Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective cohort studies
PubMed 32699048 · doi:10.1136/bmj.m2412
What was done
Systematic review and dose-response meta-analysis of prospective cohort studies searched across PubMed, Scopus, and ISI Web of Science up to December 2019. Eligible studies evaluated the association between dietary intake of total, animal, and plant protein and all-cause, cardiovascular disease (CVD), and cancer mortality in adults aged 18 or older. Random-effects models were used to calculate pooled effect sizes comparing highest versus lowest intake categories, and linear and non-linear dose-response analyses were performed.
What was found
Across 32 prospective cohort studies (31 in meta-analysis) with 715,128 participants and 113,039 deaths (16,429 from CVD, 22,303 from cancer) followed for 3.5 to 32 years: - Total protein intake was associated with lower all-cause mortality (pooled effect size 0.94, 95% CI 0.89 to 0.99, I² = 58.4%, P < 0.001), but had no significant association with CVD or cancer mortality. - Plant protein intake was associated with lower all-cause mortality (pooled effect size 0.92, 95% CI 0.87 to 0.97, I² = 57.5%, P = 0.003) and lower CVD mortality (pooled HR 0.88, 95% CI 0.80 to 0.96, I² = 63.7%, P = 0.001), but not cancer mortality. - Dose-response analysis indicated that an additional 3% energy per day from plant protein was associated with a 5% lower risk of all-cause mortality (P = 0.05 for non-linearity). - Total and animal protein intakes were not significantly associated with CVD or cancer mortality.
Why it matters
This synthesis of prospective cohort evidence demonstrates that higher plant protein intake is linked to reduced all-cause and cardiovascular mortality, supporting dietary recommendations that emphasize plant-based protein sources.
Limits
The findings are derived entirely from observational prospective cohort studies, leaving potential for residual confounding by lifestyle factors. Moderate between-study heterogeneity was observed (I² ranged from 57.5% to 63.7%). Specific food sources within broad protein categories, measurement error from dietary assessments, and subgroup differences were not detailed in the abstract.
Cited by
- contradicts Diets with high protein intake, particularly from animal sources, promote atherosclerosis and induce systemic inflammation.