According to a recent study from the Harvard TH Chan School of Public Health, women who ate a fiber-rich diet during adolescence and early adulthood significantly reduced their risk of developing breast cancer, especially if the fiber came from fruit and vegetables.
The study followed the diets of 90,534 premenopausal women age 27 to 44 for 20 years. Nearly half the women also recalled what they ate while in high school. After adjusting for factors such as tobacco and alcohol use, menstruation cycles, body mass index and family history of breast cancer, researchers then compared the women’s daily fiber intake with the number of women diagnosed with breast cancer during the study.
They found that for each additional 10 grams of fiber the young women consumed daily – say, one medium apple and a cup of broccoli – breast cancer risk dropped by up to 14%.
Why the positive outcome? Fiber may help reduce high levels of estrogen in the blood, which have been linked to breast cancer in both women and men. (The study's lead author, Maryam Farvid, notes that while published studies have indicated some similarities between male and female breast cancer, science hasn't yet pinpointed what the risk factors are for breast cancer in males.)
While fiber from fruit and vegetables produced the best results, Farvid says she can’t rule out the possibility that other nutrients found in fruit and vegetables contributed to the lower risk.
Overall, Farvid says, “Women are doing themselves a favor in terms of breast cancer prevention if they increase the amount of dietary fiber intake earlier in life rather than later.”