What are antioxidants and how do they protect your cells?

Antioxidants are often mentioned in conversations about nutrition, healthy ageing and everyday wellbeing. You will find them naturally in foods such as berries, vegetables, nuts and seeds, as well as in many food supplements.

But what exactly are antioxidants, what is oxidative stress, and which nutrients contribute to the protection of our cells?

In this guide, we take a closer look at how antioxidant defence works and explore some of the vitamins and minerals that help protect cells from oxidative stress.

What are antioxidants?

Antioxidants are substances that can interact with free radicals and other reactive molecules. To understand why this matters, it helps to first understand what free radicals are.

Free radicals are highly reactive molecules that are formed naturally during normal metabolic processes. They can also be generated in response to environmental factors.

The body has sophisticated defence systems that help maintain a balance between the production of reactive molecules and antioxidant protection. When this balance shifts too far towards reactive molecules, it is known as oxidative stress.

Antioxidant defence is therefore not about eliminating free radicals completely. Instead, it is part of the body's normal system for maintaining cellular balance.

What is oxidative stress?

Oxidative stress describes an imbalance between reactive molecules and the body's ability to manage them through antioxidant defence systems.

Our cells naturally produce reactive molecules as part of everyday metabolism. At the same time, the body uses its own antioxidant enzymes and nutrients obtained through the diet to help protect cells.

This is where several vitamins and minerals become particularly relevant. Nutrients including vitamin C, vitamin E, riboflavin, zinc, selenium, copper and manganese contribute to the protection of cells from oxidative stress.

Why do antioxidants matter?

Oxidation is a normal part of life and metabolism. The goal is not to prevent it entirely, but to maintain the body's natural balance.

A varied diet provides numerous compounds involved in antioxidant defence. Some act directly as antioxidants, while certain vitamins and minerals contribute to normal cellular protection or form part of antioxidant enzyme systems.

This is one reason why eating a varied selection of plant foods is valuable. Different foods provide different combinations of vitamins, minerals and naturally occurring plant compounds.

Which nutrients help protect cells from oxidative stress?

Several nutrients have recognised roles in protecting cells from oxidative stress. Rather than thinking of one antioxidant as the most important, it is more useful to consider how different nutrients contribute to the body's overall nutritional needs.

Vitamin C

Vitamin C contributes to the protection of cells from oxidative stress. It also contributes to the normal function of the immune system and to normal collagen formation for the normal function of skin.

Good dietary sources of vitamin C include citrus fruits, berries, peppers, broccoli, kiwi and other fruits and vegetables.

Vitamin C also increases iron absorption and contributes to the regeneration of the reduced form of vitamin E.

Vitamin E

Vitamin E contributes to the protection of cells from oxidative stress.

It is a fat soluble vitamin and can be found naturally in foods such as nuts, seeds and vegetable oils.

Because vitamin E is fat soluble, its biological behaviour differs from that of water soluble antioxidants such as vitamin C. This is a useful reminder that antioxidant defence involves several different nutrients and biological systems working together.

Riboflavin

Riboflavin, also known as vitamin B2, contributes to the protection of cells from oxidative stress.

It also contributes to normal energy yielding metabolism, the normal functioning of the nervous system and the maintenance of normal skin and vision.

Dietary sources include eggs, dairy products, meat and certain fortified foods.

Zinc

Zinc contributes to the protection of cells from oxidative stress and has several other established functions in the body.

It contributes to normal cognitive function, normal function of the immune system and the maintenance of normal skin, hair and nails.

Zinc can be found in foods including meat, shellfish, dairy products, legumes, nuts and seeds.

Selenium

Selenium contributes to the protection of cells from oxidative stress.

It also contributes to normal thyroid function and normal function of the immune system, as well as the maintenance of normal hair and nails.

Selenium is needed only in relatively small amounts, which is an important reminder that more of a nutrient is not necessarily better.

What about beta carotene?

Beta carotene is a naturally occurring plant pigment and a precursor to vitamin A. The body can convert beta carotene into vitamin A according to its needs.

Vitamin A contributes to the maintenance of normal vision, normal skin and the normal function of the immune system.

Beta carotene occurs naturally in colourful fruits and vegetables, particularly carrots, sweet potatoes, pumpkin and dark green leafy vegetables.

Rather than viewing beta carotene as a shortcut to younger looking skin or better eyesight, it is more accurate to understand it as one dietary source from which the body can obtain vitamin A.

Where can you find antioxidants in food?

A colourful and varied diet is one of the simplest ways to obtain a broad range of nutrients and naturally occurring plant compounds.

Useful foods to include regularly can include:

• Berries such as blueberries, raspberries and strawberries
• Citrus fruits and kiwi
• Peppers, broccoli and leafy green vegetables
• Carrots, pumpkin and sweet potatoes
• Nuts and seeds
• Legumes and whole grains
• Herbs and spices

No single food provides everything your body needs. Variety across your diet is more important than relying on one particular food because it has been labelled a superfood.

Do you need antioxidant supplements?

For most nutrients, food should remain the foundation of your intake. A varied and balanced diet provides vitamins and minerals alongside fibre, protein, healthy fats and numerous naturally occurring plant compounds.

Supplements can be useful when they help complement your diet or provide specific nutrients according to your individual needs.

However, taking more antioxidants does not automatically provide greater benefits. Nutrients have different recommended intakes and safe levels, so supplements should always be used according to their instructions.

If you are unsure whether a particular supplement is appropriate for you, especially if you take medication or have a medical condition, speak with a qualified healthcare professional.

Can antioxidants prevent ageing?

Ageing is a complex biological process influenced by genetics, lifestyle, environmental exposures and many other factors. It cannot be reduced to antioxidant intake alone.

Oxidative processes are part of normal biology, and antioxidant defence forms part of the body's systems for managing them. Certain nutrients contribute to the protection of cells from oxidative stress, but this should not be interpreted as meaning that antioxidant foods or supplements can stop or reverse ageing.

A more useful approach is to support your overall health through a varied diet, regular movement, adequate sleep and other sustainable lifestyle habits.

Frequently asked questions

What are antioxidants in simple terms?

Antioxidants are substances that can interact with reactive molecules such as free radicals. The body has its own antioxidant defence systems, while certain nutrients obtained through food also contribute to protecting cells from oxidative stress.

What is oxidative stress?

Oxidative stress describes an imbalance between reactive molecules and antioxidant defence. The body naturally produces reactive molecules during normal metabolism and has several systems that help manage them.

Which vitamins are antioxidants?

Vitamin C and vitamin E contribute to the protection of cells from oxidative stress. Riboflavin, also known as vitamin B2, has this recognised function as well.

Which minerals help protect cells from oxidative stress?

Zinc, selenium, copper and manganese all contribute to the protection of cells from oxidative stress.

Which foods contain antioxidants?

Many plant foods contain antioxidant nutrients and other naturally occurring compounds. Examples include berries, citrus fruits, colourful vegetables, leafy greens, nuts, seeds, legumes, herbs and spices.

Are antioxidant supplements necessary?

Not necessarily. A varied and balanced diet should remain the foundation of nutrient intake. Supplements can complement the diet when appropriate, but individual needs vary.

Are more antioxidants always better?

No. Nutrients have recommended intake levels, and taking larger amounts does not automatically provide greater benefits. Supplements should be used according to their recommended intake.

Key takeaways

• Antioxidants form part of the body's systems for managing reactive molecules.
• Oxidative stress occurs when there is an imbalance between reactive molecules and antioxidant defence.
• Vitamin C, vitamin E and riboflavin contribute to the protection of cells from oxidative stress.
• Zinc, selenium, copper and manganese also contribute to the protection of cells from oxidative stress.
• A varied diet rich in different plant foods can provide a broad range of nutrients and naturally occurring plant compounds.
• More is not necessarily better when it comes to antioxidant supplements.

This article is for informational purposes only and is not intended to diagnose, treat, cure or prevent any disease. Food supplements should not be used as a substitute for a varied, balanced diet and healthy lifestyle.