"CAM practices are often grouped into broad categories, such as natural products, mind and body medicine, and manipulative and body-based practices. Although these categories are not formally defined, they are useful for discussing CAM practices. Some CAM practices may fit into more than one category.\n\nNatural products include a variety of herbal medicines, also known as botanicals, vitamins, minerals, and other natural products. Many are sold over the counter as dietary supplements. Some uses of dietary supplements, such as taking a multivitamin to meet minimum daily nutritional requirements or taking calcium to promote bone health, are not thought of as CAM. CAM natural products also include probiotics, which are live microorganisms, usually bacteria, that are similar to microorganisms normally found in the human digestive tract and that may have beneficial effects. Probiotics are available in foods, such as yogurts, or as dietary supplements. They are not the same thing as prebiotics, which are nondigestible food ingredients that selectively stimulate the growth or activity of microorganisms already present in the body.\n\nInterest in and use of CAM natural products have grown considerably in the past few decades. The 2007 National Health Interview Survey found that 17.7 percent of American adults had used a nonvitamin, nonmineral natural product. These products were the most popular form of CAM among both adults and children. The most commonly used product among adults was fish oil or omega-3s, reported by 37.4 percent of all adults who said they used natural products. Popular products for children included echinacea, at 37.2 percent, and fish oil or omega-3s, at 30.5 percent."