Associations of dietary protein intake with all-cause, cardiovascular disease, and cancer mortality: A systematic review and meta-analysis of cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cohort studies
PubMed 32451273 · doi:10.1016/j.numecd.2020.03.008
What was done
Authors conducted a systematic review and meta-analysis of prospective cohort studies indexed in PubMed and Web of Science through February 2020. They evaluated associations between dietary intake of total, animal, and plant proteins and mortality from all causes, cardiovascular disease (CVD), and cancer. Study-specific relative risks (RR) across 12 eligible cohort studies were pooled using fixed-effect or random-effects models based on statistical heterogeneity.
What was found
Total protein intake showed no clear association with all-cause, CVD, or cancer mortality. Higher plant protein intake was associated with reduced all-cause mortality (highest vs lowest intake: RR = 0.92, 95% CI: 0.88–0.96; each 3% energy increment: RR = 0.97, 95% CI: 0.94–0.99) and lower CVD mortality (highest vs lowest: RR = 0.90, 95% CI: 0.80–1.01; each 3% increment: RR = 0.95, 95% CI: 0.91–0.99). Higher animal protein intake was associated with an increased risk of CVD mortality (highest vs lowest: RR = 1.11, 95% CI: 1.01–1.22; each 3% increment: RR = 1.02, 95% CI: 0.98–1.06).
Why it matters
This review highlights that the source of dietary protein matters more for long-term health outcomes than total protein quantity alone. It provides quantitative synthesis supporting dietary recommendations that favor plant-derived proteins over animal proteins.
Limits
Findings rely exclusively on observational cohort studies, which are susceptible to residual confounding by general lifestyle and dietary patterns (e.g., fiber intake, smoking, physical activity). The abstract does not specify total participant count, breakdown by specific animal protein types (e.g., processed meat vs poultry/fish), or methods used to measure dietary intake across the included studies.
Cited by
- supports Large-scale meta-analyses and long-term studies show that plant-based diets generally yield better health outcomes than animal-heavy diets.