A study regarding polyphenol was published recently, suggesting no influence to human health.
According to the authors, they conducted a survey in which a total of 783 participants was included. They were over 65 years old and followed for nine years.
JAMA Internal Medicine: Resveratrol Levels and All-Cause Mortality in Older Community-Dwelling Adults
The result is that the amount of Resveratrol, a kind of polyphenol they took, was not related to their mortality. They also measured some biological markers of the participants, none of which seemed to be influenced by Resveratrol. This indicates that Red wine of other polyphenol-rich foods are doubted to be beneficial to health.
The other days, "French Paradox" used to be focused. It means that French people take lots of fat and frequently smoke, but they seldom encounter acute heart failure. A hypothesis explaining it was the positive effect of Red wine on human health. Some wine companies made an advertisement about the benefit of polyphenol.
Nowadays, French Paradox is deemed as an illusion. Comparing statistical data in different countries is a little tough issue. Each country has its own health policy. In addition, there are enormous factors affecting mortality.
Even recently, there are many substances suspected to improve your health such as vitamins, omega 3 fatty acids, and so on. In my opinion, no particular nutritious element is decisive. Balanced food is the best way to maintain your body.