But Beta-Carotene Linked to Lower Odds of Cancer in Nonsmokers
Sept. 20, 2005 -- The nutrient beta-carotene may affect smoking and nonsmoking women differently, French researchers report.
Beta-carotene is a source of vitamin A. It's found in lots of fruits and vegetables, as well as in vitamin supplements.
In the French study, high beta-carotene intake (from foods or supplements) was linked to low levels of cancer in nonsmoking women and high levels of the same cancers in women who smoke.
Study: Keep Eating Fruits, Veggies
Why did smokers and nonsmokers show such different patterns? The answer isn't clear.
Smoking and high doses of beta-carotene may gang up to raise cancer risk, but more studies are needed to find out, write the researchers.
Meanwhile, they urge everyone to keep eating fruits and vegetables.
"There is no evidence that smokers should avoid consuming beta-carotene-rich foods such as fruits and vegetables," write Marie-Christine Boutron-Ruault, MD, and colleagues.
Boutron-Ruault works for INSERM, France's national health and medical research agency. The study appears in the Journal of the National Cancer Institute.
The bottom line: The study shows no reason to change recommendations to eat five to nine daily servings of fruits and vegetables as advised by the U.S. National Cancer Institute.
The French study included nearly 60,000 women. In 1994, the women completed questionnaires about the foods they ate, the supplements they took, and their smoking habits. They were in their mid-40s to late 60s at the time.
Over the next seven years or so, 700 women had developed cancers including those of the lung, thyroid, ovaries, cervix, colon, and rectum.
"We investigated all cancers for which any association with tobacco has been suggested for cancer itself," write the researchers.
Then, the scientists reviewed beta-carotene intake and cancer risk for smokers and nonsmokers.
The results are "quite provocative" but have some limitations, notes a journal editorial.
The editorial comes from Susan Mayne, PhD, FACE, of Yale University's medical school and Scott Lippman, MD, of the University of Texas M.D. Anderson Cancer Center in Houston.