How what you eat affects cancer risk

Decades of research suggests that your diet can influence the risk of various cancers

- Nina Agrawal

Over decades, a growing body of literature has shown clear links between what we eat and how likely we are to develop various cancers. In recent years, the research has moved away from the impact of individual "superfoods" and antioxidants to focus on how overall, long-term dietary habits affect risk.

That's not to say that any individual cancer diagnosis can be blamed on someone's diet; cancer, after all, arises as a result of a large constellation of factors and it occurs in people who make healthy choices.

But on a population level, there are some trends in the data. Here's what we know.

Eating patterns that emphasise whole grains, fresh fruits and vegetables, and lean or plant-based proteins have shown the most consistent association with a lower risk of cardiovascular disease, diabetes and cancer. One reason may be that people who follow these eating patterns have lower levels of insulin and inflammation, said Fred Tabung, a cancer public health researcher at The Ohio State University College of Medicine and Comprehensive Cancer Center who studies diet, metabolism and cancer.

Chronically high levels of insulin and inflammation are key features of obesity and metabolic syndrome, which mediate cancer risk. High insulin and inflammation also promote unnecessary cell division, cell growth, DNA damage and the inhibition of cell death, which are all hallmarks of cancer, Tabung said.

Whole grains, fresh fruits and vegetables, and legumes and nuts contain lots of dietary fiber, which has been associated with lower cancer risk. This may be because fiber helps speed stool along the digestive tract, limiting exposure to carcinogens, and because it feeds microbes in the gut that help protect against inflammation, said Dr Kimmie Ng, associate chief of the division of gastrointestinal oncology at Dana-Farber Cancer Institute in Boston.