A new paper in Applied Physiology, Nutrition, and Metabolism by researchers Yanni Papanikolaou, Stuart M. Phillips, and Victor L. Fulgoni III challenges one of the most persistent beliefs in nutrition science – that eating meat raises cancer risk. Drawing on data from nearly 16,000 adults in the U.S. National Health and Nutrition Examination Survey (NHANES III), the team found that animal protein was not linked to higher mortality from cancer, cardiovascular disease, or any other cause. In fact, people who consumed more animal protein showed slightly lower rates of cancer-related death.
How the Study Was Conducted
The researchers analyzed dietary and mortality data collected between 1988 and 1994 and tracked participants through 2006. Using a sophisticated statistical approach called the multivariate Markov Chain Monte Carlo method, they corrected for common measurement errors in food reporting and controlled for factors such as age, smoking, physical activity, and overall calorie intake.
Of the 15,937 adults studied, 3,843 died during the follow-up period. The researchers assessed their diets in terms of animal and plant protein consumption and also examined blood levels of insulin-like growth factor 1 (IGF-1), a hormone previously thought to mediate cancer risk.
The results were surprising:
- For all-cause mortality, animal protein had a hazard ratio (HR) of 0.99, meaning no increased risk.
- For cardiovascular disease mortality, HR was 1.02, again showing no significant effect.
- For cancer mortality, however, animal protein intake showed a small but statistically significant inverse association (HR = 0.95, 95% CI: 0.91–1.00, P = 0.04).
- Plant protein showed no meaningful relationship with mortality of any kind.
Even when the researchers analyzed protein consumption in 5- and 10-gram increments, the protective effect of animal protein persisted for cancer, with hazard ratios dropping as low as 0.60 for higher intake levels.
What the Findings Mean
In simple terms, higher meat and animal protein intake was not associated with higher death rates—and may even reduce cancer mortality risk. The researchers concluded that “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.”
Their results also showed no relationship between IGF-1 levels and cancer or overall death risk, undermining earlier theories that linked high protein diets to elevated cancer risk via IGF-1.
Why It’s Controversial
This study directly contradicts earlier high-profile research, including a 2014 study by Valter Longo and colleagues, which claimed that people aged 50–65 who consumed high levels of animal protein were four times more likely to die of cancer. The McMaster team argues that those results were likely exaggerated due to uneven sampling and failure to adjust for measurement error.
Other studies have long supported plant-based diets as protective against cancer and cardiovascular disease, leading many public health agencies—including the World Health Organization—to classify red meat as “probably carcinogenic to humans.” That classification remains, even as new data challenge its universality.
Critics also note that the new study grouped all animal protein sources together—red meat, poultry, fish, eggs, and dairy—making it impossible to distinguish which foods were driving the protective effect. Some scientists suspect that the apparent benefit may come from fish and dairy rather than meat itself.
What Other Studies Have Found
Evidence linking meat to cancer remains mixed. Some research suggests that processed meats raise the risk of colorectal cancer, while fish and yogurt appear protective. Meta-analyses have even proposed a U-shaped relationship between IGF-1 and mortality, implying that both too little and too much protein could be harmful.
Plant proteins, often associated with lower cardiovascular risk, did not show any mortality benefit in this analysis—contradicting earlier studies by Song, Naghshi, and Qi that reported lower death rates among people consuming more legumes, nuts, and soy.
The findings highlight how nutrition science often resists simple conclusions. People don’t eat nutrients in isolation; they eat mixed diets shaped by culture, lifestyle, and genetics. While the study weakens the case against meat, it doesn’t justify excessive consumption. High meat diets can still contribute to other health problems, including heart disease and diabetes, if they displace fruits, vegetables, and fiber-rich foods.
As coauthor Stuart Phillips noted in past interviews, the real message isn’t to eat more steak but to “recognize protein as part of a balanced, nutrient-dense diet.”
The paper has sparked debate across the scientific community. Supporters praise it as a much-needed correction to anti-meat bias, arguing that earlier warnings may have overstated the risks. Critics call it misleading, warning that industry ties and methodological quirks may obscure real dangers from red and processed meats.
For now, the best advice remains measured: aim for moderation, favor lean and minimally processed sources, and balance animal proteins with plenty of plants. Nutrition may never deliver absolute answers, but studies like this one ensure the conversation—and the science—keep evolving.
