Antioxidants seem to be everywhere.
You may start to hear about antioxidants and the benefits of antioxidants as soon as you start to pay attention to your diet, when you turn on the news, or when you read about the most common health conditions and natural remedies in today’s world.
But how much do you really know about antioxidants? How much do you need to know?
What do antioxidants do? Where do you get them from? Can they really help keep you healthy? How do you know if you are getting enough? What are the different types of antioxidants?
The subject of antioxidants is a big one, but take heart. This article and the other ones in this series will help answer these and more questions about antioxidants. You can learn about the benefits of antioxidants, how they work, and where you can find them. You can also find out which ones you might want to consider supplementing to get even more benefits.
What Are Antioxidants and Free Radicals?
Antioxidants and free radicals have opposite effects in your body. In general, antioxidants have positive effects, while free radicals can be harmful. They can injure the membranes that surround and protect your cells, damage your genetic material or DNA, and interfere with proteins that are responsible for most of the activity in your cells.
Reactive Oxygen Species, Free Radicals, and Oxidative Stress
Reactive Oxygen Species = ROS
ROS cause damage to your cells.
Free Radicals are ROS that are reactive because they have an unpaired electron.
ROS are generated by:
- body processes (eg. metabolism, breathing)
- environmental factors (eg. pollution, medication, unhealthy food)
Oxidative Stress is a condition resulting from dominant free radicals.
Reactive oxygen species, or ROS, get their name from their instability. They are able to react with cellular components in your body, such as proteins, fats, and DNA. According to a review article published in the “Research Journal of Immunology” in 2010, these interactions can cause damage to your cells. Free radicals are ROS that lead to a chain of instability because when they react with another compound, they cause that compound to become a reactive oxidative agent. Free radicals are reactive because they have an unpaired electron rather than a more stable pair of electrons in their outer shell.
Some reactive oxygen species, or ROS, result from processes in your body. These ROS are endogenous. Your body generates them when you breathe, when you metabolize food, and when your body synthesizes new compounds such as cell walls.
Your body can also generate ROS when you are exposed to certain compounds in the environment. You will have higher levels of reactive species when there is pollution around you, when you take certain medications such as some anti-cancer drugs and painkillers, and when you have an excessive amount of alcohol. Even too much exercise and consuming unhealthy food components such as sugar and saturated fat can drive up your levels of reactive oxygen species.
Examples of free radicals include reactive nitrogen species, such as nitric oxide and nitrous acid, and reactive oxygen species. These include breakdown products of peroxides, such as superoxide, hydroxyl, peroxyl, and alkoxyl. When free radicals become dominant in your body, the condition is known as oxidative stress.
Antioxidants and Free Radicals
Antioxidants neutralize free radicals which results in less Oxidative Stress.
Therefore, high antioxidant levels = Less risk of cellular damage.
Food & supplements can affect the amount & activity of antioxidants.
Luckily, there is a way to prevent and fight oxidative stress naturally. The role of antioxidants is to do just that. How do antioxidants work? As their name implies, they fight the harmful process of oxidation. They help neutralize free radicals, so the compounds are less reactive in your body and cause less damage. You can count on less oxidative stress and less cellular damage when you have a high amount of antioxidants compared to free radicals.
Given the high amounts of reactive species that can occur in your body and the health risks of oxidative stress, it is good that there is an abundance of antioxidants that can fight oxidation and help prevent these harmful effects. Antioxidants that your body produces and that you can get from food and supplements all help mitigate the possible effects of harmful reactive species. What you eat and the supplements you take can both affect the amount and activity of antioxidants in your body.
Health Conditions Linked to Oxidative Stress and Low Antioxidant Levels
Most chronic diseases have some link to Oxidative Stress & inadequate antioxidants.
To name a few:
- Multiple Sclerosis
- Parkinson’s Disease
- Huntington’s Disease
- Alzheimer’s Disease
- Macular Degeneration
Research suggests that having adequate antioxidant levels can lower your risk for these conditions.
Nearly all of the common chronic conditions in today’s world have at least some link to oxidative stress and inadequate antioxidant levels or function in the body. A large body of research shows that higher levels of antioxidants and prevention of oxidative stress can lower your risk for many health conditions.
As explained in the “Research Journal of Immunology,” complications of diabetes are largely linked to oxidative stress that affects the cardiovascular system. Controlling blood sugar and getting enough antioxidants can help prevent some complications.
The National Cancer Institute explains that cancer develops in part due to cellular damage that can result from high levels of oxidative stress. Higher levels of antioxidants may help prevent oxidative stress and the formation and propagation of cancer. A good amount of research has looked at dietary and supplemental antioxidants and cancer, and there is some suggestion that getting plenty of foods with antioxidants can help protect you.
Another chronic condition linked to lower levels of antioxidants is multiple sclerosis, which is a degenerative condition that progressively attacks the myelin sheaths of your nerve cells. Demyelination interferes with your brain’s ability to communicate with the cells in your body, leading to symptoms such as trouble seeing, muscle weakness or lack of coordination, and a weakened immune system. A study in the “European Journal of Neurology” found a connection between a specific type of multiple sclerosis known as neuromyelitis optica and low antioxidant levels.
Neurological diseases such as Parkinson’s and Huntington’s disease are linked to lower levels of antioxidants, and Alzheimer’s is another chronic condition related to oxidative stress. The benefits of antioxidants extend as far as the eyes, with cataracts and macular degeneration being linked to oxidative stress.
Different Types of Antioxidants
- Amino Acids
- Metabolic Factors
There are many ways to classify the vast numbers of antioxidants that are common in your body.
One way is to consider their general functions and sources.
- Vitamin A
- Vitamin C
- Vitamin D
- Vitamin E
- Vitamin K
- Folic Acid
Medline Plus describes vitamins as “substances that your body needs to grow and develop naturally.” Vitamins are also involved in processes such as energy metabolism and the repair of your cells and tissues. While there are 13 vitamins, only some of them also have antioxidant functions.
- Vitamin A takes the active forms of retinol, retinoic acid, and retinal in your body. You can get it from liver, eggs, butter, and many fruits and vegetables.
- Vitamin C is also known as ascorbic acid. Good sources include bell peppers, tomatoes, strawberries, kiwis, citrus fruits, and other fruits and vegetables.
- Vitamin D is known as the sunshine vitamin because your body can produce it when ultraviolet radiation from the sun hits your skin. Food sources include oily fish such as sardines and mackerel, eggs, and fortified milk.
- Vitamin E works closely with vitamin C to protect your body’s cells. You can get it from vegetable oils, wheat germ, and nuts and peanuts.
- Vitamin K is known as the coagulation vitamin because it is necessary for the series of events that allow your blood to clot, but it also has antioxidant properties. It helps protect against oxidative damage to the fatty or lipid layers of your cell membranes or walls, according to research published in “Biochemical Pharmacology.”
- Folic acid is required for heart health and proper fetal development, but research in “Toxicology and Industrial Health” suggests that it can also promote antioxidant activity of certain enzymes in your body.
The essential minerals are the ones that you need to get from your diet or supplements to stay healthy. Many of them have antioxidant properties or are necessary to promote antioxidant activity of other compounds in your body.
They include copper, manganese, iodine, zinc, selenium, and magnesium.
Medline Plus explains that you can generally meet your mineral requirements by eating a wide variety of nutritious foods in your diet. Vegetables, lean proteins, dairy products, nuts, and whole grains are particularly high in certain minerals.
However, supplements can be necessary or healthy in some cases.
- Allyl Sulfides
- Phenolic Acids
Phytochemicals are chemicals produced by plants. However, as Linus Pauling Institute explains, they can also have nutritive properties. There are many phytochemicals, or phytonutrients, with antioxidant properties, and it is likely that still more remain to be discovered. Phytochemicals are among the more common antioxidants.
Among the more common phytochemicals are carotenoids, such as lycopene, beta-carotene, and lutein, which are found in many yellow and orange fruits and vegetables.
Flavonoids, such as anthocyanidins and flavonols, are polyphenolic compounds found in berries, chocolate, tea, grape skins, apples, and citrus peel.
Allyl sulfides are in garlic and onions, resveratrol is in red wine, and glucosinolates are found in certain green leafy vegetables.
Soy contains phytoestrogens, and ellagic acid, caffeic acid and gallic acid are among the phenolic acids found in a variety of fruits and vegetables.
Antioxidant Enzymes and Coenzymes
- Glutathione Reductase
- CoEnzyme Q10
- Thiol antioxidants
Enzymes are compounds that help reactions in your body proceed. Coenzymes assist in enzymatic reactions.
Both enzymes and coenzymes can have antioxidant properties.
Superoxide dismutase, or SOD, glutathione reductase, coenzyme Q10, catalase, and L-carnitine are among the antioxidants enzymes that your body produces.
Glutathione peroxidase, thioreductase, and alpha lipoic acid are antioxidant amino acids, or thiol antioxidants.
Hormones regulate all sorts of aspects of your body’s environment and growth, such as nutrient metabolism, thermal regulation, and keeping blood sugar stable.
Melatonin not only regulates your sleep cycle, but also scavenges free radicals and stimulates the antioxidant activity of certain enzymes.
Dehydroepiandrosterone, or DHEA, is another antioxidant, although its more well-known role is as a steroid hormone that can boost muscle mass.
Metabolic Factors and Byproducts
- Uric Acid
Your body is a complex organism, and there are all kinds of reactions occurring nearly constantly. These can involve antioxidants.
For example, bilirubin is a breakdown product of your red blood cells at the end of their lifespan, and it can fight oxidation.
Similarly, uric acid is a “waste product” that has beneficial effects.
- Citric Acid
- Oxalic Acid
- Phytic Acid
The vast number of antioxidants includes those that are less well-categorized. For example, citric acid is used commercially as an antioxidant and preservative, and it is also found in citrus fruits.
Oxalic acid is in many dark green vegetables such as spinach and broccoli, while phytic acid is in a variety of grains, nuts and seeds, including corn, oat, hazelnuts, and sesame seeds.
These acids have the negative reputation of causing kidney stones or interfering with nutrient absorption, but they can also be beneficial in certain amounts due to their antioxidant properties.
Classes of Antioxidants
There are other ways of classifying antioxidants rather than what type of nutrient they are, as described above.
You may hear about antioxidants divided into fat-soluble versus water-soluble compounds, or into endogenous versus exogenous compounds.
Fat-Soluble versus Water-Soluble Antioxidants
These can be stored in body fat.
- Vitamins E, D & K
- Alpha Lipoic Acid
One way to categorize antioxidants is whether they are fat-soluble or water-soluble. The solubility of a compound helps determine how your body metabolizes and stores it.
Antioxidants that are soluble in fat are able to mix with fat, and your body can store them in your fat. This means that your body can store up larger amounts of these compounds for longer periods of time.
Examples of fat-soluble antioxidants include the fat-soluble vitamins vitamin E, vitamin D, and vitamin K, along with alpha-lipoic acid and the carotenoids.
Not stored in the body so must be consumed regularly.
- Vitamin C
- Folic Acid
Water-soluble compounds mix with water and not with fat.
Instead of storing them up in your fat, your body uses what it needs at the time, and excretes the rest.
You cannot store up large amounts of water-soluble nutrients for long periods of time, so you need to get them regularly in your diet to be sure your body has enough at all times.
The vitamins vitamin C and folic acid are water-soluble antioxidants, as are n-acetyl cysteine and glutathione.
Endogenous versus Exogenous Antioxidants
A balance of endogenous & exogenous antioxidants is necessary for optimal health.
Endogenous Antioxidants are produced in your body.
Examples are Antioxidant:
- Metablic Factors
- Antioxidant Byproducts
Exogenous Antioxidants come from another source eg. food or supplements.
Examples are Antioxidant:
Some Antioxidants such as L-carnitine & Vitamin D can be both.
A compound is endogenous if your body produces it. It is exogenous if your body gets it from another source, such as in your food or from a supplement. As an article published in 2010 in the journal “Oxidative Medicine and Cell Longevity” explains, a balance between levels of exogenous and endogenous antioxidants is necessary for minimizing oxidative stress and the resulting damage and negative consequences of an oxidative environment.
Endogenous compounds that your body produces include hormones, such as melatonin and DHEA. Other endogenous antioxidants include many of the enzymes that contribute to your body’s metabolism and well-being. Examples include superoxide dismutase, catalase, glutathione peroxidase, and glutathione.
Bilirubin is a waste product that results when your body breaks down heme as part of the normal pathway of breaking down red blood cells, while uric acid results from the normal breakdown of purine nucleotides, found in foods such as red meat and seafood.
While your endogenous antioxidants are necessary and quite powerful, you also need to get exogenous antioxidants from food or supplements to promote optimal antioxidant activity in your body and fight oxidation as much as possible. The main exogenous antioxidants include vitamins, minerals, and phytonutrients that you get from your diet, with vegetables, fruits, and whole grains being among the top sources.
Many antioxidants can be both endogenous and exogenous. For example, the Linus Pauling Institute explains that your body produces L-carnitine, making it an endogenous antioxidant. However, you can also get it from your diet, in sources such as meat and dairy products, and from supplements.
Another example of an antioxidant that is both endogenous and exogenous is vitamin D. It is exogenous because you can get this nutrient from oily fish such as salmon and herring, eggs, and fortified milk, but healthy individuals can also produce it when you are exposed to UV radiation from the sun. Your skin, liver, and kidneys all contribute to the production of the active form of vitamin D in your body.
Antioxidants in Everyday Food
There is so much hype about antioxidants that you may be surprised at how many you can get from everyday foods. Many nutrient-dense foods have high levels of one or more antioxidants that can help keep you healthy.
Examples of Antioxidants in Your Food
You can get plenty of oxidants from eating healthy foods.
Antioxidants in plant food sources include:
- Vitamin C
- Vitamin K
Antioxidants in animal source foods include:
- Vitamin E
Name a nutrient-rich food, and there is a good chance it contains antioxidants. Fruits and vegetables may come to mind first. They can provide antioxidants including vitamin C, carotenoids such as beta-carotene, lutein and zeaxanthin, and lycopene, flavonoids including anthocyanins, vitamin K, and coenzyme Q10.
The list of antioxidants in healthy foods continues. Animal source foods such as beef, chicken, dairy products, and seafood provide carnitine and CoQ10, not to mention supportive cofactors such as iron, copper, and zinc. Peanuts and nuts have vitamin E and unsaturated fats, and antioxidants in whole grains include selenium, flavonoids, and unsaturated fats.
You can get plenty of antioxidants by putting together healthy meals and snacks. Each of the following examples is packed with a range of antioxidants.
- Oatmeal made with skim milk or soy milk and served with pecans and berries.
- A bean and cheese burrito with avocado, salsa, and grilled eggplant on a whole grain tortilla.
- Vegetarian chili with beans, tomatoes, and soy protein chunks.
- Spinach salad with raspberries, sliced almonds, olive oil-based vinaigrette, and bell pepper slices.
- Baked chicken breast with roasted sweet potatoes and brussels sprouts brushed with olive oil.
- Grilled salmon with asparagus and brown rice.
- Sliced apples with peanut butter.
Other Healthy Nutrients in Foods
High-antioxidant foods also contain many other beneficial nutrients.
- Dietary Fiber
The beauty of eating whole foods to get your antioxidants is that these foods come as a package. By eating high-antioxidant foods, you are getting not only a good dose of antioxidants, but in most cases, a range of other nutrients as well. These can add to the benefits you are getting from antioxidants.
Here are a few examples of nutrients found in some of the foods you might be eating when you are looking for antioxidant-rich choices.
Potassium is a mineral that works opposite to sodium. It can help lower blood pressure, as well as lower risk for stroke and osteoporosis, or low bone density and a high risk of fracture. Good sources include vegetables, fruit, and beans.
Dietary fiber is a type of carbohydrate, but it is different than carbohydrates such as sugars and starches because your body does not digest it the same way. It does not spike your blood sugar; instead, it helps stabilize blood sugar. Fiber also helps lower cholesterol and prevent constipation. Sources include vegetables, fruit, whole grains, nuts, and beans.
Magnesium is a mineral linked to heart health, healthier blood pressure, and lower risk for osteoporosis. It also supports the antioxidant activity of glutathione. You will get it if you eat whole grains, green leafy vegetables, fish, and nuts.
Momentum Towards a Healthier Diet
Eating high-antioxidant foods results in a healthier diet overall.
Unhealthy components that will be reduced include:
- Trans Fats
- Added Sugars
- Refined Starches
As you can see from the above examples of additional nutrients in high-antioxidant foods, eating these types of foods helps you choose a healthier overall diet. Foods with natural antioxidants tend to be less processed. By steering clear of processed foods, you are not only likely to get higher amounts of vitamins, minerals, dietary fiber, and other nutrients, but lower amounts of unhealthy components, such as the following.
These are the worst type of worst type of fat. They can raise levels of “bad” LDL cholesterol, lower levels of “good” HDL cholesterol, and raise your risk for heart disease. They are in processed snack foods such as some cookies and crackers, as well as fried foods such as French fries, doughnuts, and fried chicken.
Sodium is an essential mineral but one that most people get in excess. Too much sodium leads to higher blood pressure, which increases your risk for heart disease and stroke. Besides being in salty foods such as pickles and soy sauce, sodium can be high in other processed foods, including fast food, frozen foods, canned soups, and surprising sources such as bread and other baked goods.
Added sugars can taste good but have no nutritional value. They can spike your blood sugar levels and increase your carbohydrate and sugar cravings. Unlike natural sugars, which tend to be in nutritious foods such as fruit and dairy products, added sugars are usually in less healthy foods, such as sugary drinks, baked goods, and ice cream.
Refined starches can spike blood sugar and add extra calories without nutrients. Examples of foods high in refined starches include white bread, rice, and pasta, along with refined cereal.
The foods high in antioxidants include vegetables, fruits, whole grains, lean proteins, legumes such as beans and lentils, and nuts. By choosing these sorts of unprocessed foods with high levels of antioxidants, you will probably be eating fewer junk foods and getting lower levels of unhealthy fats, sodium, added sugars, and refined starches.
Even with a healthy diet filled with high-antioxidant foods, you can possibly derive more benefits from antioxidants. Antioxidant supplements can supply nutrients that you may not be getting from your diet. They can also provide amounts of these nutrients that are higher than you might otherwise be able to get from eating a varied diet filled with healthy foods.
Supplementing Dietary Deficiency
Some diets (for example, the hCG diet protocol) may be low in certain antioxidants.
Even if your diet is balanced, you might supplement with certain antioxidants that are more difficult to come by.
- Vitamin E
Some dietary patterns might leave you low in certain antioxidants or even without certain ones entirely, especially if your diet excludes certain food groups. Your diet could, for example, be completely lacking in the reddish colored pigment astaxanthin if you are vegan or vegetarian, or if you simply do not eat much red seafood, such as shrimp, salmon, or red trout.
It is easier than you may think to take in less than optimal amounts of certain antioxidants. For instance, you could be low in vitamin E if you have a very low-fat diet, since the best sources of this fat-soluble vitamin include high-fat foods such as vegetable oils, avocados, and nuts. You are unlikely to get much resveratrol unless you regularly drink red wine. Vegetarians and vegans can be low in long-chain omega-3 fatty acids, which are found in fatty fish and other seafood, but have a world of heart health and other benefits.
Even if your diet is generally balanced, you might choose to supplement with certain antioxidants that are more difficult to come by. For example, the National Center for Complementary and Integrative Health reports that acai may have antioxidant properties, but you may not get much acai in your regular diet. Acai juices, powders, and tablets can give you higher doses of this potentially powerful antioxidant without needing to include fresh acai berries in your regular meals. As another example, phytoestrogens are most commonly found in soy products, which you might not be including in your regular diet.
Boosting Intake for Specific Benefits
Some people take antioxidant supplements for a specific health benefit, as disease prevention or treatment.
- Vitamin E for Cardiovascular health
- CoQ10 for Neurological health
- Omega 3 for Blood Sugar Control
Some people take antioxidants for specific health benefits, such as disease prevention or treatment, or athletic performance. The Linus Pauling Institute explains that while your body can produce carnitine and you can get it from your diet, additional amounts may reduce the effects of heart disease and heart failure.
Some evidence shows the potential for antioxidant vitamin supplements to provide health benefits. An article published in the “British Medical Journal” in 2013 analyzed published studies on the effects of certain vitamin and antioxidant supplements on cardiovascular events and deaths. Vitamin E supplementation was associated with lower risk of myocardial infarction, or heart attack, compared to control groups who did not supplement.
There is a potential for certain antioxidant supplements to be useful in the prevention, treatment, and management of some of the other diseases linked to oxidative stress. For example, the Linus Pauling Institute explains that Parkinson’s disease patients have lower Coenzyme Q10 levels than healthy controls, and some studies have shown a benefit to supplementation. Similarly, levels are typically low in Huntington’s disease, and supplementation can reduce symptoms.
In maternally inherited diabetes mellitus linked to a mutation in mitochondrial DNA, CoQ10 supplementation can slow the development of complications such as deafness. In the more common type 2 diabetes, supplementation with antioxidants from vitamin C and omega-3 fatty acids to resveratrol and flavonoids may improve insulin sensitivity and help control blood sugar levels. While cancers are varied and complicated, you may be able to lower your risk for certain ones by taking supplements.
Supplements for Athletic Performance
Antioxidants are also used to improve athletic performance.
In addition, some people take antioxidants to improve athletic performance. For example, carnitine may help increase the maximal amount of oxygen you can take in, while reducing the amount of plasma lactate that your body produces as you fatigue. However, there is no conclusive evidence about these possible benefits.
Coenzyme Q10 is another antioxidant supplement that can potentially improve aerobic and anaerobic athletic performance, but again, the evidence is mixed. It is not certain that taking antioxidant supplements will improve your recovery or physical performance.
Safety of Antioxidant Supplements
Consult your doctor before beginning any new supplement.
- You are on medications
- You have a health condition
- You are pregnant or breastfeeding
You should consult your doctor before taking any kind of dietary supplement to be sure it is right for you. Ask which antioxidant supplements can be beneficial for you, and be sure to ask whether the supplements you are considering are safe to take with any other supplements or prescription or over-the-medications you may be taking.
Some supplements can be dangerous if you take too much, if you have any kind of health concerns such as liver or kidney disease, or if they interact with any of your medications or other supplements. Women who are pregnant or nursing should be especially careful before taking supplements, since what they take may affect the growing and developing fetus or baby.
Pitfalls of the Dietary Supplement Health and Education Act of 1994
Only use trusted suppliers and brands of antioxidant supplements.
Another caution is to be sure to get your supplements only from reputable sources. Find a trusted supplier and brand for each supplement that you are considering. While the Food and Drug Administration tightly regulates food and pharmaceuticals or drugs so you can be certain they are pure and of high quality, the FDA has far less ability to control dietary supplements due to the Dietary Supplement Health and Education Act of 1994, or DSHEA.
Under DSHEA, dietary supplements may only be made with pure ingredients and they must be labeled properly. While this sounds good, another part of the act says that manufacturers are responsible for complying. In practice, the FDA has very little oversight of the dietary supplement industry and instead leaves it up to manufacturers to produce high-quality, safe supplements that are as effective as claimed. Buyer, beware!
Looking for Quality in Your Supplements
Ask for recommendations from you healthcare provider to find pure, uncontaminated antioxidant supplements.
You can take steps to protect yourself from contaminated or impure antioxidant supplements. Ask your healthcare provider to recommend a brand that he or she trusts. You can also depend on the U.S. Pharmacopeia, or USP, for help. The pharmacopeia is a collection of product quality standards published by the United States Pharmacopoeial Convention, which is a non-profit organization. Antioxidant supplements meeting USP standards and verification are more trustworthy than other supplements.
Antioxidants can be some of your biggest allies when you are trying to stay healthy. They fight potentially harmful free radicals and reactive oxygen species, and help prevent your body from being overloaded with oxidative stress.
There are all sorts of antioxidants, from ones your body makes to those which you can get from foods and supplements. Dietary antioxidant supplements can help you boost your intake and levels, with some potential benefits depending on the type.