The Impact of High Protein Diets on Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

High protein diets have gained increased popularity as a means of losing weight, increasing muscle mass and strength, and improving cardiometabolic parameters. Only a few meta-analyses have addressed their impact on cardiovascular morbidity and mortality and failed to show any significant associations without applying strict values to define high protein intake. Due to the conflicting research background, we conducted a meta-analysis to assess the impact of high protein diets compared to normal protein consumption on cardiovascular outcomes in adults without established cardiovascular disease. Fourteen prospective cohort studies were included. A total of 6 studies, including 221,583 participants, reported data about cardiovascular death, without showing a statistically significant difference in the random effect model (odds ratio: 0.94; confidence interval: 0.60–1.46; I(2) = 98%; p = 0.77). Analysis of three studies, which included 90,231 participants showed that a high protein diet was not associated with a lower risk of stroke (odds ratio: 1.02; confidence interval: 0.94–1.10; I(2) = 0%; p = 0.66). Regarding the secondary outcome of non-fatal myocardial infarction, stroke, or cardiovascular death, 13 studies that included 525,047 participants showed no statistically significant difference (odds ratio; 0.87; confidence interval: 0.70–1.07; I(2) = 97%; p = 0.19). In conclusion, according to our study results, high protein consumption does not affect cardiovascular prognosis.