Keto diet increases small-intestinal tumour risk in mice

A ketogenic diet led to more small-intestinal tumours in genetically susceptible mice than a standard diet, ERR reported, citing a study by researchers at the Massachusetts Institute of Technology.

The researchers compared how the mice responded to different diets. Earlier research had suggested that a ketogenic diet could slow the development of colorectal cancer, but the new study found that mice eating ketogenic food developed small-intestinal tumours more often than mice on a standard diet.

The mice on the ketogenic diet did not become overweight. Yet their tumour rates were similar to, and sometimes higher than, those in mice deliberately fed a very high-fat, calorie-rich diet designed to promote obesity.

The researchers said the effect may stem from how cells produce energy when sugar is scarce. Small-intestinal cells then use fatty acids as fuel. Breaking down fat activates proteins that prompt intestinal stem cells to multiply faster than usual. This can help the intestine recover from injury or illness, but increased cell division also creates more opportunities for cancer cells to develop.

The study also challenged the idea that ketones produced in the body drive the diet’s effects. Instead, the researchers said, tumour development is influenced by how stem cells digest and burn the large amount of fat in the diet. The findings were published in the journal Nature.