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 endogenous enzymatic defense systems (e.g. superoxide dismutase, catalase, glutathione peroxidase), and compounds (glutathione, uric acid, bilirubin, lipoic acid and coenzyme Q) to deal with these free radicals. The compounds that help neutralize harmful free radicals in the body are called antioxidants. While the body produces some antioxidants naturally, they can also be obtained through diet (fruits, vegetables, nuts) and supplements.

Therefore, antioxidants are molecules that are either produced by our enzymatic defense systems in our body or obtained from our diet. Their main function is to inhibit the oxidation of other molecules, protecting cells from damage caused by free radicals. Examples of these antioxidants can be found in the next page. The antioxidants can: (1) scavenge the free radicals; (2) inhibit the enzymes that generate free radicals; (3) up-regulate the endogenous enzymatic defense systems; (4) inhibit enzymes that catalyze oxidation of cellular components; or (5) chelate transition metal ions responsible for generation 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 age-related diseases, it is believed that consumption of antioxidant supplements will be beneficial to health. The health benefits of antioxidant supplements are listed below:

1. Reduces Oxidative Stress – Oxidative stress occurs when there is an imbalance between free radicals and antioxidants. Antioxidant supplements help restore balance, reducing cellular damage linked to aging and chronic diseases.

2. Supports Heart Health – Vitamin E & C may reduce LDL cholesterol oxidation, lowering the risk of atherosclerosis. CoQ10 supports energy production in heart cells and may improve heart failure symptoms.

3. Boosts Immune Function – Vitamin C enhances white blood cell function and speeds up recovery from infections. Zinc & Selenium are essential for immune response and reducing inflammation.

4. May Lower Cancer Risk – Some studies suggest antioxidants like beta-carotene, lycopene, and selenium may protect against certain cancers by preventing DNA damage. However, excessive supplementation may have adverse effects in some cases.

5. Protects Brain Health – Vitamin E & flavonoids may slow cognitive decline and reduce Alzheimer’s risk. Resveratrol (found in grapes) shows neuroprotective effects in studies.

6. Promotes Skin Health – Vitamin C & E protect skin from UV damage, improve collagen production, and reduce signs of aging. Astaxanthin may reduce wrinkles and improve skin elasticity.

7. Supports Eye Health – Lutein & Zeaxanthin protect against age-related macular degeneration (AMD) and cataracts.

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

Natural vs. Synthetic – Whole-food antioxidants may be more effective than isolated or synthetic supplements.

Overconsumption Risks – High doses of certain antioxidants (e.g., Vitamin E, beta-carotene) may have harmful effects. Furthermore, at low levels, free radicals are also used by your cells for fighting pathogens and other normal cellular signalling.  Free radicals have been shown to play a 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.  

Drug Interactions – In general, natural antioxidant supplements from plant sources are quite safe.  However, some antioxidant supplements may interact with certain medications. Some antioxidants (e.g., Vitamin K, CoQ10) may interfere with medications like blood thinners. Consult your physician before taking these supplements.

Limitation of antioxidant supplements – 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.  

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 the following page.