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.
How are proteins made? To make a protein, a cell must put a chain of amino acids together in the right order. RNA is similar to DNA: it consists of strands of four different chemical building blocks, or bases, attached to a chemical backbone. All proteins are made up of combinations of 20 different amino acids.