Polyphenols are antioxidants in plants that many believe have a substantial amount of health benefits. Among the most well known of the polyphenols are the flavonoids, which are a grouping of several thousand individual compounds. These compounds are found together in many different foods, all contributing in a unique way to an individual's overall health. They are most commonly introduced to the body through the consumption of fruits and vegetables.

In addition to flavonoids, other classes of polyphenols include tannins (both condensed tannins and hydrolyzable tannins), and lignins. Each of these polyphenols can be found from many different sources. For example, tannins are prevalent in wines, teas and fruits. Nearly any plant will carry at least some of these polyphenols.

Polyphenols work by eliminating free radicals in the body, which are known to cause a number of health problems. It is thought polyphenols help prevent premature aging and help prevent cancer, among other things. Some, such as tannins, may even have antibiotic benefits as well.

The effect of tannins can be seen in a number of different applications. It is the substance responsible for the browning, or tanning, of leather. In fact, that is how the group of chemicals received their name. Tannic acid can be seen in some lakes and rivers, especially those in in tropical and subtropical areas populated with cypress trees. However, it should be noted that while tannic acid may, in some cases, be harmful to the body, tannic acid is not the same as tannins found in other types of polyphenols.

While there are a number of health benefits though to be associated with polyphenols, there is still a lot of questions associated with them. In some cases, depending on the compound, polyphenols may not be beneficial at all and, in fact, be quite harmful. This is especially true of certain types of tannins. Without further study, it is impossible to positively state what the benefits of polyphenols are to any great degree of certainty.

However, in most of the medical community, the debate centers to what degree polyphenols benefit a person, not a question of if they do. Nearly all the health benefits of fruit, vegetables, even drinks such as tea and wine, are credited to polyphenols. With as much emphasis as is placed on eating these things, it is clear what the medical community, at large, feels about polyphenols.