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Smoking Cessation Health Center

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Secondhand Smoke Lowers Folic Acid Level

Lack of Important Nutrient May Explain Some of Smoking's Health Effects

WebMD Health News

June 30, 2003 -- Smoking may not only rob your own body of a vital nutrient, but it could also deprive those around you. A new study shows firsthand andsecondhand smoke exposure can lower folic acid levels in the body and may explain some of smoking's bad health effects.

Folic acid is an essential B vitamin that is found in leafy green vegetables, fruits, orange juice, whole grains, organ meats, and cereals fortified with folic acid. It plays a vital role in DNA synthesis and repair within the body.

Smokers at Risk

Researchers say folic acid plays an important role in preventing birth defects, and there is some evidence it may reduce the risk of breast cancer, colorectal cancer, and heart disease in adults. Previous studies have shown that smokers have lower folic acid levels. But researchers say the impact of secondhand smoke on folic acid has not been examined.

Using information on more than 15,000 American adults, the researchers compared the effects of cigarette smoke exposure on folic acid levels. The complete findings appear in the current issue of Nicotine and Tobacco Research.

Overall, researchers found the folic acid level in current smokers was 20% lower than in nonsmokers.

Nonsmokers, Too

The researchers also found that heavy exposure to secondhand smoke also resulted in lower folic acid levels among nonsmokers. People with high exposure to secondhand smoke were more likely to have low folic acid levels.

On average, researchers found that people with heavy secondhand smoke exposure had folic acid levels about 10% lower than those who had low exposure to secondhand smoke.

Researchers say those differences in folic acid levels were not due completely to lower intakes of folic acid from dietary sources or supplements and may help explain some of smoking's health effects.

"This finding provides biological support for recent studies linking tobacco smoke exposure to heart disease and breast cancer and provides biological plausibility to examine the role of tobacco smoke exposure in other folic acid-related diseases such as neural tube defects and colon cancer," write researcher David M. Mannino, MD, of the CDC, and colleagues.

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