Antioxidants: Benefits, Side Effects & More (Ultimate Guide)

When you hear of something that’s ‘high in antioxidants’, you probably think of berries, nuts, and dark chocolate! Here, we are going to go a little deeper into the world of antioxidants and learn just how important they are for our everyday health and wellbeing. 

What are antioxidants and what do they do for you?  

Antioxidants are little superheroes found in certain foods and supplements. Our body also makes antioxidants to ensure we are as protected as possible from free radicals. 

Free Radicals 

Free radicals are pesky molecules in our body that can contribute to aging and disease, if left unchecked. 

Free radicals are considered a ‘reactive oxygen species’, which basically signifies its highly reactive and unstable nature.1 Missing at least one electron, they strive for stabilization, which leads them to oxidize with other compounds like proteins, DNA, and lipids. This is what causes oxidative stress and cellular damage, which, if occurring for a prolonged period of time, could contribute to aging, disease, diabetes, and even cancer. 

Oxidative Stress Contributors:

    • Environmental pollutants 
    • Cigarette smoke 
    • Drugs
    • Pesticides 
    • Excessive alcohol intake 
    • Radiation 
    • Infections (bacterial, viral, etc.) 
    • Excessive high-intensity exercises (tissue damage) 
    • Poor diet 
    • Charred foods 
    • Chronic stress


What is an antioxidant good for?  

Antioxidants to the rescue 

In order to reduce the damage caused by free radicals, we all want to make sure we are getting a sufficient amount of antioxidants every day, as well as making dietary and lifestyle changes to avoid having too many free radicals in the body. 

Antioxidants have the ability to neutralize these free radicals by a process called ‘scavenging’. Essentially, antioxidants will seek out free radicals and suppress them before they have a chance to cause damage. 

For more practical examples, antioxidants can help protect us in environments that are chemically-ridden or prone to cause inflammation. 

Mechanics, for instance, might benefit from including more antioxidants in their diet to counter the free radicals caused from frequent exposure to automobile oils/chemicals. Whether you’re a bartender who works in a smoke-laden bar, or a healthcare worker who is often exposed to x-rays, antioxidants are a good idea! 

Furthermore, if you are under a lot of stress from life, school, or work, antioxidants can be a great addition to your diet. They can help re-balance your body from the effects of chronic stress, and support your body through intense situations. 

Types of Antioxidants  

Antioxidants come in different shapes and sizes. Here are some of the most common types of antioxidants, but keep in mind there are a lot more out there: 

    • Polyphenols and flavonoids 
    • Carotenoids 
    • Terpenoids 
    • Minerals: selenium, zinc, copper 
    • Vitamins C, A, & E 
    • Enzymes 
    • Glutathione 

Antioxidants examples 

Here are different examples of antioxidants in foods that are widely accessible to us. Keep these in mind during your next trip to the grocery store, or in your next supplement order! 

Sources of polyphenols (some sources of flavonoids included): 

    • Apples, berries, black currants, black tea, green tea, coffee, garlic, onions (especially red onions), herbs, spices, cocoa powder, olives, spinach, artichokes, chicory, nuts (hazelnuts, walnuts, almonds, pecans), red wine

Sources of carotenoids: 

    • Carrots (hence the name), bell peppers, oranges, yams, kale, spinach, watermelon, cantaloupe, tomatoes, pumpkin, collard greens, mangoes, eggs, salmon, shrimp, lobster

Sources of terpenoids: 

    • Coconut, cauliflower, garlic, onions, citrus fruits, herbs, spices, whole grains

Sources of minerals:

    • Selenium: Brazil nuts, fish, eggs, meat, dairy products
    • Zinc: Oysters (& other shellfish), meat, legumes, nuts, seeds, dairy, eggs, whole grains, dark chocolate
    • Copper: oysters, spirulina, shiitake mushrooms, liver, nuts, seeds, lobster, leafy greens, dark chocolate

Sources of vitamins:

    • Vitamin C: Berries, Brussels sprouts, broccoli, citrus fruits, kiwi, bell pepper, strawberry, kale, papaya, guava
    • Vitamin A: Carrots, grapefruit, squash, sweet potato, broccoli, pink grapefruit, lettuce, spinach, bell pepper, tuna, liver, eggs, milk
    • Vitamin E: Leafy greens, vegetables, nuts, seeds, broccoli, butternut squash, spinach, avocados, kiwi, trout, mangoes, oils



As stated previously, some antioxidants are endogenous, meaning they are made within the body.

Glutathione is a cellular antioxidant that is found in almost every cell of your body. It has a reputation for being a powerful detoxifier, especially for the liver. It plays a key role in immune function, respiratory health, energy levels, and more.

To keep your glutathione levels up, you could try incorporating aerobic exercises into your daily routine, deep breathing, or taking glutathione in supplement form.


6 Antioxidants benefits 

Here are all the more reasons to include antioxidants in your diet.  

1. Anti-Aging 

As we learned, reactive oxygen species can speed-up aging, which can mean wrinkles, dark spots, and more! 

Ageing can be a consequence when there is an imbalance between free radicals and antioxidant defenses. Studies have shown that antioxidant supplementation can have a positive effect on the aging process. 

2. Anti-Cancer 

Since antioxidants work to reduce the damage caused by free radicals and thus prevent oxidative stress, we can deem them to have powerful anti-carcinogenic effects. The damage free radicals can have to our DNA plays a role in cancer development, which is yet another reason why antioxidants are so important.

Beta-carotene (in the carotenoid family), in one study, was shown to be cancer preventative, specifically for lung and stomach cancer.

Although we need more supportive studies on antioxidants and cancer prevention, it can’t hurt to increase those antioxidants to reduce the likelihood of cancer down the line. 

3. Eye Health 

Did you know that Vitamins C and E, as well as other antioxidants, can lower chances of cataracts and AMD? 

AMD stands for Age-Related Macular Degeneration, which is a condition in which older adults may lose most of their eyesight. Cataracts are associated with blurry vision.  

Having a diet plentiful of antioxidants may significantly reduce the chances of AMD or cataracts later on in life. 

4. Heart Health 

Oxidative stress, and the damage it may cause to DNA, has also been linked to cardiovascular disease. 

Studies have shown antioxidant supplementation (vitamin C, beta-carotene, vitamin E, and selenium, in particular) has helped reduce the risk of heart disease. Later, studies also affirmed that eating antioxidant-rich foods has been just as successful at reducing heart disease, if not more, than taking supplements.

Mediterranean-style diets have made a significant impact on cardiovascular diseases in earlier studies, which is important to note because these diets are jam-packed with antioxidants, from its focus on fresh whole foods to the use of extra virgin olive oil. 

5. Type 2 Diabetes 

Chronic oxidative stress has been linked to insulin resistance and other dysfunctions with people who are pre-diabetic or who have type 2 diabetes. Insulin resistance can lead to further health complications down the line, like hypertension and neurological issues.

Studies have shown that CoQ10, an antioxidant in the body, has shown to decrease with age, in individuals with heart disease, or in individuals who take certain drugs, like statins.  

CoQ10, taken as a supplement, has been shown to be of significant help for these individuals: it may reduce blood pressure, lower cholesterol levels, and decrease chance of neurological damage (in individuals with diabetes). 

6. Anti-inflammatory 

Antioxidants and their anti-inflammatory nature is probably the most important attribute to mention, since this is how they ultimately fight off disease, cancer, and aging. 

Unfortunately, there are many things in the Western diet that can cause inflammation, which can lead to chronic health issues over time. Some of these include: 

        • Trans fats 
        • Refined sugars 
        • Processed foods 
        • Alcohol

By choosing any of the antioxidant-rich foods mentioned earlier, we are helping our bodies by supplying them with the tools it needs to combat inflammation. Antioxidants are necessary in our diet to ensure we are maintaining a strong immune system and keeping our inflammation in check.  

Antioxidants side effects

Antioxidants, since they are naturally occurring in our bodies and also necessary to obtain through dietary means, don’t have any adverse side effects.

That being said, however, everyone is different. For example, there may be cases in which certain antioxidants should be avoided for individuals who are on specific medications.

Additionally, supplementing with antioxidants is much different than consuming them through the diet. Every antioxidant, whether it be a certain vitamin or mineral, glutathione or CoQ10, is going to have potential side effects depending on the individual and dosage. Talk with your healthcare provider to see if supplementing with antioxidants is right for you.

I hope you learned something new today! Antioxidants, in conclusion, are an essential foundation to our health; they are fighting the negative elements that contribute to chronic disease & inflammation. Aim to include antioxidant-rich foods every day, or purchase a Greens First antioxidant powder from my online supplement dispensary!