Rethinking the role of dietary antioxidants through the lens of self-medication

The regulation of oxidative status is critical because fluctuations in the production of aerobic by-products relative to the antioxidant capacity of the organism can have strong fitness consequences. Towards this end, organisms can use endogenous antioxidant defences, which are efficient at combating oxidative attacks but may be costly and need time to be activated. As food items vary in their antioxidant content, animals have the possibility to optimize their oxidative status, rapidly and at a low cost, by selecting food in their environment according to its antioxidant content. However, the actual role of dietary antioxidants remains contentious because their consumption entails inconsistent effects. We propose that this inconsistency stems from the lack of methodical examination of the cost–benefit ratio related to antioxidant intake, which should reflect the actual need for antioxidants by organisms. We apply the framework of self-medication to the regulation of oxidative status, which necessarily implies assessing the physiological needs of consumers. We formulate conditions under which self-medication is likely to occur, and show that most conditions are met for the regulation of oxidative stress. Linking self-medication to oxidative ecology therefore provides a novel mechanistic framework on how oxidative stress can be regulated; it highlights the transient nature of food selection upon the regulation of oxidative status, and thereby shows why indiscriminant supplementation of dietary antioxidants is likely to be misguided.