Folic Acid May Cut Childhood Leukemia Risk

Australian study uncovers protective effect, but experts say they can't prove supplement is responsible

FRIDAY, Dec. 7, 2001 (HealthDayNews) -- Folic acid supplements, already recommended during pregnancy for prevention of some major birth defects, may also reduce the risk of the major form of childhood leukemia, an Australian study finds.

The incidence of acute lymphoblastic leukemia (ALL) was 60 percent lower among children of women who took supplements of folate, a form of folic acid, along with iron during pregnancy than in children whose mothers didn't, says a report in the Dec. 8 issue of The Lancet.

"These findings suggest a protective effect, but the association needs to be confirmed in larger studies," says Judith R. Thompson, an epidemiologist at the Cancer Center of Western Australia and lead author of the paper.

Her group assessed all the cases of ALL in children born in the district of Western Australia between 1984 and 1992, questioning parents about possible risk factors. Iron supplements alone reduced the risk by 25 percent, the researchers say, but the major protective effect was associated with folate.

ALL occurs in about 1 of every 10,000 births in the United States. The American Cancer Society estimates that there will be 2,000 new cases this year, with an 80 percent cure rate.

The Australian report is "a very interesting but doubtful finding," says Dr. Nancy S. Green, associate professor of pediatrics and microbiology at Albert Einstein College of Medicine in New York and assistant medical director of the March of Dimes Birth Defects Foundation.

Several aspects of the study raise doubts, Green says. One is that there was no relationship between the amount of folate the pregnant women took and the risk of ALL. Similarly, there was no relationship between risk and the timing of supplementation.

"Another very odd thing is that you would think that the impact of supplementation during pregnancy would more likely have an impact when the children were young," Green says. "There was no effect on the age when the children developed leukemia."

The study also showed that parents of the children with ALL were more likely to have been exposed to agricultural chemicals, industrial chemicals and radiation, Green notes. Although only radiation exposure is known to increase the risk of leukemia, she says, "some of these may contribute to the development of leukemia."

"If you take their findings at face value, it is another reason to take folic acid," Green says. "But I don't buy it."

The finding "requires further research," Thompson acknowledges, then adds, "Yes, we are planning a national study in Australia."

Women already are advised to have an adequate intake of folic acid before and during pregnancy, in large part because low levels of folic acid increase the risk of neural tube defects in children.

In 1998, the Food and Drug Administration approved folic acid enrichment for a variety of foods, including breakfast foods and wheat, rice and corn products. Natural sources of folate include green, leafy vegetables.

The recommended intake for women is 400 micrograms a day before pregnancy and 800 micrograms a day during pregnancy. Women who have had a baby with a neural tube defect are advised to take 10 times that amount in subsequent pregnancies.

What To Do

"I would encourage women to take folic acid for the documented effects of preventing certain birth defects, which are well established," Green says. "This may or may not represent an additional reason to take folic acid during pregnancy."

For information about folic acid, consult the Food and Drug Administration or the March of Dimes Birth Defects Foundation.

The National Cancer Institute has more information about ALL.

SOURCES: Interviews with Judith R. Thompson, Ph.D, epidemiologist, Cancer Center of Western Australia, West Perth; Nancy S. Green, M.D., associate professor of pediatrics and microbiology, Albert Einstein College of Medicine, Bronx, N.Y.; Dec. 8, 2001, The Lancet
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