Fruit And Vegetable Consumption Not Associated With Reduced Breast Cancer Risk.

2001 MAR 8 - (NewsRx.com) -- An analysis of studies involving more than 350,000 women suggests that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk.

Stephanie A. Smith-Warner, PhD, of the Harvard School of Public Health, Boston, Massachusetts, and colleagues analyzed data from eight prospective studies to examine the association between breast cancer risk and total and specific fruit and vegetable group intakes.

The Pooling Project of Prospective Studies of Diet and Cancer included 7,377 incident invasive breast cancer cases occurring among 351,825 women. Diet was measured at baseline in each study, using a food frequency questionnaire designed for that particular study. To take into account the various portion sizes among participants within some cohorts and between study populations, the food intake data were analyzed as grams consumed per day.

Some epidemiological studies suggest elevated fruit and vegetable consumption is associated with a reduced risk of breast cancer. However, most have been case-control studies in which recall and selection bias may influence the results, Smith-Warner et al. noted. Publication bias (in which studies showing a benefit of fruit/vegetable intake may be more likely to be published than "negative" studies) may also have influenced the literature on associations for specific fruit and vegetable subgroups, they said.

The researchers examined intake of fruits without juice (referred to as fruits); fruit juice; fruits and fruit juice (total fruits); vegetables and vegetable juice (total vegetables); and fruits, vegetables, and juice (total fruits and vegetables). Several fruit and vegetable groups were evaluated based on botanical taxonomy. Associations were examined for individual fruits and vegetables, for which intake was assessed in at least five studies.

Smith-Warner et al. report that for fruit intake, the risk estimates for breast cancer ranged from a 3% reduction to a 1% increase in risk per 100 grams daily intake. For vegetables, the risk estimates ranged from a 10% reduction to a 10% increase in risk per 100 grams daily intake.

"These results suggest that fruit and vegetable consumption is not associated with breast cancer risk when analyzed as total fruits and vegetables, fruits, fruit juice, total fruits, total vegetables, green leafy vegetables, eight botanically-defined fruit and vegetable subgroups, or 17 specific fruits and vegetables," the authors wrote.