Dietary Phenols: Antioxidants for the Brain?

Human diet contains numerous phenolic compounds which have been shown to exert protective antioxidant effects in cellular paradigms of oxidative cell death relevant to neurodegenerative disorders. Since reliable in vivo data are scarce, the question whether dietary phenols may act as beneficial neuroprotective agents in the human brain can only be estimated from the chemical composition of the diet with respect to phenolic compounds, their resorption, their metabolic fate, and their ability to cross the blood-brain barrier. We conclude that antioxidant neuroprotection by natural phenolic compounds is highly questionable. Therefore, dietary supplementation with specifically designed phenolic antioxidants has to be in the center of interest. We outline some chemical structural principles of such designer molecules, focusing on a decreased impact on hormone receptors and the absence of prooxidant side-effects.