 A recent study published in the British Journal of Nutrition suggests that interolactone, an estrogen-like compound formed by the breakdown of whole grains and other plant-based foods by gut bacteria, could protect against the risk of death due to colorectal cancer, at least for women. For men, just the opposite could be true. High concentrations of the compound might actually increase that risk. The findings published as part of a special issue on nutrition and cancer point to a potentially significant link between diet and survival after colorectal cancer that warrants a much closer look by researchers. The authors of the study reached those conclusions by examining data from the Diet, Cancer and Health study, an ongoing cohort study of older men and women in Denmark. Specifically, they compared the death outcomes of people living with varying levels of interolactone in their blood plasma before being diagnosed with colorectal cancer. The results showed that, among women, interolactone concentrations were associated with lower rates of death due to colorectal cancer. In fact, a doubling of interolactone concentration was associated with a 12% lower risk of death due to colorectal cancer. And women with the highest measured concentrations of the compound had 37% lower rate of death due to colorectal cancer compared with women with the lowest measured concentrations. For men, the relationship was reversed. A doubling of interolactone translated to a 10% higher risk of death due to colorectal cancer. The findings agree with previous evidence linking estrogen to a lower colorectal cancer risk and mortality after diagnosis. Lignans from plant-based foods are broken down into interolactone by gut bacteria. Due to its origins and its structural similarities to estrogen, interolactone is considered a phytoestrogen. The richest dietary sources of phytoestrogens include vegetables, seeds, legumes, especially soy, and whole grains. Narrowing down the protective effects of estrogen to its metabolite, interolactone could help researchers find better ways to fight against colorectal cancer through the diet.