Stevia extract enhances the fermentation and functional properties of fermented milk in human colon epithelial cells

Abstract

Yogurt or fermented milk (FM) stimulates the production of mucin in the colon epithelium, which helps protect against pathogens. Stevia is a natural sweetener containing functional compound, stevioside. In the present study, we aimed to investigate the effect of stevia leaves extract (ST) on FM and the health effect of ST-added FM on human colon cells. Thus, we investigated the impact of the extracts from stevia leaves on the fermentation and quality characteristics of FM. In addition, we assessed the impact of ST-supplemented FM on mucin production and its anti-inflammatory properties against Escherichia coli O157:H7 in human colon epithelial cells (HT-29/MTX). The FM was enriched with ST (0–0.5% w/v) and fermented using a mixture of lactic acid bacteria (LAB). A control FM supplemented with 0.5% sucrose. The results demonstrated that ST significantly increased the fermentation rate of FM by promoting the growth of LAB. ST supplementation resulted in an increase in the titratable acidity, water-holding capacity, total solid content, and viscosity of FM. Treatment of HT-29/MTX cells with STFM supernatants led to higher mucus production, as evidenced by an increase in the mRNA expression of MUC2, CDX2, and TFF3. Moreover, ST-added FM resulted in decreased mRNA levels of TNF-α, IL-1β, and IL-6, and adhesion of E. coli to HT-29/MTX cells. These results suggest that consuming ST-added FM may help reinforce the intestinal mucus layer and prevent inflammations related to pathogenic bacteria.