Metabolites Are Key to Understanding Health Effects of Wine Polyphenolics

Abstract

Phenolic compounds in grapes and wine are grouped within the following major classes: stilbenes, phenolic acids, ellagitannins, flavan-3-ols, anthocyanins, flavonols, and proanthocyanidins. Consumption of foods containing phenolic substances has been linked to beneficial effects toward chronic diseases such as coronary heart disease and colorectal cancer. However, such correlations need to be supported by in vivo testing and bioavailability studies are the first step in establishing cause and effect. Class members from all phenolic groups can be glucuronidated, sulfated, and/or methylated and detected at low concentrations in the bloodstream and in urine. But the majority of phenolic compounds from grapes and wine are metabolized in the gastrointestinal tract, where they are broken down by gut microflora. This typically involves deglycosylation, followed by breakdown of ring structures to produce phenolic acids and aldehydes. These metabolites can be detected in bloodstream, urine, and fecal samples by using sophisticated instrumentation methods for quantitation and identification at low concentrations. The health effects related to grape and wine consumption may well be due to these poorly understood phenolic acid metabolites. This review discusses the known metabolism of each major class of wine and grape phenolics, the means to measure them, and ideas for future investigations.

Antioxidant and Vasodilatory Effects of Blackberry and Grape Wines

“…25 In addition, the most recent reports indicate that anthocyanins undergo substantial metabolism after being ingested and that their metabolites, formed in the small intestine and hepatic cells, as well as low-molecular-weight catabolic products of the colonic microflora, such as phenolic acids, travel around the human body in the circulatory system and may be responsible for the distinctive biological effects of ''anthocyanins.'' 26,27 These metabolites might be the key to filling the gap between in vitro and in vivo observed biological effects of the anthocyanins.…”

In Vitro Bioconversion of Polyphenols from Black Tea and Red Wine/Grape Juice by Human Intestinal Microbiota Displays Strong Interindividual Variability

“…Consequently, each intestinal microbial community can be expected to display its own characteristic metabolic profile. It has been reported that particular beneficial effects of polyphenol-rich foods are dependent on biotransformation by intestinal bacteria to bioactive metabolites (7). For some polyphenolic compounds, bioconversion has been shown to vary between individual persons due to differences in the metabolic potential of their endogenous microbiota (8).…”

Bioavailability of phenolic compounds in grape juice cv. Autumn Royal

“…In addition to the metabolism that occurs in intestinal cells and liver, catechin can also be metabolized by gut microflora to produce phenolic acids (Kim et al, 1998). Gallic acid may be metabolized and transported or may experiment bacterial metabolism in the gut (Forester & Waterhouse, 2009). At 300 min, gallic acid level was below the detection limit.…”