Research has found a correlation between functional food components and improved health and well-being. The treatment and prevention of disease are both capabilities of functional foods. They promote physiological benefits and wellness by acting simultaneously at different or identical target sites, such as lowering blood cholesterol, neutralizing reactive oxygen species and charged radicals, having an anticarcinogenic effect, having a low-glycemic response, and a number of other effects. Plant foods (whole grains, fruits, and vegetables) are rich sources of phytochemicals known as functional ingredients. These include non-starchy carbohydrates, soluble and insoluble dietary fibres, fucoidan; antioxidants such as polyphenols, carotenoids, tocopherols, tocotrienols, phytosterols and isoflavones; plant sterols; and soy phytoestrogens. Milk, fermented milk products, and cold-water fish all contain a variety of beneficial microorganisms, including probiotics, prebiotics, conjugated linolenic acid, long-chain omega-3, 6 and 9 polyunsaturated fatty acids, and bioactive peptides. Processing a meal alters its natural properties. The lines between food and medicine are beginning to disappear as researchers reveal the connection between diet and the prevention of chronic diseases.