Another source of food-derived antioxidants are the additivescontained in foodstuffs and drinks, such as vitamins, colorants, flavoring agents, and preservatives, which are added to enhance theshelf life of products or impact consumer behavior. Limiting microbial proliferation or preventing the oxidation of molecules in themicroenvironment implies that such additives will affect all surrounding cells and biomolecules in an unbiased manner, althoughwith different sensitivities. Therefore, adverse effects on humanhealth cannot be excluded generally (EMEA, 2003). Indeed, recentdata have linked excessive antioxidant uptake to the suppressionof T helper (Th) type 1 immune responses thereby promoting Th2reactions, potentially leading to develop allergies and asthma(Zaknun et al., 2012).The term “antioxidant” implies that a compound can quench radicals or diminish the oxidation of other molecules. The preservationof a compound’s antioxidant activity until its internalization in cellsis of importance, but in particular many phytochemicals are onlypartially bioavailable, so they might not reach relevant concentrations within a cell. Additionally, within the cell, the compound mustnot be converted into an inactive metabolite (Del Rio et al., 2013).Otherwise, although each compound might only be present at a lowconcentration, effective potentiation can be achieved by additive andsynergistic interactions of the many phytochemicals present, suchas in foods or multicomponent botanical preparations (Wink, 2008).Another assumption is that internalization is not a strict prerequisite for the activity of a compound, asin vivo bioactivity mayhave already started in the gastrointestinal tract (GIT), where
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