Eating Well Now May Prevent Breast Cancer Later, Study Finds

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For many young adults, health problems seem like something to deal with in the far-off future. But a new study from the Harvard T.H. Chan School of Public Health (HSPH) says eating well in young adulthood should be a high priority.

The large-scale study, published in Pediatrics, found that women who eat many high-fiber foods during adolescence may have a significantly lower breast cancer risk—up to 19 percent less—than those who eat little dietary fiber in young adulthood.

Currently, nutrition guidelines urge women younger than 50 to eat 25 grams of fiber per day. While we’ve long known that fiber is important for overall health, the link between intake and breast cancer has been hazy. Some previous studies proved non-significant, and others never examined diet during young adulthood.

“From many other studies we know that breast tissue is particularly influenced by carcinogens and anticarcinogens during childhood and adolescence,” says Walter Willett, a professor of epidemiology and nutrition at HSPH, in a statement. “We now have evidence that what we feed our children during this period of life is also an important factor in future cancer risk.”

Researchers analyzed the food diaries of more than 90,000 women who participated in the Nurses’ Health Study II. They first recorded their eating habits in 1991, when they were between the ages of 27 and 44, and again every four years after that; they also answered questions about their diet in high school. The researchers then focused on the women’s fiber intake, while adjusting for family history of breast cancer, weight change, race, body mass index, and other dietary factors.

Depending on how much dietary fiber young women ate, overall breast cancer risk was reduced between 12 and 19 percent, with the strongest benefit linked to fruit and vegetable fiber. The authors believe that fiber-rich foods may help reduce estrogen levels in the blood, which is related to breast cancer development.

“This work on the role of nutrition in early life and breast cancer incidence suggests one of the very few potentially modifiable risk factors for premenopausal breast cancer,” says Maryam Farvid, lead author of the study, in the statement.

Add in its impact on weight loss, and fiber is looking like a woman’s best friend.