What are Antioxidants?

Antioxidants are molecules that prevent cell damage and serve as parts of enzymes. There are many types of antioxidants found in nature. There are vitamin antioxidants that are known to be protective like vitamins A, C, and E. There are mineral antioxidants like selenium and zinc and there are pigments (colors). Some pigments in plants and animals are potent antioxidants. Antioxidants trap harmful forms of oxygen and prevent them from damaging cells. Antioxidants in the diet enter the blood stream and act directly to protect cells of the body from damage. In addition, some antioxidants stimulate the immune system, and/or increase the activity of detoxifying enzymes in the liver.

What is Oxidation?

The process of oxidation is a normal function of all living things. Oxidation of various compounds is the primary means by which humans and other animals get energy. There are special compounds in nature called oxidant catalysts that provide a stable environment for oxidation to occur safely. The two most common oxidant catalysts are copper and iron.

As charges are transferred from iron and copper to oxygen for energy release, new forms of oxygen are generated. Each of these new forms of oxygen has a free set of charges; these are called reactive oxygen species or ROS. As charges are transferred from the catalyst to oxygen and new ROS are formed a destructive process of charging stable compounds continues to generate more ROS. Some ways that ROS are generated include: inflammation, strenuous exercise, detoxification, chemical exposure, exposure to radiation, cigarette smoke, alcohol, pollutants, and high fat diets. ROS are damaging to proteins, membranes, and DNA.

Damage to DNA can be the beginning of cancer initiation. The damage from ROS accumulates over time and is the major reason for aging and age-related increases in diseases such as cancer. Since ROS are produced constantly by many different pathways, defense mechanisms have evolved against ROS.

Antioxidants are small molecules that pick up ROS and prevent them from causing damage; in addition antioxidant enzymes in the body can also inactivate ROS. Aging results in a decrease in the amount of antioxidant enzymes which results in an increased risk for developing cancer and an increased incidence of immune impairment. As antioxidant enzymes decline ROS accumulate and so does the damage caused by them.

ROS are only a problem when in excess, when they are not in excess they play a positive role in health and development. Oxidants are used to help a growing fetus develop; they can alter gene expression, and activate natural detoxification systems. They are also produced and use by immune cells to kill invading infective agents. Often with chronic infection, white blood cells can produce excessive amounts of ROS, which increases the antioxidant requirement. The important point is that oxidative pathways have been implicated as a factor in a wide variety of disease states.

Why Supplement with Antioxidants?

The recognition that prevention is the most viable strategy for reducing morbidity and mortality from chronic diseases has lead to the blossoming of the field of chemoprevention. Chemoprevention is the use of specific chemicals, either alone or in combination, to decrease the incidence of disease. Antioxidant nutritional agents are the focus of attention in disease prevention because of the number and breadth of diseases in which oxidative mechanisms have been identified or hypothesized and the lack of toxicity. The lack of toxicity and side effects are critical from the standpoint of prevention. Toxicity is easily weighed and balanced when considering the treatment of a life threatening disease. But the level of toxicity acceptable for preventive applications must be much lower or non-existent in consideration of its use for a disease that does not yet exist i.e. as a preventative treatment. For the most part when considering prevention there are very few high-risk populations in which toxic side effects could be justified.

Even so, if a compound prevented half of all the cases of a particularly rare disease with no appreciable toxicity it might still be difficult to justify everyone taking such a preventive agent. Therefore the significance of preventive activity is expressed more for prevalent conditions (heart and eye diseases and cancer), or severe situations (such as risk of exposure to anthrax).

Pigment Antioxidants

The carotenoids are some of the most common pigments found in nature (Daun, H., 1988) and are fat soluble like vitamins A and E. Beta-carotene is one of the best known carotenoids and is necessary for the formation of vitamin A, however beta-carotene is only one of 400 of these naturally occurring pigments. Some other related pigments include alpha carotene, lutein, lycopene and astaxanthin. Caroteniods are pigments that are structurally related to vitamin A. Although caroteniods are not yet considered truly essential, significant health benefits have been ascribed to them allowing them to be one of very few natural products considered to be analogous to nutrients (Noel W. Solomons 2001).

Astaxanthin and other carotenoid compounds exert their effects simply by their presence in tissues. The physiological actions of other carotenoids have been investigated, in vitro, in both human and animal studies. As components of whole foods (fruits and vegetables) it is difficult to study the contributions of individual carotenoids to health. It is known that high fruit and vegetable consumption is associated with lower incidences of cancer (Mayne, 1996, 1997, Ziegler, 1991, Giovannucci. 1999). There is mounting evidence that these compounds work because of their capacity to quench reactive oxygen, (stop oxidative mechanisms) making them chemoprotective against cancer. In addition there is strong evidence that some carotenoids alter the metabolism of carcinogens in the liver and this may be one of the most important ways that they function in cancer prevention (DeFlora and Ramel 1988, Smith and Yang 1994).