Studies have shown that beta-carotene, vitamin C, zinc and other antioxidants
may protect against the harmful effects of cell-damaging substances called free
radicals. The accumulation of free radicals is suspected to increase the risk of
heart disease and several other conditions.
Men, who eat less fruits and vegetables than women in proportion to their
weight and total intake of calories, consequently also have a lower
concentration of antioxidants in their blood. If they increase their intake of
these healthy foods, they may be less likely to develop cancer, the new findings
suggest.
"Our results show the importance of the recommendations of a lifelong diet
rich in fruits and vegetables, especially in populations with a low antioxidant
status," Dr. Serge Hercberg of the Nutritional Epidemiology Unit, National
Institute of Health and Medical Research (INSERM) in Paris, told Reuters Health.
Previous studies of the health effects of an antioxidant-rich diet have
yielded inconsistent results. Some studies have suggested that such diets may
lower the risk of cancer or cardiovascular disease while others have found the
antioxidant supplementation to be ineffective or possibly even harmful.
Hercberg and colleagues re-examined the issue in a study of more than 13,000
men and women aged 35 to 60 years living in France.
These study participants were randomly assigned to a group that took an
inactive pill each day or to a group that took a daily multivitamin consisting
of 120 milligrams of vitamin C, 30 milligrams of vitamin E, six milligrams of
beta carotene, 100 micrograms of selenium and 20 milligrams of zinc.
This relatively low dosage of antioxidants was chosen because it represents
what might realistically be attained through good nutrition; many previous
studies of antioxidant supplementation used a much higher dosage, the report
indicates.
The current study also included people from the general population as opposed
to just smokers and others already at high risk for cancer.
The French study participants were followed for an average of 7.5 years,
undergoing periodic physical exams and cancer screenings. By the end of the
study, 562 men and women had been diagnosed with cancer, 271 had developed
cardiovascular disease and 174 people had died.
Antioxidant supplementation did not seem to have an effect on cardiovascular
disease rates among the study participants. However, the incidence of cancer was
lower among men on the daily antioxidant multivitamin than among their peers,
Hercberg's team reports in this week's Archives of Internal Medicine.
Specifically, 88 men on antioxidants were diagnosed with cancer during the
study period in comparison to 124 of those in the placebo group.
Men who took a daily dose of antioxidants also seemed less likely to die from
any cause, the report indicates.
Among women, however, there were no great differences in the number of cancer
diagnoses among those on antioxidant therapy in comparison to those who took an
inactive pill.
The reason for the discrepancy between men and women may be because the men
had a lower concentration of various antioxidant nutrients -- beta-carotene in
particular -- in their blood at the start of the study, the researchers
speculate. Indeed, after more than seven years of taking antioxidants, men's
beta-carotene levels were similar to that found among women in the placebo
group, the report indicates.
"The efficiency of supplementation in reducing cancer incidence may be
related to the ability to correct antioxidant status with an adequate dose of
antioxidant nutrients in individuals with a suboptimal antioxidant status (as
the men in our study)," the researchers say.
"In conclusion, our results suggest that an adequate and well-balanced
supplementation of antioxidant nutrients, at doses that might be reached with a
healthy diet that includes a high consumption of fruits and vegetables, had
protective effects against cancer in men," Hercberg and colleagues write.
SOURCE: Archives of Internal Medicine, November 22, 2004.
