A detailed guide to antioxidants

You've probably seen the word "antioxidant" referenced hundreds of times in food and nutrition articles and advertising. A Google search of the term generates a staggering 132 million results. But what exactly are antioxidants, how do they benefit your health, and what are the best ways to consume them? Here's a primer on antioxidant basics.

What are antioxidants?

Antioxidants are molecules present in the body and found in plant-based foods that counteract oxidative stress. In a nutshell, oxidative stress occurs when there is an imbalance between the production of cell-damaging free radicals and the body's ability to counter their harmful effects.

Free radicals form as a byproduct of normal metabolism and in response to exercise, sun exposure, and environmental pollutants like smog and cigarette smoke. The oxidative stress triggered by free radicals damages healthy cells and is thought to play a role in a variety of diseases, including cancer, diabetes, Alzheimer's disease, Parkinson's disease, and heart disease. Oxidative stress also negatively affects aging.

Antioxidants essentially serve as bodyguards to protect healthy cells from free radical attacks. By doing so, they help maintain proper physiological function and guard your health.


Antioxidants can protect against the cell damage that free radicals cause, known as oxidative stress. Activities and processes that can lead to oxidative stress include:

• mitochondrial activity

• excessive exercise

• tissue trauma, due to inflammation and injury

• ischemia and reperfusion damage

• consumption of certain foods, especially refined and processed foods, trans fats, artificial sweeteners, and certain dyes and additives

• smoking

• environmental pollution

• radiation

• exposure to chemicals, such as pesticides and drugs, including chemotherapy

• industrial solvents

• ozone

Such activities and exposures can result in cell damage. This, in turn, may lead to:

• an excessive release of free iron or copper ions

• an activation of phagocytes, a type of white blood cell with a role in fighting infection

• an increase in enzymes that generate free radicals

• a disruption of electron transport chains

All these can result in oxidative stress. The damage caused by oxidative stress has been linked to cancer, atherosclerosis, and vision loss. It is thought that the free radicals cause changes in the cells that lead to these and possibly other conditions. An intake of antioxidants is believed to reduce these risks.

Top sources

There are hundreds, if not thousands, of substances that act as antioxidants, from vitamin C to flavonoids and polyphenols. A wide range of plant-based foods provide antioxidants, so they're easy to come by. Some of the top sources include berries, cocoa, herbs and spices, beans, artichokes, apples, nuts and seeds, cherries, dark leafy greens, coffee and tea, whole grains, grapes, tomatoes, potatoes and sweet potatoes, avocado, and pomegranate. There are also some high-dose antioxidant supplements out there, but they aren't the best way to protect your body. So, the best way to consume antioxidants is in whole, plant-based foods.

How to boost your antioxidant intake

To take in a broader spectrum of antioxidants, as well as vitamins, minerals, and fibre, aim for a variety of plant-based food groups of different colours. Experts advice to build five cups of veggies and two cups of fruit into each day's worth of meals. For example, include one cup of veggies at breakfast, two at lunch and two at dinner, in addition to a cup of fruit at breakfast, and another as part of a daily snack.

Another way to up your antioxidant intake is to replace processed foods with whole, plant-based foods. Trade a breakfast pastry for a bowl of 'zoats' (zucchini oatmeal) topped with fruit and nuts. In place of a sandwich or wrap, go for a bowl made with a generous base of greens topped with beans, brown rice, and seasoned guacamole. Snack on fruit with nuts or seeds, or veggies with hummus. Satisfy your sweet tooth with dark chocolate. Sprinkle cinnamon into your morning coffee, and infuse water or tea with antioxidant-rich herbs and bits of fruit. It's impossible to take in too many antioxidants from whole foods. Plus, choosing antioxidant-rich foods can elevate the overall nutritional quality of your diet.

Bottom line

Antioxidants are an important aspect of proactive nutrition and may help to fend off aging and chronic disease. For these reasons, they may help you look and feel better. But antioxidants aren't a cure-all, and they shouldn't be used in supplement form to treat a medical condition without the supervision of your doctor. To best reap the benefits of antioxidants, source them from whole foods or products made from whole food ingredients – it's also the most delicious and satisfying way to get your daily dose.