Free radicals, antioxidants and ageing.

Multiple mechanisms underlie the human ageing process but interest continues in the role that free radicals and antioxidants may play. Tissue levels of lipofuscin (a mixture of proteins, peroxidised lipids, pigments and metal ions) increase with age as do plasma levels of lipid peroxides. There does not appear to be a progressive increase in free radical-induced DNA damage with age. The evidence that there is a reproducible alteration in intra- or extra-cellular antioxidant mechanisms with age is far from conclusive. Differences in geographical location, the populations studied, methodology and inadequate attention to confounding factors such as gender, alcohol consumption, smoking and disease all contribute to this lack of consensus amongst workers. It is clear, however, that elderly people suffering from chronic and acute illness have reduced protective antioxidant mechanisms. Although this may not initiate an increase in free radical-mediated cell damage it may contribute to this group being less able to deal with increased free radical activity and consequent increased lipid peroxidation. The beneficial role of antioxidant supplementation to healthy individuals remains controversial, but needs to be evaluated in the sick elderly.