Potential dangers with overuse of antioxidant enzymes as nutritional supplements: how much have we revealed?

Abstract

Even though it is known that antioxidants can be obtained from food (mainly fruits and vegetables) the consumption of antioxidant supplements in the general population is broad in extent. The results of epidemiological studies where people were treated with antioxidant supplements are inconclusive and contradictory; however, they are numerous and comprise an intensive field of research. Less is known about the supplementation of antioxidant enzymes because randomized clinical trials are limited, and the potential harmful effects of their overconsumption have only recently started to be investigated. The aim of this brief review is to investigate the potential dangers of antioxidant enzymes overuse (high doses obtained from artificial oral supplements or intravenous infusion ) on people's health status. METHODS: Original articles were searched via the online databases PubMed and Google Scholar published between 1990 and 2012. RESULTS: Data indicate that high doses of supplementary antioxidant enzymes could act as doubleedged swords in cellular redox state as they present health beneficial effects at physiologic doses versus deleterious effects at high doses. Since randomized clinical trials with regard to antioxidant enzymes are scarce there is no official recommended dosage, and if the dose is set too high, safety problems are likely to result. Excessive antioxidant action could adversely affect key physiological processes. CONCLUSIONS: The use of antioxidant enzymes is not an alternative to regular consumption of fruits and vegetables. Antioxidant compounds within fruits and vegetables may be considered as being more safe and healthy compared to isolated, high doses, such as present in nutritional supplements. Further evidence-based research should focus on the need to answer the questions regarding what effects dose and environment have on pro-oxidant/antioxidant mechanisms before recommending nutritional supplement interventions with antioxidant enzymes