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What's New - Diet Influences Hormones

Kaiser Permanente Study Shows Lower-Fat Diet During Puberty Influences Hormones Associated with Breast Cancer Risk in Adulthood

55 girls in Oregon and Southwest Washington participated

(PORTLAND, Ore.) – A study conducted at Kaiser Permanente's Center for Health Research in Portland and five other sites in the Midwest and East Coast has found that certain hormones were lower in girls eating a lower-fat diet than in a control group eating a diet higher in fat. High levels of these hormones in adulthood are associated with a higher risk of breast cancer.

The study appears in the Jan. 15th edition of the Journal of the National Cancer Institute, published by Oxford University Press. Principal investigator for this ancillary study of the Dietary Intervention Study in Children (DISC) at the Center for Health Research is Vic Stevens, PhD. DISC was funded by the federal government's National Heart, Lung and Blood Institute.

Researchers originally studied 286 girls aged 8 to 10, including 55 from Oregon and Southwest Washington. The girls were randomly assigned to a group eating a moderately low-fat diet (28 percent of calories on average came from fat) or to a group that only received educational materials. Girls in the first group consumed less total and saturated fat and ate more fiber compared with those who only received educational materials. The researchers measured blood hormone levels at the start of the study and four other times over the next seven years.

Stevens says that after five years, girls in the lower-fat group had changes in hormone concentrations compared with girls in the usual care group. Specifically, girls eating less fat had:

• 29.8 percent lower estradiol (an estrogenic hormone);
• 30.2 percent lower non-sex hormone binding globulin-bound estradiol;
• 20.7 percent lower estrone (an estrogenic hormone);
• 28.7 percent lower estrone sulfate levels during the first half of their menstrual cycles;
• 27.2 percent higher testosterone levels during the second half of their menstrual cycles.

After seven years, girls in the group eating less fat had half the progesterone levels during the second half of their menstrual cycles as did girls in the usual care group.

"The typical high-fat diet many young Americans eat is associated with greater obesity and a higher risk of type II diabetes, high blood pressure, and high cholesterol," says Stevens. "Now we see that girls who ate more fat had higher levels of estrogenic hormones during puberty than girls who ate a diet moderately lower in fat. We know from other research that high levels of these hormones are associated in adulthood with greater risk of breast cancer. We'd like to know more about the effects of these youthful hormone levels in connection with breast cancer risk over a lifetime."

A parallel study was conducted in boys, with results to be reported separately.

Kaiser Permanente is a group practice health care organization serving the health care needs of about 450,000 people in Northwest Oregon and Southwest Washington.

For more infomation contact:
Terry Fitzpatrick (503) 335-6602 or
Jim Gersbach (503) 831-4820

Released: January 17, 2003