In two new papers — one in Scientific Reports and a review article in Frontiers in Aging Neuroscience — Ai-Ling Lin, Ph.D., who studies aging at the University of Kentucky, used brain imaging techniques on mice to show that the ketone diet slows down crucial processes related to getting older. Personally this information doesn’t come as a surprise to me but it’s still great to see it in print!
Slowed brain aging in mice
The mice who adhered to the keto diet in Lin’s experiments tended to have more blood flow in their brains, which she says is a sign that the diet slows the aging process in the brain and keeps blood flow high. This process is moderated through signaling pathway called mTOR, which, Lin explains, has a huge influence on longevity.
“mTOR has been studied very well in aging research,” Lin tells Inverse. “mTOR is a nutrient sensor, so when you suppress the signal, then the body will think that it’s lacking glucose or nutrition. It will tell the body to grow slowly or expend energy slower. If you inhibit mTOR signaling, then it can extend longevity.” An easy way to do this, she says, is to restrict calories.
This makes sense on an intuitive level: The body is likely to conserve resources when it thinks there won’t be much food around in the future. What’s interesting about Lin’s research is that it showed that the keto diet — which is not a calorie-restrictive kind of diet — has a similar effect.
A typical keto diet primarily consists of fats and proteins with very few (or no) carbohydrates allowed. Lin’s results suggests this diet forces the body to burn fuel sources other than glucose, the fuel source that we obtain from carbohydrates. That fuel consists of “ketone bodies,” the biochemical byproduct of burning fat instead of sugar.
This is the crucial physiological shift that’s thought to produce an anti-aging effect. By switching to fat as a fuel source by following a keto diet, the body is tricked into suppressing the mTOR signal. It interprets the lack of glucose as a sign that it’s fallen on hard times, and slows down the growth — and aging — process as a result.
“Calorie restriction and ketone bodies are like twins,” she says. “If you reduce calorie intake then the ketone bodies will go up. If you give someone the ketogenic diet, you will automatically inhibit glucose uptake, and than will inhibit mTOR.”
But will it work for people?
Lin sees the potential for strict diets to combat aging in the human brain, but using what she calls “precision nutrition” in this way will not be as straightforward in people as it is in mice. First of all, we’ll need to know a lot more about how each potential patient’s body reacts to high fat diets. The anti-aging effect hinges on the body’s ability to metabolize fat, and some bodies are better at this than others. Fortunately, genetic testing can help identify these people.
“Everyone has very different genetic makeups, so some people’s genes can take high fat and utilize it. But some people’s genes can’t do that and it can cause ketosis, which makes the body more acidic and can lead to health concerns,” she says.
Determining the right genotype for this intervention will be the next step in her research. At this point, it’s encouraging to know that an anti-aging diet for the brain might exist, but the specifics of that diet, it seems, will probably be different for everyone.