It's a given that generally eating less is healthier than constantly chowing down on burgers and fries, but studies have shown that an ongoing diet of careful caloric restriction can drastically increase the lifespan of a range of animals. On the path to determining whether humans could benefit from the same lifestyle, a 10-year study on lemurs has now found that those on the diet lived almost 50 percent longer than usual.
Plenty of studies over the years have shown that chronic caloric restriction can slow down the aging process, increasing lifespan and healthspan – the amount of time an organism spends in good health. But it's a balancing act, requiring a reduction in calories but normal levels of vitamins and minerals to prevent malnutrition.
These studies have been conducted in fish, mice, rats, worms, and even yeast, but those results won't necessarily carry over to humans. The closest we've gotten to human trials so far is a pair of 20-year-long monkey studies, which initially came to conflicting conclusions before pooling their data to agree that yes, caloric restriction increased the lifespan of the primates.
In a similar vein, the new study looked at grey mouse lemurs, which share many physiological similarities with humans and have a manageable lifespan of around 12 years. A team of researchers from the French National Center for Scientific Research (CNRS) and the National Museum of Natural History (MNHN), compared two groups of lemurs. A control group was fed a normal diet, while an experimental group ate 30 percent fewer calories from early adulthood.
After 10 years, the median lifespan of the dieting lemurs was 9.6 years – about a 50 percent increase over the 6.4 years of the control group. The maximum lifespan also appeared to go up, with about a third of the calorie-restricted animals outliving the last survivor of the control group, who passed away at the age of 11.3 years.
The benefits weren't limited to lifespan. The scientists report that the calorie-restricted lemurs maintained better motor skills for longer, had less instances of aging-related diseases like cancer and diabetes, and generally had the bodies of younger animals. When the brains of the eldest animals were imaged, the researchers found that the diet had slowed down the natural atrophying of the white matter – although, strangely, they had also lost some grey matter, and the scientists weren't sure why.
While the study adds to a growing catalog of research showing the benefits of caloric restriction, it might be too early to declare that such a diet could offer similar benefits to humans. After all, another recent study found that evolution might have already taken advantage of this mechanism, so there might not be any extra years left to wring out of it.
In future, the French scientists plan to focus on how physical exercise and other parameters play into the effect of chronic caloric restriction on lifespan.
The research was published in the journal Communications Biology.
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