Exposure to cigarette smoke may rob people of folate, an important vitamin that helps protect against a variety of diseases, including a number of birth defects, a large nationwide study concludes. Both active smokers and those exposed to high levels of secondhand smoke had lower levels of folate in their blood than nonsmokers, according to the report in the journal Nicotine & Tobacco Research. "Overall, we found that red blood cell folate levels in current smokers were 20 percent lower than those in our entire group of nonsmokers," say David M. Mannino, M.D., of the Centers for Disease Control and Prevention and colleagues.
Nonsmokers exposed to heavy amounts of secondhand smoke also had decreased folate levels, but their folate loss was only 60 percent of the amount leeched from active smokers.
Previous studies have linked low folate levels to several different diseases, and Mannino and colleagues suggest that the association between folate and smoke exposure might help explain the increased risk of these diseases among active smokers.
"The 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 folate-related diseases such as neural tube defects and colon cancer," Mannino and colleagues say.
The study included 15,564 adults ages 17 and older who received blood tests for cotinine, a nicotine byproduct, and folate. The people were also asked about their eating and smoking habits. Older individuals in study, those ages 50 and older, were less likely to be active smokers or to be exposed to high levels of secondhand smoke.
The researchers measured folate in both red blood cells and blood serum to determine each person's overall folate levels. Levels in serum reflect recent folate intake, while levels in red blood cells reflect long-term intake and tend to be a more stable indicator of how the body is processing the vitamin. In both cases, folate levels dipped with smoke exposure.
