Some of the benefits of exercise are cancelled out by vitamins that are taken for their own health-promoting effects, according to research.
Dr Michael Ristow, from the University of Jena in Germany, says that taking vitamins C and E after a workout appears to prevent physical exercise improving the body’s energy regulation.
His research, reported in the journal Proceedings of the National Academy of Sciences, suggests that antioxidant vitamins neutralise destructive free-radical molecules.
But those same free radicals also spur the body into becoming more sensitive to insulin, which governs the way cells use sugar as an energy source. By mopping up the molecules, antioxidant vitamins cancel out this beneficial effect.
Dr Ristow also found that the body’s own free-radical defence system, which is induced by exercise and relies on the production of natural antioxidants, is also weakened by the vitamins.
He said: ‘We propose that transiently increased levels of oxidative stress reflect a potentially health-promoting process, at least in regards to prevention of insulin resistance and type 2 diabetes mellitus.’