Our cells go through a harmless process called oxidation, which releases free radicals. These free radicals cause oxidative stress by damaging cells and DNA. Oxidative stress has been linked to age-related illnesses such as cancer, neurodegenerative and cardiovascular disease.
Polyphenols are found in plants and are an important antioxidant, most importantly they can neutralize oxidation and thus reduce oxidative stress. Resveratrol is a polyphenol found in grapes, which is why red wine is well known for reducing heart disease.
The infographic below by AuthorityDiet.com lists 20 foods high in polyphenols that are ideal for low-carb dieters.