Smoking Plus Beta-Carotene May Up Cancer Odds
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
Study: Keep Eating Fruits, Veggies
Why did smokers and nonsmokers show such different patterns? The answer
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
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.
The editorial makes several points about the French study:
- Not all of the cancers on the list have clearly been linked to
- Only 2% of participants reported using beta-carotene supplements.
- Doses of beta-carotene supplements weren't reported.
- Beta-carotene is more available to the body from supplements, not
Still, future nutritional studies should note smoking habits, write Mayne
They agree with the French researchers that fruits and vegetables are vital
for smokers and nonsmokers alike.
"No evidence shows that higher fruit and vegetable intake increases
cancer risk, even in smokers," they write. The heart benefits of nutrients
in fruits and vegetables might actually be greater in smokers, they note.
"Therefore, the new research on the interaction between nutrients and
smoking should not alter our current policy recommendations with regard to
nutrients and cancer risk," states the editorial.
Quitting smoking, losing extra pounds, getting at least 30 minutes of
moderate physical activity five or more days per week, and going for
recommended checkups are also widely recommended for a healthy lifestyle.