

But folic acid helps cancerous cells grow too. Animal studies show that once cells are on the path to becoming cancers, the vitamin makes things worse.

Experts say that all women of childbearing age should get 400 daily micrograms of folic acid through food and/or supplements. Pregnant women should get 600 micrograms, adds Janis Biermann, a health educator at the March of Dimes. Breast-feeding mothers should get 500 micrograms. Pregnant or regularly breast-feeding women who have already had a child with a brain or spinal cord defect should take 1 milligram.