As a part of a large population study stretching over decades, scientists analysed nutrition and health data from almost 45,000 women. They provided data from their adolescence and early adulthood and have been followed for the past 25 years to see if there was any link between fibre intake in youth and the risk of breast cancer later in life.
Women with the highest fibre intake had a 19 per cent lower risk of breast cancer compared to women with the least fibre in their diet. With a higher fibre intake and lower risk of premenopausal breast cancer, the association was even stronger. Women with the highest intake had a 23 per cent lower risk.
Breast cancer has been linked to higher sex hormone and IGF-1 levels. The theory is that fibre may reduce breast cancer risk through decreasing the levels of these hormones, protecting hormone-sensitive tissues from high hormone exposures.
The study authors calculated that for each 10 grams of fibre per day in early life, the decrease in breast cancer risk was 13 per cent. It’s worth noting that the highest fibre intake in this study was around 30 grams a day, which is now the recommended minimum but which many people don’t reach. It’s very easy to get enough fibre on a healthy vegan diet – a portion of beans or lentils, one serving of fruit, one serving of vegetables and a serving of wholegrains will easily get you to 30 grams.
Farvid et al., 2016. Dietary Fiber Intake in Young Adults and Breast Cancer Risk. Pediatrics. 137 (3) 1-11.