The cosmetics industry has long touted products with supposed anti-aging properties. Slather this cream on your skin and it will turn back your body’s clock! Not content with using that claim just for what people put on their bodies, marketers are now applying it to what people put inside them. That’s right, food is now getting the anti-aging treatment.
What does science have to say about that? Researchers from the University of Washington and Pennington Biomedical Research Center in Louisiana recently weighed in on the matter in a review article published in the journal Science.
Three of the most popular diets widely hyped to extend lifespan and delay age-related functional declines and diseases are caloric restriction, where one cuts calories while still maintaining good nutrition; intermittent fasting, which has you take at least a 24-hour break between eating; and the ketogenic diet, in which the dieter restricts carbohydrate intake to roughly 10% of daily calories or less, so that the body produces and utilizes molecules called ketone bodies for fuel rather than sugary glucose.
All of these diets have been widely studied in rodents. What do the results suggest? Caloric restriction easily has the most credibility: When scientists reduce rodents’ calories by anywhere from 20-50% while maintaining adequate intake of vitamins and minerals, the animals generally live longer and healthier lives with reduced incidence of disease compared to normally-fed controls. Intermittent fasting, with breaks between feeding usually lasting a day or two, also delivers robust results.
However, fasted rodents generally consume fewer calories than unfasted controls, so it’s possible that the anti-aging benefits of intermittent fasting may simply arise from eating less. Lastly, a couple rodent studies suggest a ketogenic diet can slightly extend lifespan and boost memory and motor function, but the reviewers caution that this research isn’t nearly as reliable. Caloric restriction and intermittent fasting clearly come out on top according to the animal evidence.
But should we put much stock in this research when deciding how we should eat? The authors say no.
“Despite their recent popularization, there is not yet strong evidence that any of the anti-aging diets studied in laboratory animals have substantial long-term health benefits in nonobese humans,” they write.
There’s simply no adequately controlled, long-term studies in humans which clearly demonstrate that any of these diets produce longevity benefits.
Intriguing anecdotes abound, of course. One of the most enticing is the living example of Okinawans, who inhabit a few small Japanese islands off the country’s mainland. It’s estimated that Okinawans consume about 20% fewer calories than mainland Japanese and get about 85% of their calories from carbohydrates. Historically, they have also had the “longest life expectancy at birth and highest centenarian prevalence in the world, with remarkably low rates of age-associated diseases, such as cancer, heart and cardiovascular disease, and diabetes,” the researchers note.
Still, while whatever the Okinawans are doing seems to be working, the researchers can’t recommend that you attempt to emulate their diet or any of the other anti-aging diets, at least without the guidance of a medical or nutrition expert. After all, these eating interventions can bring about profound biological effects that may benefit some people while harming others. Moreover, inadequate attention to dietary detail may leave the dieter nutritionally deficient. Lastly, humans are not rodents. What works for them often doesn’t work for us.
The main takeaway, according to the researchers, is that so-called “anti-aging” diets are not ready for widespread adoption.
“Although caloric restriction and other diets hold promise, additional data from carefully controlled studies is needed before broadly recommending or implementing these diets, or other interventions, for otherwise healthy people.”