What are antioxidants?

Antioxidants are molecules that fight free radicals, which the body produces in response to environmental and other stressors.

On this page: 

1. What are antioxidants? 
2. What is oxidative stress? 
3. Types of Antioxidants 
4. Food sources 
5. Should you take antioxidant supplements?
6. Summary

Free radicals have been linked to chronic health conditions such as diabetes, cancer, and a variety of other health problems.

Antioxidants can prevent or slow cell damage caused by free radicals.

Free radicals can increase the risk of inflammation and a variety of health problems.

Antioxidants are found in many plant foods and can also be synthetic. Vitamin E and vitamin C are examples.

You’ve probably heard a lot of talk about antioxidants. However, few people know what they are.

What are antioxidants? 

Antioxidants are components that fight free radicals, which are unstable molecules that can damage your body’s cells.

Free radicals are compounds that can cause harm if their levels in your body get too high.

They’re linked to a variety of diseases, including diabetes, heart disease, cancer, and even inflammatory conditions. They are found in anti-inflammatory foods.

Your body has antioxidant defenses (endogenous antioxidants(1)) to keep free radicals in check, but sometimes they’re not enough so you need to get them from outside sources like food.

Antioxidants are also found in food, especially fruits, vegetables, and other whole, plant-based foods.

Many vitamins, such as carotenoids, vitamins E and C, are effective antioxidants for a variety of diseases.

Antioxidants may also play a role in food production as preservatives by increasing shelf life.

What is oxidative stress? 

The body needs to maintain a balance between free radicals and antioxidants. When this balance is disturbed, it can lead to oxidative stress(2).

Free radicals are constantly being created in the body, where they perform several important functions necessary for health.

For example, immune cells use free radicals to fight infection(3).

When free radicals exceed a certain level, they can cause serious damage very quickly, eventually leading to death.

As a result, the body needs antioxidants to maintain a certain balance between free radicals and antioxidants.

When free radicals outnumber antioxidants, it can lead to a condition called oxidative stress.

Prolonged oxidative stress can damage DNA and other important molecules in the body, sometimes leading to cell death.

DNA damage can increase the risk(4) of cancer and can lead to premature aging.

There are many lifestyle, stress, and environmental factors that promote the formation of excessive free radicals and oxidative stress, including:

• Alcohol consumption

• Excessive consumption of energy drinks

• Toxins

• Smoking excessively

• Air pollution

• High blood sugar

• High intake(5) of trans fatty acids

• Bacterial, fungal or viral infections

• Excessive exposure to radiation such as sunbathing

• Excessive intake of iron, magnesium, copper or zinc

• Intense exercise(6) that causes tissue damage

• Too much or too little oxygen(7) in the body

• Too little or too much antioxidants in the body

Prolonged oxidative stress increases the risk of cardiovascular disease, certain types of cancer and some neurological diseases.

Types of Antioxidants

There are hundreds, if not thousands, of substances that can act as antioxidants.

Each has its own role in the body and can interact with others to help the body work against free radicals.

Antioxidants are a large group of elements. Examples of antioxidants that come from outside the body include(8):

• Vitamin A

• Vitamin E

• Vitamin C

• Beta-carotene

• Lutein

• Selenium

• Lycopene

• Zeaxanthin

• Manganese

Flavonoids, flavonoids, catechins, polyphenols, and phytoestrogens are all types of antioxidants and phytonutrients, found in plant foods.

Each antioxidant performs a different function and cannot be substituted for another. That's why it's important to eat a varied diet to get the greatest variety of antioxidants.

What are the food sources of antioxidants?

Fruits and vegetables are the best food sources of antioxidants, plant foods(9). Foods that are high in antioxidants are called superfoods.

Foods rich in antioxidants include(10):

• Dairy products, eggs, and liver, which are rich in vitamin A

• Most fruits and vegetables, especially berries, oranges, and bell peppers, are rich in vitamin C

• Nuts, seeds, sunflower and other vegetable oils, and green leafy vegetables are rich in vitamin E

• Carrots, peas, spinach, and mangoes are rich in beta-carotene

• Red or pink fruits and vegetables are rich in lycopene

• Green leafy vegetables, corn, and oranges are rich in lutein

• Rice, corn, wheat, and other whole grains, as well as nuts and legumes

Other foods that are good sources of antioxidants include:

• Legumes such as black beans or kidney beans
• Green and black tea
• Eggplant 
• Red grapes
• Pomegranates
• Cranberries
• Blueberries
• Broccoli
• Apples
• Moringa
• Lentils

Cooking certain foods can increase or decrease antioxidant levels.

Lycopene is the antioxidant that gives tomatoes their red color. When tomatoes are heat-treated, lycopene becomes more available and easier for our bodies to use.

However, cauliflower, peas, and zucchini have been shown to lose much of their antioxidant activity in the cooking process.

The key is to eat a variety of antioxidant-rich foods, both cooked and raw, to provide your body with all the nutrients it needs.

Should you take antioxidant supplements?

Getting antioxidants in your diet is essential for optimal health, but more in supplements isn’t always better.

Taking too many antioxidants can have toxic effects and may promote oxidative damage rather than prevent it.

Some studies(11) suggest that taking high doses of antioxidants increases your risk of death.

Eating plenty of whole foods rich in antioxidants is a much better idea. Studies show that foods reduce oxidative damage to a greater extent than supplements.

One study(12) compared the effects of drinking blood orange juice and sugar-sweetened water, both of which contain equal amounts of vitamin C. It found that juice had significantly greater antioxidant power.

The best dietary strategy to ensure adequate antioxidant intake is to eat a diet rich in a variety of fruits and vegetables, along with other healthy habits.

However, low-dose supplements, such as a multivitamin, may be helpful if you are deficient in certain nutrients or are unable to follow a diet high in antioxidants.

Summary

Free radicals are linked to a range of diseases, including heart disease, cancer, and vision loss, but that doesn’t mean increasing your antioxidant intake will prevent these diseases.

Antioxidant supplements may increase your risk of certain health problems.

As a result, it’s important to look for natural sources of antioxidants, in the form of a healthy diet. Eating fruits and vegetables provides a lower risk of chronic disease.