Produce Fights Heart Disease, Not Cancer

Nov. 2, 2004 -- Eating five fruits and vegetables per day is a worthy goal if you want to prevent heart disease, but produce doesn't have a clear advantage against cancer, a new study shows.

"Our results provide further evidence that eating lots of fruits and vegetables reduces major chronic disease," writes Hsin-Chia Hung of the epidemiology department at Harvard School of Public Health. He and colleagues say that their findings support the recommendation of eating five or more servings of fruits and vegetables daily.

The study, which appears in the Nov. 3 issue of the Journal of the National Cancer Institute, includes a combined total of more than 100,000 men and women. All participants were free of heart disease or cancer in the mid-1980s when they answered the first in a decade-long series of questionnaires covering topics that included diet and health.

Every two years, participants filled out surveys about their fruit and vegetable intake. The studies also tracked how many participants developed heart disease or cancer.

Overall, those who ate the most fruits and vegetables fared best.

However, the benefit of increasing the intake of fruits and vegetables appears to be due primarily to a lower risk of heart disease, not cancer, the researchers say.

The National 5 A Day for Better Health Program recommends eating five or more servings of fruits and vegetables daily for cancer prevention. But the researchers say the protective effect of fruits and vegetables may have been overstated.

But the findings might be due to errors on the questionnaires, according to a journal editorial written by Arthur Schatzkin, MD, PhD, of the National Cancer Institute, and colleagues.

Hung's team doesn't necessarily agree with that view, and they're not sure exactly why fruits and vegetables didn't have a stronger showing against cancer. One possibility might be that cancer takes longer to develop than heart disease, requiring a longer follow-up period to see if fruits and vegetables do have some preventive effect in that area, they write.

Still, there's plenty of reason to eat plenty of fruits and vegetables, the study shows.

Participants in the study eating at least five servings of fruits and vegetables daily had a 28% lower risk of heart disease than participants eating fewer than 1.5 servings of fruits and vegetables per day, write the researchers.

Looking for high-leverage impact? Go for green, leafy vegetables, which had the strongest impact against major chronic disease and heart disease of the food groups studied. An increment of one serving was associated with an 11% lower risk of heart disease, write the researchers.