High intake of fiber-rich foods in adolescence and early adulthood could reduce women's risk for breast cancer. This is the conclusion of a new study published in the journal Pediatrics.
According to lead author Maryam Farvid, visiting scientist at Harvard T.H. Chan School of Public Health, most previous studies assessing the link between fiber intake and breast cancer risk have been "non-significant."
She notes that none of these studies have looked at diet during adolescence and young adulthood - a period that appears to be closely associated with breast cancer risk factors.
To address this research gap, the team analyzed data of 90,534 women who were part of the Nurses' Health Study II.
Information about food intake was gathered through a dietary questionnaire completed in 1991 - when the women were aged 27-44 - and every 4 years thereafter. In 1998, the women completed another questionnaire asking them about their food intake in high school.
Farvid and colleagues analyzed the women's fiber intake using the dietary data, and they also assessed breast cancer incidence among the women.
Each 10 g of daily dietary fiber linked to 13% lower breast cancer risk
Compared with women who had low fiber intake in early adulthood, those who had high fiber intake were found to be at 12-19% lower overall breast cancer risk.
High fiber intake during adolescence was associated with an overall 16% lower risk of breast cancer and a 24% lower risk of premenopausal breast cancer.
Additionally, the team found that the more fiber consumed in early adulthood, the lower the breast cancer risk; every additional 10 g of fiber consumed each day - the equivalent to one apple and two slices of whole wheat bread - was linked to a 13% lower breast cancer risk.
Fiber that came from fruits and vegetables was associated with the strongest reduction in breast cancer risk.
While the team is unclear exactly why a fiber-rich diet appears to lower the risk of breast cancer, they hypothesize that high-fiber foods may help to reduce high estrogen levels in the blood; such levels are a major risk factor for the disease.
After skin cancer, breast cancer is the most common cancer among American women; this year, more than 246,000 women in the US are expected to be diagnosed with the disease.
Based on their findings, the team suggests that young women may want to think about increasing their fiber intake in order to help reduce their risk of breast cancer.
Commenting on the results, senior author Walter Willett, Fredrick John Stare professor of epidemiology and nutrition at Harvard, says:
"From many other studies we know that breast tissue is particularly influenced by carcinogens and anti-carcinogens during childhood and adolescence. We now have evidence that what we feed our children during this period of life is also an important factor in future cancer risk."
A high-fiber diet may not only reduce breast cancer risk. A study recently reported by Medical News Today suggests that a diet rich in fiber may lower the likelihood of lung disease.
Source: Medacal News Today