Health benefits of antioxidants

This website provides the background information of free radicals, oxidative stress, age-related diseases and health benefits of antioxidants. Let me first explain what free radicals are, and their relationship with age-related diseases. Then I explain what antioxidants are and their functions in mitigation of the effect of free radicals. Finally, I describe the health benefits and issues of antioxidant supplements.

Free radicals, oxidative stress and antioxidants

As shown in the diagram above, metabolism of food and exercise will generate free radicals in the body. Radiation (dental X-ray and sunlight), toxins from food, and pollutants in the environment also contribute free radicals. Free radicals are highly reactive oxygen species (ROS) or reactive nitrogen species (RNS) that can induce oxidative damage on cellular components (proteins, DNA and lipids). Damage of these cellular components leads to inflammation and results in degenerative diseases. Damage to DNA will lead to cancer cell formation and spreading.

Our bodies have enzymatic defense systems and endogenous antioxidant molecules (glutathione, uric acid, bilirubin, lipoic acid and coenzyme Q) to deal with these free radicals. Our bodies can also obtain exogenous antioxidants from the food we eat. These antioxidants are mainly present in fruits and vegetables. They can neutralize the free radicals or inhibit the enzymes that generate free radicals. They can also induce the enzymatic defense systems to increase the production endogenous antioxidants. Furthermore, they can inhibit enzymes that catalyze oxidation of cellular components to minimize the damage of free radicals.

In young and healthy individuals, the production and removal of free radicals are well-regulated. Due to aging or poor diet, antioxidant levels in the body will be lower, and can no longer counteract the free radicals. This condition is known as oxidative stress. Prolonged oxidative stress can cause cellular damages, leading to a variety of aging-related diseases, such as cancer, cardiovascular diseases, type-2 diabetes, Alzheimer’s disease, Parkinson’s disease, cataract and macular degeneration.  Increased intake of antioxidants from food or supplements may help to mitigate the oxidative stress and slow down the manifestation of these diseases.

Health benefits of antioxidants

Since antioxidants can mitigate oxidative stress which is the cause of many aging-related diseases, it seems likely that consumption of antioxidant supplements will be beneficial to health. Experiments using cell cultures and animal models have demonstrated the health benefits of antioxidants.  However, so far there are not clinical studies that can confirm these benefits due to the lack of research funding. On the contrary, limited clinical studies have shown that some antioxidants (vitamin C, vitamin E and beta-carotene) have no protective effect. In some cases these supplements can increase risk of cancer in certain people.

Just to be fair, these clinical trials used synthetic antioxidants in high doses. The failure of these clinical trials may be due to the following reasons. First, optimal dose was not used. Second, the synthetic antioxidants used in these studies are in different chemical forms than those found in fruits and vegetables. Third, the trials were not run long enough to see the positive effects. Therefore, people who are seeking antioxidant supplements for prevention of aging-related diseases should not be discouraged by the lack of positive results of clinical trials.  Natural antioxidants will help prevent aging-related diseases in people who do not have sufficient intake of antioxidants from their diet, such as the aging folks and picky eaters.

Should I take antioxidant supplements?

Fresh fruits and vegetables are good source of antioxidants. Some doctors claim that taking antioxidant supplements is a complete waste of money. However, there are many research publications demonstrating the health benefits of antioxidant supplements.  If you are young and are eating a variety of fruits and vegetables, you probably need not take any antioxidant supplements.

On the other hand, if you are aging or normally eat only a limited types of vegetables and fruits, you may not get enough antioxidants from your diet alone. Furthermore,  poor digestion or absorption due to aging may lead to the lack of certain antioxidants.  Therefore, antioxidant supplements from plant sources may be beneficial to the aging folks.  However, you should not use antioxidant supplements to replace fresh fruits and vegetables, as the latter will provide other nutrients and fibers. You should avoid taking large amount of synthetic antioxidant vitamins, such as vitamins E and C.

Precautions in taking antioxidant supplements

In general, natural antioxidant supplements from plant sources are quite safe.  However, some antioxidant supplements may interact with certain medications. Consult your physician before taking these supplements. On the other hand, free radicals at low levels are useful for the normal function of your body. Your cells use free radicals to fight pathogens and other normal cellular signaling.  Furthermore, free radicals play an important role in the extension of life span. Therefore, do not take larger doses of the supplements than those recommended. More of a good thing does not necessarily mean better. In fact, overdose of antioxidants may have the opposite effects. Some antioxidants may have pro-oxidant properties in large doses.  

Although research has shown that antioxidant supplements have the potential of preventing or slowing down the development of aging-related diseases, they cannot cure any disease.  Antioxidants can prevent further cellular damage by mitigating free radicals, but cannot reverse damages already done.  

The decision of buying an antioxidant supplement should not be based on price alone, as many supplements in the market fail to deliver what they claimed to contain. High quality antioxidant supplements can be purchased from this website.

Antioxidant supplements and cancer

Antioxidants can mitigate free radicals, which damage DNA and cause gene mutation leading to the development of cancer.  Therefore, antioxidants supplements are good for cancer prevention.  However, cancer patients undergoing treatment should avoid taking antioxidant supplements. The reason is that antioxidant can interfere with cancer therapy and decrease its efficacy, as chemotherapy and radiation therapy of cancer utilize free radicals to kill cancer cells. Some antioxidants are able to kill cancer cells or sensitize them to chemotherapeutic drugs or radiation in the laboratory, but their potential therapeutic applications are still controversial. 

On the other hand, cancer cells are known to have increased free radical levels as compared to normal cells, antioxidant will facilitate cancer cell survival by neutralizing the free radicals. Some antioxidants can actually speed up the growth and metastasis of some cancers.  Furthermore, not all tumors will benefit from antioxidant treatment. There are a wide variety of cancers with different genetic defects and antioxidants with different mechanism of actions. It will be difficult to select the right antioxidant to treat a certain cancer. Moreover, it is difficult to determine the correct dose level, because antioxidant can have pro-oxidant activities at high doses.

Types of antioxidants

There are many types of antioxidants. Information on the internet can be confusing, because different websites are talking about different things. It is important to know the types of antioxidants. Antioxidants are classified into several groups according to their chemical structures.  For a list of common antioxidants and their properties, please go to this page. For a list of recommended antioxidant supplements, please go to this page and the following page.