A newly published study has found that eating protein—whether from plant or animal sources—is not linked to a higher risk of early death. In fact, those who consumed more animal protein showed a slight reduction in cancer-related deaths.

For years, the health impact of eating animal-based protein has been controversial, with some studies suggesting it may increase the risk of cancer or heart disease. However, this new research adds to the growing body of evidence indicating that typical protein consumption does not pose a risk to longevity.

Overview of the Research

The study analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III), which included over 15,000 U.S. adults aged 19 and older. Participants were followed for 12 years to monitor mortality from all causes, including cancer and cardiovascular disease.

To accurately assess protein intake, researchers used a multivariate Markov Chain Monte Carlo (MCMC) model. This advanced statistical method helped account for day-to-day dietary changes and reporting inaccuracies, offering a more realistic estimate of each person’s usual protein consumption. It also allowed the team to distinguish between animal-based and plant-based proteins.

The researchers also measured participants’ blood levels of insulin-like growth factor 1 (IGF-1), a hormone that has previously been associated with increased cancer risk and early death in some studies. Including IGF-1 data helped them explore any potential biological link between protein and mortality.

Lifestyle factors such as age, sex, smoking habits, physical activity, and total caloric intake were also adjusted for in the analysis to isolate the effects of protein more accurately.

Key Findings: Protein Not Tied to Premature Death

The study’s results showed no connection between higher protein intake—whether from plants or animals—and an increased risk of death from any cause. This was true for total mortality as well as deaths specifically due to cancer or heart disease.

Interestingly, those with higher animal protein intake had a slightly lower risk of cancer-related mortality.

Factoring in IGF-1 levels didn’t change the results, and the hormone itself was not significantly linked to mortality in this study, which contradicts previous concerns about its role in disease risk.

Results were consistent across different age groups, including adults under 65, those over 65, and individuals between 50 and 65. This consistency is notable, as earlier research suggested that middle-aged adults might be more vulnerable to negative effects from high-protein diets.

The researchers suggest that older studies may have relied on less accurate dietary tracking methods, which could explain conflicting results. Their use of more precise modeling techniques, combined with balanced participant group sizes, may have led to more reliable outcomes.

No Need to Change Protein Guidelines, Experts Say

Avery Zenker, a medical writer for MyHealthTeam who was not involved in the study, said the findings support current recommendations regarding protein intake.

“This study found that even going above the standard recommendation of 0.8 grams of protein per kilogram of body weight per day didn’t increase the risk of early death,” Zenker said in an interview with Healthline. She noted that participants’ protein intake remained within the recommended range of 10–35% of total daily calories.

Zenker advised that protein goals should be tailored to individual needs, such as maintaining muscle mass, achieving satiety, or supporting overall health.

She also warned against assuming all protein sources offer equal benefits. “We still know from previous research that high intake of processed meats is linked to health problems, including heart disease and certain cancers,” she said.

Zenker emphasized that observational studies like this one cannot prove cause and effect. “There could be other lifestyle variables influencing the results,” she said, though the findings do add meaningful insights into nutrition research.

Protein-rich foods often contain other nutrients—including fiber, fats, vitamins, and minerals—that also influence health outcomes, she added.

Personalized Protein Needs Based on Age, Activity, and Diet

Maura Donovan, a board-certified sports dietitian and Medical Education Specialist at Thorne (not involved in the study), highlighted that protein needs vary by individual.

“For older adults, increased protein intake is often beneficial to help preserve muscle and maintain physical function,” Donovan explained.

Athletes, she added, require more protein to support muscle repair and recovery. People healing from illness or injury also benefit from increased protein to support the immune system and tissue repair.

Vegetarians and vegans should ensure they’re consuming a variety of plant proteins to get all the essential amino acids, Donovan said.

She recommended consulting with a registered dietitian to determine personal protein requirements. The Academy of Nutrition and Dietetics provides a directory to help individuals find certified nutrition experts for tailored advice.