Antioxidants are substances that are capable of giving up electrons easily to unstable molecules missing electrons. These unstable molecules are called oxidants or free radicals.

What creates free radicals?

Oxygen, the most crucial life sustaining nutrient, is paradoxically the main source of free radicals. Free radicals are considered to be the contributing cause of many chronic illnesses and the aging process. Free radicals are very reactive oxygen fragments which are created by normal metabolic processes in the cells and also are created by exposure to air pollution, cigarette smoke, certain chemicals, ultraviolet light, radiation and other substances. Stress and excessive and strenuous exercise can produce free radicals as well.

Free radicals lack electrons and try to steal them from adjacent molecules to regain balance. This process often causes a chain reaction spreading throughout the body as stable molecules in turn become unstable and react further with other molecules causing yet more free radical damage which can result in chronic disease.

Some of the damage caused by free radicals:

  • free radicals attack DNA - our cells' genetic material - causing cells to die or mutate and possibly become cancerous;

  • free radicals can release substances which are toxic to nerves. This can lead to nerve and brain damage (as seen in Parkinson's disease);

  • free radicals react with the LDL type of cholesterol (bad cholesterol) which becomes damaged and leads to atherosclerosis, the major contributor to heart and blood vessel diseases. The damaging of LDL cholesterol is a critical link between high blood cholesterol and the build-up of vessel blocking plaque;

  • free radicals may contribute to the loss of transparency of the lenses of the eye, thus leading to cataracts and macular degeneration;

  • free radicals can damage cellular enzymes, slowing down and stopping or, on the contrary, activating the processes which depend on these enzymes leading to cell damage and death;

  • free radicals can damage mitochondria of cells responsible for energy production thus affecting the ability of cells to produce energy they need to function properly;

  • free radicals compromise your immune health by depleting Glutathione.

Reducing free radical damage:

Fortunately, our bodies are equipped with mechanisms that eliminate free radicals. This is where antioxidant compounds step in to protect our cells. Antioxidants act as "circuit breakers" by inserting themselves into these free radical chain reaction donating electrons, and most importantly, without becoming free radicals themselves; or they can bind with free radicals and be eliminated from the body; some antioxidants are able to break down free radicals into harmless compounds.

Free radical damage can be minimized by avoiding above mentioned dangerous environmental factors as much as possible (though some of them are impossible to avoid for those living in metropolitan areas), by avoiding excessive exercise, managing stress levels, and eating a variety of foods rich in antioxidants. Many foods, mostly of plant origin, contain various antioxidant compounds which can strengthen your body's defenses. Some antioxidants, i.e. Glutathione and Melatonin, are produced by the body itself.

The number of antioxidant compounds is truly overwhelming numbering in the thousands, and it is impossible to discuss them all. We will concentrate on those which are most common, provide the most benefit for your immune health, and have credible scientific research behind them.

We must mention, however, that there is no research which shows that dietary or supplemental antioxidants definitely protect from or cure any disease. Growing scientific evidence only strongly suggests that antioxidants have the ability to assist in prevention of diseases such as cancer, heart disease, cataracts, cold and flu infections, and may improve immune system function and slow down the effects of aging, most likely due to their free radical scavenging powers.

So, what antioxidant "weapons" are out there to fight free radical damage?..


We feel that Glutathione should be mentioned first in the list of antioxidant compounds because it is so much more than just an antioxidant, and one of the very few produced only by the body itself.

Glutathione, the cornerstone of your immune health, is a molecule produced in every cell of the body. It plays many roles, such as: nutrient metabolism, regulation of cellular events including gene expression, DNA synthesis and repair, protein synthesis, cell growth, recycling of vitamins C and E, metabolism of toxins, metabolism of carcinogens and immune response.

Glutathione is also able to fill in for other antioxidants missing from the diet. Consumption of a variety of antioxidant rich foods releases Glutathione, thus directing it to fulfillment of other functions, which leads to improved immune health.

Glutathione is often referred to as a master antioxidant and its importance to your immune health cannot be overstated - a whole separate chapter is devoted to it on this web-site, discussing Glutathione's functions, what depletes its resources in the body, how to safely and effectively raise Glutathione levels, scientific research and much more.

Learn more about Glutathione - the most important antioxidant.


Antioxidant properties are exerted by some of the vitamins. These are vitamins C, E and the beta-carotene form of vitamin A (which will be discussed in "Carotenoids" below).

Their antioxidant effect is expressed by their ability to insert themselves into the free radical chain reactions; this process alters or damages vitamin molecules. However, vitamins can interact in order to protect and recycle each other. Vitamin C interacts with damaged vitamin E and converts it back to its antioxidant form. Vitamins C is then returned to its antioxidant form by the master antioxidant Glutathione. In its turn, vitamin E protects vitamin A from oxidation, and plays a role in its absorption, storage and utilization.

It has been shown that vitamin C is capable of short-term elevation of Glutathione levels in red blood cells which consequently results in improved immune function. Studies with vitamin E and Glutathione resemble those with vitamin C and Glutathione because these three antioxidants depend on each other for proper function and recycling.

At the same time, two recent long-term studies conducted by the Division of Preventive Medicine of the Department of Medicine at Brigham and Women's Hospital and Harvard Medical School (Boston, MA) examining anti-cancer properties of vitamins C and E supplements concluded that there is no evidence that these vitamins taken as supplements protect from cancer or offer any benefits in the prevention of total cancer mortality.

It should be noted that in the studies synthetic vitamin supplements are usually used, and not fresh fruits and vegetables, which are absorbed much better, are more natural for our bodies, and contain hundreds of other antioxidant compounds that may in combination enhance each other's antioxidant capacities. Also, research indicates that the protective properties of antioxidant vitamins show when they are taken at doses much higher than the recommended daily amounts. For example, studies that look into anticancer effects of vitamin C usually use doses 500-1,000 mg. Studies examining the heart protective properties of vitamin E have used doses of 800 IU.

Click the links below to read in more detail about vitamins C and E, recommended daily amounts, other health benefits these vitamins provide, toxicity information, and access the comprehensive lists of the best food sources for each of them:

Vitamin C
Vitamin E


Carotenoids are a class of more than 600 naturally occurring pigments synthesized by plants and algae. They are responsible for bright orange, yellow and red colors of fruits and vegetables. The most popular carotenoids in the Western diets are alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin. Alpha-carotene, beta-carotene and beta-cryptoxanthin are precursors for vitamin A meaning that they can convert into retinol (vitamin A) in the intestinal wall and liver as the body requires. Lycopene, lutein and zeaxanthin have no vitamin A activity.

For dietary carotenoids to be released from the food and absorbed intestinally, a small amount of fat is required in the meal. Usually, 3-5 g of fat appears sufficient for carotenoid absorption. For example, oil, butter, and sour cream are a good source of fat to be added to salads or consumed with fresh carrot juice.

Antioxidant capacity of carotenoids is attributed to their ability to inhibit the oxidation of fats in vitro. Their antioxidant activity is also dependent of their interaction with other antioxidants, namely vitamins C and E. In plants carotenoids acts as deactivators of singlet oxygen which is believed to be the cause of damaging effects of sunlight on many organic materials (and as seen in skin aging). However, it is less clear if this singlet oxygen deactivation is relevant to human health.

Click the links below to read about carotenoids that interest you, their effects on health, and research the best food sources for each of them:

Alpha-carotene, Beta-carotene and Beta-cryptoxanthin
Lutein and Zeaxanthin


Polyphenol antioxidants are found in a wide range of phytonutrient-containing fruits and vegetables. So far science has identified over 4,000 distinct species of polyphenol antioxidants that are believed to be crucial in combating oxidative stress.

The largest and best studied polyphenols are the flavonoids, which include several thousand compounds, the most well-known and studied among them are:

Proanthocyanidins (condensed tannins)

The non-flavonoid polyphenols that has been studied extensively are:

Curcumin (turmeric)

There is a difficulty with singling out and evaluating the medical effects of a specific polyphenol because there can be a large number of them in a single food; also, the content of them in foods depends on the state of ripeness, specific crop, the region of growth, etc.

While individual studies seem to demonstrate the favorable health effects of all polyphenols, more research is needed to understand the interactions between a variety of these chemicals acting synergistically within the human body.

There is also a debate about the bioavailability (readiness to be absorbed) of polyphenols in the human body. In test tube trials, which showed the ability of polyphenols to suppress cancer cells for example, polyphenolic concentrations were used that are difficult to achieve in the human bloodstream as polyphenol antioxidants are not stored in the body but rather quickly flushed out.

Since polyphenol antioxidants are considered non-essential nutrients (as opposed to vitamins, for example), even though their importance to immune health has been recognized, there are no established daily requirement intakes for them.

Although the individual flavonoid intake may vary depending on the amount of fruit, tea and red wine consumption, scientists estimate that total flavonoid intake averages about 150-200 mg per day.

One should exercise caution when relying on supplements (e.g. grape seed extract, OTC, green tea extract, resveratrol, etc.) for polyphenol intake instead of a variety of food sources since the effect of supplements on human health has not been completely studied.


Melatonin is a hormone known to regulate sleep and waking cycles. It is produced by the pineal gland in the brain. Melatonin is released into the blood at night time and its production is affected greatly by light.

Melatonin is also a powerful antioxidant and plays a role in stimulating other antioxidants as well. Melatonin has been shown to effectively raise Glutathione levels in many tissues including those of the brain, liver, muscle and blood serum. In its turn Glutathione detoxifies our bodies while we sleep. That is why it is important to get at least 7-8 hours of good night sleep when Melatonin is produced and released into the blood stream.

The only known significant natural source of melatonin is sour (tart) cherries, especially the Montmorency variety, which contain substantial amounts of melatonin, enough to produce a possitive effect in the body and without any side effects unlike the synthetic form of melatonin.

Learn more about Melatonin.

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