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sulforaphane in broccoli sprouts

The Best Antioxidant Supplements for 2020

What are the most powerful antioxidant supplements?

Coenzyme Q-10 (Ubiquinol)
Alpha Lipoic Acid (ALA)
Vitamin C
PQQ (pyrroloquinoline quinone)

What are antioxidants?

Antioxidants are powerful compounds that slow down the oxidation process. Oxidation is a chemical reaction that can create free radicals. Free radicals can cause damage and inflammation to your cells.

What are the benefits of antioxidants?

Antioxidants lower inflammation and oxidation in the body which causes cholesterol to oxidize and form plaque. By lowering the oxidative stress in your body you can reduce your odds of developing cardiovascular disease and maintain efficient cellular and mitochondrial health.

Oxidative damage in DNA can also contribute to cancer and neurodegenerative diseases like dementia and Alzheimers.

This article will focus on the most powerful antioxidants according to science.

Inflammation and oxidation contribute to the formation of plaque and calcification in the cardiovascular system.

It’s well known that those on a Ketogenic Diet will sometimes develop high cholesterol. We have to stop thinking of “high cholesterol” as a dirty word. It’s the inflammation and oxidation that causes cholesterol to oxidize and form plaque.

Glutathione: The most powerful antioxidant

Several antioxidant enzymes such as superoxide dismutase, catalase, and glutathione protect DNA from oxidative stress.

Master antioxidant glutathione
Master antioxidant glutathione

Glutathione is the king of antioxidants, but it is unclear whether taking exogenous glutathione actually raises the body’s glutathione levels. Glutathione is poorly absorbed by the body according to the study.

As you can see it’s also very expensive, so I didn’t include glutathione in my list of the best antioxidants.


sulforaphane in broccoli sprouts
Sulforaphane is the ultimate antioxidant

It’s safe to say that sulforaphane (SFN) is by far the most potent antioxidant identified to date. The below graph shows the antioxidant bioavailability of sulfuraphane (SFN). When it comes to the effectiveness of antioxidants, bioavailability is the key.

powerful-antioxidant values

Glucoraphanin is actually the precursor of SFN. It is found in cruciferous vegetables such as broccoli sprouts and to a lessor extent in radish sprouts, mustard seed powder, cabbage, cauliflower, and kale. When you break the plant cell wall such as when chewing, the glucoraphanin comes in contact with the enzyme myrosinase and it forms sulforaphane (SFN).

So it’s a little tricky to actually get SFN because myrosinase is not stable when heated up past 60C degrees (140F). So chopping (blending) the sprouts or broccoli florets and then lightly steaming is the optimum way to convert the glucoraphanin into sulforaphane.

(SFN) can easily be classified as the best antioxidant.

“Cutting, chewing, or otherwise disrupting the broccoli plant cell structure initiates the synthesis of sulforaphane. The group found that 3-day-old (broccoli) sprouts of cultivars of certain crucifers contained 10–100 times higher concentration of Glucoraphanin than the corresponding mature plants.”

Sulforaphane and Other Nutrigenomic Nrf2 Activators

Sulforaphane is a powerful isothiocyanate and the health benefits are almost too numerous to list. But here is a list of proven health benefits of sulforaphane: (Source: Broccoli or Sulforaphane: Is It the Source or Dose That Matters?)

  • Aflatoxin Toxicity
  • Air Pollution Detoxification
  • Arthritis
  • Asthma and allergic Responses
  • Cancer prevention
  • Improvement of autism in children
  • Type 2 diabetes and metabolic syndrome
  • Helicobacter Pylori Infection
  • NASH/NAFLD (Fatty Liver)
  • Neurodegenerative diseases
  • Reduces inflammation

“We report that a short-term administration of sulfo­raphane was sufficient to significantly increase peripheral (glutathione) GSH levels in human subjects.

Sulforaphane Augments Glutathione and Influences Brain Metabolites in Human Subjects

N-Acetylcysteine NAC

The antioxidant N-Acetylcysteine NAC
N-Acetylcysteine NAC

I also didn’t include NAC in my review. It’s an immensely powerful antioxidant and should definitely be included as one of the best antioxidants. However, I recently wrote an in-depth review of NAC called:

Keto Diet and Fatty Liver

So if you want to read more about NAC and how it can detoxify your liver I would highly recommend that article.

PQQ (pyrroloquinoline quinone)

The other powerful antioxidant that I am not going to focus on today is PQQ. I recently wrote an article on Speed Keto. In that article, I discussed PQQ as a way to speed up the process of getting into ketosis and becoming fat adapted. pyrroloquinoline quinone can help regenerate new keto-friendly mitochondria.


Fisetin is a powerful antioxidant

After sulforaphane, one of the most powerful antioxidants is fisetin. It looks to have the most promising cellular repair properties. Fisetin (3,3′,4′,7-tetrahydroxyflavone), is a botanical flavonoid found in the following fruits and vegetables:

  • Strawberries
  • Apples
  • Persimmons
  • Grapes
  • Onions
  • Cucumber

However it would be unrealistic to eat enough fruits and vegetables to obtain any benefit from fisetin. You need to consume the concentrated fisetin extract.

“The highest concentration of fisetin was found in strawberries (160 μg/g)”

Fisetin: A Dietary Antioxidant for Health Promotion

This study titled, “A method to screen for the antioxidant effect of compounds on low-density lipoprotein (LDL),” shows Fisetin inhibits human low-density lipoprotein (LDL) oxidation in vitro. In other words, it slows down cholesterol’s oxidative damage and might reduce cardiovascular disease.

In this study, Fisetin was reported to be the most potent senolytic compound. Senolytics are small molecules that can selectively induce death of senescent cells and improve health in humans. Senescent cells are damaged cells and cause inflammation and dysfunction. In other words, fisetin can destroy damaged cells which stimulate the biogenesis of new, younger cells.

Fisetin is a powerful antioxidant with potential in extending health and lifespan.

“Telomere damage, epigenetic dysregulation, DNA damage, and mitochondrial dysfunction are primary drivers of damage in aging.”

Senescence as a central hallmark of aging.

The problem with fisetin, as with most antioxidants, is the dosage. Most of the research that I found was done on rodents and used between 40 and 50 mg/per kg body weight. That translates to almost 3600 milligrams for a 200-pound human. Most dosages that I saw being sold on amazon were only 100-350 milligrams.

You can’t always equate rodent doages with human dosages, so it might have value at smaller doses in humans. However, I haven’t seen any scientific human studies at the lower doses.

Lazy Keto contributes to oxidation

The ingestion of vegetable and seed oils are one of the leading causes of oxidation. That is why the type of fats we eat on the Ketogenic Diet is so important.

There are literally hundreds of different antioxidants. However, extensive research, these (arguably) are the most powerful antioxidants to support a Ketogenic Diet. I will caution you however that the science on antioxidants is mixed. Most antioxidants except sulforaphane have limited bioavailability.


Astaxanthin is the best antioxidant for the skin
Astaxanthin is the best antioxidant for the skin

Astaxanthin (ASX) is another powerful antioxidant. It’s a ketocarotenoid metabolite naturally synthesized by bacteria, microalgae, and yeasts. ASX is the compound that gives krill, lobsters, and salmon their orange-red pigment.

It’s safe to say that Astaxanthin is the best antioxidant for the skin.

This study from the US National Library of Medicine shows astaxanthin is especially good for the skin, reducing wrinkles, age spots and improving moisture and elasticity. The study further goes on to give astaxanthin credit for protecting the skin against radiation damage. It (Astaxanthin) (ASX) also appears to be a natural sunscreen.

The beauty of ASX is it has been shown to be effective at relatively low doses of between 6-12 mg. However, ASX should be consumed together with dietary fats to optimize bioavailability.

ASX pairs well with krill oil. The omega 3 fats in the krill oil are also good for your skin and work synergistically with astaxanthin. This combination will help you speed up your keto results and look better in the mirror.

ASX is really keto-friendly because as we lose weight on the ketogenic diet we tend to develop loose skin. It can also help keep the skin tight, supple and elastic and less susceptible to wrinkles


Quercetin: one of the best antioxidants
Quercetin: one of the best antioxidants

Quercetin is a phenolic flavonoid (antioxidant) and is one half of the rutin molecule. It has demonstrated promising biological functions including anticarcinogenic, anti-inflammatory and antiviral.

It looks like most of the studies are done with 500 mg of quercetin along with 250 mg of vitamin C. In this study, 60 male students with an athletic history of at least 3 years were given the quercetin-vitamin C combo for 8 weeks. 

Lean body mass, total body water, basal metabolic rate, and total energy expenditure increased significantly.

Additionally, this study showed quercetin-vitamin C was effective in reducing oxidative stress and reducing inflammatory biomarkers including CRP (C Reactive Protein) and IL-6.

Treatment with quercetin has been shown to prevent liver damage. Flavonoids have been shown to reduce the risk of coronary heart disease, hypercholesterolemia (high cholesterol), atherosclerosis, and heart failure. Source: International Journal of Medical Sciences.

The antioxidant-rich foods that contain Quercetin are:

  • red onions
  • apples
  • berries
  • Brassica vegetables
  • capers*
  • grapes
  • shallots
  • tea
  • cabbage
  • tomatoes
  • seeds
  • nuts
  • mulberries
  • broccoli sprouts and florets
  • radish sprouts
  • soybeans (Natto)
  • peanuts
  • red wine
  • *Capers (raw) has the highest concentration of quercetin at 234 mg/100 g.

Coenzyme Q-10 (Ubiquinol)

Coenzyme Q-10 Antioxidant
Coenzyme Q-10 Antioxidant

Coenzyme Q-10 (CoQ10) is a powerful antioxidant and probably the most common antioxidant available. Also known as ubiquinone, it gained its popularity along with the massive increase in the prescription of statin drugs.

Statins are well known to deplete CoEnzyme Q-10 and doctors quite often recommend CoEnzyme Q-10 supplements along with statins.

It helps provide energy to the mitochondria. Coenzyme Q10 also benefits people with heart failure, high blood pressure, gum disease, Parkinson’s disease, and muscle weakness and pain associated with statin drugs.

Coenzyme Q10 has shown to significantly reduce inflammation in the body.

This in-depth study shows that CoQ10 decreases as we age and supplementing with CoQ10 provide health benefits to the elderly. It appears to lessen chronic oxidative damage and mitochondrial dysfunction associated with cardiovascular and neurodegenerative diseases.


Resveratol and pterostilbene
Resveratol and pterostilbene

Resveratrol and Pterostilbene are in the stilbenoid family, they provide “phytoalexin” which is produced by plants in response to injury. The stilbenoid compounds are found in the skin of the below-listed foods.

Food sources for Resveratrol and Pterostilbene are:

  • grapes
  • blueberries
  • raspberries
  • mulberries
  • bilberry
  • lingonberry
  • huckleberry
  • cranberry
  • almonds
  • peanuts

Resveratrol and Pterostilbene are best when taken together. They provide a synergistic effect. Resveratrol has been around a while, but pterostilbene is the powerful newcomer. Pterostilbene is much more potent, (80% more bioavailable) than resveratrol.

In this study titled, “Neuroprotective action of Resveratrol.” Resveratrol has been shown to increase the clearance of beta-amyloid, a leading contributor to Alzheimer’s disease.

The link between calorie restricting (fasting) and aging is still emerging, but preliminary studies show fasting can increase longevity and health by stimulating sirtuins and autophagy. Yes, fasting might be the fountain of youth we’ve been looking for.

Read this article on how certain antioxidants can improve longevity and increase your lifespan.

Similar to fasting, pterostilbene has shown to activate sirtuins (Sirt1) and may be able to extend lifespan and provide protection against the health decline associated with aging.

Pterostilbene is commonly referred to as the “fasting-mimicking supplement.” You can read all about this amazing antioxidant at

Why should pterostilbene and resveratrol be taken together?

Not only pterostilbene and resveratrol but quercetin also. It looks like when you take all three antioxidants together they have a powerful effect.

This study from Springer Link showed even at low doses, resveratrol, pterostilbene, and quercetin synergistically lessened oxidative injury of membrane lipids.

Pterostilbene has a much longer half-life and is much more bioavailable, but resveratrol activates more sirtuins. So when taken together they have a good 1-2 punch.

Alpha Lipoic Acid (ALA)

Alpha Lipoic Acid Antioxidant
Alpha Lipoic Acid Antioxidant

What Is Alpha-Lipoic Acid (ALA)?

Is an organic compound that contains sulfur (organosulfur). It is made from caprylic acid (octanoic acid). ALA is derived from animals and is important for aerobic metabolism. ALA has shown to have antioxidative properties and works in the mitochondria to help enzymes turn nutrients into energy.

Alpha-Lipoic Acid is one of the best antioxidants available as a supplement. It has been shown to improve insulin sensitivity, reduce inflammation, improve skin elasticity and protect against neurogenerative diseases.

Here is the link from Pubmed that shows the mechanism that alpha-lipoic acid improves insulin sensitivity.

C-reactive protein (CRP) is the biomarker for inflammation. This study from Science Direct shows that alpha-lipoic acid supplementation could significantly decrease CRP level in patients with elevated levels of this inflammatory marker.

Acetyl L- Carnitine and Alpha Lipoic Acid

One of the best antioxidant is Acetyl L Carnitine
Acetyl L Carnitine: one of the best antioxidants for insulin sensitivity

Synergistic combination: Acetyl L- Carnitine and Alpha Lipoic Acid are an interesting antioxidant supplement combination. You see this being sold in most grocery stores along with the common vitamins.

The popularity of this combination primarily comes from a very promising study from the US National Library of Medicine National Institutes of Health.

The study showed the benefit of alpha-lipoic acid/acetyl-L-carnitine in patients with metabolic syndrome with improvement to insulin sensitivity and lowering of blood pressure. Those results are consistent with the mounting evidence linking insulin resistance to mitochondrial dysfunction.

The Most Powerful Antioxidants (video)

What’s old is new: Vitamin C

Vitamin C
Vitamin C is back

Vitamin C is the red-headed stepchild of antioxidant supplements. I didn’t want to include it because it’s old and boring. However, as I continued my research for this article, vitamin C kept surfacing.

Every stone I overturned told me vitamin C is an amazingly under-rated antioxidant. Pubmed has 62,468 published studies on Vitamin C. 

Vitamin C is a water-soluble vitamin so it has to be replenished daily. Don’t worry about getting too much because excess amounts of the vitamin pass from the body through urine. Vitamin C is needed for the growth and repair of bodily tissues.

It works with collagen to make and repair teeth, bone, cartilage, skin, tendons, ligaments, and blood vessels. Vitamin C is one of the best antioxidants to take with red meat because It also helps the absorption of iron. Many women are low on iron.

Vitamin C is one of the oldest supplements in humankind history.

Centuries ago, sailors frequently died of scurvy because vitamin C was in short supply on most ships.

It was not until 1753 that scurvy was recognized in the British medical community as directly related to vitamin C deficiency.

In 1933 Dr. Szent-György synthesized vitamin C. He produced three pounds of pure crystalline vitamin C from the spice paprika.

In 1937, he was awarded the Nobel Prize in Physiology or Medicine “for his discoveries in connection with the biological combustion processes, with special reference to vitamin C.”

Vitamin C Inventor Dr. Szent-György
Dr. Szent-György

New Studies on Vitamin C

Make no mistake vitamin C was and is one of the best antioxidant supplements available. This study on Pubmed showed vitamin C significantly reduced glucose concentrations in patients with type 2 diabetes if taken greater than 30 days.

Vitamin C is predominantly found in fruit and those of us on a Ketogenic Diet eat very little fruit.

Many of us on the ketogenic diet don’t eat fruit and not enough vegetables. Vitamin C is a mandatory nutrient and must come from dietary sources. For those of us on a ketogenic diet supplementing with vitamin C is highly recommended.

These are the antioxidant dense foods with the highest Vitamin C content:

  • †Bell Peppers
  • Broccoli
  • Brussels Sprouts
  • Cauliflower
  • Kale
  • Strawberries
  • Cabbage
  • Bok Choy
  • Grapefruit
  • Greens
  • Raspberries
  • Swiss Chard
  • Tomatoes
  • Spinach
  • Asparagus

As we get older reducing inflammation gets more and more important. Focusing on the best antioxidants available is an efficient strategy while trying the keto diet after 40.

Want to learn more about the ketogenic diet? Here is a good keto diet explanation and a Ketogenic Diet Beginners Guide to help you get started.

Robert Bryant
Robert Bryant

I love to read and dissect scientific studies on Pubmed. They are difficult to read, but I enjoy interpreting them to provide our readers with science-based solutions to good health.

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