Animal protein isn’t linked to a shorter life — and may even offer some protection against cancer.
A large new analysis of nearly 16,000 U.S. adults followed for up to 18 years found no evidence that eating animal protein raises the risk of dying from cancer, heart disease, or any other cause. More surprising still: animal protein appeared to offer modest protection against cancer death.
Meanwhile, plant protein showed no clear survival benefit in this dataset, contrasting with some earlier studies that suggested advantages for vegetarian diets.
Published in Applied Physiology, Nutrition, and Metabolism, this analysis challenges a controversial 2014 study that claimed high animal protein intake increased cancer risk by more than four times in middle-aged adults. That earlier research helped fuel the plant-based movement and convinced millions of Americans to swap their steaks for salads.
“Our data do not support the thesis that source-specific protein intake is associated with greater mortality risk; however, animal protein may be mildly protective for cancer mortality,” the researchers concluded in their paper. It’s also worth noting that the study was funded by the National Cattlemen’s Beef Association; however, the authors stated that the sponsor had no role in the study design, data collection, analysis, interpretation, or manuscript preparation.
Large-Scale Study Finds No Link Between Animal Protein and Death Risk
Led by Stuart Phillips, a professor at McMaster University, the study followed 15,937 adults aged 19 and older, tracking nearly 4,000 deaths between 1988 and 2006. Unlike many earlier studies that relied on people’s memories of what they ate, this analysis used more sophisticated methods to estimate what people typically consumed over time.
The results were reassuring for meat eaters. People who ate more animal protein weren’t any more likely to die early than people who ate less. That was true for deaths from all causes combined, as well as deaths specifically from heart disease. Plant protein showed the same pattern: no sign that it extended life, but also no sign of harm.
But when the researchers zeroed in on cancer deaths, they noticed something unexpected. People who ate more animal protein were actually less likely to die of cancer. The effect wasn’t huge, but it was clear: eating a little more animal protein each day was tied to a small reduction in cancer deaths.
And when researchers looked at bigger differences in intake, the numbers became more striking. People who ate the equivalent of about half an ounce more animal protein a day had roughly a 20% lower risk of dying from cancer. Those who ate about an ounce more had close to a 40% lower risk.
Plant protein, on the other hand, didn’t seem to affect cancer deaths in either direction.
Why These Results Differ From Previous Cancer Studies
So why did this study come to such different conclusions than the famous 2014 paper that warned against meat? It comes down to how the studies were designed.
Earlier studies often divided people into uneven groups — for example, “low protein” eaters versus “high protein” eaters — and then compared outcomes between them. That can lead to skewed results, especially if the groups are small or imbalanced.
The new study, however, looked across the entire spectrum of protein intake and used more advanced modeling to account for errors in how diets are typically measured. It even used the same government dataset as the controversial 2014 study but reanalyzed it in a more rigorous way.
The 2014 study claimed that people aged 50 to 65 who ate the most protein were four times more likely to die of cancer than those who ate the least. But in this new analysis, no such spike in risk was seen for that age group. In fact, the opposite pattern emerged: animal protein was linked to a modest protective effect against cancer.
The researchers also investigated a hormone called IGF-1, which rises when people eat protein and has been suggested as a possible cancer promoter. But here again, the data didn’t support the fear. People with higher or lower IGF-1 levels were no more likely to die of cancer, heart disease, or any other cause.
What These Findings Mean for American Diets
With nearly 16,000 participants and close to 4,000 deaths, this study had substantial statistical power to detect meaningful associations. The demographic makeup broadly represented the American population across different age ranges.
Researchers controlled for factors that could affect results: age, sex, physical activity level, smoking status, and total calorie intake. When they included both animal and plant protein in their statistical models simultaneously, animal protein retained its protective association while plant protein showed no effect.
The protective effect remained even after accounting for plant protein intake, suggesting the link wasn’t simply due to people eating less of something else. Still, the study can’t prove cause and effect.
These results don’t mean people should abandon plant-based diets or consume unlimited meat. The study examined protein sources in isolation, not overall eating patterns. Plant foods provide fiber, antioxidants, and other beneficial compounds that weren’t measured here. The research also didn’t distinguish between different types of animal protein such as processed versus unprocessed meats.
However, the results do suggest that widespread fears about animal protein’s effects on longevity may be misplaced. For millions of Americans who enjoy meat, eggs, and dairy products, this research provides reassurance that these foods aren’t shortening their lives.
Source : https://studyfinds.org/animal-protein-linked-to-lower-cancer-death-risk/
