(P29-016-23) Dietary Plant to Animal Protein Ratio and Risk of Cardiovascular Disease in Three Prospective Cohort Studies

Objectives: Dietary guidelines recommend substituting animal protein with plant protein. However, the optimal ratio of plant to animal protein in the diet remains uncertain. We therefore examined plant to animal protein ratios in three large cohorts and assessed associations with incident cardiovascular disease (CVD), coronary heart disease (CHD), and stroke.

Methods: Participants included 70,918 women in the Nurses’ Health Study (NHS) (1984-2014), 89,205 women in the NHSII (1991-2017), and 42,740 men from the Health Professionals Follow-up Study (HPFS) (1986-2016) without CVD and cancer at baseline. Diet was assessed using validated food frequency questionnaires at baseline and every four years. Plant protein to animal protein ratios were calculated using percentage of calories from plant and animal protein. Cumulative averages were calculated using repeated measures of diet. Cox proportional hazard regressions were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Restricted cubic spline plots were used to explore the shape of the associations.

Results: During 30 years of follow-up, 16,118 incident CVD cases, including 10,187 CHD cases and 6,137 stroke cases, were documented. The plant to animal protein ratio increased from ~0.36 to ~0.50 over follow-up. After multivariable adjustment of lifestyle factors and diet quality, participants had a lower risk of total CVD (pooled HR: 0.85; 95% CI: 0.79-0.91, P trend < 0.001) and CHD (pooled HR: 0.77; 95% CI: 0.71-0.84, P trend < 0.001), but not stroke (pooled HR: 1.00; 95% CI: 0.90-1.12, P trend=0.87), when comparing highest to lowest deciles (ratio of ~0.24 vs. ~0.76). In dose-response analyses, CVD and CHD showed evidence of linear and non-linear relationships (P curvature < 0.001; P linearity < 0.001), with marked risk reductions observed at lower plant to animal protein ratios followed by more gradual reductions. There was no evidence of linear or non-linear associations for stroke (P curvature=0.22; P linearity=0.55).

Conclusions: These findings provide further evidence that partial replacement of animal protein with plant protein may lower the risk of CVD and CHD.

Funding Sources: The NHS and HPFS cohorts are supported by NIH grants. AJG is supported by a Canadian Institutes of Health Research Postdoctoral Fellowship.