"Women who eat more highfiber foods during adolescence and young adulthoodespecially lots of fruits and vegetablesmay have significantly lower breast cancer risk than those who eat less dietary fiber when young according to a new largescale study led by researchers at Harvard T.H. Chan School of Public Health. The study will be published online February   in Pediatrics. Previous studies of fiber intake and breast cancer have almost all been nonsignificant and none of them examined diet during adolescence or early adulthood a period when breast cancer risk factors appear to be particularly important said Maryam Farvid http visiting scientist at Harvard Chan School and lead author of the study. 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. The researchers looked at a group of  women who participated in the Nurses Health Study II a large longrunning investigation of factors that influence womens health. In  the womenages  at the timefilled out questionnaires about their food intake and did so every four years after that. They also completed a questionnaire in  about their diet during high school. The researchers analyzed the womens fiber intake while adjusting for a number of other factors such as race family history of breast cancer body mass index weight change over time menstruation history alcohol use and other dietary factors. Breast cancer risk was  lower among women who ate more dietary fiber in early adulthood depending on how much more they ate. High intake of fiber during adolescence was also associated with  lower risk of overall breast cancer and  lower risk of breast cancer before menopause. Among all the women there was a strong inverse association between fiber intake and breast cancer incidence. For each additional  grams of fiber intake dailyfor example about one apple and two slices of whole wheat bread or about half a cup each of cooked kidney beans and cooked cauliflower or squashduring early adulthood breast cancer risk dropped by . The greatest apparent benefit came from fruit and vegetable fiber. The authors speculated that eating more fiberrich foods may lessen breast cancer risk partly by helping to reduce high estrogen levels in the blood which are strongly linked with breast cancer development. From many other studies we know that breast tissue is particularly influenced by carcinogens and anticarcinogens during childhood and adolescence said Walter Willett http Fredrick John Stare Professor of Epidemiology and Nutrition at Harvard Chan School and senior author of the study. We now have evidence that what we feed our children during this period of life is also an important factor in future cancer risk.  Other Harvard Chan School researchers involved in the study included Heather Eliassen associate professor in the Department of Epidemiology and Xiaomei Liao research scientist in the Departments of Epidemiology and Biostatistics.  The study was supported by National Institutes of Health grants R CA and UM CA and a grant from The Breast Cancer Research Foundation. Farvid was supported by the Japan Pharmaceutical Manufacturers Association. Dietary Fiber Intake in Young Adults and Breast Cancer Risk Maryam S. Farvid A. Heather Eliassen Eunyoung Cho Xiaomei Liao Wendy Y. Chen and Walter C. Willett online February   Pediatrics e doi .peds. Visit the Harvard Chan School website for the latest news press releases and multimedia offerings. Harvard T.H. Chan School of Public Health http brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists educators and students we work together to take innovative ideas from the laboratory to peoples livesnot only making scientific breakthroughs but also working to change individual behaviors public policies and health care practices. Each year more than  faculty members at Harvard Chan School teach plus fulltime students from around the world and train thousands more through online and executive education courses. Founded in  as the HarvardMIT School of Health Officers the School is recognized as Americas oldest professional training program in public health."