A Yale-led study found that eating fewer calories may lower inflammation connected to aging.
Participants reduced their calorie intake by about 11% to 14% over two years.
Researchers say the findings could help explain how calorie restriction affects long-term health.
Scientists have long wondered whether eating fewer calories could help people stay healthier as they age. Studies in animals have shown that calorie restriction may help extend lifespan, but researchers still have a lot to learn about how it works in humans.
Now, a new study from Yale School of Medicine suggests that cutting calories in a moderate, realistic way may help lower inflammation in the body that is linked to aging. The research, published in Nature Aging, looked at how eating less affects the immune system and certain proteins tied to age-related inflammation.
The study
Researchers stressed that the participants were not following extreme diets or starving themselves. Instead, they reduced their calorie intake by about 11% to 14% over two years. That could mean skipping extra snacks, cutting back on portion sizes, or making small adjustments to meals over time.
The study used data from a clinical trial called CALERIE, which followed healthy adults over a two-year period. Researchers collected blood samples from 42 participants and studied thousands of proteins in their blood to look for changes caused by calorie restriction.
One protein caught the researchers’ attention: a protein called C3, which is part of the immune system. Normally, this protein helps the body fight infections. But past research has suggested that too much activity from this part of the immune system may also contribute to chronic inflammation as people get older.
Chronic inflammation has been linked to many age-related health problems, including heart disease and other conditions that become more common later in life. Scientists sometimes refer to this slow, ongoing inflammation as “inflammaging.”
The results
The researchers found that participants who reduced their calorie intake had lower levels of activity tied to the C3 protein. The changes appeared to happen largely in body fat tissue, especially deeper belly fat known as visceral fat.
To better understand what was happening, the researchers also studied mice. They found that levels of the C3 protein increased with age, particularly in fat tissue. They also identified certain immune cells in fat tissue that seemed to produce the protein.
Interestingly, the improvements seen in the study did not appear to depend entirely on weight loss itself. Researchers said the findings suggest that calorie restriction may change how fat tissue and the immune system behave, beyond simply helping people lose weight.
The team also tested a drug in mice that blocks the activity of the C3 protein. The treatment reduced age-related inflammation in ways that looked similar to calorie restriction. Researchers say this could eventually help scientists develop therapies that target aging-related inflammation without requiring people to dramatically cut calories.
Still, the researchers caution that more studies are needed to fully understand the long-term effects. The study does not prove that eating less will slow aging in every person, but it does offer new clues about how moderate calorie reduction may affect the body over time.
“This concept demonstrates that aging is actually malleable and a process that can be targeted,” senior author Vishwa Deep Dixit, Ph.D., said in a news release.