Combined Diet Effects: The Women’s Healthy Eating and Living Study

Combined Diet Effects: The Women’s Healthy Eating and Living Study in Foods and Breast Cancer Survival - How Foods Fight Cancer

These dietary factors tend to work together: A diet that is higher in fruits
and vegetables will also tend to be high in fiber and low in fat. In turn,
women who eat such diets tend to be slimmer than other women, thus
avoiding the risks of overweight. One study suggested that there may be a
measurable benefit of these combined effects. Researchers at Mt. Sinai
Medical Center in New York found that women with breast cancer who
were slimmer tended to live longer, and those who had lower cholesterol
levels also lived longer. But the women at greatest risk of dying were those
who were overweight and had high cholesterol levels.20

The Women’s Healthy Eating and Living (WHEL) Study included more
than 3,000 pre- and postmenopausal women previously treated for breast
cancer in a test of two different diets rich in fruits and vegetables.21 Half
the participants (the intervention group) were asked to include in their daily
diets five vegetable servings, 2 cups of vegetable juice, three fruit servings,
30 grams of dietary fiber, and no more than 15–20 percent of calories from
fat. A comparison group was asked to consume at least five fruit and vegetable
servings per day.

In 291 of the study participants, changes in diet and hormone function
were compared between the two diet groups.22 The women who ate
less fat and more fiber found that the amount of estrogen in their blood fell
to safer levels, confirming that diet changes really do help get hormones
into better balance.

In the same study, the investigators tracked the experience of 1,551
women assigned to the comparison group, using blood tests for plasma
carotenoids as an indicator of vegetable and fruit intake.23 As in any large
group, their diets varied from one person to another. It turned out that
those with the highest carotenoid concentrations—indicating high vegetable
and fruit intake—had a 43 percent lower risk of either cancer
recurrence or a new primary breast cancer compared to women with lower
blood levels of carotenoids.

After approximately seven years of follow-up, those women in the
comparison group who followed the guideline of eating at least five fruit
and vegetable servings daily and who were also physically active had an
almost 50 percent reduction in mortality compared to women who did
not meet these healthful guidelines.24 However, the recommendations for
even greater vegetable and fruit intake made for the intervention group
did not extend benefits beyond those achieved by the five-a-day (comparison)
group.25
While the WHEL participants succeeded at emphasizing vegetable and
fruit intake, they did not maintain a low fat intake or a high fiber intake.
The intervention group did reduce fat intake to 21 percent of calories in the
first six months, but fat intake gradually climbed back to 29 percent by the
six-year point. Similarly, fiber intake was only slightly higher at six years
(24 grams per day) compared to the study’s onset (21 grams). As a result,
neither the intervention nor the comparison group succeeded at weight loss;
both groups were overweight at the beginning of the study and gained a small
amount of weight as the study progressed. A vegetarian or vegan regimen
may have been a better choice; the meat and dairy products that were permitted
in the WHEL guidelines contain significant amounts of fat and
contribute no fiber.

Nonetheless, the WHEL study demonstrated that women previously
treated for breast cancer who consume at least five vegetable and fruit servings
daily and are physically active have a large measure of protection
(nearly 50 percent reduction in mortality), and their protection is not
increased by pushing vegetable intake even higher. The study did not test
other potentially helpful dietary measures.