Independent and interactive association of blood antioxidants and oxidative damage in elderly people.

Oxidative stress is recognized as one of the major contributors to the increased risk of several diseases. Many recent population studies have established a close link between antioxidant defense and lowered risk of morbidity and mortality from cancer and heart disease, but little is known about the cooperative interactions of antioxidants. We examined the cross-sectional independent and interactive association of serum lipid-soluble antioxidant levels and free radical scavenging enzymes to serum malondialdehyde (MDA) levels, as a marker of oxidative damage. The participants were 160 nonsmoker institutionalized elderly. Upper tertile values of erythrocyte-superoxide-dismutase (E-SOD) constituted the strongest-associated single compound with a 74% decreased risk of high MDA. Upper tertiles of carotenoids and alpha-tocopherol independently showed a similar lowering of risk of about 57%. The highest tertiles of lycopene and either beta-carotene or alpha-tocopherol simultaneously reveal a higher decreased risk for oxidative damage (74 and 71%, respectively), very similar to those in the upper tertiles of all these three vitamins (75%). This study represents one of the few attempts to date to understand the interactive effect between antioxidants and suggests that lipid-soluble antioxidants act not individually, but rather cooperatively with each other. The efficacy of this interaction is more effective when lycopene is present.