The Ultimate Guide to Antioxidants

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ultimate guide to antioxidants

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  • Antioxidants are a class of stable molecules that are capable of inhibiting the damaging effects of free radicals
  • Your body naturally circulates a variety of nutrients for their antioxidant properties and manufactures antioxidant enzymes to curb oxidative stress
  • Antioxidants are nature's way of providing your cells with adequate defense against reactive oxygen species (ROS). As long as you have these important micronutrients, your body will be able to resist aging caused by your everyday exposure to pollutants

WARNING!

This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

Antioxidants are, without a doubt, an essential part of optimal health. Even conventional Western physicians now acknowledge the significance of getting sufficient antioxidants from your diet or taking high-quality antioxidant supplements. But do you know how antioxidants function in your body and what types you need?

I have compiled some basic facts about antioxidants to broaden your understanding of these nutrients, so you can better appreciate their importance in helping keep you youthful and healthy.

What Are Antioxidants?

Antioxidants are a class of stable molecules that are capable of inhibiting the harmful effects of free radicals, which are unstable and highly reactive molecular species that target lipids, nucleic acid, proteins and other important molecules. Your body naturally circulates a variety of nutrients for their antioxidant properties and manufactures antioxidant enzymes in order to control oxidative stress.1

Some antioxidants are produced by your body, but some are not. As you age, your body's natural antioxidant production can decline.2 Since antioxidants play a significant role in delaying the aging process by fighting free radicals, losing your body's antioxidant defense could speed up aging.3

The Health Benefits of Antioxidants: How Do They Stop Free Radical Damage?

To fully understand how antioxidants truly benefit your well-being, you should first be familiar with free radical formation. Biogerontologist Denham Harman was the first to discover the concept of free radicals in 1954, while researching an explanation for aging.4,5

Free radicals are a type of a highly reactive metabolite that is naturally produced by your body as a result of normal metabolism and energy production. They are your natural biological responses to environmental toxins like cigarette smoke, sunlight, chemicals and cosmic and man-made radiation. They even are a key feature of pharmaceutical drugs. Your body also produces free radicals when you exercise and when you have inflammation anywhere in your body.6

Free radical molecules are missing one or more electrons, which are responsible for biological oxidation. The incomplete molecules aggressively attack other molecules in order to replace their missing parts. These reactions are called "oxidation."7 Oxidation is essentially biological rusting, as it's an effect caused by too much oxygen in your tissues.8

Free radicals steal electrons from the proteins in your body, which badly damages your DNA and other cell structures. They can create a "snowballing effect," which means that, as molecules steal from one another, each one becomes a new free radical, leaving a trail of biological carnage.9

Free radicals tend to collect in cell membranes (lipid peroxidation), which makes the cell lipids prone to oxidative damage. When this happens, the cell membrane becomes brittle and leaky, causing the cell to fall apart and die.10

Free radicals can severely affect your DNA by disrupting the duplication of DNA, interfering with DNA maintenance, and breaking open or altering its structure by reacting with the DNA bases.11,12 Free radicals are linked to over 60 different diseases, including:13,14

  • Cancer
  • Parkinson's disease
  • Alzheimer's disease
  • Cataracts
  • Atherosclerosis

If your body does not get adequate protection, free radicals can become rampant, causing your cells to perform poorly. This can lead to tissue degradation and put you at risk of diseases. This is where antioxidants come in. Antioxidants are electron donors, so they can break the free radical chain reaction by sacrificing their own electrons to feed free radicals, but without turning into free radicals themselves.15

Antioxidants are nature's way of providing your cells with adequate defense against reactive oxygen species (ROS). As long as you have these important micronutrients, your body will be able to resist aging caused by your everyday exposure to pollutants. If you don't have an adequate supply of antioxidants to help squelch free radicals, then you can be at risk of oxidative stress, which leads to accelerated tissue and organ damage.16

"Numerous studies have confirmed the benefits of antioxidants and the role they play in maintaining good health and reducing your risk of heart disease, Parkinson's, Alzheimer's and cancer."

Antioxidants also help slow down the aging process, which can have immense effects on your skin health.17 Other important benefits of antioxidants include:

  • Repairing damaged molecules — Some unique types of antioxidants may help repair damaged molecules by donating a hydrogen atom. This is very important when the molecule is a critical one, like those that make up the nucleic acids in your DNA.18
  • Blocking metal radical production — Certain antioxidants have a chelating effect that may help keep toxic metals from causing free radical formation and inhibit any chemical reaction from taking place.19
  • Stimulating gene expression and endogenous antioxidant production — Some forms of antioxidants may help stimulate your body's genes and increase your natural defenses.20
  • Providing a "shield effect" — Antioxidants, such as flavonoids, may act as a virtual shield by attaching to your DNA to help protect it from free radical attacks.21
  • Reducing the risk for cancer — Antioxidants may help fight against cancer by interfering with the metabolic activation of chemical carcinogens, causing regression of premalignant lesions and inhibiting the development of tumors.22

In the book "The Antioxidants," author Richard A. Passwater, Ph.D., says that humans have one of the longest natural life spans in the animal kingdom, most likely because of the wealth of antioxidants in our omnivorous diet. Human bodies also produce antioxidant enzymes that cannot be found in other creatures. According to him, "our natural antioxidant processes compensate for one another, covering up momentary deficiencies by their overlap."23

Many people think that taking just a few antioxidants — just one or two mega doses, for example — is sufficient to maintain optimal health. But I strongly disagree. Instead, you must get a wide variety of antioxidants to optimize your well-being.

Different Types of Antioxidants

The science of antioxidants can be quite complex, and this often causes people to be confused about what types they should be taking. In fact, I've been asked several times whether it's necessary to take astaxanthin if you're already taking a resveratrol supplement. The answer is yes — astaxanthin is actually a lipid-soluble antioxidant,24 while resveratrol is a water-soluble antioxidant.25 Each type of antioxidant has its own special function.

When classified according to their solubility, antioxidants can be categorized as either soluble in lipids or fat (hydrophobic) or soluble in water (hydrophilic). Both of these forms are required by your body in order to protect your cells, since the interior of your cells and the fluid between them are composed of water, while the cell membranes themselves are mostly made of fat.26

Since free radicals can strike either the watery cell contents or the fatty cellular membrane, you need both types of antioxidants to ensure full protection from oxidative damage. Lipid-soluble antioxidants are the ones that protect your cell membranes from lipid peroxidation. They are mostly located in your cell membranes.27 Some examples of lipid-soluble antioxidants are vitamins A and E, carotenoids and coenzyme Q10 (CoQ10).28

Water-soluble antioxidants are found in aqueous body fluids, like your blood and the fluids within and around your cells (cytosol or cytoplasmic matrix).29 Some examples of water-soluble antioxidants are vitamin C, polyphenols and glutathione.30

However, solubility is not the only way to categorize antioxidants. They can also be categorized as enzymatic and nonenzymatic:31,32

Enzymatic antioxidants help break down and remove free radicals. They also help flush out dangerous oxidative products by converting them into hydrogen peroxide, then into water. This is done through a multistep process that requires a number of trace metal cofactors such as zinc, copper, manganese and iron.

Enzymatic antioxidants cannot be found in supplements, but instead are produced in your body. The main enzymatic antioxidants in your body are:33

Superoxide dismutase (SOD) — This can break down superoxide into hydrogen peroxide and oxygen, with the help of copper, zinc, manganese and iron. It is found in almost all aerobic cells and extracellular fluids.

Catalase (CAT) — This works by converting hydrogen peroxide into water and oxygen, using iron and manganese cofactors. It finishes the detoxification process started by SOD.

Glutathione peroxidase and glutathione reductase — These are selenium-containing enzymes that help break down hydrogen peroxide and organic peroxides into alcohols. They are most abundant in your liver.

Nonenzymatic antioxidants help convert free radicals into nonradical, nontoxic forms, thereby interrupting free radical chain reactions. Some examples are carotenoids, vitamin C, vitamin E, plant polyphenols and glutathione.34

Antioxidants can also be classified in terms of their molecular size:35

  • Small-molecule antioxidants work by mopping up or "scavenging" the reactive oxygen species and carrying them away through chemical neutralization. The main players in this category are vitamins C and E, glutathione, lipoic acid, carotenoids and CoQ10.
  • Large-protein antioxidants tend to be the enzymatic enzymes outlined above, as well as "sacrificial proteins" that absorb ROS and stop them from attacking your essential proteins. One example of these sacrificial proteins is albumin, which "takes the bullet" for crucial enzymes and DNA.

Isn't it wonderful how nature has equipped you with the perfect combination of different defenses to cover almost every possible biological contingency?

Antioxidants You Should Not Miss Out On

As mentioned, it is crucial that you do not stick to getting just one or two types of antioxidants. You need a wide array of antioxidants to provide you with optimal benefits. Some antioxidants can be produced by your body. These are:

Glutathione — Known as the most powerful antioxidant, glutathione is a tripeptide found in every single cell in your body.36 When others are talking about it they sometimes refer to it as the "master" antioxidant because it's intracellular and has the unique ability of maximizing the performance of all the other antioxidants, including vitamins C and E, CoQ10 and alpha-lipoic acid, as well as the fresh vegetables and fruits that you eat every day.37

Glutathione's primary function is to protect your cells and mitochondria from oxidative and peroxidative damage. It is also essential for detoxification, energy utilization and inhibition of age-related diseases. Glutathione helps eliminate toxins from your cells and protect them against the damaging effects of radiation, chemicals and environmental pollutants.38,39

Your body's ability to produce glutathione decreases with aging.40 However, there are foods you can include in your diet that may help promote glutathione production, such as high-quality whey protein,41 curcumin,42 raw dairy, eggs and grass fed meat.43,44

Alpha-Lipoic Acid (ALA) — Aside from its free radical scavenging abilities, this powerful antioxidant may also help:

Modify gene expression to reduce inflammation

Chelate heavy metals

Enhance insulin sensitivity

Like melatonin,45,46 ALA is an antioxidant that can be easily transported into your brain so it can benefit people with brain diseases like Alzheimer's.47 ALA may also help regenerate other antioxidants like vitamins C and E, as well as glutathione. This means that if your body has used up these antioxidants, ALA may help regenerate them.

CoQ10 (Ubiquinone) — Used by every cell in your body, CoQ10 is converted by your body to its reduced form, ubiquinol, to maximize its benefits.48,49 CoQ10 has been the subject of thousands of studies. Aside from naturally protecting you from free radicals, it also helps:50

Produce more energy for your cells

Support your heart health, immune system and nervous system

Reduce the signs of normal aging

Maintain blood pressure levels within the normal range

As you get older, your body becomes more and more challenged to convert the oxidized CoQ10 to ubiquinol. When this happens, you may need to take a ubiquinol supplement.51

There are antioxidants that cannot be manufactured inside your body and must be obtained from antioxidant-rich foods or potent antioxidant supplements. These are:

Resveratrol — Found in certain fruits like grapes, vegetables, cocoa and red wine,52 this antioxidant can cross the blood-brain barrier, providing protection for your brain and nervous system.53

Resveratrol

Resveratrol has been found to be so effective at warding off age-related diseases that it was dubbed the "fountain of youth."54 Aside from providing free radical protection, this antioxidant may help:55

Inhibit the spread of cancer, especially prostate cancer

Lower your blood pressure

Keep your heart healthy and improve elasticity of your blood vessels

Normalize your anti-inflammatory response

Reduce your risk for Alzheimer's disease

Carotenoids are a class of naturally occurring pigments that have powerful antioxidant properties. They are the compounds that give foods their vibrant colors.56 There are over 700 naturally occurring carotenoids,57 which can be classified into two groups:58

Carotenoids

Carotenes — These do not contain oxygen atoms. Some examples are lycopene (found in red tomatoes) and beta-carotene (found in carrots), which is converted by your body into vitamin A.

Xanthophylls — These contain oxygen atoms. Examples include lutein, canthaxanthin, zeaxanthin and astaxanthin. Zeaxanthin is the most common carotenoid that naturally exists in nature and is found in peppers, kiwi fruit, maize, grapes, squash and oranges.59

Astaxanthin — Although it's technically a carotenoid, I believe this antioxidant deserves its own special mention due to its superb nutritional advantage. Astaxanthin is a marine carotenoid produced by the microalgae Haematococcus pluvialis when its water supply dries up, to give itself protection from ultraviolet radiation.60

Astaxanthin

I believe that astaxanthin is the most powerful carotenoid in terms of free radical scavenging. It is 65 times more powerful than vitamin C, 54 times more powerful than beta-carotene and 14 times more powerful than vitamin E.61

Aside from its ability to cross the blood-brain barrier like resveratrol, astaxanthin can also cross the blood-retinal barrier — something that beta-carotene and lycopene cannot do.62

Astaxanthin is more effective than other carotenoids at "singlet oxygen quenching," a particular type of oxidation caused by sunlight and various organic materials.63,64 It's also 550 times more powerful than vitamin E and 11 times more powerful than beta-carotene at neutralizing this singlet oxygen.65 It may also help:

Support your immune function66

Improve your cardiovascular health by reducing c-reactive proteins (CRP) and triglycerides and increasing beneficial high-density lipoprotein (HDL) cholesterols67

Protect your eyes from cataracts, macular degeneration and blindness68

Reduce your risk of dementia, Alzheimer's and certain types of cancers69

Promote recovery from spinal cord injury70

Reduce inflammation71

Improve your endurance, workout performance and recovery72

Relieve indigestion and acid reflux73

Stabilize your blood sugar levels74

Increase sperm strength and count, which in turn improves fertility75

Protect against sunburn and the damaging effects of ultraviolet radiation76

Reduce the oxidative damage to your DNA77

Relieve the symptoms of different diseases, including pancreatitis,78 multiple sclerosis79 and neurodegenerative diseases,80 among others

To learn more about this antioxidant's benefits, I recommend reading "Research on Astaxanthin Demonstrates Significant Whole Body Benefits."

Vitamin C — This vitamin is a monosaccharide antioxidant that can be obtained from both animals and plants. It's an essential micronutrient for humans.81 Vitamin C plays a role in collagen synthesis, which is an important structural component of your bones, blood vessels, tendons and ligaments.82 It also helps:

Fight oxidation by acting as a major electron donor83

Maintain optimal electron flow in your cells84

Protect proteins, lipids and other vital molecular elements in your body85

The best sources of vitamin C are raw, organic vegetables and fruits, but you can also take it as a supplement or have it administered intravenously (IV).86 When taking a vitamin C supplement, opt for one made with liposomal technology, which makes the nutrient more absorbable to your cells.

Vitamin E — Natural vitamin E is a family of eight different compounds: four tocopherols and four tocotrienols. You can obtain all these vitamin E compounds from a balanced diet composed of wholesome foods.87 However, if you take a synthetic vitamin E supplement, you will get only one of the eight compounds.88

6 Antioxidant Food Sources You Should Add to Your Diet

I believe that when it comes to obtaining nutrients, your diet — not supplements — should be your primary source. If you consume a balanced, unprocessed diet that's full of high-quality, raw organic foods, especially fruits and vegetables, your body will acquire the essential nutrients and antioxidants it requires to achieve or maintain optimal health. Here are some of my top recommendations for antioxidant-rich foods:

Fresh, organic vegetables — Most of the vegetables you eat, especially the green leafy ones, are loaded with potent phytochemicals, which are plant compounds that act as antioxidants. Phytochemicals can reduce inflammation and eliminate carcinogens.89

However, to maximize the antioxidants in vegetables, you must consume them raw, in a state closest to when they were harvested. I highly recommend juicing as one way to absorb all the nutrients in the vegetables — it is one of the healthiest antioxidant drinks you can add to your diet.90 You may also eat the pulp instead of throwing it away. For valuable tips in vegetable juicing, read my article, "Benefits of Juicing: Your Keys to Radiant Health."

Sprouts and microgreens — They're powerful sources of antioxidants, minerals, vitamins and enzymes,91 and they allow you to get the most benefit from a plant in the most biologically concentrated and bioavailable form. My top favorites are pea shoots, sunflower sprouts and broccoli sprouts.

Fruits — Fresh berries like blueberries, blackberries, cranberries and raspberries are the best antioxidant-rich fruits you can consume, as they contain powerful phytochemicals that may help reduce the risk for inflammatory disorders, cardiovascular diseases and cancer.92

Some berries also contain vitamin C, carotenes and carotenoids, as well as nutrients like potassium, iron, calcium and magnesium.93 However, I advise you to consume fruits in moderation, as they contain fructose, which can be detrimental to your health in high amounts.

Nuts — Pecans, walnuts and hazelnuts are excellent antioxidant foods that may help boost your heart health and overall well-being.94,95 Look for nuts that are organic and raw, not irradiated or pasteurized. I do not recommend consuming peanuts, as they are usually pesticide-laden and can be contaminated with a carcinogenic mold called aflatoxin.96

Herbs and spices — Aside from being an abundant source of antioxidants, herbs and spices may have potential anticancer benefits.97 Herbs and spices differ mainly by source, as herbs typically come from the plant's leaves while spices come from the bark, stem and seeds. Both have been used for thousands of years to flavor foods and help treat illnesses.98

Some of your best choices are ground cloves, ground cinnamon, oregano, turmeric, ginger and garlic. Ideally, you should opt only for fresh herbs and spices, as they are healthier and have higher antioxidant levels than processed, powdered versions.99

Another antioxidant source to consider is sedge, specifically Cyperus rotundus. The extracts obtained from the plant’s aerial plants were found to contain multiple flavonoids and phenols, which contribute to its antioxidant, antimicrobial and antigenotoxic properties.100

Organic green teaThis antioxidant-rich drink contains epigallocatechin-3-gallate (EGCG), a catechin polyphenol that's considered one of the most powerful antioxidants known today.101

EGCG helps lower your risk of heart attack, stroke, glaucoma, high cholesterol levels and more.102,103 Studies have also found that it may help improve your exercise performance, increase fat oxidation and even reduce the risk for obesity due to its regulatory effect on fat metabolism.104

However, remember that not all green teas are created equal. Some processed green tea brands can contain very little or no EGCG at all.105 Some tea bags are also contaminated with fluoride or hazardous plastics that can leach into your tea when brewing.106

To ensure you're drinking high-quality green tea, be sure to buy only organic, loose-leaf tea from a reputable source. My top tea choices are organic matcha tea and tulsi tea.

I also recommend consuming high-quality whey protein that's cold-pressed, derived from grass fed cows, and free of hormones, sugar and chemicals. Whey protein provides all the essential key amino acids for glutathione antioxidant production: cysteine, glycine and glutamate.107 It also contains glutamylcysteine, a unique compound that's considered to be the key factor in the glutathione-promoting activity of whey protein mixture.108

Recommended Antioxidant Supplements

As many of you know, I do not recommend taking many supplements, as they cannot replace the nutrients and benefits you can get from whole organic foods. Supplements should only be taken to supplement your diet, and not to completely replace it.

However, due to today's fast-paced and busy lifestyle, many people are now neglecting the importance of consuming whole, organic foods. They do not have time to cook and prepare wholesome meals, causing them to miss out on essential nutrients, including antioxidants. In this case, taking a high-quality antioxidant supplement may be an ideal option. Some of my personal recommendations are:

  1. Astaxanthin
  2. Krill oil
  3. Resveratrol
  4. Acai berry
  1. Vitamin E
  2. Liposomal vitamin C
  3. CoQ10/ubiquinol

However, remember that overloading on antioxidants, especially from supplements, can have negative effects on your health.109 It can be easy to overdose when taking antioxidants as supplements, so always remember the Goldilocks equation: not too many, but not too few.

6 Lifestyle Changes That Help Maximize Your Antioxidant Intake

An antioxidant-rich diet will not work to your advantage if you do not follow a healthy lifestyle. Remember, there are unhealthy lifestyle habits that can promote free radical formation.110

Failure to put a stop to unhealthy habits can result in the levels of free radicals in your body rising to dangerous levels, putting you at risk of inflammation and paving the way for disease and illness. Aside from consuming a wholesome diet, here are a few lifestyle pointers I highly recommend:111

1. Reduce and eventually eliminate sugar (especially fructose) and grains from your diet — According to Dr. Robert Lustig, professor of pediatrics in the Division of Endocrinology at the University of California, San Francisco (UCSF), fructose undergoes the Maillard reaction with proteins, which leads to superoxide free radicals to form in your body. These damaging free radicals can cause liver inflammation similar to that caused by alcohol.112

Fewer sugars and grains (which convert into sugar in your body) in your diet may help decrease your antioxidant stress. Plus, the antioxidants you have will work better and last longer. I also advise against consuming any type of processed foods, especially soda, as these usually contain high amounts of fructose.113

2. Exercise — Exercise may help boost your body's antioxidant production but in a paradoxical way, as it actually creates potent oxidative stress. However, if you do it properly and in moderation, it may help improve your body's capacity to produce antioxidants. This is why I recommend doing short bursts of high-intensity exercises like Peak Fitness instead of prolonged cardio like marathon running, which puts excessive stress on your heart.

3. Manage your stress — Stress can exacerbate the inflammation and poor immune function caused by free radical formation. Studies have found significant links between acute and/or chronic emotional and psychological stress and numerous health issues.114

To manage your stress effectively, I recommend using energy psychology tools, like the Emotional Freedom Techniques (EFT). EFT is a form of psychological acupuncture — but without the needles — that can help you can correct the emotional short-circuiting that contributes to your chronic stress.

4. Avoid smokingSmoking forms free radicals in your body, which accelerates the aging process.115 Even being around people who smoke can affect your health by narrowing the blood vessels in the outermost layer of your skin, which limits its blood flow and impairs its ability to absorb oxygen and nutrients, leading to accelerated wrinkling and aging.116

Smoking also contributes to the pathobiology of various diseases, the most well-known of which is lung cancer.117

5. Get enough sleep — High-quality sleep is one of the cornerstones of good health, and science has now established that a sleep deficit can have severe far-reaching effects on your health.118 Six to eight hours of sleep per night seems to be the optimal amount for most adults, and too much or too little can have adverse effects on your well-being. If you are having problems sleeping, I recommend reading "Top 33 Tips to Optimize Your Sleep Routine."

6. Try grounding — Also called "earthing," grounding may provide potent antioxidant effects that help alleviate inflammation in your body. Walking barefoot on the earth may help you absorb large amounts of electrons through the soles of your feet.119

The best way to incorporate grounding into your lifestyle is to exercise barefoot outdoors, such as on the beach or in your yard. It's one of the most wonderful, inexpensive and powerful ways to uplift your health.

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