Free radicals, antioxidants and international nutrition.

The oxidative degradation of polyunsaturated fatty acids is the primary factor in limiting the shelf-life of most manufactured foods. Free radical mechanisms are implicated in the pathogenesis of human diseases and in the process of ageing. This has led to the suggestion that antioxidants, and plant diet-derived antioxidants in particular, might have health benefits as prophylactic agents. Delineating the in vivo contribution of plant extracts and/or plant-derived antioxidants (the pure active principles in plant extracts with antioxidant indications) to the modulation of the pathological consequences of oxidative stress in the human body is complicated by the fact that antioxidant actions may be achieved through more than one mechanism. The interest in the health promoting qualities of plant foods may be ascribed to the observation that various compounds present in these foods possess antioxidant properties in vitro. From a food stability perspective, one would be interested in the integrity of the food and the effects of storage on the molecular components of the food. For humans, the emphasis is on the importance of nutritional antioxidants in health and disease management.