Antioxidants: Food, Supplements, and Health Explained

Medically Reviewed By Imashi Fernando, MS, RDN
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Antioxidants can boost immunity and neutralize the damage caused by chemicals known as free radicals. The safest way to take advantage of the benefits of antioxidants is by consistently including a variety of fruit and vegetables in your diet.   Many sources, including product marketers, licensed clinicians, and dietary guidelines, emphasize the importance of antioxidants for health and nutrition.

2018 study states that the term “antioxidant” has become one of the most confusing definitions within the science field. 

Many people promote the overall health benefits and several other claims related to antioxidants, such as anti-aging effects. Therefore, it is important to understand what antioxidants are and how to safely gain their benefits.

This article explains what antioxidants are, dietary sources of antioxidants, supplements, and how to take advantage of their potential benefits. 

What are antioxidants? 

4 glass bottles of brightly colored juices stand on a plain blue background, amongst slices of watermelon, lemon, orange, and pineapple. A hand enters the shot to pick up one of the bottles.
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Antioxidants are chemical substances that can prevent or reverse damage caused by free radicals.

Free radicals are particles that the body produces due to environmental causes or oxidative stress. An excess of free radicals can cause damage to cells.

Appropriate levels of antioxidants may help subdue free radicals in the body and boost immunity.

You can gain antioxidants through your diet. The Academy of Nutrition and Dietetics recommends a diet filled with various fruits and vegetables as the best source of natural antioxidants.

Dietary supplements are also available but require medical guidance. Some forms of antioxidant supplements may interact negatively with medications.  

Hundreds of different chemical substances can have antioxidant activity in the body. Some common antioxidants include: 

  • vitamins A, C, and E
  • beta carotene
  • lycopene
  • lutein
  • selenium

What do antioxidants do?

There is an ongoing debate about the specific power of antioxidants and their ability to protect against certain chronic conditions. 

In 1956, a scientist called Denham Harman published the free radical theory of aging. This theory links the accumulation of oxidative cellular damage with cellular aging and DNA mutations. Over time this theory has evolved to help clinicians understand the effect of free radicals and the role of antioxidants. 

It is important to understand that the human body already produces free radicals and antioxidants as part of an adequate balance for proper physiological function. Our bodies produce free radicals for several reasons, such as:

  • a byproduct of turning food into energy
  • inflammation
  • exposure to environmental pollution
  • exposure to sunlight
  • exposure to cigarette smoke

However, when the body cannot process and balance out those free radicals, it can result in oxidative stress. This stress harms cells and optimal body function.

Oxidative stress may contribute to developing diabetes, Alzheimer’s disease, and Parkinson’s disease. It may also contribute to developing certain eye diseases and inflammatory diseases.

Antioxidants may prevent or delay this cell damage by helping the immune system neutralize free radicals. 

Researchers suggest that this may further reduce the risk of diseases, such as cardiovascular disease or cancer, and mortality.

Antioxidant-rich foods

The best way to nourish your body with antioxidants and other nutrients is by consuming at least 1.5 cups of fruits and 2.5 cups of vegetables per day.

Regardless of your choice of fresh, frozen, or canned fruits and vegetables, try to choose options without added preservatives, including sugar and salt. Whole grains, seeds, and nuts also provide valuable nutrients.

Some people may refer to foods high in antioxidants as “superfoods” due to their antioxidant-rich profile. However, you should include a variety of colorful foods to obtain the most health benefits. 

Clinicians suggest that the action of antioxidants is most effective when we take them with other nutrients.

Because of their varying chemical properties, each antioxidant will have a specific effect on the body. One single antioxidant will not counteract every single free radical type. 

The following list explains the dietary sources of some common antioxidants. 

Vitamin A

You can gain vitamin A from:

  • eggs
  • dairy products, such as:
    • milk
    • butter
    • cheese
  • organ meats, such as liver

You can also find vitamin A in some types of fish, and some fruits and vegetables, such as leafy green vegetables and stone fruits.

Vitamin C

Most fruits and vegetables contain vitamin C.

Fruits can include:

  • berries
  • citrus fruits
  • stone fruits, such as melon and peach
  • kiwis

Vegetable options include:

  • cruciferous vegetables, such as:
    • kale
    • broccoli
    • cauliflower
    • Brussels sprouts
  • bell peppers
  • tomatoes

Vitamin E

Vitamin E is common in many nuts and seeds, plant and nut oils, and leafy green vegetables, such as:

  • peanuts
  • almonds
  • hazelnuts
  • sunflower seeds and sunflower oil
  • soybean oil, safflower oil, wheat germ, avocado oil, and olive oil
  • spinach
  • kale
  • rhubarb
  • arugula
  • watercress
  • radicchio
  • broccoli

Lutein

Leafy green vegetables also contain lutein.

In addition, you can also gain lutein from papayas, oranges, broccoli, peas, and corn.

Beta carotene

Beta carotene is present in many colorful fruits and vegetables. Bright yellow, orange, and red fruits and vegetables have high concentrations of beta carotene. Some dark leafy green vegetables are high in this antioxidant, too.

You can include beta carotene in your diet by eating various fruits and vegetables.

Lycopene

Lycopene is present in pink and red fruits and vegetables. For example, this can include tomatoes, watermelon, apricots, and pink grapefruits.

Selenium

You can gain selenium from whole grains, animal products, nuts, legumes such as beans and pulses, and dairy.

Examples include:

  • whole pasta, bread, rice, corn, and other grains
  • poultry, such as chicken and turkey
  • beef
  • fish and other seafood
  • eggs
  • cheese

Additional sources

These are just a few examples of antioxidant nutrients you can include in your diet. Other foods can also offer additional important antioxidants.

These foods include:

  • dark chocolate or cocoa
  • green and black tea
  • coffee
  • red wine
  • spices

Tips for an antioxidant-rich diet

Following a balanced diet with various whole foods will provide you with natural sources of antioxidants, minerals, and vitamins. A balanced diet will also provide varied macronutrients, such as fiber and protein.

Consider the following tips to help you boost your food’s antioxidant and nutrient value.

Eat the rainbow

Plant-based foods all contain different color pigments, which give them their bright and distinctive colors.

Each of these distinctive pigments contains different nutrients.

Therefore, “eating the rainbow” by including a wide range of colorful whole and plant-based foods throughout the day provides a good variety of nutrients.

Plan your meals

Take the time to plan your meals and include a serving of fruit and vegetables on every plate. It may also help to plan your shopping list in advance.

Add in colorful foods higher in antioxidants, such as kale, beets, peppers, broccoli, and sweet potatoes.

Use half the plate for fruits and vegetables

Through their healthy eating program MyPlate, the Department of Agriculture recommends filling half of your plate with fruit and vegetables in each meal.

Enhance flavor

If you are incorporating new foods into your diet, you can use antioxidant-rich herbs and spices to enhance their flavor.

Examples include cinnamon, turmeric, oregano, parsley, cumin, and basil. 

You can also add antioxidant-rich citrus fruits such as lemon, lime, and orange to enhance flavor.

Adapt your cooking methods

Some forms of cooking may alter the nutritional properties of food.

Consider the following recommendations to preserve antioxidant properties as much as possible while cooking: 

  • Reduce the amount of cooking water to maximize fiber and nutrient density. 
  • Peel and cut vegetables after cooking for less heat and water exposure.
  • Substitute cooking oils and spreads for ones that have higher antioxidant levels, such as sunflower oil, olive oil, or avocado oil.

Antioxidant supplements 

Although an intake of antioxidants may reduce oxidative stress, there is a lack of evidence to demonstrate the health benefits of supplements. 

A 2018 study finds that it may be beneficial for disease prevention to take in higher levels of certain antioxidants through the diet. However, researchers from the study suggest that there is no evidence supporting the recommendation or use of antioxidant supplements to prevent chronic disease.

Researchers from a different 2018 study suggest that supplements may help people in cases where they have a confirmed nutrient deficiency.

However, the researchers also clarify that they do not recommend supplements for regular consumption otherwise.

The National Center for Complementary and Integrative Health (NCCIH) also advises against using antioxidant supplements in place of a balanced diet or regular medical attention. 

Some people use antioxidants in high doses to treat inflammation and degenerative diseases through holistic practices. Clinicians do not recommend antioxidants for these purposes.

Be aware when considering supplements

Before adding a dietary supplement to your nutritional routine, consider reliable information from trustworthy sources.

No antioxidant supplement should claim to prevent or treat a medical condition. 

Additionally, high doses of antioxidant supplements may be dangerous to health in some cases and can carry a risk of disease. Some supplements may also offer inappropriately high dosages.

Always contact your doctor or a pharmacist before starting a new supplement. Like any medication or supplement, they may interact negatively with your other medications or any underlying conditions.

Safety and risks

The safest way to take advantage of the benefits of antioxidants is by consistently including fruit and vegetables in your diet. 

The NCCIH recommends medical supervision when taking supplements. Some studies have linked high doses of antioxidant supplements with an increased risk of hemorrhagic stroke. The same studies link high doses of antioxidant supplements with lung cancer in people who smoke.

A 2014 study also advises precaution when taking antioxidant supplements as it may decrease endurance exercise performance.  

If you are pregnant or trying to conceive, consider that researchers have not yet tested many supplements specifically for pregnant or breastfeeding people.

Summary

Our bodies naturally produce antioxidants and free radicals for proper physiological function. However, an excess of free radicals can cause cellular damage.

Antioxidants may boost immunity and neutralize the damage caused by free radicals.

An effective way to nourish the body and increase antioxidant intake is to consume a diet filled with colorful fruits and vegetables, whole grains, and some lean meats.

Although dietary supplements are available, doctors advise against taking high doses of supplements. High doses may be harmful to health and interact with medications. There is also limited evidence that supplements help prevent disease more effectively than dietary antioxidants.

Contact your doctor if you wish to make any substantial changes to your dietary habits, consider supplementation, or are concerned about your nutrition.

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Medical Reviewer: Imashi Fernando, MS, RDN
Last Review Date: 2022 Jun 6
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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