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

Abstract

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; I2 = 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; I2 = 0%; p = 0.66). Regarding the secondary outcome of non-fatal myocardial infarction, stroke, or cardiovascular death, 13 studies that included 521,155 participants showed no statistically significant difference (odds ratio; 0.87; confidence interval: 0.70–1.07; I2 = 97%; p = 0.19). In conclusion, according to our study results, high protein consumption does not affect cardiovascular prognosis.

Exploring high-protein diets in the context of cardiac rehabilitation

“…The most recent systematic review and meta-analysis of prospective cohort studies (fourteen studies, healthy participants, n 656 490) by Mantzouranis et al (22) found no relationship on total protein for cardiovascular death, stroke or a composite endpoint of stroke, nonfatal myocardial infarction and cardiovascular death, but did not investigate differences between animal and plant proteins. Part of the rationale for this study was that previous meta-analyses used a vague definition of high(er) protein diets, where they split the sample population by percentiles and compared highest with lowest protein intakes.…”

“…Part of the rationale for this study was that previous meta-analyses used a vague definition of high(er) protein diets, where they split the sample population by percentiles and compared highest with lowest protein intakes. Pointing this out as a limitation that even the highest intake may still be within normal range intakes, Mantzouranis et al (22) created an arbitrary cut-off of 18 % EI, equivalent to approximately 1⋅3-1⋅4 g/kg/d protein intake, based on previous definitions of HPD falling between 1⋅2 and 1⋅6 g/kg/d. The meta-analysis included thirteen studies (n 656 490), the HPD group consumed 92⋅5 g/d of protein daily, and 72⋅8 g/d in the SPD groupless than the aforementioned 1⋅4 g/kg/d cut-off for average male and female weight of 85 and 72 kg respectively and more like a combined 1⋅2 g/kg/d although still higher than the global 0⋅8 g/kg/d.…”