How is ROS produced?
ROS are produced in the body in day-to-day life by:
- Metabolism (synthesis of energy) / Respiration.
- ROS Produced by Red Blood Cells
- ROS Produced by WHITE Blood Cells - When body reacts to an adverse factor, e.g. A wound, fever, nervous imbalance (stress), microbial infection or toxin.
- Emotional Stress – creates free radicals - Possibly today’s main oxidation-causing stressor.
- Infectious Microbes - such as bacteria, viruses, protozoa initiate an inflammatory process that leads to increased ROS production by phagocytes - E.g. infectious bacteria Chlamydia pneumoniae and the Herpes simplex virus have been proposed as initial inflammatory infectious agents in atherosclerosis.
- Physical Trauma
- Environmental Toxins – induce inflammatory response leading to damaging ROS and E.g. cigarette smoking by-products, exhaust fumes, household chemicals, heavy metals, pesticides/herbicides, certain drugs, radiation
- ROS is produced by hyperglycemia
- ROS is produced by other body processes e.g. as necessary intermediates in a variety of enzymatic reactions; involved in intercellular / intracellular signalling; it is increased by exedrcise and some health problems such as diabetes.
ROS can be directly introduced into the body:
- ROS in oxidized (i.e. damaged) lipids (e.g. Trans Fats)
- Oxidized Cholesterol from fried, cooked, cured, aged or processed foods – mainly meats, eggs and dairy.
- Trans Fats
- Certain “Healing Therapies” (e.g. ozone therapy, hydrogen peroxide therapy and PDT are deliberately introduced in controlled amounts of ROS into the body)
The Antioxidant Process
Antioxidants block the process of oxidation by neutralizing free radicals. In doing so, the antioxidants themselves become oxidized. That is why there is a constant need to replenish our antioxidant resources.
How they work can be classified in one of two ways:
- Chain-breaking - When a free radical releases or steals an electron, a second radical is formed. This molecule then turns around and does the same thing to a third molecule, continuing to generate more unstable products. The process continues until termination occurs -- either the radical is stabilized by a chain-breaking antioxidant such as beta-carotene and vitamins C and E, or it simply decays into a harmless product.
- Preventive - Antioxidant enzymes like superoxide dismutase, catalase and glutathione peroxidase prevent oxidation by reducing the rate of chain initiation. That is, by scavenging initiating radicals, such antioxidants can thwart an oxidation chain from ever setting in motion. They can also prevent oxidation by stabilizing transition metal radicals such as copper and iron.
The effectiveness of any given antioxidant in the body depends on which free radical is involved, how and where it is generated, and where the target of damage is. Thus, while in one particular system an antioxidant may protect against free radicals, in other systems it could have no effect at all. Or, in certain circumstances, an antioxidant may even act as a "pro-oxidant" that generates toxic oxygen species.
- Williams et al. Flavonoids: antioxidants or signalling molecules? Free Radical Biology and Medicine. 2004.
- Arts et al. Polyphenols and disease risk in epidemiologic studies. The American Journal of Clinical Nutrition. 2005.
- Boffetta et al. Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC). J Natl Cancer Inst. 2010
- Robin Brett Parnes