Diary of Unknown Symptoms

Mystery of the Internal Vibration

Entry for August 06, 2007

“We know best…”

Cancer fears over hikes in folic acid
Vitamin B reduces birth defects but may increase rate of colon cancer

Aug 07, 2007 04:30 AM
Denise Gellene
Los Angeles Times

Adding folic acid to flours, pastas and rice has reduced the rate of spina bifida and anencephaly, sparing 1,000 U.S. babies each year from these devastating birth defects.

But a new study suggests those health gains may have come at a cost: an extra 15,000 cases of colon cancer annually.

The report, from Tufts University, is the latest caution about a public-health policy that has been largely viewed as a success.

“Have we done more harm than benefit?” says Dr. John Potter, a colon cancer expert at the Fred Hutchinson Cancer Center in Seattle, who was not connected to the latest research.

Writing last month in the journal Cancer Epidemiology Biomarkers and Prevention, scientists reported that colon cancer cases in the U.S. spiked after manufacturers began fortifying cereal grains with folic acid in the late 1990s.

They saw a similar trend in Canada, which began fortification with the B vitamin around the same time.

The pattern was surprising, researchers said, because colon cancer rates had been steadily dropping since the mid-1980s. Greater consumption of folic acid looked like the explanation.

Joel Mason, lead author and professor of nutrition science and policy at Tufts, said the report does not prove that extra dietary folic acid causes colon cancer but does suggest fortification may have unforeseen trade-offs.

One-third to one-half of adults older than 50 have precancerous cells in their intestines, Mason said, so too much folic acid could put them at even greater risk. About 130,000 Americans are diagnosed with colon cancer each year; 56,000 of die from it.

Nutritionists have long known that younger women need 400 micrograms of folic acid daily to reduce their chances of giving birth to infants with neural tube defects, caused by the failure of the fetal spinal column to fully close.

Spina bifida can cause paralysis, and infants with anencephaly – in which much of the brain does not develop – are stillborn or die soon after birth.

Since 1998, U.S. food manufacturers have been required to add 140 micrograms of folic acid to each 100 grams of cereal grains that are labeled “enriched.” Breads, cereals and other grain-based foods shipped across state lines are all fortified with folic acid, a B vitamin naturally found in green leafy vegetables, fruits, dried beans and nuts.

In only a few years, the rate of neural tube defects in the U.S. fell, from 10.6 per 10,000 births in 1996, before fortification, to 7.6 per 10,000 births in 2000.

Canada also saw a sharp decline: to 8.6 per 10,000 births in 2002 from 15.8 per 10,000 births in 1993, according to a report last month. Those results deepened the desires of some scientists and health advocates for even greater improvements.

The nonprofit March of Dimes will ask the U.S. Food and Drug Administration to further boost folic acid levels in cereal grains.

The March of Dimes said U.S. government surveys show that many women 18 to 45 do not receive adequate amounts of folic acid in their diets. In fact, the majority of those women consume about 130 micrograms of folic acid daily, well below the recommended dose, according to R.J. Berry, an epidemiologist at the U.S. Centers for Disease Control and Prevention.

But some researchers have cautioned against increased fortification because of possible downsides. Folic acid can mask symptoms of vitamin B-12 deficiency, common in the elderly. Unaddressed, a B-12 lack can lead to neurological problems.

Some researchers now caution against adding more folic acid to the diet until the possible cancer link is better understood.

“This is not the right time to be moving ahead and increasing the level of folic acid in the food supply,” Mason said.


August 7, 2007 - Posted by | Health | , ,

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