Micronutrients in Health and Disease: Antioxidants and Phytochemicals

Antioxidant vitamins (vitamins C and E), carotenoids, and minerals that are constituents of antioxidant enzymes (eg, zinc, magnesium, and manganese in superoxide dismutase; selenium in glutathione peroxidase) are essential for minimizing free–radical reactions and the resulting destruction of cellular structures. However, clinical trials indicate that simply adding supplemental antioxidant nutrients to a typical American diet does not reduce the risk for common diseases such as cardiovascular disease and cancer.³⁰ Evidence suggests that a healthful overall diet is required–namely, a diet that is both low in factors that promote disease and high in antioxidant nutrients.

In addition, an increasing body of evidence indicates that the presence of nonvitamin, nonmineral antioxidants (eg, phytochemicals) in foods is responsible for the majority of antioxidant effects.³¹ In general, populations eating greater amounts of phytochemical–containing foods (eg, fruits, vegetables, whole grains) have a significantly lower mortality risk³² and a lower risk for cardiovascular disease, cancer, diabetes mellitus, hypertension, and arthritis.^33,34 Population studies do not, however, typically isolate the effect of micronutrients, and they also involve significant macronutrient differences, compared with unmodified diets. Nevertheless, these studies suggest that any additional nutrients should be supplemental to, and not substituted for, a plant–based diet.