Examples of antioxidants include vitamins C and E, selenium, and carotenoids, such as beta-carotene, lycopene, lutein, and zeaxanthin. This fact sheet provides basic information about antioxidants, summarizes what the science says about antioxidants and health, and suggests sources for additional information. Key Points Vegetables and fruits are rich sources of antioxidants.
Proteins, among the most complex of all organic compounds, are composed of amino acids (see Figure 2-4), which contain carbon, hydrogen, oxygen, and nitrogen atoms. Certain amino acids also have sulfur atoms, phosphorus, or other trace elements such as iron or copper.
In an analogous fashion, proteins are made up of twenty common amino acids in a precise order dictating the protein's structure and function. Every amino acid has a common structure, in which a central carbon is covalently bonded to a carboxyl group (COOH), an amino group (NH2), a hydrogen, and a variable R group.