Protein-fortified foods are popping up everywhere, from cereal and coffee to even protein water. But a new review covering over 350 papers on protein restriction and aging-publishing July 31 in the Cell Press journal Cell Press Blue-suggests that consuming less protein could have greater health benefits and could, in some cases, extend lifespan. The authors describe how protein restriction slows aging by improving metabolism, changing how cells respond to nutrients, reducing cellular damage, and preserving healthy cell function.\u00a0<\/p>\n
“It’s absolutely crystal clear that there are benefits of protein to muscle growth and exercise response\u00a0of active individuals,” says Dudley Lamming, the paper’s corresponding author,\u00a0of the University of Wisconsin-Madison.\u00a0“But because most people are relatively sedentary,\u00a0many people are\u00a0likely consuming more protein than\u00a0they\u00a0actually need, which probably\u00a0has\u00a0negative health consequences.”\u00a0<\/p>\n
For decades, scientists have known that\u00a0eating\u00a0less\u00a0calories can extend lifespan in many organisms and reduce the risk of\u00a0age-related\u00a0diseases\u00a0like cancer.\u00a0But\u00a0maintaining\u00a0a calorie-restricted diet is difficult for most people.\u00a0<\/p>\n
Previous\u00a0studies\u00a0have\u00a0found that\u00a0eating less protein\u00a0can extend the lifespan of flies and rodents without\u00a0reducing their calorie consumption.\u00a0Several recent clinical trials in humans have\u00a0also\u00a0shown that reducing protein intake can reduce weight\u00a0and\u00a0fat mass and improve fasting blood sugar in humans, even though protein-restricted individuals tend to eat more calories.\u00a0<\/p>\n
But\u00a0at the same time,\u00a0some\u00a0studies have found that\u00a0eating more protein could promote weight loss and reduce\u00a0age-related muscle loss in older\u00a0adults\u00a0when paired\u00a0with exercise.\u00a0Those\u00a0findings\u00a0prompted US\u00a0authorities\u00a0to update its dietary guidelines\u00a0this year, recommending an increase in\u00a0daily protein intake\u00a0to 1.2\u20131.6 grams per kilogram of body weight (0.5\u20130.7 grams per pound), nearly doubling the\u00a0previous\u00a0recommendations.\u00a0<\/p>\n
With\u00a0Americans\u00a0consuming more protein than ever and older adults encouraged to boost their intake,\u00a0Lamming and his\u00a0colleague\u00a0set off to review\u00a0decades of\u00a0research on protein restriction and aging. Drawing\u00a0on\u00a0more than\u00a0350 papers, the team\u00a0outlined\u00a0potential mechanisms that consistently\u00a0emerge\u00a0across studies\u00a0and may\u00a0explain how\u00a0protein-restricted\u00a0diets could improve health and promote longevity.\u00a0These\u00a0mechanisms\u00a0suggest that\u00a0protein restriction\u00a0slows\u00a0aging by improving metabolism, changing how cells\u00a0respond to\u00a0nutrients, reducing\u00a0cellular\u00a0damage,\u00a0and preserving healthy cell function.\u00a0<\/p>\n
One of the key players\u00a0is\u00a0a hormone\u00a0called\u00a0fibroblast growth factor 21 (FGF21), which\u00a0rises when protein intake is low. FGF21 can\u00a0increase the body’s\u00a0energy expenditure, improve\u00a0blood sugar\u00a0control,\u00a0and reduce\u00a0inflammation<\/a>.\u00a0Studies in mice have shown that animals with higher\u00a0FGF21\u00a0levels lived longer than normal mice, and\u00a0the benefit was more pronounced in male mice than female\u00a0mice.\u00a0Eating less protein raises FGF21 levels in humans as well.\u00a0<\/p>\n The review\u00a0also\u00a0highlights\u00a0several amino acids, the building blocks of protein, that\u00a0appear to drive\u00a0many of these effects, including methionine,\u00a0isoleucine,\u00a0and valine.\u00a0Studies\u00a0show\u00a0that\u00a0consuming too much of these amino acids\u00a0could\u00a0trigger biological processes that promote growth, increasing the risk of obesity,\u00a0inflammation,\u00a0and\u00a0other age-related diseases.\u00a0<\/p>\n “These studies show that\u00a0the amount of protein\u00a0sedentary\u00a0people\u00a0are\u00a0eating today may have negative\u00a0health\u00a0consequences,\u00a0at least at\u00a0the population level,” Lamming\u00a0says.\u00a0<\/p>\n He\u00a0adds\u00a0that\u00a0while some people, like pregnant women\u00a0and\u00a0some older adults, have higher protein needs, for most sedentary adults, protein-fortified food may not provide the health benefits people expect.\u00a0<\/p>\n Lamming notes\u00a0that athletes often consume\u00a0large amounts\u00a0of protein without developing metabolic\u00a0diseases. He suspects that regular exercise,\u00a0perhaps by\u00a0using protein to build strong healthy muscles,\u00a0helps protect them from the negative\u00a0health\u00a0effects associated with a protein-rich diet.\u00a0<\/p>\n “Recent recommendations have encouraged people to eat more protein, but they’ve also encouraged people to exercise more,” Lamming\u00a0says. “We probably need to personalize protein recommendations based not just on age, but also on how physically active people are.”\u00a0<\/p>\n Source:<\/p>\n Journal reference:<\/p>\n