September 5, 2017

expert reaction to two studies investigating the health effects of ketogenic diets in mice

Two new mouse studies, published in Cell Metabolism, investigate whether ketogenic diets improve memory in older animals, as well as the chances of the animals living to old age.

Prof. Ilaria Bellantuono, Professor of Musculoskeletal Ageing, University of Sheffield, said:

“The two studies by Newman et al and Roberts et al, test the effects of a diet with low or no carbohydrates and rich in fat (ketogenic diet) for their effects on lifespan and health in mice in mice. These studies are important to further our understanding of the role of different nutrients on health and life extension. However, they should be interpreted with extreme caution as potential interventions in humans.

“The testing in these studies has been performed only in one strain of male mice and showed overall encouraging but variable results. The discrepancies in the effects on both extension of lifespan and improvement in physical activity may be due to small differences in the composition of the ketogenic diets or the regimen of administration (intermittent vs continuous). In addition, the measurements to test life extension and health are known to be complex to perform in a reproducible manner across laboratories as they are influenced by many variables, often unknown to the operators, including the level of stress the mice experience when handled. The memory tests are particularly difficult to interpret in aged mice because they rely on the sensory system (vision, hearing, sense of smell) which are known to decrease with age. It is therefore difficult to tease out whether mice taking a ketogenic diet have an improved sensory system or better memory.

“Finally mice differ in lipid metabolism from humans and so may respond to a high fat diet differently. For example they do not develop spontaneous atherosclerosis with age, a build-up of fatty material inside the arteries and one of the main causes of heart disease in humans. Therefore more extensive studies are required to explain the differences observed between the two studies, using mice of both sexes, different strain of mice and other models such as non-human primates, which better resemble certain aspects of human disease.”

* ‘Ketogenic Diet Reduces Midlife Mortality and Improves Memory in Aging Mice’ by Newman et al. published in Cell Metabolism on Tuesday 5 September. 

^‡ ‘A Ketogenic Diet Extends Longevity and Healthspan in Adult Mice’ by Roberts et al. published in Cell Metabolism on Tuesday 5 September.

Declared interests

Prof. Ilaria Bellantuono: “I have funding from MRC Arthritis Research UK, Horizon 2020, Cancer Research UK, and BBSRC, and I am chair of the BBSRC Bioscience skills and career strategy panel, and NC3Rs studentship panel.”