New research suggests there's a link between the amount of saturated fat girls consume as teenagers and their breast density later in life.
For the study, published in Cancer Epidemiology, Biomarkers & Prevention, researchers had 177 girls between the ages of 10 and 18 fill out questionnaires about their diet on five occasions. When the participants were between the ages of 25 and 29, the researchers measured their breast density using an MRI scan.
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They found that women who had eaten higher amounts of saturated fat—the kind found in meat and dairy products such as cheese, butter, and milk—as teens had denser breasts in their 20s. (Those who had consumed the most saturated fat had an average "dense breast volume" of 21.5%; while those who ate the least had an average dense breast volume of 16.4%.)
The opposite was true for women who had consumed higher amounts of healthful unsaturated fats—the type in olive oil, avocados, nut butters, and fatty fish like salmon—during their teen years. These women had lower breast density in their 20s.
The data suggest that what teenage girls eat matters well into adulthood. "If confirmed, [our] results indicate that adolescent diet could potentially have long-term effects on breast health," says senior author Joanne Dorgan, PhD, a professor of epidemiology at the University of Maryland School of Medicine in Baltimore.
Denser breasts contain more fibrous or glandular tissue, which can make it harder for radiologists to spot tumors on a mammogram. Denser breast tissue is also thought to raise a woman's odds of developing breast cancer.
But research on the link between breast density and cancer risk is ongoing. Last winter, researchers from Croatia evaluated thousands of mammogram reports and did not find a substantial difference in breast density among women who were diagnosed with breast cancer and those who were not.