Impact of Quantity and Type of Dietary Protein on Cardiovascular Disease Risk Factors Using Standard and Network Meta-analyses of Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and network meta-analysis of randomized controlled trials
PubMed 39013196 · doi:10.1093/nutrit/nuae086
What was done
The authors conducted a systematic review and meta-analysis across PubMed, Embase, CINAHL, Web of Science, and the Cochrane Library (PROSPERO CRD42022369931) assessing the effects of dietary protein quantity and type on cardiovascular risk factors. Data from 100 randomized controlled trial articles were evaluated via standard meta-analysis, and 41 articles were analyzed using network meta-analysis to evaluate comparative macronutrient patterns.
What was found
Compared with lower-protein diets, higher-protein diets significantly reduced systolic blood pressure (mean difference [MD] = -1.51 mmHg; 95% CI: -2.77, -0.25) and diastolic blood pressure (MD = -1.08 mmHg; 95% CI: -1.81, -0.35), and increased flow-mediated dilation (MD = 0.78%; 95% CI: 0.09, 1.47). In network meta-analysis, a high-protein, high-carbohydrate, low-fat diet was ranked most effective for reducing blood pressure, total cholesterol, and LDL-C. Compared to animal-protein-rich diets, plant-protein-rich diets significantly improved total cholesterol (MD = -0.12 mmol/L; 95% CI: -0.19, -0.05), triglycerides (MD = -0.05 mmol/L; 95% CI: -0.09, -0.01), LDL-C (MD = -0.11 mmol/L; 95% CI: -0.18, -0.04), and HDL-C (MD = 0.03 mmol/L; 95% CI: 0.02, 0.04).
Why it matters
This review distinguishes the vascular benefits of overall protein quantity from the lipid-modulating benefits of plant versus animal protein sources. It highlights the importance of overall background macronutrient composition when designing higher-protein diets.
Limits
The abstract reports only surrogate cardiovascular risk markers rather than hard clinical endpoints like cardiovascular events or mortality. Absolute numerical effect sizes on blood pressure and lipid fractions were very small. Study-level characteristics such as trial durations, participant demographics, baseline cardiovascular risk, and heterogeneity statistics were not reported in the abstract.
Cited by
- contradicts Diets with high protein intake, particularly from animal sources, promote atherosclerosis and induce systemic inflammation.