(RxWiki News) High-fiber diets offer many health benefits, such as regular bowel movements and lower cholesterol levels. But they may do much more.
A new study from Harvard University found that women who ate fiber-rich diets, especially lots of fruits and vegetables, in adolescence and early adulthood were at a lower risk of developing breast cancer as an adult.
"Previous studies of fiber intake and breast cancer have almost all been non-significant, and none of them examined diet during adolescence or early adulthood, a period when breast cancer risk factors appear to be particularly important," said lead study author Maryam Farvid,PhD, in a press release.
Dr. Farvid is a visiting scientist at Harvard's T.H. Chan School of Public Health.
This study looked at 90,534 women who participated in the Nurses' Health Study II. In 1991, these women (ages 27 to 44 at the time) answered survey questions about their food intake. This process was repeated every four years, including one survey in 1998 about their food intake in high school.
Researchers looked specifically at fiber and adjusted for several factors, including ethnicity, family history of breast cancer, body mass index, alcohol use and others.
Women who ate more fiber during early adulthood were between 12 and 19 percent less likely to develop breast cancer — depending on how much fiber they ate.
Women who ate a high-fiber diet during adolescence were 16 percent less likely to develop breast cancer during their entire lives, and 24 percent less likely to develop breast cancer before menopause.
Dr. Farvid and team said that, if a woman ate an additional 10 grams of fiber daily in early adulthood, her risk of developing breast cancer dropped 13 percent overall.
Ten grams of fiber could include an apple, two slices of whole wheat bread, or about half a cup each of cooked beans and cauliflower or squash.
Researchers noted that the greatest benefits appeared to come from fruit and vegetable fiber.
In an accompanying editorial, Kathleen K. Harnden, MD, and Kimberly L. Blackwell, MD, explained that there is longstanding evidence that fiber reduces estrogen levels. High levels of estrogen are linked to breast cancer risk.
This study was published Feb. 1 in the journal Pediatrics.
The National Institutes of Health and the Breast Cancer Research Foundation funded this research. The authors disclosed no conflicts of interest.