Antioxidants – v – Free Radicals
The fight against cancer and coronary artery disease
by Dr. Warwick D. Raymont Ph.D., D.Sc., Grad. Dip. Sc. Tech. Comm., M.A.C.S., M.N.Y.A.S., D.G., O.I.A.
© Dr. W. D. Raymont 1994
Introduction
Much has been written of late on the subject of free radicals and the often serious, sometimes fatal, effects that hey have on human health … and on antioxidants, the naturally occurring substances that are the body’s only naturally occurring defence against them.
The purpose of this brief paper is to provide a relatively understandable reference to all who are concerned about increasing protection against heart disease and many, if not most, forms of cancer. Space does not permit discussion of the acceleration of the effects of ageing now also justifiably attributed to free radicals.
Free Radicals
Simplistically, free radicals are unstable atoms or groups of atoms – unstable because they have one or more unpaired electrons in their atomic structure. This structure is technically unusual as electrons normally exist in pairs in stable structures, atoms and molecules alike, where each electron is “balanced” by another in its orbit.
This instability of free radicals causes them to have a “voracious appetite” for other molecules that they can “lock” onto and they usually do so in an instant – and, in doing so, can cause serious damage to the nuclei and DNA structure of the body’s cells.
The usual free radicals are the hydroxyl and superoxide radicals, forms of reactive oxygen which are released naturally during the body’s metabolism and produced by white blood cells in their fight against infective invasion. These are normally kept under control by the body’s natural mechanisms. For example, the more common free radical, the superoxide radical, is usually conquered immediately by the naturally occurring bodily enzyme called superoxide dismutase, “SOD”, and thus a balance is maintained.
However, especially during modern times, there have emerged many new factors which have increased free radical production to a level which the human body was simply neither designed nor equipped to contend with. For example:
Cigarette smoke and air pollution enter the body through the respiratory system and, besides causing direct tissue damage to the lungs, bring free radicals into the body and trigger the release of even more as this pollution contacts cells and is countered by the body’s white blood cells.
Certain drugs, too, are now known to trigger the release of free radicals, often with serious cardiovascular implications.
Exposure to ultraviolet light, X-rays and other forms of radiation also initiates the formation of numerous free radicals.
Asbestos and similar mineral fibres enter the blood through the lungs and damage white blood cells, triggering the release of free radicals.
Pesticides, heavy metals and other chemical contaminants can not only accumulate in the body, but arte also known to be prime causative agents of atherosclerosis (the hardening of artery walls by cholesterol build-up) and many forms of cancer – again often by stimulating the production of free radicals.
Emotional stress and excessive exercise are two further modern-day means by which free radical production is enhanced. Even the fittest athlete with ideal blood pressure and cholesterol levels can suffer the same cardiovascular failure as the cholesterol-loaded and highly stressed bureaucrat. This is because exercise stimulates free radical production which cannot be countered by the body’s natural means and can, therefore, be equally as dangerous to cardiovascular health as little or no exercise at all.
It has been clearly established that a light to moderate exercise régime (twenty to thirty minutes per day) is the ideal to maintain high density lipoprotein (HDL) levels and maintain general cardiovascular health.
Atherosclerosis
“Bad cholesterol” – low density lipoprotein (LDL) – when oxidised by free radicals, can build up in coronary and other arteries as plaque. The formation of such plaque is usually catalysed by radicals of the heavy metal, cadmium, which have been ingested from foods grown with artificial fertilisers (superphosphate) and from other forms of pollution.
Cancer and Carcinogens
The potential to form cancerous cells is a dormant factor in most parts of the bodies of most animal life, especially humans.
There is now little doubt that free radicals trigger the propagation of cancerous cells and are therefore responsible for most, if not all, forms of cancer. Free radicals are believed to achieve this by entering cells and attacking the nucleus and DSNA molecules.
The current hypothesis is that carcinogens, or cancer causing chemicals, do not actually directly cause cancer, but do so indirectly by producing or stimulating the production of free radicals which, in turn, trigger the cancer by attacking the structure of cellular and nuclear DNA.
In short, free radicals damage health by oxidation and by attacking DNA and the only measure available against them is antioxidants. Unfortunately, the body is unable to produce sufficient itself and even normal dietary antioxidant can be insufficient to counter today’s increases in free radical intake from the food we eat, the water we drink and the air we breathe.
Antioxidants
As the name suggests, antioxidants prevent the damage caused by free radicals. Antioxidants come only from two sources – both natural. One is within the body, or “endogenous”, while the other is external, or “exogenous”.
Endogenous Antioxidants
As already mentioned, the most important of the body’s endogenous antioxidants is Superoxide dismutase (SOD) which acts upon superoxide free radicals to convert them to hydrogen peroxide which, in turn, is converted by the body into water and oxygen, the latter being utilised in energy production by converting carbohydrates n(foods) into carbon dioxide, water and energy.
Glutathione (GSH) peroxidase is the equally important antioxidant which reacts with the hydrogen peroxide as described above and thereby further prevents the intracellular nuclear and DNA damage thought to be the precursor to cancer.
Catalase, the third member of the endogenous antioxidant trilogy, also helps in the removal of hydrogen peroxide.
Exogenous antioxidants, the Free Radical Scavengers
1. The Vitamins – betacarotene (Vitamin A precursor), Vitamin C and Vitamin E.
Vitamin A, itself, can pose a hazard to human health and even the risk of birth defects when taken in excess. Its precursor, betacarotene, can be taken in virtually any quantity without harmful effect. At the same time, it provides the body with a store of the raw material from which it produces Vitamin A naturally according to needs. Betacarotene has been linked to increased protection against many forms of cancer, including lung, bladder, rectal, oral and dermal (skin) cancers.
Vitamin C acts synergistically with Vitamin E and, with Vitamin E, assists not only in the prevention of the formation of arterial cholesterol plaque but also, in sufficient quantities, has been shown to actually assist in the chelation (“dissolving”) of existing cholesterol plaque thereby helping clear occluded (blocked) arteries, particularly coronary. Vitamin C is also specifically known to assist in the prevention of many forms of cancer, including pancreatic, rectal, cervical, oesophageal and oral cancer. It is also a powerful free radical scavenger and thereby helps clean up the residues of cigarette smoke and other forms of air pollution that enter the body.
Vitamin E is present in small quantities in may foods but its uptake is all too often inhibited by low-fat or no fat diets as fats and oils are the essential carriers of Vitamin E, without which absorption or uptake of this, the most powerful of the antioxidant vitamins, is severely restricted. Vitamin E is known to fight infection, promote healing and to assist in the prevention of lung and gastrointestinal (including bowel) cancer. It achieves this by again preventing free radicals from entering the cell where nuclear and DNA damage would otherwise ensue.
2. The New Generation (Herbal) Antioxidants
Known to be up to 50 times more powerful than the antioxidant Vitamins C and E ands betacarotene, numerous sources of herbal antioxidants have now been identified.
These herbal antioxidants, the Proanthocyanidins, are also known or referred to as, among many bother names, anthocyanosides, polymers of catechin, “Proanthenols” and “Pycnogenol”.
They are, however, very dissimilar in their bio-availability and/or bio-uptake. Furthermore, some sources and/or extraction procedures used have been reported to contain toxins, even carcinogens. There is, for example, increasing concern being expressed around the world with the proanthocyanidin extract from the bark of the Maritime Pine (Pinus pinaster) and other pines. (Note: since this article was written, Horphag has released a Maritime Pine Extract that is totally free of carcinogens such as orthotolidine, pesticides and fungicides)
Some extracts may demonstrate a bioavailability of less than 5%. However, the latest research has shown the (Indena) proanthocyanidin extract from organically grown dark grape (Vitis vinifera) seed to be not only one of the most bioavailable (up to 95%), but also totally free from contamination from toxins or potential carcinogens. Two other excellent sources are from Bilberry (Vaccinium myrtillus) fruit and Lime (Tilia cordata) flowers. Proanthocyanidins are also found in Garlic (Allium sativum) and in citrus bioflavonoids.
BIBLIOGRAPHY
- (Too numerous to itemise individually) from: Sauberlich, H.E. & Machlin, L.J. (eds), Annals of the New York Academy of Sciences, 669 (1992).
- Esterbauer, Hermann et al., Ann. Med., 23, 573-581 (1991)
- Ibid, Free Radical Biol. and Med., 13, 341-390 (1992)
- Comstock, G.W. et al., Am. J. Epidemiology, 135, 115f (1992)
- Harris, W.S. Clin. Cardiology, 15, 636-640 (1992)
- Prasad, K.N. et al., J. Am. Coll. Nutr., 11, 487-500
- Ibid, Am. Heart J., 125, 958ff (1993)
- Byers, T. & Perry, G., Ann. Rev. Nutr., 12, 139-159 (1992)
- Canfield, L.M. et al., Proc. Soc. Exp. Biol. & Med., 200, 260ff (1992)
- Knecht, P. et al., Am. J. Epidemiology, 127, 28-41 (1988)
- Blumberg, J.B., Contemp. Nutr., 17, 1 (1992)
- Jenkins, R.R. et al., Med & Sc. In Sports & Exercise, 25, 210-212 (1993)
- Sohal, R.S., Aging Clin. Exp. Res., 5, 3-17 (1993)
- Bast, J. et al., Am. J. Med., 91, Supp. 3C, 25ff (1991)
- Rimm, E.B., New Engl. J. Med., 328, 1450-6 (1993)
- (Too numerous to itemise individually) from: Am. J. Clin. Nutr., 53, 1 (Supp), 189-396 (1991)
- Bolton-Smith, C. et al., Eur. J. Clin. Nutr., 46, 85-93 (1992)
- Chen, J. et al., Int. J. Epidem., 21, 4, 625ff (1992)
This paper has been republished widely in journals ranging from the Western Australian Cancer Support News to the Iranian Journal of Medicine. In August 1998, in Perth, Professor Keith Kaye of the Department of Medicine at the University of Western Australia, at the end of a lecture on hormones presented by the author at the St John of God Hospital at Subiaco, WA, commended this paper highly as not only very understandable and complete, but as one he gives to all his cancer patients.
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