The body also needs phytochemicals or phytonutrients. These are bioactive substances found in fruits, vegetables, grains and legumes that give these foods color and flavor. They are natural antioxidants and have antibacterial and antiviral properties that help support the immune system. There are thousands of these nutrients that are grouped into different classes depending on their molecular structure and beneficial function to the body. Some of these classes include: carotenoids, flavonoids, gluosinolates, indoles, isoflavones, lipoic acid, phytosterols, polysaccharides and tocopherols amongst others.