How do Dietary Pectin and its Fermentation Products Affect Nutrient Metabolism and Systemic Actions Beyond gut Homeostasis? A Comprehensive Review

Abstract

Pectin is indigestible by human enzymes and is metabolized in the human gastrointestinal tract (GIT) by gut microorganisms to yield short-chain fatty acids (SCFAs) and other metabolites. Pectin ingestion has been shown to lower blood cholesterol levels and low-density lipoprotein cholesterol, without changing levels of high-density lipoprotein cholesterol or triglycerides. Pectin also appears to be effective in reducing the postprandial rise in glucose in normal, obese, and diabetic individuals. Research has suggested that while some of these observed impacts could directly be attributed to pectin in its polymeric state, others are indirectly mediated via the production of SCFAs as major fermentation end products. Here, we comprehensively review the metabolic processes underpinning observed clinical benefits associated with pectin ingestion, with special emphasis on disentangling the contribution of direct (mediated by pectin as a polymeric molecule) versus indirect (mediated by SCFAs, its major fermentation end products) effects on the process. In addition, we highlight the role played by pectin in modulating the metabolism of macronutrients, including carbohydrates, lipids, and proteins.