"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.
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.
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.
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.
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.
Sources and Additional Information:
