What is an Example of an Antioxidant?

November 17, 2025 •

3 min read

According to research, a diet high in antioxidants may reduce the risk of many diseases, including heart disease and certain cancers. But for many, the term “antioxidant” remains a mystery. So, what is an example of an antioxidant? Vitamin C is a well-known example, playing a crucial role in neutralizing free radicals that can harm your cells.

Quick Summary

This article explores various types of antioxidants, explaining how they work to combat free radicals and oxidative stress in the body. It provides specific examples found in food and highlights the benefits of a diet rich in these compounds.

Key Points

Vitamin C: A prominent water-soluble antioxidant, Vitamin C is found in citrus fruits and berries, and neutralizes free radicals in the body's fluids.
Vitamin E: This fat-soluble antioxidant protects cell membranes and is abundant in nuts, seeds, and vegetable oils.
Flavonoids: A class of plant-based antioxidants, flavonoids are responsible for the colors in many fruits and vegetables and are found in items like berries and green tea.
Carotenoids: These lipid-soluble compounds, including beta-carotene and lycopene, are found in brightly colored produce such as carrots and tomatoes.
Selenium: An essential mineral, selenium acts as a cofactor for several antioxidant enzymes, enhancing the body's internal defense system.
Whole Foods are Superior: Obtaining antioxidants from a varied diet of whole foods is more effective and safer than relying on high-dose supplements.
Oxidative Stress: Antioxidants counteract oxidative stress, a process caused by an imbalance of free radicals that can damage cells and contribute to disease.

Understanding the Role of Antioxidants

Free radicals are unstable molecules with an unpaired electron that are constantly being formed in the body. While a certain level is normal for processes like fighting infection, an overabundance can cause oxidative stress, damaging cells, DNA, and other vital molecules. Antioxidants act as the body’s defense by donating an electron to these free radicals, neutralizing them and preventing them from causing harm.

Vitamin C: A Powerful Water-Soluble Antioxidant

Vitamin C, or ascorbic acid, is one of the most prominent examples of a water-soluble antioxidant. As an essential dietary nutrient, it operates in the watery fluids both inside and outside your cells.

How it works: Vitamin C effectively donates electrons to unstable free radicals, stabilizing them and stopping their damaging chain reaction.
Synergistic effect: It also plays a vital role in regenerating other antioxidants, such as vitamin E, enhancing their effectiveness.
Food sources: Excellent sources include citrus fruits, berries, kiwi, broccoli, and bell peppers.

Vitamin E: A Fat-Soluble Protector

In contrast to vitamin C, vitamin E is a fat-soluble antioxidant that works primarily within cell membranes. It is a collective term for tocopherols and tocotrienols, with alpha-tocopherol being the most biologically active form. Its fat-soluble nature allows it to protect cell membranes from lipid peroxidation, a process where free radicals steal electrons from fats in cell membranes, causing damage.

Flavonoids and Carotenoids: Plant-Based Powerhouses

Beyond the well-known vitamins, many other compounds found in plants act as potent antioxidants. Flavonoids are a large group of polyphenolic compounds responsible for the vibrant colors of many fruits and vegetables. They function by scavenging reactive oxygen species and can even activate antioxidant enzymes. Carotenoids, such as beta-carotene and lycopene, are another class of lipid-soluble antioxidants found in brightly colored produce.

Flavonoid sources: Berries, red grapes, green tea, and cocoa are rich in various flavonoids.
Carotenoid sources: Carrots, sweet potatoes, spinach, and tomatoes are excellent sources of carotenoids.

Comparison of Antioxidant Types

To highlight the diversity of antioxidants, here is a comparison of some key types based on their solubility and common sources.


Antioxidant Type	Solubility	Primary Function	Common Food Sources
Vitamin C	Water-soluble	Neutralizes free radicals in cellular fluid, regenerates vitamin E	Citrus fruits, strawberries, broccoli, bell peppers
Vitamin E	Fat-soluble	Protects cell membranes from oxidative damage	Nuts, seeds, vegetable oils, green leafy vegetables
Flavonoids	Water-soluble	Scavenge reactive oxygen species, activate enzymes	Berries, tea, grapes, dark chocolate
Carotenoids	Fat-soluble	Quench singlet oxygen, protect membranes	Carrots, sweet potatoes, spinach, tomatoes
Selenium	Mineral	Cofactor for antioxidant enzymes like glutathione peroxidase	Brazil nuts, fish, whole grains

Natural Antioxidant Enzymes

In addition to dietary antioxidants, the body produces its own endogenous antioxidant enzymes. These include:

Superoxide Dismutase (SOD): Converts the dangerous superoxide radical into hydrogen peroxide.
Catalase (CAT): Breaks down hydrogen peroxide into water and oxygen.
Glutathione Peroxidase (GPx): Reduces hydrogen peroxide and lipid hydroperoxides.

These enzymatic antioxidants are our body's first line of defense against free radicals. Mineral nutrients like selenium, zinc, and manganese act as cofactors for these enzymes, making them essential for proper antioxidant function.

Conclusion

What is an example of an antioxidant? Vitamin C is a classic example, but the world of antioxidants is vast and varied. From the water-soluble vitamin C in oranges to the fat-soluble vitamin E in nuts, and the diverse phytochemicals like flavonoids and carotenoids in colorful produce, a wide array of compounds protect our cells from oxidative stress. Consuming these antioxidants through a balanced diet of whole foods is far more beneficial than relying on supplements alone. By incorporating a variety of antioxidant-rich foods, we support our body's natural defense systems and promote long-term health.

For more information on antioxidants and free radicals, explore the Harvard T.H. Chan School of Public Health website, a reputable resource for nutritional science.

Frequently Asked Questions

The primary function of an antioxidant is to neutralize unstable molecules called free radicals by donating an electron. This prevents the free radicals from damaging healthy cells, DNA, and other vital molecules in the body.

It is better to get antioxidants from food because they work synergistically with other nutrients present in whole foods, providing a more comprehensive benefit. High-dose, isolated antioxidant supplements can sometimes cause toxic effects or increase risk for certain conditions.

Yes, excessive intake of high-dose antioxidant supplements can have toxic effects and, in some cases, act as pro-oxidants, which promote oxidative damage. This is particularly a risk with supplements, not from consuming whole foods.

While minerals are not antioxidants themselves, they are cofactors for antioxidant enzymes. Selenium is found in Brazil nuts and fish, and zinc is present in beef, poultry, oysters, and chickpeas.

No, antioxidants differ in their chemical properties, solubility, and how they behave in the body. They can be water-soluble (like Vitamin C) or fat-soluble (like Vitamin E) and come in various forms, including vitamins, minerals, and phytochemicals.

The term 'superfood' is often used to refer to foods particularly high in antioxidants and other nutrients. Examples include berries, dark chocolate, and goji berries. However, the term is primarily a marketing tool, and a diverse diet is key.

Dietary choices significantly impact antioxidant levels. A diet rich in a variety of fruits, vegetables, whole grains, and nuts ensures a steady supply of different antioxidants, helping to maintain the body's balance and combat oxidative stress.