Consuming foods that are rich sources of antioxidants can help reduce damage caused by free radicals in the body. Consuming lemon peel now and again can be beneficial as it contains loads of antioxidants, as well as vitamin C and D-limonene. Antioxidants can also help reduce your risk of type 2 diabetes and cardiovascular disease. Researchers discovered the peel of a lemon contained more antioxidant activity than a grapefruit peel. A study conducted on animals found D-limonene helps to increase enzyme activity that can reduce oxidative stress, which has been found to speed up the ageing process.