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Antioxidants - A Clear And Simple Explanation

By Jeremy Chin
Posted on 03 Mar, 2015

Antioxidants - a clear and simple explanation

Antioxidants are touted as the elixir for all things, from cancer to heart disease to aging. You see its name flaunted on food packaging, across shampoo bottles, in magazine articles, on facial creams. But do we actually know what they are and how they work? This article will help you with that.


A journey to the center of the universe

The concept of antioxidants is fairly complex. To understand what they are, we first have to examine the world on a molecular level.

All matter in the universe as we’ve come to know is comprised of atoms. Each atom has protons and neutrons in its core, and electrons occupying its orbit.

Here is a simple diagram of an atom:

atom diagram

When two or more atoms link, they become molecules. Our body is composed of large molecules in the form of protein, fat, DNA and other substances. And there are chemical interactions within each of them at all times.

All the chemical reactions needed to sustain life are collectively known as metabolism, and one of the by products of metabolism are free radicals. Free radicals hold the key to our understanding of antioxidants.


Free Radicals


free radical diagramFor a molecule to be stable, it must contain the right amount of electrons. If the molecule loses an electron when it isn’t supposed to, it can turn into a free radical.

Free radicals are unstable, electrically charged molecules that can react with other molecules (like DNA and cell membranes) and damage them.

Once formed, free radicals start a chain of damaging chemical reactions because the molecules they damage can also turn into free radicals.

The biggest source of free radicals in our body comes from its interaction with oxygen. Oxygen, because it carries two unpaired electrons in its outer shell, is very reactive to anything it comes in contact with.

Free Radical SourcesFree radicals are not only generated by the body, they are present in the chemically-altered foods you eat and in the unclean air you breathe. Free radicals can also result from exposure to sunlight.

There is mounting evidence that free radicals promote the development of Alzheimer’s, arthritis, cataracts, diabetes, heart disease, kidney disease and age-related blindness.


And finally, antioxidants

Antioxidants are molecules with free electrons to give, and they safely interact with free radicals to stop the chain of damaging reactions.

antioxidant diagram


Where do we get antioxidants from?

Plants and animals have their own defenses against the oxidative damage caused by free radicals. As such, antioxidants are found in pretty much all foods of plant and animal origin.

antioxidant foods

Although meat products and fish contain antioxidants, they exists in smaller amounts compared to fruits and vegetables. Berries are a particularly good source. Other good sources of antioxidants include green tea, coffee and raw cacao.

According to some studies, coffee is actually the single biggest source of antioxidants in the Western diet, but this is partly because the “average” individual doesn’t eat that many antioxidant-rich foods.

Antioxidants can increase the shelf life of both natural and processed food products. Therefore, they are frequently used as food additives. For instance, vitamin C is often added to processed foods to act as a preservative.

Some antioxidants, such as glutathione, Alpha-Lipoic Acid and CoQ10 (Ubiquinone) are produced internally by our own body.

antioxidants marker

The Different Antioxidant Attributes

There are many classes of antioxidants. Like a well-formed military, each have their own specialized functions and thrive in different environments.

water iconCertain antioxidants are hydrophilic (water soluble), meaning they operate in aqueous environments like your blood and the fluids around your cells. Certain other antioxidants are lipids/fat soluble, so they exist in cell membranes to protect against lipid peroxidation.

enzymaticAntioxidants can also be categorized as enzymatic. Enzymatic antioxidants break down dangerous oxidative products and flush them from your system. Sometimes this is done by converting them into hydrogen peroxide and then into water. Trace metals like iron, manganese, zinc and copper are required for this process to take place, which is why it is important that these minerals are a part of our diet.

Antioxidants can also be non-enzymatic in nature. Non-enzymatic antioxidants help prevent enzymatic antioxidants from being depleted by doing a first sweep to neutralize free radicals. Most antioxidants found in foods are non-enzymatic.

Antioxidants can also be classified by their molecule size. Small-molecule antioxidants scavenge for reactive oxygen molecules and disarm them through chemical neutralization.

pawnLarge-protein antioxidants on the other hand play a sacrificial role. To preserve crucial enzymes and DNA, sacrificial proteins like albumin ‘take the bullet’ by absorbing reactive oxidants.


Dietary Antioxidants


Found in deeply pigmented fruits and vegetables, carotenoids neutralize free radicals, bolster cellular antioxidant defences and contain anti-cancer and anti-aging compounds. They also enhance the function of the immune system and help reduce the risk of many diseases.

Carotenoids can be classified into two groups:

carrotsCarotenes (which contain no oxygen atoms)
Some of the more famous carotenes are lycopene (found in red tomatoes) and beta-carotene (found in orange carrots). The biggest advantage of carotenes are that they get converted by your body into vitamin A based on the requirements of the body. This means you will not get an over-supply of vitamin A, which can be harmful.


egg yolkXanthophylls (which contain oxygen atoms)
There are several kinds of Xantophylls. Lutein (found in green leafy vegetables and egg yolk), canthaxanthin (the gold in chanterelle mushrooms), zeaxanthin (the most commonly caretenoid found in the leaves of most green plants), and astaxanthin (the red in salmon and shellfish).



The largest nutrient family known to scientists, flavanoids perform many functions vital to our health. There are many varieties of flavanoids.

onionsQuercetin, which can be found in large amounts in onions and capers, helps alleviate eczema, sinusitis, asthma, and hay fever.

Flavonols, which you can find in cocoa and chocolate, have anti-inflammatory properties.

green teaOf the flavonoids, the one that perhaps has been making the most waves are the catechins found in green tea. Research have shown them to be cardioprotective, neuroprotective, anti-obesity, anti-carcinogenic, anti-diabetic, anti-artherogenic, liver protective and beneficial for blood vessel health.

Many studies have also proven that tannins, a type of flavonoid abundant in red wine, can help protect against heart disease.

Interesting fact:
The general rule is that the more colorful a food item is, the richer it will be in flavonoids. Oranges, however are an exception to the rule because the flavonoids contained in this fruit are mainly found in the white and pulp interior of the skin.



Isothiocyanates work at the molecular level to eradicate carcinogenic compounds from your cells and they do so by halting the uncontrolled and uninhibited cell division that cancer usually brings about.

The way isothiocyanates work is rather fascinating. They suppress tumor growth by inducing cycle arrest leading to apoptosis (cell suicide).

Apoptosis is sometimes referred to as programmed cell death because it follows a controlled, predictable routine, kind of like a time bomb that has been triggered. The diagram below demonstrates how the process of apoptosis breaks a cell down, dials in the cleaners, and has its remains vacuumed up.

apoptosis diagram

broccoliFoods with the highest levels of isothiocyanates are from the cruciferous or cabbage family, such as broccoli, cauliflower, watercress, bok choy, kale, collards, turnips, brussel sprouts, cabbage and radish.

A word of caution for those of you with thyroid problems. A Cornell University study found that isothiocyanates can produce goiter by blocking the absorption and uptake of iodine by the thyroid gland.



grapesResveratrol is type of antibiotic produced by plants in response to injury or when the plant is under attack by pathogens such as bacteria or fungi. Natural food sources rich in resveratrol include grapes, blueberries, cranberries and peanuts.

Resveratrol can cross the blood-brain barrier and provide protection for your brain and nervous system. To date, there have been more than 4000 studies conducted on the benefits of resveratrol and they are:

Lowers your blood pressure by protecting the endothelial lining of your arteries—so blood flows as it should.

Reduces oxidative stress, which prevents premature aging of cells.

Normalizes your anti-inflammatory response by blocking the production of nf kappa b, a powerful, noxious inflammatory agent.

Provides cellular support that improves mental function, and promotes oral/dental health.

Inhibits the spread of cancer, especially prostate cancer, by preventing cancer cell replication through apoptosis.

Promotes muscle health, by reducing muscle wasting associated with diabetes and cancer.

Interesting fact:
Resveratrol is found in the skin of red grapes. Grapes grown in cooler climates have higher resveratrol levels than those from warmer climes (such as California and Spain).



salmonAlthough it's technically a carotenoid, this antioxidant deserves its own special mention.

Unlike other carotenoids which originate from plants, astaxanthin is a marine carotenoid produced by microalgae to give itself protection from the effects of singlet oxygen that accompany ultraviolet rays. Singlet oxygen is oxygen in a highly reactive state, making it extremely disruptive. Astaxanthin is 550 times more powerful than vitamin E and 11 times more powerful than beta-carotene at neutralizing singlet oxygen.

Astaxanthin is also well known for its free radical scavenging capabilities—it is 65 times more powerful than vitamin C, 54 times more powerful than beta-carotene, and 14 times more powerful than vitamin E.

Like resveratrol, astaxanthin can cross the blood-brain barrier, and the blood-retinal barrier – something that beta-carotene and lycopene cannot do.

Astaxanthin has a wide ranging benefits which include:

  • Preventing sunburn and protecting you from damaging radiation effects
  • Protecting your eyes from cataracts, macular degeneration, and blindness
  • Improving your endurance, workout performance, and recovery
  • Protecting your brain from dementia and Alzheimer's
  • Reducing your risk of different types of cancer
  • Reducing inflammation from all causes, including arthritis and asthma
  • Reducing oxidative damage to your DNA


Internally Produced Antioxidants


Present in every cell in your body, glutathione is your most powerful and pervasive antioxidant. It eliminates toxins from your cells and provides protection from the damaging effects of radiation, chemicals, and environmental pollutants.

It is called a "master antioxidant" because it is intracellular and has the unique ability of maximizing the performance of all the other antioxidants.


Alpha-Lipoic Acid (ALA)

This antioxidant not only scavenges for free radicals, but has the ability to modify gene expression to reduce inflammation.

ALA also enhances insulin activity and is very effective at suppressing damage caused by heavy metals.

ALA is the only antioxidant that can be easily transported into your brain, which offers numerous benefits for people with brain diseases like Alzheimer's.


CoQ10 (Ubiquinone)

Used by every cell in your body, CoQ10 is converted by your body into its reduced form called ubiquinol to maximize its benefits. Besides protecting you from free radicals, it produces more energy for your cells, strengthens your immune system, boosts heart health and regulates blood pressure.

Take Home Message

different colored food

No one antioxidant can provide the protection required by our body to stay healthy, so it is best to eat foods that represent every band of the spectrum. Blue or purple foods like blueberries and plums provide one type of antioxidant. Bright orange fruits and vegetables like pumpkin, carrots and apricots provide another. Green vegetables, such as broccoli and cabbage, and red foods like cherries and tomatoes, each have their own antioxidant packages. Curcumin, the substance that makes turmeric yellow, is also believed to offer benefits.

Each color provides a unique benefit so get creative.

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