Effects of the Treatment with Flavonoids on Metabolic Syndrome Components in Humans: A Systematic Review Focusing on Mechanisms of Action

Abstract

Diets high in bioactive compounds, such as polyphenols, have been used to mitigate metabolic syndrome (MetS). Polyphenols are a large group of naturally occurring bioactive compounds, classified into two main classes: non-flavonoids and flavonoids. Flavonoids are distributed in foods, such as fruits, vegetables, tea, red wine, and cocoa. Studies have already demonstrated the benefits of flavonoids on the cardiovascular and nervous systems, as well as cancer cells. The present review summarizes the results of clinical studies that evaluated the effects of flavonoids on the components of the MetS and associated complications when offered as supplements over the long term. The results show that flavonoids can significantly modulate several metabolic parameters, such as lipid profile, blood pressure, and blood glucose. Only theaflavin and catechin were unable to affect metabolic parameters. Moreover, only body weight and body mass index were unaltered. Thus, the evidence presented in this systematic review offers bases in support of a flavonoid supplementation, held for at least 3 weeks, as a strategy to improve several metabolic parameters and, consequently, reduce the risk of diseases associated with MetS. This fact becomes stronger due to the rare side effects reported with flavonoids.

Pharmacological Treatments and Natural Biocompounds in Weight Management

“…Suzuki et al [ 94 ] found a positive effect of black and green tea catechins on obesity. Quercetin and other flavonoids with antioxidant, anti-inflammatory, and hepatoprotective effects can effectively prevent metabolic diseases [ 95 , 96 , 97 ]. The intake of flavonoids can reduce the risk of metabolic syndrome disorders and rare side effects [ 95 ].…”

Proanthocyanidins: Impact on Gut Microbiota and Intestinal Action Mechanisms in the Prevention and Treatment of Metabolic Syndrome

“…Another flavonoid of interest in ameliorating the signs of MS is quercetin due to its antihypertensive, antihyperlipidaemic, antihyperglycaemic, and other properties [ 37 ]. For more information, we recommend referring to the review by Gouveia et al [ 38 ].…”

Selected Seeds as Sources of Bioactive Compounds with Diverse Biological Activities

“…They are best-known for their antioxidant properties, but the range of their activity is much wider [ 2 , 23 ]. Many pre-clinical and clinical (both observational and intervention) studies have suggested, that increased intake of phenolic compounds is related to a lower risk of cardiovascular diseases, diabetes, cancer, and neurodegenerative diseases [ 24 , 25 , 26 , 27 ]. In the past, beneficial effects of polyphenols were attributed mainly to their antioxidant activity, but currently, evidence suggests that dietary intake might not provide a high enough concentration in tissues for radical-scavenging properties to be significant.…”