Fatty foods during teen years could increase risk of breast cancer

June 6, 2016 | by City of Hope



Young women who eat high amounts of saturated fat or lower amounts of healthy fat have denser breasts 15 years later, according to a new study. Dense breasts are considered a risk factor for breast cancer because greater breast density results in lower sensitivity for mammography, increasing the likelihood that cancer will escape detection, according to the American College of Radiology.

The effect of fat on the development of breast density appeared to be modest, however: The researchers didn’t note a large change in breast density volume based on dietary fat intake.

The study found an association, but could not confirm a cause and effect. However, researchers speculate from the findings that different fats may play different roles in breast tissue formation.

The study appears in the June issue of the journal Cancer Epidemiology, Biomarkers & Prevention.

Researchers from the University of Maryland School of Medicine in Baltimore reviewed data from the Dietary Intervention Study in Children, a clinical trial sponsored by the U.S. National Heart, Lung, and Blood Institute that started in 1988 and enrolled more than 600 children between the ages of 8 and 10. More than half were girls.

Over the course of the study, participants reported what they ate. In a later follow up, researchers used MRI scans to measure breast density in 177 female participants who were then ages 25 to 29.

The researchers found that the women who ate the most saturated fat during adolescence (about 13 percent of their total calories) had an average breast density of 21.5 percent. Women who ate the least amount of saturated fat (about 8 percent of their total calories) had a breast density of 16.4 percent.

The study uncovered a similar difference in those who ate the lowest levels of healthy fats during the teen years compared to those who ate the highest levels. Eating more healthy fats was linked to less breast density, according to the study.

The American Heart Association (AHA) recommends that a healthy diet contain no more than 5 percent saturated fat. Saturated fats come from beef, lamb, pork, poultry with skin, butter, cream, cheese and other whole or 2 percent dairy products.

“Healthy,” or polyunsaturated and monounsaturated fats, are found in fatty fish like tuna and salmon, avocados, walnuts, olives and liquid vegetable oils.

The findings were reviewed by breast surgeon, Laura Kruper, M.D., M.S., co-director of City of Hope's Breast Cancer Program. Kruper noted some limitations of the study, including relying on dietary self-reports and the relatively small number of study participants.

In addition, "It is not known whether breast density measured at 25 to 29 will persist into the 40s and 50s, when the risk of breast cancer begins to increase," she told HealthDay, which recently reported on the study.

More research is needed, she said, but if the correlation holds up, "it would potentially have implications regarding dietary recommendations for adolescents."

Study author Joanne Dorgan, Ph.D., M.P.H., concurred in the article that this was an “initial” study that “would need to be confirmed before making any recommendation [about diet]."

As a general health guideline, the AHA recommends a diet low in saturated fats and high in fruits, vegetables, whole grains, low-fat dairy products, poultry, fish and nuts, while limiting red meat and sugary foods and beverages. 

It also advises eating foods made with liquid vegetable oil, consuming fish and nuts, and replacing some of the meat you eat with beans or legumes. “In general, you can’t go wrong eating more fruits, vegetables, whole grains and fewer calories,” the association says.


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