A drug that mimics a zero-carbohydrate diet could help people live longer, healthier lives and have better memories in old age, US researchers claim.
Scientists hope to develop a medication after two independent studies showed that mice fed on a diet stripped of all carbohydrate lived longer and performed better on a range of physical and mental tasks than those that had regular meals.
Because the diet is hard to stick to, the researchers are working on a compound that aims to deliver the same benefits for humans. If they are successful, it would amount to an extra seven to ten years of life on average, and protection against the weakening muscles and faltering memories that are defining aspects of human ageing.
“I’m excited about this, and it’s hard not to be after what we’ve seen that it does. These are pretty profound effects,” said Eric Verdin, a physician who led one of the studies at the Buck Institute for Research on Aging in California.
The zero carb diet was designed to induce a dramatic change in metabolism, by fooling the mice into thinking they were fasting. When deprived of carbohydrate, the body shifts from using glucose as its main energy source to burning fat and producing chemicals in the liver known as ketone bodies.
In 2013, Verdin showed that a ketone body called BHB served as fuel in the body and might also protect animals against the microscopic damage that builds up in cells as part of the natural ageing process.
In a new study published in the journal Cell Metabolism, Verdin and his colleagues describe how they fed one-year-old mice either a normal high-carbohydrate diet; a high-fat, low-carb diet; or a high-fat, zero-carb diet, also known as a ketogenic diet. They found that mice on the zero-carb diet were more likely to reach old age and scored better on memory tasks than those on the other diets.
Similar benefits of the ketogenic diet were seen in a separate study by scientists at the University of California in San Diego. Megan Roberts and others found that mice fed on a zero-carbohydrate diet lived 13% longer, reaching an average age of 1,003 days compared with 886 days for mice given standard meals.
But while the zero-carb diet appeared to benefit mice, its health effects have yet to be proven in humans. To make up the calories, the mouse diet contained 90% fat, which could be dangerous for humans to adopt.
Stephen O’Rahilly, director of the Metabolic Research Laboratories at Cambridge University, said high-fat diets drive up LDL or “bad” cholesterol in humans, and so raise the risk of heart disease. “Mice don’t really use LDL cholesterol in the first place, so it doesn’t have that bad impact on them,” he said.
The work could still lead to valuable insights though. “We may be able to learn from these studies what some of the pathways are that this sort of diet influences to keep mice somewhat generally healthier as they age. But for it to be useful in humans we would have to somehow dissociate these effects from the adverse effects on circulating LDL cholesterol,” O’Rahilly added.
Verdin said that the difficulty of sticking to the diet was a major reason his team was searching for drugs to mimic the its effects. Tests are underway on a compound that produces BHB in the body in the hope that it could be taken as a supplement, he said.
“The biggest problem with the diet is that it is difficult to maintain as a lifestyle,” Verdin said. It’s an antisocial diet. You can hardly eat anything that most of us like.”