As life expectancy continues to rise in many parts of the world, living a long, healthy life has become increasingly attainable. While genetics and overall lifestyle play important roles, nutrition can influence biological aging—the process by which the body’s cells and systems accumulate damage and gradually lose their function over time.

Although it can be tempting to search for a single “superfood” that slows aging, research suggests that no individual food can independently extend lifespan, says Rachele Pojednic, Ph.D., Ed.M, FACSM. “The strongest evidence points to overall dietary patterns rather than individual foods,” she says. “Diets rich in minimally processed foods, adequate protein, fiber-dense plants and unsaturated fats are consistently associated with increased longevity.”

While your overall diet pattern and lifestyle matter most, protein is one nutrient that certainly plays a role in healthy aging. Thanks to the role it plays in maintaining muscle mass, helping to build a strong immune system and its effect on cognitive function, protein is an essential part of a diet that promotes a long, healthy life.

To better understand protein’s role in aging, we spoke with registered dietitians and nutrition scientists to explore the latest research and practical ways to include more protein in your diet.

How Biological Aging Is Measured

To assess how diet and nutrients like protein influence biological aging, scientists examine short-term effects of food choices and long-term outcomes. “Researchers often measure all-cause mortality, disease incidence or survival curves in large epidemiologic (population) studies to show associations with nutrients or dietary patterns,” says Pojednic.

“In shorter or mechanistic studies, they rely on biomarkers associated with biological aging, such as inflammation, insulin sensitivity, lipid profiles, or, more recently, epigenetic aging clocks.” Pojednic also emphasizes that fitness- measures—like muscle mass, strength and cardiometabolic health—serve as important aging- endpoints in addition to nutrition.

Why Protein Helps Slow Biological Aging

It Aids in Muscle Maintenance

As muscle loss increases with age, protein intake becomes a key modifiable risk factor for healthy aging. “Adequate protein intake is essential for maintaining muscle mass, insulin sensitivity and resilience with aging,” says Pojednic. Over time, natural changes in body composition—especially in women—lead to a gradual decline in muscle mass. Muscles also become less responsive to exercise and diet, meaning it’s even more important to prioritize as we age.

Eating enough protein, coupled with an active lifestyle that includes strength training, helps to maintain muscle mass throughout life. Preserving muscle supports balance, coordination, bone density and metabolism, all of which help to maintain independence and reduce the risk of chronic disease.,

Insufficient protein intake and physical inactivity contribute to age- muscle loss, increasing the risk of frailty and sarcopenia, a condition characterized by gradual declines in muscle mass, strength and function. Prioritizing both protein and strength training can help preserve physical function and metabolic health across the lifespan.

It Supports Immune Function

One important—and often overlooked—role of protein is its contribution to immune health. Amino acids, the building blocks of protein, are essential for producing antibodies and cytokines, key components of the immune system. “Think of protein as the “maintenance crew” for your body: it repairs cellular damage, supports immune function and combats the age- muscle loss that speeds up biological aging,” says Devon Golem, Ph.D., RD, LDN.

However, consuming protein alone is not enough to ensure a healthy immune system. Other components of the diet like antioxidant-rich fruits and vegetables and anti-inflammatory unsaturated fats also have an important role in supporting immune function.

It Benefits the Brain

A healthy brain is a crucial part of increasing healthspan, or the years a person lives in good health. Good nutrition—including eating enough protein—plays a key role in brain health and cognitive function. In fact, research shows that high protein intake is associated with a reduced risk of cognitive decline, while lower protein intake is linked to frailty and diminished cognitive function.

“As we age, we need more protein—around 1.0 to 1.2 grams protein per kilogram body weight per day (0.45 to 0.54 grams protein per pound of body weight per day),” says Golem. “This supports muscle protein synthesis, which naturally declines with age, helping to maintain metabolic health and physical function that are key markers of biological age.”

It’s Packed with Other Nutrients

While protein can be eaten in isolation—such as through protein supplements—whole, protein-rich foods naturally come with other nutrients that support health and longevity. For example, fish is a high-quality protein that also provides omega-3 fats, an unsaturated fat linked with better biological aging. “Unsaturated fats, such as extra virgin olive oil, avocado, nuts, seeds and certain fish, help slow down biological aging,” says Lindsey Schoenfeld, M.S., RDN. “They enhance membrane fluidity and flexibility, enabling cell membranes to more effectively regulate the entry and exit of nutrients, oxygen, hormones and signaling molecules.”

Other sources of protein, such as those from plants and dairy, also offer beneficial nutrients to slow biological aging, like fiber, vitamins and minerals. “Protein plays a role in slowing biological age, but the quality of protein is extremely important,” says Schoenfeld. This highlights the value of a well-rounded diet rather than focusing on a single nutrient.

Food Sources of Protein

• Fish: Fatty fish like salmon, mackerel and sardines are rich in unsaturated fats like omega-3 fatty acids, which support heart, brain and cellular health.
• Poultry and Red Meat: Chicken, turkey, pork, beef and lamb are all high-quality protein sources. Choose lean cuts and minimally processed options for maximum health benefits.
• Beans and Legumes: These fiber-rich foods are a budget-friendly source of protein. “Canned beans are easy and affordable to add to soups, bean and corn salads, or even taco meat to make bean and beef burgers or tacos,” says Schoenfeld.
• Nuts and Seeds: “If you’re not a fan of fish, swap it out for a daily dose of omega-3-rich seeds [like] hemp, chia, or ground flax,” says Golem.
• Dairy: Milk, cheese and yogurt provide protein along with important nutrients like calcium. Fermented dairy products—such as yogurt and kefir—offer added benefits through probiotics that help reduce inflammation, protect cells and support immunity, says Schoenfeld.

Other Nutrients to Focus On

We rarely eat nutrients in isolation, meaning it’s important to look at your diet pattern as a whole to promote longevity. “Nutrients that support metabolic health and reduce chronic inflammation, such as adequate protein, omega-3 fatty acids and fiber, consistently show associations with lower mortality risk and longevity,” says Pojednic.

Here are some additional nutrients to prioritize for healthier biological aging:

• Omega-3 Fatty Acids: “Unsaturated fats—particularly omega-3s from fatty fish and monounsaturated fats from olive oil, nuts and seeds—act like bodyguards against aging,” says Golem. “They reduce chronic inflammation, protect telomeres (the caps on our chromosomes that shorten as we age) and support brain and cardiovascular function.”
• Vitamin D: “Recently, vitamin D has earned its place as a standout nutrient for slowing down aging,” shares Kelsey Kunik, RDN. “Researchers found that adults who took 2,000 IU of vitamin D per day for four years had slower loss of DNA telomere length than those who took the placebo.” Though, more research is needed to determine its overall impact on aging.
• Fiber: “Dietary fiber helps keep your digestive system working properly as you age and helps provide a source of prebiotics for a healthy gut which has been linked to decreased heart disease risk,” says Shelley Balls, M.D.A., RDN, LDN.
• Probiotics: While probiotics aren’t necessarily nutrients, they are beneficial compounds when it comes to health. “Aim to consume probiotic rich foods and beverages at least two times per day,” says Balls. “Certain types of healthful bacteria may improve longevity and healthspan by aiding in antioxidative, immunity and signaling pathways.” Foods rich in probiotics include kefir, fermented vegetables, kombucha, natto and kimchi.

Our Expert Take

Protein is a key player in slowing biological aging and supporting overall health. It’s linked to stronger muscles, better brain function and a more resilient immune system—all important factors for longevity. However, it’s important to look at your overall dietary pattern rather than focusing on a single nutrient. “Researchers have identified several foods and nutrients that can help slow down biological aging, but there’s not one specific nutrient or one specific food that stands out above the rest,” says Kunik.

Along with a healthy diet, other lifestyle habits like exercise, sleep and stress reduction also play a role in long-term health. “Nutrition alone cannot meaningfully slow biological aging without these other powerful levers of health. Longevity is ultimately a systems-level outcome driven by how these behaviors work together over decades,” notes Pojednic.