Researchers from the Washington University School of Medicine in St. Louis, Dana-Farber Cancer Institute and Harvard Medical School found an association between regularly eating peanut butter and having a lower risk of developing benign breast disease in early adulthood. Benign breast disease is noncancerous, and occurs when there are changes to the breast or an injury or infection leads to lumps in the breast tissue. The research team did not investigate a link between peanut butter and malignant breast lumps or cancer.
Other sources of vegetable fats and proteins — for example soybeans, beans and lentils — may also have the same effect, but researchers noted which the data on these particular foods inside study was not as considerable as data on peanut butter.
It is advisable to note that the study only showed a connection between peanut butter consumption and breast disease, and doesn’t show that peanut butter can definitively prevent breast disease.
The study, published in the journal Breast Cancer Research and Treatment, included health data on 9,039 U.S. girls ages 9 to 15 who were recruited to the Growing Up Today Study in 1996. They filled out food-frequency questionnaires once a year from their recruitment year until 2001, and then biennially until 2010.
In 2005, researchers also started keeping track of benign breast disease diagnoses among the study participants, who had entered adulthood and were now between ages 18 and 30. Researchers found that 112 of them had developed the condition.
Researchers found that eating peanut butter twice a week during childhood/adolescences was linked with a 39 percent lower risk of developing benign breast disease, and this effect seemed especially strong among girls who had a family history of breast cancer.