Dietary Modification Study Fact Sheet
WHAT WAS THE PURPOSE OF THE DIETARY MODIFICATION CLINICAL
The dietary modification (DM) clinical trial component
studied the effect of a low-fat, high fruit, vegetable and grain diet on
breast cancer, colorectal cancer and heart disease in postmenopausal women.
HOW WAS THE DM STUDY CONDUCTED?
There were 48,835 women aged 50-79 are participating in the DM
component of WHI. Participants were either randomized to a comparison group
or a dietary change group. DM study participants were followed for 8 to 12
years. Participants' health s assessed every six months by the clinical
WHAT WAS REQUIRED OF THE COMPARISON GROUP?
Comparison group participants maintained their usual eating
habits and receive standard information on nutrition guidelines. They kept a
periodic food diary and filled out health forms every six months.
WHAT WAS REQUIRED OF THE DIETARY CHANGE GROUP?
Women in the dietary change group decreased their fat intake
to 20 percent of their total daily calories; increased fruit and vegetable
consumption to five or more servings per day; and increased grains to six or
more servings per day. Additionally, they monitored their food intake and attended
nutrition group meetings to learn more about changing their diets in the first
year; thereafter they attended four meetings per year. These meetings
were led by
registered dietitians or nutritionists.
WHAT ABOUT RECENT STUDIES SHOWING NO LINK BETWEEN DIET AND
An analysis of seven cohort studies that was recently
published in the New England Journal of Medicine1 found no link between dietary fat intake and
incidence of breast cancer. This cohort study analysis used recall of recent
food intakes to calculate an estimate of total fat, which was then related to
the incidence of breast cancer. This study "pooled" data from seven studies in
which women were observed for several years. The validity of data from
observational studies such as these depends largely on accurate dietary
measurements and accurate measurements are not possible. Additionally, this
study did not attempt to alter eating patterns, thus it cannot directly assess
the health benefits that may follow adoption of a low-fat eating pattern.
In contrast, the WHI DM study compared the health
outcomes of women randomly assigned to one of the two study groups.
Randomization eliminated the possibility that other personal characteristics or
lifestyles may explain differences in cancer risk.
1D.J. Hunter, et al. "Cohort
Studies of Fat Intake and the Risk of Breast Cancer -- A Pooled Analysis,"
New England Journal of Medicine, Feb. 8, 1996: pgs 356 - 361.