Polyphenols are plant compounds acting like antioxidants. Most common groups are flavonoids and phenolic acids. Best sources include cloves, cocoa, dark fruits like berries, cherries, black current, plums and grapes, artichokes and tea. They are suitable for diabetes and its prevention since they can lower blood sugar levels and likelihood of blood sugar spikes and stimulate release of insulin. Especially anthocyanins, typically found in berries and grapes. Polyphenols also lower risk of heart disease and inflammation, specifically the polyphenol group called lignans, found in flax seeds. The ones found in green tea can have anti-cancer effect and promote good gut health and digestion and certain polyphenol groups can also boost brain health and memory, particularly the ones found in Ginkgo biloba and cocoa.