A ketogenic diet causes damaged cells to accumulate in the organs of mice. Their build-up suggests the keto diet may accelerate organ ageing, raising the risk of conditions like heart disease and cancer.

Although many people have adopted low-carbohydrate diets like keto for weight loss and controlling blood sugar, research on their health effects is mixed, with some studies finding they increase the risk of heart attacks.

To learn more, David Gius at the University of Texas Health Science Center at San Antonio and his colleagues fed six mice a ketogenic diet for three weeks. More than 90 per cent of their calories came from fat and less than 1 per cent from carbohydrates. A control group ate a standard diet where 17 per cent of calories came from fat and 58 per cent came from carbohydrates.

The researchers then analysed heart, kidney, liver and brain tissue samples from the mice, looking for senescent cells. Senescence occurs when cells become too damaged to function, but instead of dying, they enter a zombie-like state. These cells linger in tissues, spewing toxins that stoke inflammation.

Animals on the ketogenic diet had significantly more senescent cells in their organs compared with those on a standard diet. For instance, their kidneys contained, on average, four times the amount of a marker of cellular senescence as those from animals fed a regular diet.

Senescent cells increase with age. So, these findings suggest the keto diet might accelerate organ ageing, which would raise the risk of conditions like heart disease, cancer and type 2 diabetes. However, switching mice back to a standard diet decreased senescent cells.

“While the ketogenic diet is probably a good thing, [it is not for] everyone. And importantly, you need to take a break,” says Gius. “I think our paper really says we need to study this more rigorously.”

It isn’t clear how these experimental findings may translate to people, says Russell Jones at the Van Andel Institute in Michigan. “They’re running a 90 per cent fat diet, and that would be virtually impossible to adhere to as a human,” he says.