A Very Simplistic Explanation of Free Radicals and Anti-Oxidants

Free radicals are atoms or molecules with unpaired electrons. Once formed, these highly reactive radicals may cause damage to cells, organelles, and DNA. Antioxidants are molecules that can safely interact with free radicals and terminate their reactive behaviour before vital cellular components are harmed. The body cannot manufacture many antioxidants (including micronutrients like vitamin C), so they must be supplied by the diet.

ANTIOXIDANTS TUTORIAL, PART 1: What are antioxidants?

Free radicals (pro-oxidants) are atoms or molecules with unpaired electrons. These highly reactive substances can be formed in a number of ways, and once formed they may use their reactivity to damage important cellular components - such as the cell membrane - or macromolecules like DNA. This damage can lead to mutation, impaired function, and even cell death. To minimize potential damage from free radicals, the body utilizes a defense system of antioxidants.

Antioxidants are molecules that can safely interact with free radicals and terminate their reactivity before vital cellular components are damaged. Although there are several enzyme systems within the body that scavenge free radicals, the principle micronutrient (vitamin/mineral) antioxidants are vitamin E, beta-carotene, vitamin C, and selenium. The body cannot manufacture these micronutrients, so they must be acquired by diet. In addition, there are many plant-derived nutrients (phytonutrients) that can act as powerful antioxidants in the human body.

It is impossible to completely avoid damage from free radicals. Free radicals arise from sources both inside (endogenous) and outside (exogenous) our bodies. Oxidants that develop from processes within our bodies form as a result of normal breathing, metabolism, and inflammation. Exogenous free radicals form from environmental factors such as pollution, sunlight, strenuous exercise, smoking, and alcohol. Unfortunately, no antioxidant system is perfect, so cells and DNA damaged by oxidation accumulate as we age.

Plentiful intakes of antioxidants have been associated with reduced risk of some chronic diseases, in the same way that generous intakes of fruits, vegetables and grains have been associated with similar health benefits.

ANTIOXIDANTS TUTORIAL, PART 2: Health benefits of antioxidants

There are many known health benefits of antioxidant intake. Some scientific examples include the following:

Cancer

• People with high beta-carotene intakes have about one-third the cancer risk as people with low beta-carotene intakes. (Peto R. Cancer Surveys 1983;2:327-340.)
   

• People with higher intakes of vitamin C have about half the risk for many types of cancer when compared to people with low vitamin C intakes. (Block G. Am J Clin Nutr 1991;53:270S-282S.)
   

• People with low intakes of several antioxidants have more DNA damage than people with generous intakes. (Ames BN. Metat Res 2001;475:7-20.)
   

• People with the highest intakes of vitamin C, E, and beta-carotene have a significantly lower risk of lung cancer. (Yong LC et al. Am J Epidemiol 1997;146:231-43.)
   

• Men who took vitamin E supplements for 10 years or more had a 30% lower risk of bladder cancer. (Michaud DS et al. Am J Epidemiol 2000;152:1145-53.)
   

• There are over 66 studies showing cancer-prevention activity of green tea, black tea, and their constituents. These include cancer reduction in the skin, lung, oral cavity, esophagus, stomach, liver, pancreas, bladder, small intestine, colon and prostate. (Lambert JD et al. Am J Clin Nutr 2005;81:284S-291S.)

Heart Disease

• Elderly people who took both vitamin C and vitamin E supplements had a decreased risk of death from heart disease as well as overall mortality. (Losonczy KG, Harris TB, Havlik RJ. Am J Clin Nutr 1996;64:190-196.)
   

• Men who took vitamin supplements had a 70% lower risk of dying from heart disease and a 50% lower risk of heart attack. (Meyer F, Bairati I, Dagenasis GR. Can J Cardiol 1996;12:930-934.)
   

• In the Nurses' Health Study involving over 87,000 women, there was a 41% reduction in risk of heart disease for those who took vitamin E for more than two years. (Stampfer MJ, Hennekens CH, Manson JE, et al. New Engl J Med 1993;328:1444-1449.)
   

• In the Nurses' Health Study, vitamin C supplements were also related to a lower risk of heart disease. (Osganian SK et al. J Am Coll Cardiol 2003;42:246-52.)
   

• In the Health Professionals Follow-Up Study involving almost 40,000 men, there was a 37% reduction in risk of heart disease in men who took vitamin E for more than two years. The average intake in the lowest risk group was 400 IU per day. (Rimm EB, Stampfer MJ. Ascherio A, et al. New Engl J Med 1993;328:1450-1456.)
   

• To date, 17 human group studies have been published on flavonoid intake and the risk of coronary artery disease and stroke. Positive studies have shown reduction in mortality risk of up to 65%. (Arts ICW and Hollman PCH. Am J Clin Nutr 2005;81:317S-325S.)
   

• The largest and longest study to date, done as part of the Harvard-based Nurses' Health Study and Health Professionals Follow-up Study, included almost 110,000 men and women whose health and dietary habits were followed for 14 years. The higher the average daily intake of fruits and vegetables, the lower the chances of developing cardiovascular disease. Compared with those in the lowest category of fruit and vegetable intake (less than 1.5 servings a day), those who averaged 8 or more servings a day were 30% less likely to have had a heart attack or stroke. (Joshipura KJ, et al. Ann Intern Med 2001 Jun 19;134(12):1106-14.)

Other Chronic diseases

• Several long-term studies have shown a reduced risk of cataracts in those who have taken vitamin C and/or vitamin E supplements for more than 10 years. (Jacques PF et al. Arch Ophthalmol 2001;119:1009-19.)
   

• The Age-Related Eye Disease Study (AREDS) at NIH found that daily supplementation with antioxidants, zinc, and copper delayed progression of age-related macular degeneration. (AREDS report no. 8. Arch Ophthalmol 2001;119:1417-36.)
   

• Research has shown a significant relationship between flavonoid intakes and the occurrence of asthma. (Knekt P et al. Am J Clin Nutr 2002;76:560-8.)
   

• Other research suggests antioxidants may help support lung function and protect the lungs from oxidative damage. (Schunemann HJ et al. Am J Respir Crit Care Med 2001;163:1246-55.)
   

• In a study on Alzheimer's disease, high levels of vitamin E delayed progression of the disease. (Sano M et al. N Engl J Med 1997;336:1216-22.)

Since the average intake of 3 servings or less of fruits and vegetables fails to provide minimum levels of even basic vitamins, intakes of the numerous other antioxidants provided by a typical modern diet are sure to be well under optimal and beneficial levels. It has been established that a good multivitamin can fill in gaps in missing vitamins, but availability of broad-spectrum antioxidant supplements has lagged behind.

ANTIOXIDANTS TUTORIAL, PART 3: Sources and dietary intakes

Antioxidants can be vitamins, minerals, enzymes, or plant-derived nutrients called phytonutrients.

The major vitamin antioxidants are vitamin C, vitamin E and beta-carotene, while selenium is the major mineral antioxidant. Unfortunately, many researchers and nutritionists discuss and report on these as if they are the only sources of antioxidants. However, a thorough examination of antioxidants and their importance to human health must include a much larger list of compounds potentially present in a healthy, varied diet. The following list is an example of the wide variety of phytonutrient antioxidants present in a healthy diet:
 

The recommendation from the National Cancer Institute, the U.S.D.A., and nutrition experts is to eat a minimum of 5-13 servings of fruits and vegetables per day depending on your individual caloric needs. Based on these recommendations, a typical varied diet would provide approximately 200-600 mg of vitamin C and 10-20 mg (16,000-32,000 IU) of carotenoids. Additionally, polyphenols " the most abundant antioxidant in the diet " could have a daily dietary intake as high as 1 gram/day in a mixed, varied diet of fruits, vegetables, grains, and beverages.

Possible intakes of other phytonutrient antioxidants could include:

• Anthocyandins:1,500 mg in two oz. of black grapes

• Proanthocyanidins: 100-300 mg/day from red wine

• Catechins: 50 mg/day from tea (one cup brewed green tea " 240-320 mg catechins), chocolate, apples, pears, grapes, red wine

• Isoflavones: 50 mg/day from soy foods

• Chlorogenic acid: as high as 800 mg/day in coffee drinkers

Although it may seem reasonable that a consistently healthy and varied diet could provide high doses of antioxidants, the average American gets a total of just three servings of fruits and vegetables each day. As previously mentioned, dietary guidelines call for five to thirteen servings. For a person who needs 2,000 calories a day, this translates into a recommendation of nine servings, or 4½ cups of fruits and vegetables each day.

The 2001-2002 NHANES survey of dietary intakes shows that 93% of Americans fail to get even the Estimated Average Requirement (EAR) for vitamin E, let alone the RDA. More than half of adults fail to get even the average requirement for vitamin A. About one-third of non-smokers and two-thirds of smokers fall short on minimum vitamin C requirements. Obviously, since the average intake of 3 servings or less of fruits and vegetables fails to provide minimum levels of even basic vitamins, intakes of numerous other antioxidants are sure to be well under optimal and beneficial levels.

It is well-established that a good multivitamin can fill gaps in vitamin and mineral requirements unmet by a poor diet, but broad-spectrum supplemental availability of antioxidants has lagged. Although there is much to be learned about the individual characteristics of the hundreds of potential dietary antioxidants, it seems reasonable that providing supplements of various antioxidant classes may also fill nutritional gaps and provide health benefits potentially missing from the typical western diet.

Advanced levels of antioxidants are a common thread among nearly every population less prone to chronic degenerative disease. While high levels of single nutrients and foods may pose a risk of danger and toxicity, there is no known unsafe level of total antioxidants.

ANTIOXIDANTS TUTORIAL, PART 4: Safety of antioxidants

Nutritional supplements have been used and valued by American consumers ever since vitamins were first discovered and commercialized, beginning largely in the early decades of the 20th century.

Multivitamin/mineral supplements are an effective means of delivering adequate amounts of essential nutrients to help people achieve their recommended intakes. The great majority of dietary supplements, including multivitamins, are safe for regular use. Despite widespread usage, there have been no specific published reports of toxicity or adverse effects associated with the proper use of multivitamins.

A series of well-publicized clinical trials utilizing relatively high doses of single nutrients or combinations of nutrients (such as vitamin E and/or beta-carotene) in diseased patients have yielded disappointing results, and even suggested the presence of harm. However, those trials were conducted in patients with serious illnesses (such as cancer or cardiovascular disease), who were on multiple medications, or who were smokers. The results of these trials should be placed in their proper context, including the fact that they are not applicable to the generally healthy population.

Advanced levels of antioxidants are a common thread among nearly every population found to be less prone to chronic degenerative disease. As an example, the Japanese - often cited as an example of longevity - have high levels of fruit, vegetables, green tea and soy as part of their traditional diet. Vegetarians have lower levels of heart disease and cancer when compared to the typical mixed diet, in part due to their generally higher intake of antioxidants.

While high levels of single nutrients and foods may pose a risk of danger and toxicity, there is no known unsafe level of total antioxidants. As far as we can tell, as long as they are varied and balanced, the more antioxidants the better.

By Karin Henderson - Nurse, Retired.

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I trust you now have a better understanding of what antioxidants and free radicals are. You also now understand the damage that the free radicals can create and how that can lead to oxidative stress. In turn this oxidative stress leads to degeneration of a body part ( as it does in Multiple Sclerosis by damaging the myelin sheath: the material that surrounds and protects your nerve cells in or by allowing too much glucose to remain in your blood as in diabetes). Oxidative stress seems to be the long term effect. The obvious solution is to repair or strengthen your immune system. But would you not ask yourself what the body does at the start? When it first recognizes an intruder/free radical? If nature is wonderful enough to provide long term solutions, surely it also provides short term interventions. It does (if we don't shut it down with "anti-inflammatory drugs). The inflammatory process is one of nature's immediate protective mechanisms and involves bringing extra fluid (interstitial) to the area. In simple terms, it tries to wash out the intruder.

We have some additional articles on the inflammatory process on the website, they can be found here;