Polyphenols are heat-sensitive and can degrade when exposed to high temperatures during cooking or processing. To retain their benefits, choose gentle cooking methods such as steaming or stir-frying and avoid overcooking. Store foods in dark, airtight containers to shield them from light exposure and oxidation, preserving polyphenol content.Polyphenols are heat-sensitive and can degrade when exposed to high temperatures during cooking or processing. To retain their benefits, choose gentle cooking methods such as steaming or stir-frying and avoid overcooking. Store foods in dark, airtight containers to shield them from light exposure and oxidation, preserving polyphenol content.