Antioxidants: Benefits, side effects, types, uses, precautions

Antioxidants are powerful substances naturally present in various foods. They are known for their exceptional ability to combat harmful molecules in our bodies, known as free radicals.

The protective shield they cast is linked with myriad health benefits, from boosting the immune system and skin health to offering some protection against life-threatening conditions such as heart disease and cancer.

In this comprehensive guide, we will explore the fascinating topics of antioxidants. We’ll start off with understanding what antioxidants are and the critical roles they play within our bodies. We’ll then look into the numerous types of antioxidants and their respective benefits. 

Moreover, we’ll examine how they can be integrated into your daily life, and the precautions to be aware of to use them safely and effectively.

We will also discuss the potential side effects of antioxidants and provide insights into the recommended dosages.

Whether you’re just learning about antioxidants or looking to deepen your knowledge, this guide is a valuable resource. So, sit back, grab a cup of antioxidant-rich green tea, and let’s get started!

What are antioxidants?

Antioxidants are a diverse group of substances that protect our cells from damage. They are molecules, either naturally occurring or man-made, that inhibit the oxidation of other molecules in our bodies.

Oxidation is a chemical reaction that produces free radicals, unstable molecules that can cause harm if their levels become too high. 

This process can lead to a state known as oxidative stress, a significant player in the onset of various chronic diseases like heart disease, cancer, diabetes, and neurological disorders like Alzheimer’s.

Antioxidants work by neutralizing these free radicals, stabilizing them and preventing them from damaging cells [1]. They essentially donate an electron to the free radicals, reducing their reactivity. 

Some antioxidants, like Vitamin C, are water-soluble, working within our body’s fluids, while others like Vitamin E, are fat-soluble, protecting the cell membranes.

Antioxidants are present in various foods, mainly fruits and vegetables, but also in nuts, grains, some meats, poultry, and fish. Moreover, the human body also produces some antioxidants, known as endogenous antioxidants.

What is the role of antioxidants in human health?

Antioxidants safeguard our health at a cellular level by neutralizing free radicals [2]. They prevent these harmful particles from inducing cellular damage, a phenomenon that could lead to various diseases. 

This role is vital considering that free radical production is a natural outcome of many body processes, like digestion and energy production, as well as external influences like pollution, tobacco smoke, and radiation.

Additionally, antioxidants contribute to the immune defense and reduce the risk of infection and cancer by enhancing immune response.

They can also protect the skin by combating environmental damage from exposure to the sun and pollution and delay skin aging by promoting cell repair and reducing inflammation.

Some protect the eyes, heart, and other organs against oxidative damage. While other antioxidants even help regenerate others, creating a cascade of protection throughout the body, making them indispensable for overall health and well-being.

What is the role of antioxidants in human health?
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Types of antioxidants

Antioxidants, indispensable for maintaining the body’s equilibrium, can broadly be classified into two types: natural and synthetic. 

Natural antioxidants are found abundantly in the food we consume and are synthesized in our bodies, while synthetic antioxidants are man-made, and often used in food and other industries. 

These natural or synthetic antioxidants play a critical role in counteracting oxidative stress, thereby protecting our bodies from various diseases.

Natural antioxidants

These are substances naturally occurring in various foods and plants [3]. They have numerous health benefits primarily because of their ability to combat harmful free radicals. Here are some key natural antioxidants:

Vitamin C

Found in citrus fruits like oranges and lemons, strawberries, kiwi, bell peppers, and broccoli. It boosts the immune system and aids in collagen production.

Vitamin E

Located in foods like almonds, sunflower seeds, spinach, and avocados. It promotes healthy skin and eyes, and strengthens the body’s natural defense against illness and disease.

Beta-carotene

This is in brightly colored fruits and vegetables like carrots, spinach, and apricots. It converts into Vitamin A, essential for maintaining healthy skin and vision.

Flavonoids

Present in green tea, red wine, citrus fruits, and onions. Flavonoids have been found to lower the risk of asthma, stroke, and heart disease.

Polyphenols

Found in green tea, red wine, honey, olive oil, and several fruits and vegetables. They may improve digestion, manage weight and control diabetes.

Selenium

Present in Brazil nuts, fish, brown rice, and eggs. Selenium can help defend against oxidative stress, heart disease, and cancer.

Synthetic antioxidants

These are man-made substances used to help preserve food and other products [4]. They are used in several industries, including food, cosmetics, and pharmaceuticals. Here are some of the main synthetic antioxidants:

Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT)

These are added to foods to prevent oxidation and spoilage, found in products like cereals, chewing gum, and vegetable oils.

Propyl Gallate

This protects fats and oils from oxidizing, mainly used in products such as processed meats, chicken soup base, and chewing gum.

Tertiary Butylhydroquinone (TBHQ)

This synthetic antioxidant is added to fat-containing foods, including frozen dinners, microwave popcorn, and fast food.

Ascorbyl Palmitate and Ascorbic Acid (Vitamin C)

These synthetic forms of Vitamin C are used in cosmetics and food to prevent oxidation and spoilage.

Alpha-Tocopherol (Vitamin E)

This is a synthetic form of Vitamin E, added to cosmetic products and supplements for its antioxidant benefits.

Although synthetic antioxidants serve a valuable purpose in preserving the shelf life of certain products, their health effects are not entirely understood and, in some cases, are a cause for concern. Thus, they should be consumed with caution and under guidance.

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Health benefits of antioxidants

Antioxidants are powerful substances known for neutralizing harmful molecules called free radicals in our bodies.

The beneficial impacts of antioxidants are extensive, spanning the prevention of chronic diseases, skin health, eye health, immune system strengthening, and more [5]. 

The following are some of the beneficial effects of antioxidants:

1. Prevents chronic diseases

One of the most significant benefits of antioxidants is their role in the prevention of chronic diseases.

The body’s oxidative stress, caused by an imbalance of free radicals and antioxidants, has been linked to several chronic conditions, including heart disease, cancer, and diabetes.

  • Heart disease: Antioxidants like flavonoids, found in foods such as berries, dark chocolate, and red wine, help improve heart health. They lower the risk of heart disease by reducing blood pressure and inflammatory markers, increasing the ‘good’ HDL cholesterol, and reducing the ‘bad’ LDL cholesterol’s oxidative stress.
  • Cancer: Antioxidants help prevent cancer by protecting the body’s cells from damage. For instance, carotenoids, found in fruits and vegetables like carrots, squash, and tomatoes, can reduce the risk of lung, mouth, pharynx, and larynx cancers.
  • Diabetes: Oxidative stress has been linked to insulin resistance and diabetes. Antioxidants like alpha-lipoic acid can improve insulin resistance, lower fasting blood glucose levels, and reduce complications of diabetes.

2. Protects the skin 

Antioxidants play a crucial role in maintaining skin health. They protect the skin from damage caused by the sun, pollution, and other environmental factors.

  • Protects against sun damage: Antioxidants such as vitamins C and E help protect the skin from the harmful effects of the sun’s ultraviolet (UV) rays. They reduce signs of aging and prevent skin cancers.
  • Promotes skin repair: Antioxidants promote the growth of new cells and repair damaged ones, contributing to a youthful appearance.
  • Reduces inflammation: Certain antioxidants, like polyphenols found in green tea, possess anti-inflammatory properties that can soothe the skin and improve conditions like psoriasis and rosacea.

3. Boosts eye health

Many antioxidants contribute to maintaining good eye health. For instance, vitamins C and E, beta-carotene, zinc, and lutein have been found to lower the risk of certain eye conditions.

  • Age-related macular degeneration (AMD): This condition, which results in vision loss, can be slowed by a diet rich in antioxidants. Leafy green vegetables, eggs, and other foods rich in lutein and zeaxanthin can help prevent AMD.
  • Cataracts: Antioxidants can slow down the development of cataracts. Regular intake of vitamins C and E from fruits, vegetables, and nuts may prevent or delay the growth of cataracts.

4. Improves cognitive function

Emerging research has associated antioxidant-rich diets with improved cognitive function and a reduction in the symptoms of mental disorders.

  • Alzheimer’s disease: Antioxidants can help prevent Alzheimer’s disease. For instance, curcumin, an antioxidant found in turmeric, has been found to cross the blood-brain barrier and has shown promise as a neuroprotective agent in diseases such as Alzheimer’s.
  • Parkinson’s disease: Oxidative stress has been linked to Parkinson’s disease, and antioxidants may help manage this condition. For instance, the antioxidant coenzyme Q10 has shown some promise in early research.
Supports immune health
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5. Supports immune health

Antioxidants like vitamins A, C, and E are vital in supporting the immune system. They boost immune health, enabling the body to fight off infections and diseases effectively.

6. Contributes to longevity

Since antioxidants help prevent chronic diseases, promote overall health, and slow down the aging process, they can contribute to a longer lifespan.

Uses of antioxidants

Antioxidants, whether derived from natural sources or synthesized, play a pivotal role in a range of applications, both health-related and industrial.

Their primary function — neutralizing free radicals — has been harnessed in various ways to benefit the human body and improve product shelf life and quality. Below is an exhaustive exploration of the diverse uses of antioxidants:

1. Dietary supplements

Given the numerous health benefits associated with antioxidants, they are a mainstay in the dietary supplements industry. From standalone vitamin E or C supplements to complex multivitamins containing a blend of antioxidants, these supplements are taken by millions to boost overall health, support the immune system, and combat the effects of oxidative stress.

2. Skin care and cosmetics

The skin is the body’s largest organ and is constantly exposed to environmental stressors like UV radiation and pollution that can cause oxidative damage. As a result:

Many skincare products, especially serums, moisturizers, and sunscreens, contain antioxidants like vitamins C and E to protect the skin from environmental damage and reduce signs of aging.

Makeup products, especially foundations and lipsticks, might include antioxidants to provide skin protection benefits alongside cosmetic appeal.

3. Eye health products

Antioxidant-rich formulations, often containing lutein, zeaxanthin, and vitamins C and E, are marketed for eye health. These supplements aim to reduce the risk of age-related macular degeneration and cataracts.

4. Sports nutrition

Athletes and fitness enthusiasts are particularly prone to oxidative stress due to increased metabolism during exercise. To counteract this:

Antioxidant supplements, often containing vitamins C and E, selenium, and beta-carotene, are popular in sports nutrition to reduce muscle damage and inflammation, aiding in quicker recovery.

Many energy drinks and pre-workout formulations also incorporate antioxidants to combat oxidative stress induced during physical activity.

5. Food preservation

Antioxidants have long been employed in the food industry as preservatives:

Natural antioxidants, such as rosemary extract or vitamin C, are added to organic and natural food products to extend shelf life and prevent rancidity.

Synthetic antioxidants like butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are used in many processed foods to prevent fat oxidation and maintain freshness.

6. Therapeutic uses

Research is continuously unveiling therapeutic applications for antioxidants in treating a range of medical conditions:

Conditions like rheumatoid arthritis and inflammatory bowel disease, which are characterized by inflammation, might benefit from antioxidant treatment due to their anti-inflammatory effects.

Antioxidants are being studied for their potential in cancer therapy, both in prevention and as a complement to traditional treatments to mitigate side effects.

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Precautions to consider before taking antioxidants

While antioxidants provide an array of health benefits, there are precautions that need to be considered for safe and effective use. Here’s what you need to know:

1. Potential for overdose

Although it may seem that more antioxidants mean more health benefits, this isn’t necessarily true. Overdosing on antioxidant supplements can lead to harmful effects [6]. For instance, excessive intake of vitamin A can lead to nausea, dizziness, and even hair loss, while high doses of vitamin E can lead to hemorrhage and disrupt blood coagulation.

2. Interaction with medications

Antioxidants can interact with certain medications and potentially interfere with their efficacy. For example, vitamin E can interfere with cholesterol-lowering drugs, while antioxidant supplements can decrease the effectiveness of certain cancer treatments. It’s crucial to discuss any supplements with your healthcare provider if you’re taking prescribed medication.

3. Balance between antioxidants and free radicals

While free radicals are generally harmful, they do have a role in the body such as in fighting infections. Having too many antioxidants could interfere with this process. Therefore, a balance is necessary to maintain optimal health.

4. Synthetic vs natural antioxidants

There’s a distinction between synthetic and natural antioxidants. While the former can provide concentrated amounts of antioxidants, the latter come packaged with other beneficial nutrients. Whole foods offer a variety of antioxidants along with dietary fiber, proteins, and other essential nutrients.

5. Dependence on supplements

Relying on supplements instead of getting antioxidants from food can lead to an unbalanced diet lacking other nutrients. It’s best to aim for a diet rich in fruits, vegetables, whole grains, and healthy fats, which naturally contain antioxidants.

Dependence on supplements
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Potential side effects of antioxidants

Just like any substance, antioxidants can have potential side effects, especially when consumed in excessive amounts or in isolated forms, like supplements. It’s essential to approach antioxidant consumption with an understanding of these potential pitfalls.

1. Vitamin A toxicity

  • Sources: Vitamin A is found in foods in two primary forms: preformed vitamin A in animal products like dairy, fish, and meat; and provitamin A (like beta-carotene) in plants.
  • Side effects: Overconsumption, mainly from supplements, can lead to hypervitaminosis A. Symptoms include dizziness, nausea, headaches, skin irritation, joint and bone pain [7]. Chronic overdose can lead to hair loss, confusion, and even liver damage.

2. Excessive Vitamin E

  • Sources: Vitamin E can be found in nuts, seeds, vegetable oils, and green leafy vegetables.
  • Side effects: When taken in extremely high doses, vitamin E can thin the blood leading to bleeding and hemorrhaging. It can also lead to nausea, diarrhea, stomach cramps, fatigue, weakness, headache, blurred vision, and gonadal dysfunction.

3. Vitamin C overconsumption

  • Sources: Commonly found in citrus fruits, bell peppers, strawberries, and tomatoes.
  • Side effects: While generally considered safe, in extremely high doses (often from supplements), it can cause nausea, diarrhea, and stomach cramps. It might also lead to the formation of kidney stones in susceptible individuals.

4. Selenium excess

  • Sources: Brazil nuts, fish, ham, and enriched macaroni are good sources of selenium.
  • Side effects: High selenium levels can result in selenosis. Symptoms include garlic breath odor, hair loss, fatigue, irritability, and mild nerve damage.

5. Potential pro-oxidative effects

In specific contexts, some antioxidants can act as pro-oxidants, leading to increased oxidative stress. This effect has been observed in isolated in-vitro studies where high concentrations of antioxidants like vitamin C acted as pro-oxidants under particular conditions.

6. Reduced medication efficacy

Antioxidants can interfere with the effectiveness of certain medications. For example:

  • Chemotherapy and radiation: Some studies suggest antioxidants might protect cancer cells against damage from chemotherapy and radiation treatments.
  • Statins and niacin: Antioxidants might reduce the efficacy of these drugs for lowering cholesterol.

7. Risk in smokers

Certain antioxidant supplements, particularly beta-carotene, have been found to increase the risk of lung cancer in smokers.

8. Interference with natural defense mechanisms

The body has defense mechanisms to combat oxidative stress. Overreliance on antioxidant supplements might make the body less efficient in producing its antioxidants, leading to increased vulnerability when not on supplements.

9. Imbalance in nutrient uptake

High doses of one antioxidant can lead to decreased absorption of another. For instance, excess zinc can deplete the body of copper. Similarly, overconsumption of calcium can inhibit the absorption of other minerals like magnesium, zinc, and iron.

10. Gastrointestinal distress

Certain antioxidant supplements, when taken in large doses, can cause gastrointestinal issues like diarrhea, abdominal cramps, and nausea. This is commonly observed with vitamin C and magnesium supplements.

How much antioxidants should you take?

The recommended dosage for antioxidants can vary depending on the specific antioxidant in question, the individual’s health status, age, sex, and lifestyle factors. Here are some general guidelines [8]:

  • Vitamin A: 1076 mg (including 46% of retinol and 55% of beta-carotene)
  • Vitamin C: 107 mg 
  • Vitamin E: 9 mg

Please note that these are the amounts recommended for a healthy individual to maintain good health and may not be applicable in cases of deficiency or therapeutic uses.

The best approach is to obtain these antioxidants from a balanced diet rich in fruits, vegetables, whole grains, and lean proteins.

However, in cases where supplements are being considered, it’s crucial to consult with a healthcare provider. Certain conditions, medications, or life stages may require adjustments in these dosages. 

Also, there can be risks of overdose or interactions with other nutrients or medications when consumed in large amounts. As always, the principle of ‘more is not necessarily better’ applies to antioxidant consumption.

How to incorporate antioxidants into your diet

Incorporating antioxidants into your diet can be achieved by embracing a variety of nutrient-rich foods. Here are some tips to boost your antioxidant intake:

1. Diversify your fruit and veggie intake: Fruits and vegetables are a powerhouse of antioxidants. Aim for at least 5 servings a day and try to vary the types and colors to get a wide range of antioxidants.

2. Choose whole grains over refined: Opt for whole grains like brown rice, oats, and whole-grain bread or pasta, which contain more antioxidants compared to their refined counterparts.

3. Snack on nuts and seeds: Walnuts, almonds, flaxseeds, and chia seeds are excellent sources of vitamin E. Incorporate them into your snacks, salads, or breakfast cereals.

4. Eat more lean proteins: Fish and lean meat are rich in selenium. If you’re vegetarian, include more lentils and beans in your diet.

5. Use spices and herbs: Not only do they enhance flavor, but spices and herbs like turmeric, cinnamon, and oregano also pack a powerful antioxidant punch.

6. Hydrate with green tea: Green tea is rich in antioxidants called catechins. Substitute one of your daily coffees with a cup of green tea.

7. Limit processed foods: Highly processed foods often lack antioxidants and can be high in unhealthy fats, sugar, and sodium.

A balanced, diverse diet is the best approach to ensure you’re getting a variety of antioxidants essential for optimum health.

Closing thoughts

Navigating the world of antioxidants might seem complex, but it boils down to simple, everyday choices.

Making a conscious effort to add more colors to your plate, swap processed foods with whole ones, and hydrate with antioxidant-rich beverages like green tea can help elevate your health to new levels.

Yet, it’s important to strike a balance. Overdoing anything, even antioxidants can lead to adverse effects.

Consider antioxidants as part of a broader picture of balanced nutrition rather than isolated super-compounds.

So, are you ready to boost your antioxidant intake? Start today by adding an extra serving of fruits or vegetables to your meal, or replacing a processed snack with a handful of antioxidant-rich nuts or seeds. Let’s embrace a healthier lifestyle, one antioxidant-rich meal at a time!

FAQs

What are best antioxidants?

Antioxidants come from natural sources like vitamins A, C, and E, minerals like selenium and zinc, and flavonoids in fruits, veggies, nuts, seeds, and grains. A diverse diet with these antioxidants is healthy.

What are 3 examples of antioxidants?

Antioxidants include Vitamin C (citrus fruits, bell peppers), Vitamin E (nuts, seeds, green leafy veggies), and Beta-Carotene (carrots, sweet potatoes, spinach).

What foods are rich in antioxidants?

Colorful fruits and veggies, nuts, whole grains, fatty fish, green tea, dark chocolate, turmeric, and cinnamon are all rich in antioxidants.

Are bananas high in antioxidants?

Yes, bananas are a good source of antioxidants like dopamine and vitamin C, with unripe green bananas having higher dopamine levels.

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[1] https://www.healthline.com/nutrition/antioxidants-explained 
[2] https://www.betterhealth.vic.gov.au/health/healthyliving/antioxidants 
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5297730/ 
[4] https://www.intechopen.com/chapters/81679 
[5] https://www.betterhealth.vic.gov.au/health/healthyliving/antioxidants
[6] https://www.cbc.ca/news/health/antioxidant-supplement-overload-can-be-hazardous-1.1412993 
[7] https://www.msdmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/vitamin-a-toxicity 
[8] https://pubmed.ncbi.nlm.nih.gov/23789312/

The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.