Bulletproof Your Immune System

Lesson 8: Reduce Baseline Inflammation With Nutraceuticals

Lesson 8 Protocol 2

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Become aware of which nutraceuticals can help reduce baseline inflammation, and decide which ones you want to consume based upon the scientific evidence that supports their use.

Lesson Summary

Vitamins D, A and C, the trace mineral zinc, the polyphenol quercetin, and fish oil can improve your baseline immunity to SARS-CoV-2 infection mainly by helping to help regulate the immune system so it doesn’t respond to a SARS-CoV-2 infection in a hyperinflammatory manner.

Reduce Baseline Inflammation With  Nutraceuticals 

The focus of Lesson 8 is to reduce your baseline inflammation with nutraceuticals, which is a fancy name for vitamins, herbs, medicinal mushrooms, and similar compounds often referred to as supplements. These do not replace, but supplement your anti-inflammatory diet reviewed in Lesson 6.

Remember, the reference to baseline inflammation speaks to the level of chronic inflammation in your body. The lower it is, the less dangerous is the added inflammation that a Sars infection introduces to the body.

The importance of dietary nutrition supplied by food has been addressed in Lesson 6, and now we turn to nutrition enhancement and immune targeting via nutraceuticals. The role of nutrition as immune modulators is well known in the scientific community, whether by food or in the more concentrated form delivered by nutraceuticals. [1]

The nutraceuticals I’m going to review can support a well-functioning immune system, and many of them play dual roles in immunology, in that they can support immune surveillance, while also reducing inflammation. What we want is to help modulate your immune system response to SARS-CoV-2 or COVID-19. 

As you’ll see in this and subsequent lessons, I’ve consulted dozens of scientific studies to curate the nutraceuticals presented in this course. Mind you, to date there are no credible studies supporting specific nutraceuticals that can stop you from getting infected with SARS-CoV-2 or healt some subsequent COVID-19 disease, but there’s a rich amount of evidence indicating that certain nutraceuticals have been effective for influenza and other virus, and/or to help reduce baseline inflammation.

The nutraceuticals described in this lesson are meant to supplement a nutritious diet, not substitute for it. Nutritious food is your greatest medicine. Nutraceuticals supplement nutritious food, not the other way around.

If you don’t want to take all the nutraceuticals covered here or in any subsequent lesson, you can use this process to whittle down your selection:

  • First identify the nutrients you may be deficient in, given your diet, lifestyle, health and age vulnerabilities. 
  • Second, decide which ones have the most appealing scientific or clinical support.
  • Third, which are affordable to you.
  • Finally, consult the Nutraceutical Table to see various options.

As you’ll see in subsequent lessons, there will be other nutraceuticals recommended for specific targets. Taking all of them would be a stretch for most people, so use the process just described to help you decide which ones you want to take. Also, consult the Nutraceutical Guide and Nutraceutical Table. 

These are the nutraceuticals covered in this lesson:

  • Vitamin D
  • Vitamin A
  • Vitamin C
  • Zinc
  • Quercetin
  • Fish Oil
  • Elderberry

As you’ll see in subsequent lessons, there will be other nutraceuticals recommended for specific targets.

Vitamin D

The correlation between low vitamin D levels and death from COVID-19 is statistically significant, so it behooves you to ensure you have an adequate amount in your body. [2]

Vitamin D is a fat-soluble vitamin that functions like a steroid hormone in the body. It comes in two forms in your diet, D2 and D3, and can also be produced in your skin when exposed to sunlight. D3 is the form typically sold as a supplement.

UVB sunlight exposure on your skin makes Vitamin D. It’s then transported to the liver and then to the kidneys.

The kidneys change it into an active hormone that helps ensure your body has an adequate amount of calcium to keep the skeleton strong and free of osteoporosis, which is a condition where your bones become brittle and fragile.

A lot of people have a vitamin D deficiency.  In the U.S. a 2011 study estimated that more than 41% of American adults are Vitamin D deficient. But it was even worse for people of color: for Africian Americans it was 82%, and for Hispanics 69%. [3]

A 2016 study found that Vitamin D deficiency is so low in Europe that it should require a public health governmental response. [4]

The rest of the world isn’t doing any better. A study published in the American Journal of Clinical Nutrition reported that Vitamin D deficiency is now recognized as a pandemic throughout the world. [5]

The major cause of vitamin D deficiency is the lack of moderate sun exposure, which is the major source of vitamin D for most of us. Very few foods naturally contain vitamin D, and foods that are fortified with it are often inadequate to satisfy what our body needs.

Counterintuitively, people in countries at lower latitudes and typically sunny countries, such as Spain and Northern Italy, have low concentrations of vitamin D and high rates of vitamin D deficiency. These countries also experienced the highest infection and death rates in Europe due to Covid.

The northern latitude countries of Norway, Finland, and Sweden, have higher vitamin D levels despite less UVB sunlight exposure, because supplementation and fortification of foods are more common. Several Nordic countries have had lower COVID-19 infection and death rates, except perhaps for Sweden, which did not push its population to stay at home, thinking that they would quickly get to herd immunity by continuing with normal social and work activities. 

If you’re a person of color, are elderly, spend most of your time indoors, or live in areas with little sunshine, you have reason to be concerned about having a vitamin D deficiency, because people with these attributes have a higher than average deficiency. 

These are the tell-tale signs for vitamin d deficiency:

  • Having dark skin
  • Being elderly
  • Being overweight or obese
  • Not eating much fish or milk
  • Living far from the equator where there is little sun year-round
  • Always using sunscreen when going out
  • Staying indoors
Vitamin D Immune Support

Vitamin D can support the immune system through a number of immune pathways involved in fighting SARS-CoV-2, and is likely to reduce serious COVID-19 complications. People with low levels of vitamin D are at greater risk of viral respiratory tract infections such as influenza.

There are many studies that support the ability of Vitamin D to help enhance immune system function; for instance, Vitamin D:

  • Can lower viral replication rates and reduce concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs, leading to pneumonia. [6]
  • Is critical for the production of antimicrobial peptides, thereby enhancing resistance to infections. Vitamin D also appears to reduce levels of a proinflammatory cytokine that causes inflammation called Interleukin-6, which is associated with the severe breathing difficulties seen in COVID-19. [7]
  • Enables the macrophages in our lungs to kill bacteria and viruses directly. It also tweaks the activity of other immune cells, such as B and T cells, which orchestrate longer-term responses. [7]
  • Changes the availability of the same ACE2 receptor on lung cells that SARS-CoV-2 uses to gain entry to these cells and establish an infection. If vitamin D has already altered these receptors, then it may make it harder for the virus to gain a foothold in the body. [8]

Importantly, vitamin D Is an immunomodulator -- not an immune booster, per se, so it helps the immune system not to either overreact or underreact to pathogens, like a virus. [9]

This may be because vitamin D is important in the regulation and suppression of the inflammatory cytokine response, which causes the severe consequences of COVID-19 and ‘acute respiratory distress syndrome’ which can lead to being put on a ventilator.

So, the bottom line with Vitamin D is that it can enhance our innate immune system, and prevent either the innate or adaptive systems from becoming dangerously overactive. This means that having healthy levels of vitamin D has the potential to protect us against severe complications, including death, from COVID-19.

How to get Vitamin D:
  • Sunshine -- 30 minutes/day, 3x/week
  • Food -- Dairy, fatty fish
  • Supplements -- Vitamin D3

You can maintain an adequate blood level of vitamin D by getting proper sun exposure, which in this context means exposing your hands, arms, legs, and face for at least three times a week for about 30 minutes.

Foods rich in Vitamin D include cod liver oil, sardines, salmon and other fatty fish, milk and other dairy products.

Vitamin D3 supplements are recommended for most of us, particularly as we’re getting too little sunshine exposure while staying indoors during this pandemic. 

A daily dose of 2,000 IU daily is generally effective and safe. Check out the Nutraceuticals Guide for more on dosage and recommended brands.

Vitamin A 

Vitamin A is a group of unsaturated, fat-soluble nutritional organic compounds. It was the first fat-soluble vitamin to be identified.

Deficiencies in vitamin A are difficult to assess as numbers vary widely worldwide and criteria are inconsistent. Nonetheless, it’s estimated that deficiency is common worldwide, with epidemic prevalence in Saharan Africa at 48% of the population and South Asia at 44%. [10]

Vitamin A deficiency is also common in the US with 34% of adults consuming less than the estimated average requirement. [11]

Vitamin A Immune Support

How much vitamin A you have in your body is a major determinant of overall immune status. In fact, Vitamin A was once known as the “anti-infective vitamin”. 

People deficient in vitamin A experience impaired antibody response, decreased levels of helper T cells, and impaired integrity of the mucosal linings of the respiratory and gastrointestinal tracts. 

Overall, vitamin A–deficient individuals are more susceptible to infectious diseases, respiratory conditions like asthma and allergies, and have higher mortality rates. [12] Vitamin A levels drop during various types of infection and multiple studies have shown that vitamin A supplementation improves resistance and recovery rate. [13]  Multiple studies have shown that vitamin A deficiency increases inflammation and more limited research has shown that vitamin A supplementation decreases inflammation. [14]

How to get Vitamin A:
  • Diet: Animal products, sweet potato, spinach 
  • Supplements: Use the beta carotene form

If you regularly eat foods high in vitamin A, you may not need to supplement with it. Foods high in vitamin A include liver, herring, carrots, sweet potato, kale, spinach, broccoli, butter, eggs, red and yellow peppers, apricots, cantaloupe, mangoes, bell peppers, butternut and other winter squash.

If you think you may need an extra boost of vitamin A, use the beta carotene form of it. Beta-carotene is actually a "pre-vitamin A" -- it’s converted in the body to vitamin A based on the body's need for it. 

This should make beta-carotene a "safer" form of vitamin A, since too much vitamin A can be toxic.

For suggestions about dose and preferred brands, check out the Nutraceuticals Guide.

Vitamin C

Vitamin C is also known as ascorbic acid. It’s a water-soluble flavonoid and an essential nutrient that’s involved in many of our biological systems. For instance, it helps the repair of tissue; it’s required for the functioning of several enzymes; it’s an antioxidant, and vitamin C is important for immune system function.

Vitamin C Immune Support

Like other flavonoids, vitamin C inhibits the production of certain  pro-inflammatory cytokines in the innate immune response to a pathogen. [15]

There’s been an on-going debate about the value that vitamin C may or may not have to either prevent SARS infection or minimize its symptoms. Some people discount its value entirely, and others claim that it’s a solution. The truth is closer to the middle of those extremes.

Let’s examine the science.

Vitamin C is recognized as an essential nutrient in many aspects of the immune system, especially immune cell function of both the innate and adaptive immune responses. [16,17]

Vitamin C deficiencies contribute to decreased immune responsiveness and increased vulnerability to infections. Once infected, the enhanced inflammation and metabolic requirements place a further demand for additional vitamin C. [18]

Vitamin C supplementation has been shown to both prevent and treat respiratory and systemic infections, and that’s why it’s been evaluated as an intervention against SARS-CoV-2. 

Various studies indicate that:

  • You need some level of vitamin C saturation in your body as a preventative measure, while treatment of infections requires significantly higher doses. [19,20]
  • Vitamin C’s role as an antioxidant is important in protecting the body against the damage from oxidative stress generated during an infection. [21,22] 
  • Vitamin C also plays a critical role in stabilizing the interior surface of blood vessels, supporting nitric oxide generation (which among other things, dilates blood vessels) and vasodilation (which is when the diameter of blood vessels increase). This support of blood vessel health is a valuable attribute of Vitamin C given that those with COVID-19 have issues with their blood coagulating, which can cause prolonged or excessive bleeding.

OK, so what about Vitamin C delivered intravenously? 

In some cases it seems to help those who get respiratory disease syndrome, one of the potential effects of COVID-19.

One study published in 2019 showed a decrease in mortality in 167 patients with acute respiratory disease syndrome receiving approximately 15 grams per day of IV vitamin C for four days. [23]

At Northwell Hospital in New York, there are multiple anecdotal reports of the use of IV vitamin C in COVID-19 patients in doses ranging from 1500 mg three to four times a day. Those receiving the IV vitamin C did significantly better than those not receiving it. [24]

How to get Vitamin C:
  • Food: red acerola cherries, rose hips, kale
  • Supplements: Ascorbate form

Vitamin C-rich foods include red acerola cherries, rose hips, chili peppers, guavas, sweet yellow peppers, blackcurrants, mustard spinach, kale, kiwis, broccoli, Brussels sprouts, lemons and oranges.

The ascorbate form is recommended because it may be easier on your stomach. 

For short periods of time, say a couple of months, most people can tolerate up to six grams of vitamin C a day before diarrhea happens. 

Yes, you can get diarrhea from too much vitamin C. If that happens, reduce your dose.

Mind you, I’m not recommending six grams per day of vitamin C; that’s just the upper limit. Go to the Nutraceuticals document for information on dosing.


Zinc is a trace element found in our cells. It helps the immune system fight off invading bacteria and viruses. It also helps make proteins and DNA.

Zinc deficiency affects around 2 billion people worldwide and is very common in older adults. It’s estimated that up to 30% of older adults are considered deficient in this nutrient. [25]

Zinc Immune Function 

Zinc is an essential micronutrient that’s involved in the regulation of the innate and adaptive immune responses. It has specific and well-known antiviral properties, such as to impair the ability of RNA viruses to replicate. [26]

As you know, SARS-CoV-2 is an RNA virus.

Coronaviruses in general appear to be susceptible to the viral inhibitory actions of zinc. Zinc may prevent coronavirus entry into cells and appears to reduce the damage that coronavirus can cause. [15]

Zinc deficiency can lead to immune dysfunctions, especially given how the absence of zinc can elevate the inflammatory response. An adequate amount of zinc helps modulate this proinflammatory response. It also helps control oxidative stress. [27,28]

As you might have heard, the loss of smell and a distorted sense of taste are commonly being reported in patients at every phase of COVID-19; they are classic symptoms of zinc deficiency. 

How to get Zinc:
  • Diet: Pumpkin seeds, beans, beef
  • Supplements: Try lozenges, as they coat your throat 

Foods rich in zinc include pumpkin seeds, beans, grass fed beef, lamb, sesame seeds, garbanzo beans, lentils, cashews, quinoa, eggs, organic poultry, shellfish, raw sprouts, liver, spinach, watermelon seeds, garlic, peanuts and dairy products.

It’s a good idea to use zinc lozenges as the form of supplementation, because they  can provide direct protective effects in the upper respiratory tract, but don’t overdo it. 

You need to know the amount of zinc in each lozenge, which is typically between five and seven mgs. A daily dosing of Zinc is usually between 15 and 30 mg a day.

If you regularly eat zinc-rich foods it’s unlikely that you’re deficient; however, taking zinc lozenges may be useful, because, as I just said, it can coat your throat with zinc which could help inhibit viruses. [29,30]


Quercetin is a plant flavonol from the flavonoid group of polyphenols. 

Flavonoids are in vegetables, fruits, grains, tea and wine. They’ve been linked to several health benefits, including reduced risks of heart disease, cancer, and degenerative brain disorders. The reason for this is due to their ability to function as antioxidants inside your body.

As you’ll learn more about in the next lesson, antioxidants are compounds that can bind to and neutralize those pesky free radicals. 

Free radicals are unstable molecules that may cause cellular damage when their levels become too high. Damage caused by free radicals has been linked to numerous chronic conditions, including cancer, heart disease, and diabetes.

Quercetin Immune Support

An important study that looked a the ability of quercetin, among other compounds, to protect against SARS-CoV-2 infection found that quercetin was the fifth most effective in binding to the SARS-CoV-2 Viral Spike Protein, and thereby helps inhibit its ability to infect people. 

Of the 19 compounds studied, only four were superior to quercetin in the study. Of the four, only one was a natural compound called luteolin-monoarabinoside, but it was barely better, and it’s not as available to use as quercetin. [31]

How to get Quercetin
  • Foods: Capers, peppers, onions
  • Supplement: Use the phytosomal or liposomal forms

Foods that contain quercetin include, capers, yellow and green peppers, red and white onions, kale, cooked asparagus, cherries and tomatoes.

The downside with Quercetin is its low bioavailability. Because it’s not well absorbed, Quercetin requires special formulations to achieve clinically effective blood levels. 

Various studies have found that a phytosomal and liposomal forms of Quercetin formulation improve oral absorption.

Phytosomal formulations can increase absorption up to 20 times greater than unformulated quercetin. [32] The liposomal form is also better absorbed than regular quercetin. [33]

If you’re going to use quercetin, use either the phtyosomal or liposomal forms to ensure that it’s actually getting into your bloodstream to do some good.

Fish Oil

Fish oil refers to the oils obtained from fatty fish, such as salmon, herring and mackerel. These are fish whose oil contains high amounts of EPA and DHA, which are long-chain omega-3 polyunsaturated fatty acids.

Fish Oil Immune Support

Fish oil can reduce chronic inflammation, but it takes too much time to do that for it to be useful as a strategy for influencing the body’s inflammatory equilibrium in an acute care situation. Consequently, to benefit from fish oil you need to be using it as a preventative measure to influence a low baseline level of inflammatory equilibrium, as opposed to using it once infected.

The primary active constituents of fish oil are EPA and DHA. They play an important role in the resolution phase of the inflammatory process. [34]

They do this via downstream products of the metabolism of EPA and DHA called specialized pro-resolving lipid mediators, or “SPMs”. SPMs can inhibit priming and activation of macrophage NLRP3 inflammasome. Basically, this again is about reducing excess inflammation.

How to get Fish Oil:
  • Foods: Any fatty fish
  • Supplements: Capsules or liquid

Foods rich in Fish Oil include anchovies, salmon, herring, mackerel, tuna, halibut and some algae, such as spirulina.

Supplements offered typically come in the form of the Fish Oil in a capsule, or liquid form. It’s important you choose a brand that tests for heavy metals and other contaminants. Recommended brands are in the Nutraceutical Guide.


Elderberry (Sambucus nigra) is the dark purple berry from the European elder tree. They’re rich in antioxidants (anthocyanidins, flavonols, and vitamin C), meaning they also have the power to fight inflammation and free radical damage in the body. 

Various elderberry extracts are used in many medicinal preparations, including widespread historical use as an antiviral herbal medication. [35]

In a 2019 study at University of Sydney, scientists found that common elderberries have a potent antiviral effect against the flu virus. Elderberry extract binds to the tiny spikes on a virus protein that are used to pierce and invade healthy cells and destroy them so that the virus is minimized or made ineffective. [36]

A review of 4 randomized control studies in 180 people found that elderberry supplements significantly reduced upper respiratory symptoms caused by viral infections. [37]

Based on animal research, elderberry is likely most effective in the prevention of and early infection with respiratory viruses. [38]

A report published in the Journal of International Medical Research revealed that when elderberries were consumed within the first 48 hours of catching flu, the symptoms dissipated approximately four days earlier than the average. Moreover, the use of pain relief was considerably less amongst those who received the elderberry compared to the placebo. [39]

One in-vitro study reported an increase in TNF-alpha levels related to a specific commercial preparation of elderberry, leading some to caution that its use could initiate a “cytokine storm.” However, these data were not confirmed when the same group performed similar studies, which were published in 2002.[106] Therefore, these data suggest it is highly implausible that consumption of properly prepared elderberry products (from berries or flowers) would contribute to an adverse outcome related to overproduction of cytokines or lead to an adverse response in someone infected with COVID-19. [40,41]

Your Takeaway

Vitamins D, A and C, the trace mineral zinc, the polyphenol quercetin, and fish oil can improve your baseline immunity to SARS-CoV-2 infection mainly by helping to help regulate the immune system so it doesn’t respond to a SARS-CoV-2 infection in a hyperinflammatory manner.

The next lesson addresses antioxidant support.