Phenol is a toxic and corrosive compound often used in DNA extractions -- not exactly the kind of thing you want to eat. A variety of organic compounds, however, contain the same chemical group and structural features that distinguish phenol, and many of these other compounds are beneficial for your health. Compounds in this class are collectively called phenols.
Some phenolic compounds are believed to be cancer chemopreventives, compounds that may decrease your risk of developing cancer. Epigallocatechin-3 gallate, for example, is a phenolic compound found in green tea and believed to be a cancer chemopreventive. A broad group of phenolic compounds called flavonoids are common in plants; according to a review in the "British Journal of Nutrition," there is evidence to suggest many flavonoids like anthocyanins may have anticancer effects.
Many phenolic compounds found in plants may have antioxidant effects, meaning they react with and capture dangerously reactive compounds called free radicals before the radicals can react with other biomolecules and cause serious damage. Flavnoids and tocopherols are two broad classes of phenolic compounds with antioxidant properties. Resveratrol, a phenolic compound found in grape skins and red wine, also has antioxidant effects. According to "Organic Chemistry: Structure and Function," there is evidence to suggest it, too, may have anticancer effects.
The book "Organic Chemistry: Structure and Function" points out that recent research has found resveratrol can extend lifespan in yeast, fruit flies and other similar experimental models. Other phenolic compounds that act as antioxidants might also help promote healthy aging by minimizing DNA damage caused by free radicals. As noted in a 2002 review in the journal "Free Radical Biology and Medicine," there is evidence to suggest some of the deterioration associated with aging is caused by oxidative damage to DNA; this hypothesis is called the oxidative stress or free-radical theory of aging.
Not all phenolic compounds are good for you, of course. Phenol itself is toxic, and another phenolic compound called bisphenol-A has become controversial because it behaves as an estrogen mimic. Moreover, scientists still have a lot to learn about how phenolic compounds like resveratrol or flavonoids are metabolized and what other effects they may have on the human body. Aside from their possible health benefits, some phenolic compounds are also very flavorful, too. 4-(4-hydroxyphenyl)-2-butanone is responsible for the flavor of raspberries, for example, and capsaicin is the phenolic compound that gives hot peppers like jalapenos and chilies their searing warmth.