Antioxidant relevance to human health.

Human ecology requires both oxygen and water with the generation from food of an immediate energy source, ATP, by oxidative phosphorylation. A continuing balance between oxidation and antioxidation is necessary for longer less-disabled lives, taking account of oxidative stresses and the critical roles of oxidants in defence against infection, tissue repair and signalling. Antioxidant capacity is derived both exogenously (from food, beverage and sunlight) and endogenously (from enzymatic and non-enzymatic pathways). A number of oxidant food factors service antioxidant metallo-enzymes. The capacity operates extra- or intracellularly. Uric acid is the major antioxidant in primate blood. Uric acid synthesis is increased by dietary fructose from fruit, sugary foods and drinks. This indirect antioxidant effect of fruit is separate from that attributable to its flavonoids. Alcohol also increases serum uric acid. Urate excess and retention is associated with disease. The high prevalence of hyperuricaemia in NE Asia presents a major public health dilemma in regard to putative benefits and risks. Foods with high antioxidant activity include berries, nuts and legumes, tomatoes and sweet potato leaves. Each of the antioxidants in these foods is pleiotropic being inter-alia anti-inflammatory, anti-angiogenic or anti-neoplastic. Moreover, food matrices and patterns contribute to the safety of antioxidant consumption. There is no evidence to date that isolated antioxidants as food supplements improve health outcomes or survival; and some that indicate unacceptable risk. Their use as biomarkers of food cannot justify their isolated use. Nevertheless, a spectrum of dietary pluripotential antioxidants for tissues, metabolic and immune systems is advantageous.