According to a new research review, consuming a diet high in fibre may help guard against breast cancer.
Because studies have generated inconsistent results regarding the potential link between fibre intake and breast cancer, researchers from the Harvard T.H. Chan School of Public Health combined data from 20 large prospective studies, published prior to July 2019, on fibre and breast cancer risk.
Prospective studies follow thousands of people forward for many years and gather diet, lifestyle and medical information at regular intervals. After a specified amount of time, researchers see if those who developed risk factors, or became ill, adhered more or less to a certain diet or consumed more or less of a food or nutrient than those who stayed healthy.
The findings
Compared to women who had the lowest daily fibre intake, those whose diets provided the most were 8 per cent less likely to be diagnosed with breast cancer. The reduction in risk was similar for all sources of fibre including cereal grains, vegetables, fruits and pulses (beans and lentils).
When the researchers investigated the effect of fibre on premenopausal and postmenopausal breast cancers separately, they found that a high-fibre diet reduced the risk of both by 18 per cent.
A high intake of soluble fibre (found in oats, oat bran, barley) was found to significantly lower breast cancer risk. The findings, while not statistically significant, suggested that a diet high in insoluble fibre (found in wheat bran, vegetables, nuts) was also protective.
Related: WHO – High fibre, whole grains protect from chronic disease
The findings do not demonstrate that dietary fibre directly reduces breast cancer risk; a randomized clinical trial is needed to test cause and effect.
How fibre may protect
Still, there are several ways in which fibre may help guard against breast cancer. There’s longstanding evidence that fibre lowers circulating estrogen levels; being exposed to estrogen over a long period of time is thought to increase risk.
A high-fibre diet also helps control blood sugar, as well as insulin and insulin-like growth factors, hormones implicated in breast cancer risk. And fibre nourishes the community of microbes that live in our gut, which plays an important role in regulating circulating estrogen.
A high-fibre diet also helps control blood sugar, as well as insulin and insulin-like growth factors, hormones implicated in breast cancer risk. And fibre nourishes the community of microbes that live in our gut, which plays an important role in regulating circulating estrogen.
Source: Cancer, published online, April 6, 2020.
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