More Fruits and Vegetables Do Not Prevent Breast Cancer Reoccurrence, Study Says

A diet rich in fruits and vegetables probably will not prevent a breast cancer recurrence. At least that is what the latest research found in a study released in the July 17 issue of the Journal of American Medical Association (JAMA).

This recent study - the Women's Healthy Eating and Living (WHEL) Study - followed 3,088 women who had had a breast cancer diagnosis and treatment within the previous four years. The randomized comparison study followed women over the course of 7 years and found no discernable difference in breast cancer reoccurrence between the women on a high fruit and vegetable diet, and those following the USDA recommended 5-a-Day diet.

Conflicting Results

The intervention group ate a diet of at least 3 fruit servings, 5 vegetable servings, and 30 grams of fiber each day, with a reduced fat intake of 15-20 percent of total calories. Both diets have more fruits and vegetables than the average American woman eats on a daily basis. The breast cancer reoccurrence rate was 16.7 percent among women on high fruit and vegetable diet and 16.9 percent among women in the control group, with approximately 10 percent of women who died from breast cancer during the study. Additionally, neither group of women showed weight loss as a result of the eating plan.

Previous research results have been mixed as to the preventative factors of fruits and vegetables for women in breast cancer remission. The results released in 2006 from the Women's Intervention Nutrition Study (WINS) showed significant health benefits among women following a low-fat diet versus those in a control group.

The WINS study followed 2,437 women within one year of early-stage breast cancer diagnosis. This study was more focused on early-stage breast cancer survivors, and found the beneficial effect of a low-fat diet may be isolated to women with "estrogen and progesterone receptor-negative breast cancers." Why the effect is limited to these types of cancers is still being researched. Regardless, the low-fat diet showed results in lower reoccurrence rates at both the 5-year and 8-year follow up.

Self-Reported Food Intake

Both studies relied on women's documentation of what they ate over the course of a day. According to blood test results from the WHEL study, women were eating higher amounts of fruits and vegetables as verified by the cartenoid levels in their blood.

However, at no point during either study did women meet the low-fat intake goal of 15-20 percent, and they significantly under-reported the amount of calories they ate. Similar to participation in a Weight Watchers program, the women were supposed to diligently record everything they ate and translate it to calories. If, as reported, the groups did reduce caloric intake by an average of 180 calories, all would lose weight. Instead, women in the WHEL study gained weight in both the high fruit and vegetables group and the control group; conversely, the women in the WINS low-fat group lost approximately 6 pounds more than their counterparts.

The weight gain differential is likely because the WINS study focused solely on fat intake, while the emphasis of the WHEL study was fruits and vegetables. Regardless, this indicates one of the flaws of studies such as these as research assumptions are based on false data, and indicates that future research requires more careful monitoring of self-reported data.

Consensus Results

Though the results of the fruit and vegetable study indicate no demonstrated benefit for women, the two studies support findings that a lower energy intake, also known as eating less fat, is better for women and results in fewer breast cancer reoccurrences. This suggests that high levels of obesity or weight gain is associated with breast cancer.

Together, the high fruit and vegetable diet and the low-fat diet studies indicate that lifestyle habits may affect breast cancer survival and reoccurrence, but it is an area requiring further study, and that eating fruits and vegetables alone is not enough.

Source:

Journal of American Medical Association