Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors: a systematic review and meta-analysis of randomised controlled trials
Vogtschmidt, Yakima D.; Raben, Anne; Faber, Ilona; Wilde, Claudia de; Lovegrove, Julie A.; Givens, D. Ian; Pfeiffer, Andreas F. H.; Soedamah-Muthu, Sabita S.
Abstract:
Abstract
Background and aims
Higher protein (HP) diets may lead to lower cardiometabolic risk than lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP vs. LP diets on cardiometabolic risk factors in adults, using most up-to-date evidence from randomised controlled trials (RCTs).
Methods
Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.
Results
Fifty-seven articles reporting on 54 RCTs were included, involving 4,344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m2), with a mean study duration of 18 weeks (range: 4 to 156). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.
Conclusions
Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.
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