Grapes and Gastrointestinal Health: Implications with Intestinal and Systemic Diseases

The anti-inflammatory, antioxidant, or antimicrobial properties of phytochemicals found in fruits and vegetables are well documented. Phytoactive compounds and their metabolites have typically been monitored in blood or non-intestinal tissues of animals or human subjects consuming whole foods, extracts, or individual phytochemicals or examined after phytochemical treatment of cells in culture. Much less is known about the influence of polyphenols, in particular those found in grapes (e.g., anthocyanins), on intestinal health and how these polyphenols indirectly influence systemic metabolism. Notably, polyphenols may influence nutrient digestion and absorption, and gut microbiota taxa and their fermentation products, in part, because they are poorly absorbed in the upper gut and thus persist in the colon. Here, they come in direct contact with microbes, influencing microbial growth and metabolism, as well as undergoing enzymatic modification based on the available microbes. Whereas a great deal is known about the fermentation of fiber, there are gaps in the literature concerning how polyphenols influence microbial metabolism and vice versa. Therefore, this paper will focus on studies examining the influence of polyphenols in general and grape polyphenols in particular, on intestinal health, and subsequent metabolic consequences.