BERKELEY, CALIFORNIA. Oxidative stress occurs when the body's antioxidant defenses are overwhelmed by free radicals generated whether internally or by environmental exposure. It can damage DNA, proteins and lipids (fats) and has been linked to several diseases and disorders. A group of American researchers has just released the results of a study aimed at measuring the extent of oxidative stress found in a representative sample of the US population.
The study involved 298 healthy adults between the ages of 19 and 78 years who completed food frequency questionnaires and provided blood samples. The researchers analyzed the samples for two markers of oxidative stress; malondialdehyde (MDA) and F2-isoprostanes (Iso-P). MDA is a decomposition product of polyunsaturated fatty acids while Iso-P are eicosanoids produced by oxidation of metabolites of arachidonic acid. There was a clear correlation between MDA and Iso-P levels and gender with women having significantly higher levels than men. Smokers had significantly higher levels of MDA while obese individuals had significantly higher levels of Iso-P. A high intake of fruits, a high blood level of ascorbic acid (vitamin C), and a high blood level of beta-carotene were all associated with lower levels of both markers indicating that fruits, beta-carotene, and especially vitamin C are highly protective against oxidative stress. There were no correlations between markers of oxidative stress and age, alcohol consumption, fat intake, meat consumption, and vitamin E (alpha-tocopherol) level. A high C-reactive protein level was, however, associated with a high MDA level and a high level of gamma-tocopherol was, somewhat surprisingly, associated with higher levels of both MDA and Iso-P.
The researchers conclude that high blood levels of ascorbic acid may be protective against oxidative stress,
particularly DNA damage and urge that all future epidemiologic studies include measurements of blood
levels of ascorbic acid and, at least, one of the biomarkers for oxidative stress.