Is high protein only risky with unhealthy habits?

other primary study · 2016 · landmark · cited on tape

“In summary, while higher intake of animal protein was associated with higher mortality and plant protein was associated with lower mortality, these associations were confined to participants with at least one lifestyle risk factor.”

Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med
Who: US health professionals free of cancer, CVD and diabetes at baseline (Nurses' Health Study and Health Professionals Follow-up Study)
PMID 27479196

other primary study · 2026

“When we stratified the analysis by smoking status, we observed that AP was associated with a markedly higher mortality risk among ever smokers (current and former).”

Association of Dietary Animal and Plant Protein Composition with All-Cause Mortality: 24-Year Population-Based Cohort Study. Nutrients
Who: Adults aged 40-74 years (mean 57) from a population registry in two districts of Lombardy, Italy (BEST-FU cohort)
PMID 42356421

pooled analysis · 2020

“We also observed no interaction effects of protein intake with age, BMI, or physical activity, but we did observe a significant interaction effect of animal protein intake with sex for all-cause mortality ( P value for the interaction term = 0.02).”

Dietary protein intake and all-cause and cause-specific mortality: results from the Rotterdam Study and a meta-analysis of prospective cohort studies. Eur J Epidemiol
Who: 7786 Rotterdam Study participants aged 45+ (mean 63.7) free of CVD, diabetes and cancer, plus 11 prospective cohorts of mainly middle-aged general populations
PMID 32076944

other primary study · 2016 · landmark · cited on tape

“The positive association with all-cause mortality for animal protein and the inverse association for plant protein were both restricted to the unhealthy-lifestyle group (Pinteraction<0.001), although the association with animal protein did not reach statistical significance.”

Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med
Who: US health professionals free of cancer, CVD and diabetes at baseline (Nurses' Health Study and Health Professionals Follow-up Study)
PMID 27479196

other primary study · 2019

“In line with results from a previous study (7), protein intake did not appear to be associated with mortality among those without disease history.”

Dietary proteins and protein sources and risk of death: the Kuopio Ischaemic Heart Disease Risk Factor Study. Am J Clin Nutr
Who: 2,641 Finnish men aged 42-60 at baseline (1984-1989), 1,547 without and 1,094 with a history of type 2 diabetes, CVD or cancer
PMID 30968137

other primary study · 2026

“Stratification by BMI status revealed that AP was significantly associated with increased mortality only among individuals with a BMI < 25 kg/m 2 (HR 1.91, 95% CI 1.07, 3.41) ( Table 2 ).”

Association of Dietary Animal and Plant Protein Composition with All-Cause Mortality: 24-Year Population-Based Cohort Study. Nutrients
Who: adults aged 40-74 from a population-based cohort in two districts of Lombardy, Italy (BEST-FU study)
PMID 42356421

pooled analysis · 2020

“As shown in Table 2 , in multivariable models (Model 2), higher total protein intake was associated with higher risk of all-cause mortality, CVD mortality, and non-stroke CVD mortality [e.g. for all-cause mortality, the highest quartile versus the lowest quartile of total protein intake as percentage of energy (Q4 versus Q1), HR: 1.12, 95%CI (1.01, 1.25); per 5 E% increment in total protein, HR: 1.09, 95%CI (1.02, 1.17); and for CVD mortality, per 5 E% HR: 1.20, 95%CI (1.05, 1.37)].”

Dietary protein intake and all-cause and cause-specific mortality: results from the Rotterdam Study and a meta-analysis of prospective cohort studies. Eur J Epidemiol
Who: 7786 Rotterdam Study participants aged 45+ (mean 63.7) free of CVD, diabetes and cancer, plus 11 prospective cohorts of mainly middle-aged general populations
PMID 32076944