- Antioxidants: Health benefits and nutritional information
- Effect of cooking
- Why do you need antioxidants?
- Super Foods for Optimal Health
- Understanding antioxidants
- Antioxidants Explained in Simple Terms
- What Are Antioxidants (and Do You Really Need Them)?
- The Need-To-Know
- YOUR ACTION PLAN
- What are antioxidants? And are they truly good for us?
- What are antioxidants?
- What is oxidation?
- What are free radicals?
- All antioxidants aren’t equal
- Too much of a good thing
Antioxidants: Health benefits and nutritional information
- Food sources
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Antioxidants are substances that can prevent or slow damage to cells caused by free radicals, unstable molecules that the body produces as a reaction to environmental and other pressures.
They are sometimes called “free-radical scavengers.”
The sources of antioxidants can be natural or artificial. Certain plant-based foods are thought to be rich in antioxidants. Plant-based antioxidants are a kind of phytonutrient, or plant-based nutrient.
The body also produces some antioxidants, known as endogenous antioxidants. Antioxidants that come from outside the body are called exogenous.
Free radicals are waste substances produced by cells as the body processes food and reacts to the environment. If the body cannot process and remove free radicals efficiently, oxidative stress can result. This can harm cells and body function. Free radicals are also known as reactive oxygen species (ROS).
Factors that increase the production of free radicals in the body can be internal, such as inflammation, or external, for example, pollution, UV exposure, and cigarette smoke.
Oxidative stress has been linked to heart disease, cancer, arthritis, stroke, respiratory diseases, immune deficiency, emphysema, Parkinson’s disease, and other inflammatory or ischemic conditions.
Antioxidants are said to help neutralize free radicals in our bodies, and this is thought to boost overall health.
Antioxidants can protect against the cell damage that free radicals cause, known as oxidative stress.
Activities and processes that can lead to oxidative stress include:
- mitochondrial activity
- excessive exercise
- tissue trauma, due to inflammation and injury
- ischemia and reperfusion damage
- consumption of certain foods, especially refined and processed foods, trans fats, artificial sweeteners, and certain dyes and additives
- environmental pollution
- exposure to chemicals, such as pesticides and drugs, including chemotherapy
- industrial solvents
Such activities and exposures can result in cell damage.
This, in turn, may lead to:
- an excessive release of free iron or copper ions
- an activation of phagocytes, a type of white blood cell with a role in fighting infection
- an increase in enzymes that generate free radicals
- a disruption of electron transport chains
All these can result in oxidative stress.
The damage caused by oxidative stress has been linked to cancer, atherosclerosis, and vision loss. It is thought that the free radicals cause changes in the cells that lead to these and possibly other conditions.
An intake of antioxidants is believed to reduce these risks.
According to one study: “Antioxidants act as radical scavenger, hydrogen donor, electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and metal-chelating agents.”
Other research has indicated that antioxidant supplements may help reduce vision loss due to age-related macular degeneration in older people.
Overall, however, there is a lack of evidence that a higher intake of specific antioxidants can reduce the risk of disease. In most cases, results have tended to show no benefit, or a detrimental effect, or they have been conflicting.
There are thought to be hundreds and possibly thousands of substances that can act as antioxidants. Each has its own role and can interact with others to help the body work effectively.
“Antioxidant” is not really the name of a substance, but rather it describes what a range of substances can do.
Examples of antioxidants that come from outside the body include:
Flavonoids, flavones, catechins, polyphenols, and phytoestrogens are all types of antioxidants and phytonutrients, and they are all found in plant-based foods.
Each antioxidant serves a different function and is not interchangeable with another. This is why it is important to have a varied diet.
Share on PinterestPomegranate is one source of antioxidants.
The best sources of antioxidants are plant-based foods, especially fruits and vegetables.
Foods that are particularly high in antioxidants are often referred to as a “superfood” or “functional food.”
To obtain some specific antioxidants, try to include the following in your diet:
Vitamin A: Dairy produce, eggs, and liver
Vitamin C: Most fruits and vegetables, especially berries, oranges, and bell peppers
Vitamin E: Nuts and seeds, sunflower and other vegetable oils, and green, leafy vegetables
Beta-carotene: Brightly colored fruits and vegetables, such as carrots, peas, spinach, and mangoes
Lycopene: Pink and red fruits and vegetables, including tomatoes and watermelon
Lutein: Green, leafy vegetables, corn, papaya, and oranges
Selenium: Rice, corn, wheat, and other whole grains, as well as nuts, eggs, cheese, and legumes
Other foods that are believed to be good sources of antioxidants include:
- legumes such as black beans or kidney beans
- green and black teas
- red grapes
- dark chocolate
- goji berries
Goji berries and many other food products that contain antioxidants are available to purchase online.
Foods with rich, vibrant colors often contain the most antioxidants.
The following foods are good sources of antioxidants. Click on each one to find out more about their health benefits and nutritional information:
Effect of cooking
Cooking particular foods can either increase or decrease antioxidant levels.
Lycopene is the antioxidant that gives tomatoes their rich red color. When tomatoes are heat-treated, the lycopene becomes more bio-available (easier for our bodies to process and use).
However, studies have shown that cauliflower, peas, and zucchini lose much of their antioxidant activity in the cooking process. Keep in mind that the important thing is eating a variety of antioxidant-rich foods, cooked and raw.
Share on PinterestDrinking a cup or two of green tea is thought to provide health benefits because of the antioxidants.
The following tips could help increase your antioxidant intake:
- Include a fruit or a vegetable every time you eat, meals and snacks included.
- Have a cup of green or matcha tea every day.
- Look at the colors on your plate. If your food is mostly brown or beige, the antioxidant levels are ly to be low. Add in foods with rich colors, such as kale, beets, and berries.
- Use turmeric, cumin, oregano, ginger, clove, and cinnamon to spice up the flavor and antioxidant content of your meals.
- Snack on nuts, seeds, especially Brazil nuts, sunflower seeds, and dried fruit, but choose those with no added sugar or salt.
Or, try these healthy and delicious recipes developed by registered dietitians:
There is no set recommended daily allowance (RDA) for antioxidants, but a high intake of fresh plant-based produce is considered healthful.
It is worth remembering that, while studies link the consumption of fruits and vegetables with better overall health, it is not clear whether how far this is due to the activity of antioxidants. In addition, caution is needed regarding supplements.
The National Institutes of Health (NIH) warn that high doses of antioxidant supplements can be harmful.
A high intake of beta-carotene, for example, has been linked to an increased risk of lung cancer in smokers. A high dose of vitamin E has been found to increase the risk of prostate cancer, and the use of some antioxidant supplements has been linked to a greater risk of tumor growth.
Antioxidant supplements may also interact with some medications. It is important to speak with a health provider before using any of these products.
Overall, research has not proven that taking any particular antioxidant as a supplement or through a food can protect against a disease.
There may be some benefit for people at risk of age-related macular degeneration, but it is essential to seek advice from a doctor about whether to use supplements, and which ones to use.
Free radicals have been linked to a range of diseases, including heart disease, cancer, and vision loss, but this does not mean that an increased intake of antioxidants will prevent these diseases. Antioxidants from artificial sources may increase the risk of some health problems.
As a result, it is important to seek out natural sources of antioxidants, in the form of a healthful diet.
Consuming fruits and vegetables has been linked to a lower rate of chronic diseases, and antioxidants may play a role. However, it is unly that consuming added antioxidants, especially in processed foods, will provide significant benefits.
In addition, anyone considering taking antioxidant supplements should speak to a health provider first.
Why do you need antioxidants?
Why do we need antioxidants? We know that they are good for us, but why do we need them? Why are they so crucial to help with preventing chronic disease and the ageing process? We use the term a lot, but do we understand what it actually means and its implications for health? Let’s take a look…
An antioxidant is basically something that reverses or stops ‘oxidation’. But what exactly is oxidation?
In scientific terms, oxidation is the gain of oxygen by a substance. Imagine a freshly cut apple or avocado turning brown, a nail becoming rusty or a copper statue turning green. These are examples of everyday oxidation. In most instances the process of oxidation causes damage or destruction.
Oxidation creates free radicals, boisterous molecules that have been freed from their usual home to go and cause damage and destruction in the body.
These free radicals are unstable and need to be ‘caught’ before they can cause more damage to other healthy functioning cells.
These free radicals negatively affect cell membrane health, proteins, and DNA expression which can trigger a number of human diseases. Antioxidants are our natural protectors.
Antioxidants are abundant in nature, because plants contain antioxidants to protect themselves too. The nutritional content of natural whole foods is just what our body needs to negate the effects of our own biochemical processes.
However we sometimes struggle to obtain sufficient antioxidants in the modern world due to a nutritionally deficient society – due to urbanization, overuse of agricultural land, intensive farming, stress-fueled society and easy access to processed foods, we are unable to provide our body with the essential nutrition required to defuse this free radical activity.
Not only do free radicals naturally occur in the body, we can also absorb them from our environment. This can be from consumption burnt or fried foods or exposure to chemicals as pesticides in the home, cosmetic and domestic products and various other sources through our environment.
Antioxidants are therefore vital for our health as they are implicated in healthy ageing, reducing the virulence of chronic disease, improving cognition and mental health. Ultimately they work to maintain and improve general health and wellbeing.
So what can we do to protect ourselves?
- Eat organic and/or local produce as much as you can afford. Look out for the ‘dirty dozen’ and ‘clean fifteen’ as a basis.
- Base your diet on whole foods in forms of fresh fruit and vegetables and good quality protein
- Minimize and ideally eliminate processed foods, usually void of any antioxidant nutrition.
- Keep a healthy mind by staying hydrated and maintaining good balance between work and home.
- Look after your gut. A healthy gut is a healthy body!
- Include key nutrients in your diet that help support high antioxidant activity, such as:
- Turmeric – containing the active ingredient curcumin. This spice is known, improving cognition and reducing the signs of ageing.
- Vitamin C – improves immune cell function (neutrophils & lymphocytes),  reduces tiredness and fatigue, acting as a co factor for iron absorption and supports collagen formation. 
- Vitamin D – appears to enhance innate immunity and inhibits the development of autoimmunity.
- Zinc – supports enzymic activity in the body and regulates immune cells.
- Billberry – Acts as a natural anti-inflammatory agentsupports circulation and strengthens capillaries
- Hesperidin – supports cardiovascular function, protects our muscles and bonesand reduces inflammation.
- Rutin – Found to be an effective free radical scavenger  and supports circulation. 
- Grapeseed extract (as Vitaflavan®) – an excellent source of oligomeric proanthocyanidins (OPCs). These antioxidant molecules have approximately 50 times more free radical scavenging ability than vitamins C and E.
- Manganese – works as a key part antioxidant enzymes in the mitochondria which are the batteries of the cell.
- Probiotics – along with all the other reputed benefits of probiotics for digestive and immune health the friendly bacteria in our gut have been associated with reduced oxidation and inflammation.
- Quercetin – One of the most potent antioxidants that is used often by nutritionists to support normal histamine release and support an overactive immune system.
- Rosehip – this is the whole berry fruit from the rose plant. It is abundant in nutrients including vitamin C, providing high antioxidant activity.
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 Tauler et al. Differential response of lymphocytes and neutrophils to high intensity physical activity and to vitamin C diet supplementation. Free Radic Res. 2003; 37:931-8.
 Hallberg L, Brune M, Rossander L. The role of vitamin C in iron absorption. Int J Vitam Nutr Res Suppl. 1989;30:103-8.
 Boyera et al. Effect of vitamin C and its derivatives on collagen synthesis and cross-linking by normal human fibroblasts. Int J Cosmet Sci. 1998; 20 (3): 151-8.
 Griffin, M.D., Xing, N. and Kumar R. (2003) Vitamin D and its analogs as regulators of immune activation and antigen presentation. Annual Review of Nutrition, 23, 117-145.
 Sandstead HH. Understanding zinc: recent observations and interpretations. J Lab Clin Med 1994;124:322-7.
 Encyclopedia of Human Nutrition. Caballero B, Allen L, Prentice A (eds.). Academic Press, San Diego, 447-454
 Triebel et al. Modulation of inflammatory gene expression by a bilberry ( Vaccinium myrtillus L.) extract and single anthocyanins considering their limited stability under cell culture conditions. J Agric Food Chem. 2012; 60 (36): 8902-10.
 Mian E et al Anthocyanosides and the walls of microvessels: Further aspects of the mechanism of action of their protective in syndromes due to abnormal capillary fragility. Minerva Med 1977;68:3565–81.
 Balakrishnan, Menon. Effect of hesperidin on matrix metalloproteinases and antioxidant status during nicotine-induced toxicity. Toxicology. 2007; 238 (2-3): 90-8.
 In-Young Choi et al. Hesperidin inhibits expression oh hypoxia inducible factor-1 alpha and inflammatory cytokine production from mast cells. Molecular and cellular biochemistry 2007; pp153-161
 Kostyuk VA, Potapovich AI. Antiradical and chelating effects in flavonoids protection against silica induced cell injury. Arch Biochem Biophys 1998 Jul 1;355(1):43-8
 Escarpa A, Gonzalez MC. High performance liquid chromatography with diode-array detection for the determination of phenolic compounds in peel and pulp from different apple varieties. J Chromatogr A. 1998 Oct 9;823(1-2):331-7
 Clement D L. Management of venous edema: insights from an international task force. Angiology. 2000; 51:13-17
 Leach RM, Harris ED. Manganese. In: O'Dell BL, Sunde RA, eds. Handbook of nutritionally essential minerals. New York: Marcel Dekker, Inc; 1997:335-355.
 Lamprecht M et al. Probiotic supplementation affects markers of intestinal barrier, oxidation, and inflammation in trained men; a randomized, doubleblinded, placebo-controlled trial. J Int Soc Sports Nutr. 2012 Sep 20;9(1):45.
 Tumbas et al. Effect of rosehip (Rosa canina L.) phytochemicals on stable free radicals and human cancer cells. J Sci Food Agric. 2012 Apr; 92 (6): 1273-81
Super Foods for Optimal Health
Do your immune system a favor and pack more fruits and vegetables on your plate.
They're loaded with nutrients, called antioxidants, that are good for you.
Add more fruits and vegetables of any kind to your diet. It'll help your health. Some foods are higher in antioxidants than others, though.
The three major antioxidant vitamins are beta-carotene, vitamin C, and vitamin E. You’ll find them in colorful fruits and vegetables, especially those with purple, blue, red, orange, and yellow hues.
Beta-carotene and other carotenoids: apricots, asparagus, beets, broccoli, cantaloupe, carrots, corn, green peppers, kale, mangoes, turnip and collard greens, nectarines, peaches, pink grapefruit, pumpkin, squash, spinach, sweet potato, tangerines, tomatoes, and watermelon
Vitamin C: berries, broccoli, Brussels sprouts, cantaloupe, cauliflower, grapefruit, honeydew, kale, kiwi, mango, nectarine, orange, papaya, snow peas, sweet potato, strawberries, tomatoes, and red, green, or yellow peppers
Vitamin E: broccoli (boiled), avocado, chard, mustard and turnip greens, mangoes, nuts, papaya, pumpkin, red peppers, spinach (boiled), and sunflower seeds
These foods are also rich in antioxidants:
- Red grapes
- Alfalfa sprouts
Other antioxidants that can help keep you healthy include:
Zinc: oysters, red meat, poultry, beans, nuts, seafood, whole grains, some fortified cereals (check the ingredients to see if zinc has been added), and dairy products
Selenium : Brazil nuts, tuna, beef, poultry, fortified breads, and other grain products
Cooking tip: To get the biggest benefits of antioxidants, eat these foods raw or lightly steamed. Don’t overcook or boil them.
Foods have many different nutrients and fiber, all of which work together. Supplements don't have that same mix.
If you can’t get enough fruits and vegetables in your diet, you may want to consider taking a multivitamin with minerals.
But chances are, you can get what you need from your diet. If you want to check that you're on track, ask your doctor or a dietitian.
WebMD Medical Reference: ''Antioxidants — Topic Overview;'' ''Spring Allergies;'' “Vitamins and Supplements Lifestyle Guide;” and “Food Sources for Vitamins and Minerals.”
U.S. Department of Agriculture: ''Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods.''
MedicineNet: “Vitamin and Calcium Supplements.”
National Institutes of Health: ''Facts About Dietary Supplements: Zinc;'' ''Dietary Supplement Fact Sheet: Selenium;'' ''Dietary Supplement Fact Sheet: Vitamin A and Carotenoids;'' and ''Vitamin E.''
Oregon State University Micronutrient Information Center: ''Vitamin C.''
Scott Berliner, supervising pharmacist, Life Science Pharmacy, Harriman, NY.
WebMD Health News: ''Can Celery Help Cut Brain Inflammation?''
WebMD Features: ''Health Benefits of Tea'' and ''How Antioxidants Work.''
© 2019 WebMD, LLC. All rights reserved.
Some vitamins and minerals — including vitamins C and E and the minerals copper, zinc, and selenium — serve as antioxidants, in addition to other vital roles.
“Antioxidant” is a general term for any compound that can counteract unstable molecules called free radicals that damage DNA, cell membranes, and other parts of cells. Because free radicals lack a full complement of electrons, they steal electrons from other molecules and damage those molecules in the process.
Antioxidants neutralize free radicals by giving up some of their own electrons. In making this sacrifice, they act as a natural “off” switch for the free radicals. This helps break a chain reaction that can affect other molecules in the cell and other cells in the body.
But it is important to recognize that the term “antioxidant” reflects a chemical property rather than a specific nutritional property.
While free radicals are damaging by their very nature, they are an inescapable part of life. The body generates free radicals in response to environmental insults, such as tobacco smoke, ultraviolet rays, and air pollution, but they are also a natural byproduct of normal processes in cells.
When the immune system musters to fight intruders, for example, the oxygen it uses spins off an army of free radicals that destroy viruses, bacteria, and damaged body cells in an oxidative burst. Some normal production of free radicals also occurs during exercise.
This appears to be necessary in order to induce some of the beneficial effects of regular physical activity, such as sensitizing your muscle cells to insulin.
Because free radicals are so pervasive, you need an adequate supply of antioxidants to disarm them. Your body's cells naturally produce some powerful antioxidants, such as alpha lipoic acid and glutathione. The foods you eat supply other antioxidants, such as vitamins C and E.
Plants are full of compounds known as phytochemicals—literally, “plant chemicals”—many of which seem to have antioxidant properties as well.
For example, after vitamin C has “quenched” a free radical by donating electrons to it, a phytochemical called hesperetin (found in oranges and other citrus fruits) restores the vitamin C to its active antioxidant form.
Carotenoids (such as lycopene in tomatoes and lutein in kale) and flavonoids (such as flavanols in cocoa, anthocyanins in blueberries, quercetin in apples and onions, and catechins in green tea) are also antioxidants.
News articles, advertisements, and food labels often tout antioxidant benefits such as slowing aging, fending off heart disease, improving flagging vision, and curbing cancer.
And laboratory studies and many large-scale observational studies (those that query people about their eating habits and supplement use and then track their disease patterns) have noted antioxidant benefits from diets rich in them, particularly those coming from a broad range of colorful vegetables and fruits. But results from randomized controlled trials of antioxidant supplements (in which people are assigned to take specific nutrient supplements or a placebo) have not supported many of these claims. Indeed, too much of these antioxidant supplements won't help you and may even harm you. It is better to supply your antioxidants from a well-rounded diet.
To learn more about the vitamins and minerals you need to stay healthy, read Making Sense of Vitamins and Minerals, a Special Health Report from Harvard Medical School.
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Antioxidants Explained in Simple Terms
Written by Atli Arnarson, PhD on July 29, 2019
You may have heard a lot of talk about antioxidants.
However, few people know what they are or how they work.
This article tells you everything you need to know about antioxidants.
Antioxidants are molecules that fight free radicals in your body.
Free radicals are compounds that can cause harm if their levels become too high in your body. They’re linked to multiple illnesses, including diabetes, heart disease, and cancer.
Your body has its own antioxidant defenses to keep free radicals in check.
However, antioxidants are also found in food, especially in fruits, vegetables, and other plant-based, whole foods. Several vitamins, such as vitamins E and C, are effective antioxidants.
Antioxidant preservatives also play a crucial role in food production by increasing shelf life.
SUMMARY Antioxidants are molecules that neutralize free radicals, unstable molecules that can harm your cells.
Free radicals are constantly being formed in your body.
Without antioxidants, free radicals would cause serious harm very quickly, eventually resulting in death.
However, free radicals also serve important functions that are essential for health (1).
For example, your immune cells use free radicals to fight infections (2).
As a result, your body needs to maintain a certain balance of free radicals and antioxidants.
When free radicals outnumber antioxidants, it can lead to a state called oxidative stress.
Prolonged oxidative stress can damage your DNA and other important molecules in your body. Sometimes it even leads to cell death.
Damage to your DNA increases your risk of cancer, and some scientists have theorized that it plays a pivotal role in the aging process (3, 4).
Several lifestyle, stress, and environmental factors are known to promote excessive free radical formation and oxidative stress, including:
- air pollution
- cigarette smoke
- alcohol intake
- high blood sugar levels (5, 6)
- high intake of polyunsaturated fatty acids (7)
- radiation, including excessive sunbathing
- bacterial, fungal, or viral infections
- excessive intake of iron, magnesium, copper, or zinc (1)
- too much or too little oxygen in your body (8)
- intense and prolonged exercise, which causes tissue damage (9)
- excessive intake of antioxidants, such as vitamins C and E (1)
- antioxidant deficiency (10)
Prolonged oxidative stress leads to an increased risk of negative health outcomes, such as cardiovascular disease and certain types of cancer.
SUMMARY Your body needs to maintain a certain balance between free radicals and antioxidants. When this equilibrium is disrupted, it can lead to oxidative stress.
Antioxidants are essential for the survival of all living things.
Your body generates its own antioxidants, such as the cellular antioxidant glutathione.
Plants and animals, as well as all other forms of life, have their own defenses against free radicals and oxidative damage.
Therefore, antioxidants are found in all whole foods of plant and animal origin.
Adequate antioxidant intake is important. In fact, your life depends on the intake of certain antioxidants — namely, vitamins C and E.
However, many other non-essential antioxidants occur in food. While they’re unnecessary for your body, they play an important role in general health.
The health benefits associated with a diet rich in plants is at least partially due to the variety of antioxidants they provide (11).
Berries, green tea, coffee, and dark chocolate are renowned for being good sources of antioxidants (12).
According to some studies, coffee is the single biggest source of antioxidants in the Western diet, but this is partly because the average individual doesn’t eat that many antioxidant-rich foods (13, 14).
Meat products and fish also contain antioxidants, but to a lesser extent than fruits and vegetables (15, 16).
Antioxidants can increase the shelf life of both natural and processed foods. Therefore, they’re frequently used as food additives. For instance, vitamin C is often added to processed foods to act as a preservative (17).
SUMMARY Your diet is an essential source of antioxidants, which are found in animal and plant foods — especially vegetables, fruits, and berries.
Antioxidants can be categorized as either water- or fat-soluble.
Water-soluble antioxidants perform their actions in the fluid inside and outside cells, whereas fat-soluble ones act primarily in cell membranes.
Important dietary antioxidants include:
- Vitamin C. This water-soluble antioxidant is an essential dietary nutrient.
- Vitamin E. This fat-soluble antioxidant plays a critical role in protecting cell membranes against oxidative damage.
- Flavonoids. This group of plant antioxidants has many beneficial health effects (18).
Many substances that happen to be antioxidants also have other important functions.
Notable examples include curcuminoids in turmeric and oleocanthal in extra virgin olive oil. These substances function as antioxidants but also have potent anti-inflammatory activity (19, 20).
SUMMARY Many types of antioxidants occur in foods, including flavonoids and vitamins C and E.
Dietary intake of antioxidants is essential for optimal health, but more is not always better.
Excessive intake of isolated antioxidants can have toxic effects and may even promote rather than prevent oxidative damage — a phenomenon termed the “antioxidant paradox” (21, 22).
Some studies even show that high doses of antioxidants increase your risk of death (23, 24).
For this reason, most health professionals advise people to avoid high-dose antioxidant supplements, although further studies are needed before solid conclusions can be reached.
Eating plenty of antioxidant-rich whole food is a much better idea. Studies indicate that foods reduce oxidative damage to a greater extent than supplements.
For example, one study compared the effects of drinking blood-orange juice and sugar water, both of which contained equal amounts of vitamin C. It found that the juice had significantly greater antioxidant power (25).
These results suggest that foods’ compounds work synergistically. Taking just one or two isolated nutrients won’t have the same beneficial effects.
The best strategy to ensure adequate antioxidant intake is to follow a diet rich in various vegetables and fruits, alongside other healthy habits (26).
However, low-dose supplements, such as multivitamins, may be beneficial if you are deficient in certain nutrients or unable to follow a healthy diet.
SUMMARY Studies suggest that taking regular, high-dose antioxidant supplements may be harmful. If possible, get your daily dose of antioxidants from whole foods, such as fruits and vegetables.
Adequate antioxidant intake is essential to a healthy diet, although some studies suggest that high-dose supplements may be harmful.
The best strategy is to get your daily dose of antioxidants from healthy plant foods, such as fruits and vegetables.
What Are Antioxidants (and Do You Really Need Them)?
Share on Pinterest
“An apple a day keeps the doctor away,” and if modern food packaging is to be believed, that’s often due to a hefty dose of antioxidants. From sports drinks to protein bars, we’re constantly bombarded with foods claiming to be packed with these supposedly healthy compounds. But what exactly are antioxidants, and how many of them do we really need?
Antioxidants are nutrients — including vitamins E and C — that prevent or slow oxidative damage throughout the body. Without busting out the biochemistry books, when cells use oxygen, they naturally generate free radicals (by-products) which can cause cellular damage.
Antioxidants act as free radical bounty hunters that often prevent and repair damage done by the free radicalsOxidant-antioxidant system: role and significance in the human body. Irshad, M., Chaudhuri, PS. Department of Laboratory Medicine, New Delhi, India.
Indian Journal of Experimental Biology 2002 Nov; 40(11):1233-9.. Oxidative damage and free radicals can contribute to serious health problems such as heart disease, macular degeneration, and diabetes Sunlight exposure, antioxidants, and age-related macular degeneration. Fletcher, AE., Bentham, GC., Agnew, M., et al.
Department of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, Keppel Street, London, England. Archives of Ophthalmology 2008 Oct; 126(10):1396-403.Role of oxidative stress in cardiovascular diseases. Dhalla, NS., Temsah, R., Netticadan, T.
Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada. Journal of Hypertension 2000 June; 18(6):655-73.Oxidative stress and the use of antioxidants in diabetes: Linking basic science to clinical practice.
Johansen, JS., Harris, AK., Rychly, DJ., et al. University of Tromso, Tromso, Norway; Medical College of Georgia Vascular Biology Center, Augusta, Georgia, USA. Cardiovascular Diabetology 2005 Apr 29; 4(1):5..
But while many of today’s popular health foods contain massive doses of antioxidants vitamin C, loading the body with as many of the nutrients as possible isn’t the cure-all some might hope; in fact, ingesting large quantities of antioxidants might actually contribute to some of the very categories of disease they’re touted to prevent.
One now-famous study — which was actually stopped early because of the risk to patient health — showed an association between taking beta-carotene supplements with an increased risk of lung cancer in smokersAlpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. Albanes, D., Heinonen, O., Taylor, P., et al. Division of Cancer Prevention and Control, National Cancer Institute, Bethesda, MA, USA. Journal of the National Cancer Institute 1996 Nov 6; 88(21):1560-70.. And other research has come up short in definitively linking antioxidant supplements to increased longevity or decreased risks of serious disease.
YOUR ACTION PLAN
But while the evidence isn’t strong in support of antioxidant supplements as the key to good health, that doesn’t mean they don’t serve an important purpose in our diets.
Consuming nutrients vitamin C in normal doses — easily acquired in many fresh, whole foods — can help the body function normally and fight off infection.
Upping those quantities to thousands of times the daily recommended value probably won’t do much additional good.
Luckily, a healthy diet packed with antioxidants is relatively easy to stock up on, so grab a pen and paper and add these to the shopping list for a natural nutrient boost:
Vitamin E: Nuts, whole grains, vegetables, vegetable oil, and liver oil.
Vitamin C: Citrus fruit, tomatoes, green leafy veggies, and strawberries.
Vitamin A: Apricots, cantaloupe, squash, broccoli, sweet potatoes, carrots, kale, collards, and prunes.
Selenium: Brazil nuts, fish/shellfish, red meat, grains, eggs, garlic, and milk.
Flavonoids: Soy, red wine, pomegranate, cranberries, blueberries, and tea.
Lignan: Flax seed, barley, rye, and oatsMammalian lignan production from various foods. Thompson, L.U., Robb, P., Serraino, M., et al. University of Toronto. Nutr Cancer. 1991; 16(1):43-52.
Lutein: Dark green fruits and vegetables such as kiwi, spinach, brussels sprouts, kale, and broccoli.
Originally published May 2011. Updated August 2013.
What are antioxidants? And are they truly good for us?
Antioxidants seem to be everywhere; in superfoods and skincare, even chocolate and red wine. Products that contain antioxidants are marketed as essential for good health, with promises to fight disease and reverse ageing.
But are they really as good for us as we’re led to believe?
What are antioxidants?
The term antioxidant covers a wide range of molecules (atoms bound together by chemical bonds) that protect other molecules from a chemical process called oxidation. Oxidation can damage vital molecules in our cells, including DNA and proteins, which are responsible for many body processes.
Molecules such as DNA are needed for cells to function properly, so if too many are damaged, the cell can malfunction or die. This is why antioxidants are important. They can prevent or reduce this damage. In the body, uncontrolled oxidation is typically caused by highly reactive molecules known as free radicals.
Products that contain antioxidants are marketed as essential for good health. Alpha/Flickr, CC BY
What is oxidation?
Oxidation is a common chemical reaction where electrons are transferred from one molecule to another. Electrons are one of the subatomic (smaller than an atom) particles that make up pretty much everything. As electrons move during an oxidation reaction, bonds can be broken and the structure of the molecules changed.
Unpaired electrons make free radicals unstable and highly reactive. Author provided
Not all oxidation reactions are bad. They are essential for life and involved in many important processes. In cellular respiration, glucose (a sugar from the food we eat) is oxidised by oxygen (from the air we breathe), producing carbon dioxide, water and energy to fuel our bodies. Household bleaches oxidise coloured stains into colourless molecules.
Less desirable oxidation reactions include the rusting of metals and oxidative food spoilage.
What are free radicals?
Free radicals are simply molecules with one or more unpaired electrons. Electrons to be in pairs, so unpaired electrons can result in unstable and highly reactive molecules. To become stable, the free radical must steal an electron from another molecule (or give one away). When a molecule loses an electron, that molecule has been oxidised and itself becomes a free radical.
This new free radical can steal an electron from another molecule, starting a chain reaction. This process permanently changes the structure of the molecules, causing irreversible damage.
A free radical can steal an electron from another molecule, which then becomes a free radical.
But if an antioxidant is present, it can donate an electron to the free radical, stabilising it and stopping the chain reaction.
The antioxidant sacrifices itself and is oxidised instead of the other molecule, becoming a free radical.
But un most molecules, the antioxidant is able to stabilise the unpaired electron and does not become highly reactive. This process deactivates the antioxidant.
An antioxidant donates an electron to a free radical and stops the chain reaction. Author provided
Free radicals aren’t always bad for you. Their highly reactive and destructive nature is used by the body’s immune system. Certain white blood cells, called phagocytes, can engulf foreign particles, such as bacteria, then seal them off and release free radicals to destroy them.
Free radicals are generated naturally by our bodies, but can be increased by lifestyle factors such as stress, poor diet, pollution, smoking and alcohol. Our bodies can handle some free radicals, but if too many are formed it can overwhelm the body’s normal defences.
Free radical damage is thought to be one of the causes of ageing and contribute to various diseases. For example, free radical damage to DNA can cause genetic mutations and promote cancer.
All antioxidants aren’t equal
So, if free radicals are dangerous and cause ageing and disease, and antioxidants can neutralise them, then getting more antioxidants should be good for you, shouldn’t it? Unfortunately, it’s not as simple as that. Yes, high antioxidant levels and low oxidative stress are associated with good health, but not all antioxidants are equal.
A healthy diet is the most effective way to get antioxidants. www.shutterstock.com
Antioxidants come from many sources. Some are naturally produced in the body and some naturally occur in foods we eat. Antioxidants (natural or synthetic) can also be added to foods that don’t normally contain them, either for their (supposed) health value or to preserve the food (antioxidants also prevent oxidation in foods).
A healthy diet is the most effective way to get the antioxidants your body needs. Fruits, vegetables, grains, eggs and nuts are all useful sources of antioxidants. Despite the marketing hype, antioxidants found in so-called superfoods are no more effective than those in regular fruit and veg, so you’re better off saving your money.
But it’s a different story when it comes to antioxidant supplements. Research has found antioxidant supplements may cause more harm than good.
A 2012 meta analysis of over 70 trials found antioxidant supplements are ineffective or even detrimental to health.
The reasons are unclear, but the added nutritional benefits from consuming antioxidants in a healthy diet is ly to contribute to this. Also, the high concentrations of antioxidants associated with supplement use can lead to problems.
Superfoods and regular fruit and veg both provide the same types of antioxidants. www.shutterstock.com
Too much of a good thing
There are a number of reasons why high concentrations of antioxidants may be harmful. At high concentrations, antioxidants may:
There is no magic pill, but a healthy diet can provide you with all the antioxidants you need to fight free radical damage.