A recent study has demonstrated that a ketogenic diet significantly improved memory in aging mice and increased the animal’s chances of surviving to old age, opening up a new area of inquiry in aging research.
Eating a ketogenic diet – which is high in fat and low in protein and carbohydrates – ramps up the number of ketone bodies. In this study, Newman et al. carefully designed three diets that were matched in every way except fat and carbohydrate content: a normal high-carbohydrate diet, a zero-carbohydrate ketogenic diet, and a high-fat, low-carbohydrate diet that was not ketogenic. Mice were fed the ketogenic diet intermittently to prevent them from becoming obese, starting at one year old, which is middle age for mice.
The ketogenic diet-fed mice had a lower risk of dying as they aged from one to two years old, although their maximum lifespan was unchanged. Another group of mice underwent memory testing at both middle age (one year old) and old age (two years old). Mice that had been eating a ketogenic diet performed at least as well on memory tests at old age as they did at middle age, while mice eating the normal diet showed an expected age-associated decline. Mice who ate the ketogenic diet also explored more, and their improved memory was confirmed with another test a few months later.
According to the paper, gene expression could explain the cognitive improvement. Future work to understand the nature of the persistent effect on memory in particular may lead to therapies to promote cognitive resilience to dementia or illness-associated delirium.
As more people age well past their 70s, researchers have increasingly explored the issues of health and quality of life during aging. A recent mouse study at the UC Davis School of Veterinary Medicine sheds revealed that a high-fat, or ketogenic, diet not only increases longevity, but improves physical strength as well.
Ketogenic diets have gained popularity for a variety of health benefit claims, but scientists are still teasing out what happens during ketosis, when carbohydrate intake is so low that the body shifts from using glucose as the main fuel source to burning fat and producing ketones for energy.
While calorie restriction has been shown to slow aging in many animals, Roberts et. al. were interested in how a high-fat diet may impact the aging process. In their research, they found a 13% increase in median life span for the mice on a high-fat versus high-carb diet.
The study mice were split into three groups: a regular rodent high-carb diet, a low-carb/high-fat diet, and a ketogenic diet (89-90 percent of total calorie intake). Originally concerned that the high-fat diet would increase weight and decrease lifespan, the researchers kept the calorie count of each diet the same.
In addition to significantly increasing the median lifespan of mice in the study, the ketogenic diet increased memory and motor function, prevented an increase in age-related markers of inflammation, and reduced the incidence of tumors. This indicates that a ketogenic diet can have a major impact on life- and health span without major weight loss or restriction of food intake. It also opens a new avenue for possible dietary interventions that have an impact on aging.
Future studies are warranted to investigate the mechanisms through which this diet works and to optimize diet composition and feeding approaches to further extend healthspan.