Tuesday, November 15, 2011

Free Radical Theory of Aging


"The perpetual but futile struggle of individual cells to stay alive and function normally, in the face of chemical disintegration - is the genesis of aging and all its consequences...Indeed, the free radical theory of aging is so big it encompasses virtually every disease you can think of that comes with increasing age. That, then, makes aging the primary and only disease most of us ever have to worry about. As Dr. Harman notes, we have pressed the life span about as far as it will go without attacking aging at its origin... Degenerative diseases such as cancer, Lou Gehrig's disease and Alzheimer's are not separate and distinguishable entities. They are merely different forms of expression, influenced by genetics and environment, of the free radical aging process that has caught up with us. " ( Jean Carper, 1995).

What is Free Radical Theory of Aging?

The free-radical theory of aging (FRTA) states that organisms age because cells accumulate free radical damage over time. A free radical is any atom or molecule that has a single unpaired electron in an outer shell. While a few free radicals such as melanin are not chemically reactive, most biologically-relevant free radicals are highly reactive. For most biological structures, free radical damage is closely associated with oxidative damage. Antioxidants are reducing agents, and limit oxidative damage to biological structures by passivating free radicals.

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History

This now very famous theory of aging was developed by Denham Harman MD at the University of Nebraska in 1956, when prevailing scientific opinion held that free radicals were too unstable to exist in biological systems, and before anybody had invoked free radicals as a cause of degenerative diseases. Two sources inspired Harman: 1) the rate of living theory, which holds that lifespan is an inverse function of metabolic rate. In turn, this is proportional to oxygen consumption, and 2) Rebbeca Gershman's observation that hyperbaric oxygen toxicity and radiation toxicity could be explained by the same underlying phenomenon: oxygen free radicals. Noting that radiation causes "mutation, cancer and aging" Harman argued that oxygen free radicals produced during normal respiration would cause cumulative damage which would eventually lead to loss of functionality of the organism, and ultimately death. In later years, the free radical theory was expanded to include not only aging per se, but also age related diseases.

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How it Works?

The term free radical describes any molecule that has a free electron, and this property makes it react with healthy molecules in a destructive way. Because the free radical molecule has an extra electron it creates an extra negative charge. This unbalanced energy makes the free radical bind itself to another balanced molecule as it tries to steal electrons. In so doing, the balanced molecule becomes unbalanced and thus a free radical itself.

In biochemistry, the free radicals of interest are often referred to as reactive oxygen species (ROS) because the most biologically significant free radicals are oxygen-centered. But not all free radicals are ROS and not all ROS are free radicals. For example, the free radicals superoxide and hydroxyl radical are ROS, but the ROS hydrogen peroxide (H2O2) is not a free radical species, however the term "free radical theory of aging" usually refers to these compounds as well.

It is known that diet, lifestyle, drugs (e.g. tobacco and alcohol) and radiation etc., are all accelerators of free radical production within the body.

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However, there is also natural production of free-radicals within the body. This is the result of the production of energy, particularly from the mitochondria. The simple process of eating, drinking and breathing forms free-radicals from the energy production cycles, as the body produces the universal energy molecule Adenosine Triphosphate (ATP). Note that oxygen is a potent free-radical producer.

Free radicals are known to attack the structure of cell membranes, which then create metabolic waste products. Such toxic accumulations interfere with cell communication, disturb DNA, RNA and protein synthesis, lower energy levels and generally impede vital chemical processes.

Yet we do not want to destroy all free radicals in our body as they are necessary for life. The body's ability to turn air and food into chemical energy depends on a chain reaction of free radicals. Free radicals are also a crucial part of the immune system, floating through the veins and attacking foreign invaders.

Hydrogen peroxide is a prime example of a free radical. Your blood actually contains trace amounts of hydrogen peroxide, an internal germ fighter. In fact, you could not fight bacteria without free radicals.

Antioxidants

Free radicals can however be transformed by free-radical scavengers (otherwise known as anti-oxidants). Particular anti-oxidants will bind to particular free radicals and help to stabilize them.

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Actually, the human body produces essential antioxidant defenses internally. Enzymes that control free radicals include superoxide dismutase, glutathione peroxidase, and catalase, as well as other molecules such as cholesterol, steroid hormones and sulfur-containing amino acids that neutralize free radicals. It is also possible to choose many nutrients in both foods and supplements that help fight free radicals.

Free radicals come in a hierarchy (according to their potential for damage) with the hydroxyl-radical and the superoxide-radical at the top of the list. It is therefore necessary to take a cross-section of anti-oxidants in order for the process of elimination of the free radicals to occur, otherwise higher damage free radicals may be converted into a greater number of lower damage free radicals.

Most free radical protection involves eating a better diet, exercising, maintaining a clean environment both internally and externally, and reducing stress, in addition to taking dietary supplements.

Eating better means eating whole, organic foods whenever possible and avoiding processed foods and artificial chemicals used for preservation, coloring and flavoring. Exercising increases production of free radical-scavenging enzymes, which protect the body from the increased oxygen-related stress associated with a higher respiratory rate. A clean environment means avoiding excessive exposures to toxic air pollution, chemicals such as solvents and industrial waste that leach into water supplies, harsh cleaning and cosmetic chemicals, heavy metals, unnecessary medications, and pesticides. Pesticides can generate free radicals, and many also mimic hormones and can disrupt the normal hormonal balance. Stress increases the metabolic rate and alters hormonal balance, which also generates free radicals.

You can start taking dietary supplements, including powerful anti-oxidants as beta carotene, vitamin C, grape seed extract, vitamin E and possibly also stronger substances such as Hydergine, Melatonin and Vinpocetine. However, one of the main problems with the free radical theory is the failure of antioxidants administered as dietary supplements, like vitamins E and C, to significantly increase maximum lifespan. Proponents of the radical theory believe that dietary antioxidants, unlike natural antioxidants produced by cells, do not reach mitochondrial DNA, leaving this site susceptible to radical attack. Interestingly, even though supplemental antioxidants fail to increase maximum lifespan, they do increase the chances of living to the maximum lifespan. This may be due to antioxidant protection of other parts of the cell, like cellular proteins and membranes, from radical damage.

More than that, some recent studies tend to show that antioxidant therapy have no effect and can even increase mortality. Proponents of the theory claim that this phenomenon can be explained by hormesis: The addition of antioxidants can lead to a decrease of normal biological response to free radicals and lead to a more sensitive environment to oxidation. Furthermore, a recent study tracking the eating habits of 478,000 Europeans suggests that consuming lots of fruits and vegetables has little if any effect on preventing cancer.

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