Associations between plant-based dietary patterns and risks of type 2 diabetes, cardiovascular disease, cancer, and mortality - a systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective observational cohort studies.
PubMed 37789346 · doi:10.1186/s12937-023-00877-2
What was done
Systematic review and meta-analysis (PROSPERO CRD42022290202) of prospective observational studies searched across PubMed/MEDLINE, Embase, and Web of Science. The review evaluated associations between adherence to plant-based dietary patterns and incident type 2 diabetes (T2D), cardiovascular disease (CVD), cancer, and all-cause mortality among adults aged 18 years and older.
What was found
Across 76 publications with 2,230,443 participants (60,718 T2D cases, 157,335 CVD cases, 57,759 cancer cases, and 174,435 deaths), higher plant-based diet adherence was inversely associated with: - T2D: RR 0.82 (95% CI: 0.77–0.86) - CVD: RR 0.90 (95% CI: 0.85–0.94) - Cancer: RR 0.91 (95% CI: 0.87–0.96) - All-cause mortality: RR 0.84 (95% CI: 0.78–0.92) Heterogeneity was moderate to high (I² ranged 47.8%–95.4%). When restricted to healthy plant-based diets (rich in vegetables, fruits, whole grains, and legumes), inverse associations strengthened for T2D (RR 0.79 [0.72–0.87]), CVD (RR 0.85 [0.80–0.92]), and cancer (RR 0.86 [0.80–0.92]), while mortality was RR 0.86 (0.80–0.92). Unhealthy plant-based diets were positively associated with these disease outcomes. In 4 studies examining dietary pattern changes, increasing plant-based adherence reduced T2D risk (RR 0.83 [0.71–0.96]) and marginally reduced mortality (RR 0.95 [0.91–1.00]).
Why it matters
This large meta-analysis demonstrates that the quality of plant foods matters: diets emphasizing healthy whole plant foods correlate with broad reductions in major chronic diseases and mortality, whereas unhealthy plant-based diets are linked to adverse outcomes.
Limits
All included data derive from observational cohort designs, limiting causal inference and subject to residual confounding. Significant heterogeneity was present across studies (I² up to 95.4%). Only 4 studies evaluated longitudinal changes in dietary pattern adherence over time.