Polyphenols, Saponins and Phytosterols in Lentils and Their Health Benefits: An Overview

The lentil (Lens culinaris L.) is one of the most important legumes (family, Fabaceae). It is a natural functional food rich in many bioactive compounds, such as polyphenols, saponins and phytosterols. Several studies have demonstrated that the consumption of lentils is potentially important in reducing the incidence of a number of chronic diseases, due to their bioactive compounds. The most common polyphenols in lentils include phenolic acids, flavan-3-ol, flavonols, anthocyanidins, proanthocyanidins or condensed tannins, and anthocyanins, which play an important role in the prevention of several degenerative diseases in humans, due to their antioxidant activity. Furthermore, lentil polyphenols are reported to have antidiabetic, cardioprotective and anticancer activities. Lentil saponins are triterpene glycosides, mainly soyasaponins I and βg. These saponins have a plasma cholesterol-lowering effect in humans and are important in reducing the risk of many chronic diseases. Moreover, high levels of phytosterols have been reported in lentils, especially in the seed coat, and β-sitosterol, campesterol, and stigmasterol are the most abundant. Beyond their hypocholesterolemic effect, phytosterols in lentils are known for their anti-inflammatory activity. In this review, the current information on the nutritional composition, bioactive compounds including polyphenols, saponins and phytosterols, and their associated health-promoting effects are discussed.