High Animal Protein Diet Increases Mortality Risk

A recent study found that a diet rich in animal protein may be associated with a higher mortality risk. 

The study authors evaluated the relationship between dietary protein and protein sources with the risk of disease-related mortality. A total of 2,641 participants were included, who were Finnish men aged between 42 and 60 years at baseline (1984–89); 4-d dietary records were used to estimate protein intakes, and disease death data were gathered from the national Causes of Death Register. Primary outcomes included cardiovascular disease, carotid atherosclerosis, and death; secondary outcomes included type 2 diabetes, dementia, cancer, and infectious disease. Average follow-up was 22.3 years. 

A total of 1,225 participants died due to disease during follow-up, and there was a significant correlation between high intakes of total protein and animal protein and increased mortality risk (multivariable-adjusted HR [95% CI] in the highest compared with the lowest quartile for total protein intake = 1.17 [0.99, 1.39; P-trend across quartiles = 0.07] and for animal protein intake = 1.13 [0.95, 1.35; P-trend = 0.04]. Increased mortality risk was also observed in participants with a higher animal-to-plant protein ratio extreme-quartile HR = 1.23; 95% CI: 1.02, 1.49; P-trend = 0.01) and higher meat intake (extreme-quartile HR = 1.23; 95% CI: 1.04, 1.47; P-trend = 0.01). Fish, egg, dairy, and plant protein source intakes were not tied to mortality. 

When evaluated based on disease history at baseline, the association of total protein with mortality appeared more evident among those with a history of type 2 diabetes, cardiovascular disease, or cancer (n = 1094) compared with those without disease history (n = 1547) (P-interaction = 0.05 or 0.07, depending on the model),” the researchers wrote. 

Results Are Not One Size Fits All 

The study’s findings should not be applied across the board, cautioned study author Heli Virtanen, a PhD student from the University of Eastern Finland. 

“However, these findings should not be generalised to older people who are at a greater risk of malnutrition and whose intake of protein often remains below the recommended amount,” Virtanen said in a press release. 

Nevertheless, the study authors concluded, “Higher ratio of animal to plant protein in diet and higher meat intake were associated with increased mortality risk. Higher total protein intake appeared to be associated with mortality mainly among those with a predisposing disease. 

In a separate study recently published in Circulation, researchers conducted a meta-analysis of randomized controlled trials comparing diets with red meat with diets that replaced red meat with a other foods. A total of 36 studies (n = 1,803) were included. The study authors concluded that, “In comparison with red meat, consumption of high-quality plant protein sources (ie, soy, nuts, and legumes) leads to more favorable changes in blood concentrations of total cholesterol and LDL-C. Future interventions should consider appropriate comparison foods when examining the effects of red meat intake on cardiovascular risk factors.