OXYGEN The cells get nutrients and amino acids through the cell membrane. The nutrients need to bond with oxygen to produce energy. Next, oxygen has to couple with amino acids to form complete proteins. Oxygen readily enters into chemical reactions necessary for metabolism to take place.  The products of these reactions are carbon dioxide, water, and heat. To start, oxygen gets into the body by way of the mouth down into the lungs, where it is absorbed into the blood stream as the blood passes through capillaries of the lungs. The blood then takes it to the cells, where the oxygen and nutrients pass through the membrane and carbon dioxide and water and waste are passed back out into the blood to be expelled. This exchange is called respiration. The respiration process does not use all the available oxygen and this is where the problems arise. As substances lose electrons to this oxygen through oxidation, the resulting highly volatile free radicals can cause cell damage. Free radicals can attract electrons from almost any nearby molecule to replace the electrons they lost during oxidation. Such attacks can damage the cell. This oxidation is linked to cancer. Antioxidants are enzymes, vitamins C and E, and certain chemicals such as carotenoids and flavonoids (also known as bioflavonoids). COMMON ANTIOXIDANTS INCLUDE: theobromine, carotene, cryptoxanthin, lycopene, lutein, zeaxanthin, and chlorophyll. FREE RADICALS Looking at our cells as though they were like fireplaces can give some insight into free radicals. For instance, wood is used in the fireplace to create energy (heat), similar to how nutrients, such as glucose, are used by the cell to create energy (ATP). As sparks are created by a fireplace, free radicals are created by our cells. Free radicals are literally sparks of metabolism. ENDOGENOUS SOURCES OF FREE RADICALS: -Cooked Food (especially animal products and refined goods) -Oxidized and hydrogenated oils can significantly contribute to free radical buildup -Food additives (preservatives, colorings, etc.) -Nutrient deficiencies can still occur even in the best diet (even fresh, raw foods contain only as many nutrients as the soil they were grown in). -Alcohol and Smoking (including passive smoking) -Environmental pollution (from air, water, household chemicals, asbestos, pesticide residues, & other man-made pollutants including plastic and other synthetics) -Exposure to excess heat or cold, bacteria and parasites, chemotherapy, prescription, over-the-counter drugs, radiation (includes electromagnetic radiation such as outside power lines; wires at home/work, microwave oven), emotional stress, and any other non-positive mental state -Biological damage by oxygen radicals, computer monitors/TVs, etc. Reactive oxygen species interact with different constituents of the human body: cellular membrane bound, and extra-cellular proteins, with RNA and DNA and with membrane lipids. Such chemical processes that result in free radical formation can permanently damage the human organism. Proteins become crossed-linked, losing their physiological function, and DNA mutates, leading to cancer. The oxidation of lipids (fat) may lead to cardiovascular diseases.  Due to a highly compromised environment, people have far more free radicals and far less metabolic antioxidant enzymes than needed for optimal health. Each human cell has 4 main endogenous enzymatic defense antioxidants by which it defends itself against free radical exposure and destroys reactive oxygen species. HOW DO ANTIOXIDANTS WORK? Antioxidants have three ways of counteracting free radicals. They can prevent damage by trapping free radicals before they have a chance to wreck healthy cells. They provide a missing electron to the free radical that stops the free radical from attacking and damaging a healthy cell.