A Systematic Review of the Effects of Plant Compared with Animal Protein Sources on Features of Metabolic Syndrome

Abstract

Dietary protein may play an important role in the prevention of metabolic dysfunctions. However, the way in which the protein source affects these dysfunctions has not been clearly established. The aim of the current systematic review was to compare the impact of plant- and animal-sourced dietary proteins on several features of metabolic syndrome in humans. The PubMed database was searched for both chronic and acute interventional studies, as well as observational studies, in healthy humans or those with metabolic dysfunctions, in which the impact of animal and plant protein intake was compared while using the following variables: cholesterolemia and triglyceridemia, blood pressure, glucose homeostasis, and body composition. Based on data extraction, we observed that soy protein consumption (with isoflavones), but not soy protein alone (without isoflavones) or other plant proteins (pea and lupine proteins, wheat gluten), leads to a 3% greater decrease in both total and LDL cholesterol compared with animal-sourced protein ingestion, especially in individuals with high fasting cholesterol concentrations. This observation was made when animal proteins were provided as a whole diet rather than given supplementally. Some observational studies reported an inverse association between plant protein intake and systolic and diastolic blood pressure, but this was not confirmed by intervention studies. Moreover, plant protein (wheat gluten, soy protein) intake as part of a mixed meal resulted in a lower postprandial insulin response than did whey. This systematic review provides some evidence that the intake of soy protein associated with isoflavones may prevent the onset of risk factors associated with cardiovascular disease, i.e., hypercholesterolemia and hypertension, in humans. However, we were not able to draw any further conclusions from the present work on the positive effects of plant proteins relating to glucose homeostasis and body composition.

The effect of consumption of soy foods on metabolic syndrome in women: a case study from peri-urban Qwa-Qwa, South Africa

“…These results are contradictory to a metaanalysis that showed statistically beneficial relationships between soy protein intake with hypertension, lowering serum cholesterol and glucose levels. 34 Despite the beneficial metabolic effects observed in this study, a relationship between soy protein consumption and MetS risk factors could not statistically be confirmed.…”

Dietary protein and changes in markers of cardiometabolic health across 20 years of follow-up in middle-aged Americans

“…(41) In another recent systematic review of studies comparing plant with animal protein intake in relation to metabolic syndrome-related conditions, authors concluded that soy protein (with isoflavones), but not soy protein alone or other plant proteins, led to greater decreases in total and LDL cholesterol compared with animal-sourced protein intake. (60) Future research should investigate the long-term of effects on changes in cardiometabolic health of specific food sources of protein, other components (e.g., food matrices) of plant versus animal protein sources and/or differences in diet quality between those consuming more protein from plants or animals, and vice versa. For example, one question might be whether low saturated fat or high fiber protein food sources have a different relationship with cardiometabolic health than high saturated fat or low fiber protein sources.…”

Replacing Animal-Based Proteins with Plant-Based Proteins Changes the Composition of a Whole Nordic Diet—A Randomised Clinical Trial in Healthy Finnish Adults

“…Higher protein intake, particularly from plant-based sources, may also be associated with attenuated inflammatory burden in aging populations [16]. In diabetics, replacing animal protein with plant proteins may help to improve glycaemic control and prevent the onset of risk factors associated with CVD [14,17,18].…”