The juice of a lemon is mostly Vitamin C and citric acid, but the peel (the zest) is concentrated with D-Limonene. This compound is a powerful activator of “Phase II detoxification” in the liver—the specific pathway that neutralizes fat-soluble toxins. Adding just half a teaspoon of lemon zest to your water or meals provides the “chemical key” your liver needs to flush out pollutants that the juice can’t touch.