Sorrel is a green leafy herb that is also considered to be a vegetable. The leaves from the sorrel plant are known to be especially beneficial for those suffering from certain health issues due to the presence of antioxidants and other essential nutrients. Here are the 5 superb health benefits of sorrel leaves. Some may be allergic to sorrel leaves if they are allergic to plants like rhubarb & buckwheat. These leaves can also block the absorption of calcium due to the presence of oxalate.