Scientists May Have Found a Shortcut to Calorie Restriction's Anti-Aging Benefits

Keypoints:

• • A Yale-led study published in Nature Aging identifies an immune protein called C3 tied to chronic inflammation
  • Moderate calorie restriction, a 14% cut sustained for two years, lowered C3 levels in human participants
  • Blocking C3 in aged mice reduced age-related inflammation directly
  • Researchers are now exploring whether existing FDA-approved drugs could safely lower C3 in humans
  • The findings come from the long-running CALERIE human calorie-restriction trial

Cutting calories has been shown to extend lifespan in mice, monkeys, and fruit flies. But pushing that restriction too far in humans tends to backfire, weakening immunity and disrupting normal growth. A new Yale-led study, published in Nature Aging, points to a specific reason moderate calorie cutting might deliver real benefits without those costs.

The protein at the center of the discovery is called complement component 3, or C3. Researchers analyzed plasma samples from participants in the CALERIE trial, a long-running human study where volunteers cut their calorie intake by roughly 14% over two years. C3 levels dropped significantly in those participants over that stretch.

C3 is closely tied to chronic inflammation, one of the most consistent drivers of age-related disease in the human body. When researchers tested the same mechanism directly in aged mice, blocking C3 reduced age-related inflammation on its own. Notably, the mice didn't need to actually eat less to see that benefit, the protein itself appeared to be doing the work.

Senior author Vishwa Deep Dixit, who directs the Yale Center for Research on Aging, said the finding shows aging is a process that can genuinely be targeted rather than something fixed purely by genetics or time. His team is now investigating whether existing, already-approved drugs could safely lower C3 activity in humans. 

The goal is mimicking part of what calorie restriction does to the body, without requiring anyone to actually restrict their diet. Dixit was careful to frame this as restoring balance rather than shutting the immune system down entirely, since the same complement pathway is essential for fighting off infections in the first place.