6 minute read
Health & Science
A NEW study has reviewed the e cacy of popular diets that claim to have anti-aging bene ts. e diets reviewed in the study included intermittent fasting, calorie restriction, and the ketogenic diet. Although these diets show promising results in studies with rodents, the researchers noted that more research was needed to con rm whether they yielded anti-ageing bene ts in humans. e cosmetics industry has long touted products with supposed anti-ageing properties. Lather 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, marketing executives are now applying it to what people put inside them. at’s right, food is now getting the anti-ageing treatment.
So, what does science have to say about that Researchers from the University of Washington and Pennington Biomedical Research Centre in Louisiana recently weighed in on the matter in a review article published in the journal Science. ree 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 person on the diet restricts carbohydrate intake to roughly 10% of daily calories or less, so that the body produces and utilises molecules called ketone bodies for fuel rather than sugary glucose.
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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, fasting rodents generally consume fewer calories than those not fasting, so it’s possible that the anti-aging bene ts of intermittent fasting may simply arise from eating less.
Lastly, a couple of studies of rodents 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? e authors say no.
“Despite their recent popularisation, there is not yet strong evidence that any of the anti-aging diets studied in laboratory animals have substantial long-term health bene ts in non-obese humans,” they write. ere’s simply no adequately controlled, long-term studies in humans which clearly demonstrate that any of these diets produce longevity bene ts.
Intriguing anecdotes abound, of course.
One of the most enticing is the living example of Okinawans, who inhabit a few small Japanese islands o 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-ageing diets, at least without the guidance of a medical or nutrition expert. After all, these eating interventions can bring about profound biological e ects that may bene t some people while harming others.
Moreover, inadequate attention to dietary detail may leave the dieter nutritionally de cient. Lastly, humans are not rodents. What works for them often doesn’t work for us. e 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.”
The science behind ‘anti-ageing’ diets
Some of the most popular ‘anti-ageing’ diets show promise in studies with rodents . But are they e ective for us humans?
How Galapagos tortoise live, cancer-free, to well over 100 years
GALAPAGOS giant tortoises evolved to have extra copies of genes — called duplications — that may protect against the ravages of ageing, including cancer, researchers report. e tortoises can weigh well over 300 pounds and often live over 100 years.
Laboratory tests on Galápagos giant tortoise cells corroborate the idea that the animals have developed such defences, says Vincent Lynch, associate professor of biological sciences at the University at Bu alo.
Speci cally, experiments showed that the creatures’ cells are super sensitive to certain types of stress relating to damaged proteins. When exposed to these pressures, the cells self-destruct much more readily than other turtle cells through a process called apoptosis, the researchers found.
Destroying glitchy cells before they have the chance to form tumours could help the tortoises evade cancer, Lynch says.
“In the lab, we can stress the cells out in ways that are associated with ageing and see how well they resist that distress. And it turns out that the Galápagos tortoise cells are really, really good at killing themselves before that stress has a chance to cause diseases like cancer,” says Prof. Lynch. e ndings, which appear in the periodical Genome Biology And Evolution, both con rm and build on results of past research, such as a 2018 study by another team that also used genetic analyses to explore longevity and age-related disease in giant tortoises. e ndings are particularly intriguing because — all things being equal — huge animals that live for a long time should have the highest cancer rates. at’s because big, long-lived things have many more cells, and the more cells a body has, the more opportunities there are for cancerous mutations to arise.
One major focus of Lynch’s work is understanding the biological mechanisms that help big animals like Galápagos tortoises live long and prosper. (His team explored this question in elephants in a 2021 study). e research is driven by simple curiosity. But the ndings could have practical implications, too.
“If you can identify the way nature has done something — the way certain species have evolved protections — maybe you can nd a way to translate those discoveries into something that bene ts human health and disease,” Lynch says.
“We’re not going to go treating humans with Galápagos tortoise genes, but maybe we can nd a drug that mimics certain important functions.”
Research of this kind also underscores the value of conservation.
“Studies like this demonstrate why preserving biodiversity is so important,” says rst author Scott Glaberman, an assistant professor of environmental science and policy at George Mason University.
“Extreme species like Galápagos giant tortoises probably hold many secrets for dealing with major human challenges like ageing and cancer, and even climate change. Our study also shows that even within turtles, di erent species look, act, and function di erently, and losing any species to extinction means that a piece of unique biology will be lost to the world forever.”
