Nutritional Methodology—Research Communication Free Radicals in Licorice-Flavored Sweets Can Be Detected Noninvasively Using Low Frequency Electron Paramagnetic Resonance after Oral Administration to Mice

The observation of the fate of free radicals coming from food after oral administration could be important in evaluating their reactivity in vivo. The aim of this study was to demonstrate that it is feasible to detect directly in vivo free radicals coming from food with the use of low frequency electron paramagnetic resonance (EPR) spectroscopy. Because polyphenols are easily oxidized into stable radicals, we assumed that these radicals could be detected in food. We chose licorice, which contains several types of polyphenols. The presence of free radicals was demonstrated in licorice-flavored sweets. Using low frequency EPR spectroscopy, we detected these free radicals directly and noninvasively after oral administration to mice. These radicals were rather stable in the guts of the mice. This study is the first report demonstrating noninvasively the presence of free radicals in vivo coming from food. J. Nutr. 130: 1831–1833, 2000.