Many phytonutrients are bioavailable in humans. Once absorbed they interact with receptors and other proteins in the body and cause physiological changes that can affect health. However, it is becoming increasingly evident that a number of phytochemicals in plant foods do not need to be absorbed to have beneficial health effects. Red wine is a complex mixture of polyphenolic phytochemicals, many of which have not been identified or characterised. Resveratrol, a stilbene is perhaps the best studied red wine polyphenol, and when absorbed has a particularly strong antioxidant effect. This effect is what is thought to allow resveratrol to protect from cardiovascular disease. However, the antioxidant effects of resveratrol and other antioxidants in red wine may be able to act in the gut to protect fatty acids from oxidation. When oxidised fatty acids are absorbed they cause cellular damage and metabolic dysfunction. By inhibiting this oxidation, resveratrol is able to prevent disease without the need to be absorbed. In fact, the red wine might not even have to be consumed, as the act of cooking with wine is enough to inhibit fat oxidation in susceptible food such as fish, thus decreasing the potential for detrimental health effects. Red wine may also change the profile of the gut bacteria to one more conductive to good health by providing a food source to beneficial gut bacteria.