Tannin has a mouth drying quality that causes the wine to feel firm in your mouth. When a red wine is young, this firmness can be quite intense.
Over time, the qualities of the tannin will mellow and blend harmoniously with the other characteristics of the wine. This is one of the main reasons that red wines usually age better than whites.
The French seem to know something about the health benefits of red wine. In a study that compared French and German red wines, the French red wines delivered a greater health benefit due to their higher level of antioxidants. This may partially account for the "French paradox," where studies show that in areas of France where the diet is high in fat those who drink red wine with meals have a lower incidence of heart attack than other parts of the world. Due to vast differences in diets, the evidence is inconclusive, but experts believe that red wine contains certain compounds that help protect the heart. This has opened the door for other researchers to study the components in red wine that may be responsible for its health benefits.
The condition does not occur after consumption of white wine or other alcoholic beverages. Some individuals report that they get a migraine headache hours later from drinking some red wines. No one knows for certain why this syndrome occurs. It probably has more than one cause such as tannins, prostagladins, histamines, sulfites.