Join the enews community - Terms
Filter by Categories

How to reset your immune system

Reading time: 15 minutes

In all the fear and news obsession about coronavirus this past year, there is one rarely asked question that has loomed like an unsanitized elephant in the room: 

why is it that some people (most children and young people, for example) wouldn’t even notice if they were infected with this “deadly” virus, while most others experience Covid infection as a typical cold or flu and only a small minority, mostly the frail, elderly and those weakened already by another disease, experience a crushing battle that ends in the graveyard? What makes some so resilient and others so vulnerable?

The answer was provided by a group of scientists and doctors in a paper published toward the end of 2020 which stated simply: “A degraded/dysfunctional immune system appears to be the main determinant of serious/fatal reaction to viral infection (for Covid-19, SARS, and influenza alike).”1 

It’s hardly surprising that viruses exploit weakened immune systems, yet none of the public health strategies adopted globally in response to Covid-19 tackle the underlying problem of the dysfunctional immune systems of those most at risk of the disease. 

Instead, as the Toxicology Reports paper, authored by leading Israeli physician and author of 26 immunology textbooks Yehuda Shoenfeld, Italian biochemist Darja Kanduc, Georgia Institute of Technology research associate Ronald Kostoff, extensively published Greek toxicologist Aristidis Tsatsakis and a handful of other researchers, noted, the public health Covid-19 response has rested on three tactics: 1) avoid the virus indefinitely (via lockdowns, masks and social distancing), 2) mitigate symptoms with traditional pharmaceutical treatments when the immune system is overwhelmed and serious infection occurs and 3) vaccinate against the specific strain of the virus, repeating as often as necessary.  

All of these recommendations, say the researchers, are “based on the concept that pandemics/outbreaks can be controlled/prevented while maintaining the immune-degrading lifestyles followed by much of the global population.”

What if we addressed the plagued immune system instead? It is indisputable that alcohol wreaks havoc on the immune system, for example, yet no public health agency in the world has launched massive campaigns advising people to quit drinking to help their immune system defend against Covid infection. 

There are also no poster campaigns warning about vitamin C and D deficiency among the vulnerable elderly, though a huge body of medical literature has documented the problem. While public health agencies have saturated the media with messages about masks and vaccines, there are no public campaigns about the benefits of exercise, the immune system dangers of a sedentary lifestyle or the powerful natural antioxidants with potent antiviral and antibacterial activity that are being used in hundreds of hospitals. 

The trouble with the tactics that evade the real problem—and increase fear and stress—is they don’t work in the long term. A weak immune system that survives one viral attack is still vulnerable to other killer diseases. A degraded immune system that is vaccinated against one virus will still be susceptible to every other virus in the neighborhood. 

As the Toxicology Reports researchers observed: “The only real protection against a future Covid-19 pandemic or any other viral pandemic/outbreak is the one that was demonstrated to work in the SARS, MERS and Covid-19 pandemics, and in the annual influenza pandemics/outbreaks: a healthy immune system capable of neutralizing incoming viruses as nature intended.”

Building the immune system has added perks, as Robert Verkerk, PhD,  founding director of the Alliance for Natural Health International (, observes: “If you help populations improve their nutritional status and metabolic function in order to reduce susceptibility to Covid-19, you simultaneously reduce the risk of almost every single chronic and autoimmune disease. 

“These include heart disease, cancer, obesity, type 2 diabetes, dementia and a rash of autoimmune diseases like Crohn’s, rheumatoid arthritis and ulcerative colitis, that have, prior to the emergence of Covid-19, been seen as diseases that might break modern healthcare systems.” Verkerk has identified 52 factors that influence immune system function, more than half of which are factors under our control.3 

It is not a coincidence that people are more likely to get a disease as they get older. With Covid-19, for example, the risk of death increases with age from a miniscule 0.003 percent risk in those under age 20 to 0.456 percent for 60–64-year-olds, 3.2 percent for 75–79-year-olds and then shoots up to 8.3 percent for those over age 80. The average age of death is 78.6 in the US, while the average age of death from Covid-19 is 80 in the US and 82.4 in the UK.4 

It’s all in your telomeres

One measure of aging is the length of telomeres—cap-like structures at the end of chromosomes that protect DNA like plastic tips at the ends of shoelaces keep them from fraying. Telomeres shorten each time a cell divides. The length of telomeres is a biological marker of premature aging. Chronological years and telomere length do not always correlate. 

Short telomere length is associated with many chronic diseases, including heart disease, stroke, cancer, arthritis, osteoporosis, cataracts, type 2 diabetes, hypertension, mental illness, chronic obstructive pulmonary disease and dementia.5 

Hardly surprising then that a new study has found those with the most severe cases of Covid-19 have shorter telomeres.6 While the rate of telomere shortening is somewhat hereditary, it is also affected
by environmental factors from smoking and physical activity to nutrition and vitamin intake.

Here we look at some of the most well-documented and easily attainable factors associated with longer telomeres and stronger immune systems that can fortify your defenses against every killer disease on the loose.

Vitamin D

Roger Seheult, cofounder of and a California frontline worker in critical care, internal medicine and pulmonary disease, says that “the supplement that has the best level of evidence” for strengthening the immune system against Covid-19 is vitamin D.7 

Actually a hormone rather than a vitamin, vitamin D powerfully affects every system in the body and especially the immune system. 

It helps produce antibiotic-like compounds (called antimicrobial peptides) that kill infectious microbes. It also balances the immune system response to infection to limit hyper-inflammatory responses—so-called “cytokine storms”—that are a major cause of death in Covid and influenza, and it keeps the immune system from turning on itself in crippling, disfiguring and incurable autoimmune diseases.

Research dating back more than a decade has shown that people with higher levels of vitamin D are less likely to have infections. 

One study looked at more than 19,000 people and found that those with the highest levels of vitamin D were least likely to report having upper respiratory
tract infections.

It’s been established that serum levels of vitamin D (measured as the metabolite 25-hydroxyvitamin D or 25OHD, see box) decline with age and that this decline is associated with impaired immune function.9 Vitamin D has also been shown to reduce the rate of telomere shortening.10 

One recent study looking at 20 different European countries found that the level of Covid-19 mortality went up as the country’s average serum vitamin D level declined.11  It’s not surprising then that another recent study reported that more than 82 percent of people hospitalized with Covid-19 infections were vitamin D deficient compared to just 47 percent of controls in the general population. And among hospitalized Covid-19 patients, those who were vitamin D deficient had a greater prevalence of hypertension and cardiovascular diseases and a longer length of hospital stay than those with serum 25OHD levels in the “adequate” range of at least 20 ng/mL (see box, right).12 

You can’t change your age, but supplementing with vitamin D has been demonstrated to protect against viral invasion. A major 2017 review of 25 different studies involving more than 11,000 patients showed that vitamin D supplementation was safe and protected against upper respiratory tract infection.13 

A growing number of studies have now shown that using high “booster” or “bolus” doses of vitamin D in hospitalized patients with Covid-19 infections results in lower death rates.14 

It is increasingly accepted in mainstream medicine that vitamin D works to prevent and subdue infection and prevent deaths, but there is still debate about dosing. Currently, there are 73 clinical trials underway worldwide using vitamin D in various doses to prevent and treat Covid-19 infection.15 Among them is the Coronavit trial at Queen Mary University of London, which is doling out vitamin D to 5,000 UK residents to determine if it prevents Covid and other respiratory infections.16 

Scotland is not waiting for trial results but has begun handing out vitamin D to those who have been locked away indoors during the pandemic.17 And in November a group of French physicians advised that all citizens in France—where 41 percent of the population is vitamin D deficient in winter—take supplemental vitamin D.18 

The many faces of vitamin D 

Vitamin D comes in two forms: D2 and D3. D3 appears to be more readily converted into the biologically active form of vitamin D in the body, and it’s the only form the body creates from sunlight. The other form, D2, is found in mushrooms and added to vitamin D-“fortified” milk and other foods. Look for supplements that contain only vitamin D3 (most nowadays do).

Vitamin D3 travels from the blood to the liver, where it is converted to 25-hydroxyvitamin D (25OHD). This is the compound measured in vitamin D blood tests, in units of either nanograms (ng)/mL or nanomoles (nmol)/L. 

While the Institute of Medicine set 20 ng/mL (50 nmol/L) as the threshold for “adequate” vitamin D, many physicians consider this a low bar. According to the Alliance for Natural Health International, vitamin D expert Dr Damien Downing, president of the British Society for Ecological Medicine, recommends a vitamin D blood level of at least 30 ng/mL (75 nmol/L) for immune support. 

The dosage of vitamin D supplement necessary to get to this level varies from person to person and likely from season to season, depending on how much we produce naturally from sunlight. Hence, repeated blood tests for vitamin D, as well as working with an experienced practitioner to interpret the results, can be critical to reaching and maintaining optimal levels. 

Public health negligence

Most public health officials have not shared the enthusiasm of frontline doctors about vitamin D, however. They’ve been strangely silent about the science showing the dangers of vitamin D deficiency and its power against the pandemic and other viruses—as well as the lower death rates linked to vitamin D supplementation. A US federal court even ordered a Georgia company to stop marketing vitamin D as a Covid-19 prevention or treatment strategy.

“Americans expect and deserve medical treatments that have been scientifically proven to be safe and effective. Making claims that unproven drugs can cure or prevent diseases, including Covid-19, places consumers’ health at risk,” said US Food and Drug Administration (FDA) Chief Counsel Stacy Amin. “We remain committed to pursuing and taking swift action against those who attempt to subvert the regulatory functions of the FDA by repeatedly disregarding the law and distributing unapproved products.”19 

So while it is scientifically documented that vitamin D deficiency leaves immune systems vulnerable to attack and people vulnerable to disease, count on the FDA to curb access to the vitamin that can save lives. Could it be that vitamin D is so powerful that it threatens to undermine the FDA’s fast-tracked and extremely profitable coronavirus vaccination strategy? 

Microbes and immune health

Our intestines are colonized by a vast and varied ecology of microorganisms including bacteria, viruses and fungi that all profoundly impact our immunity.  

In the last decade, new sequencing technologies have revealed that every one of us is colonized by a distinct bacterial flora, and that the microbiota can be manipulated to treat and even cure some diseases. Different species of microbes affect immune system players differently and can produce pro- or anti-inflammatory effects, so ultimately the bugs in your gut determine your resistance to infection and disease.1 

This beneficial effect of the gut microbiota in immunity is not limited to the gut but also extends throughout the body to distant organs including the lungs, according to a paper published this January. 

In the paper, researchers from the Center for Infection and Immunity at the University of Lille, France, review how the use of antibiotics can destroy intestinal bacteria or specific species and increase susceptibility to infections like salmonella and E. coli. 

They cite a dozen studies showing how “mice lacking microbiota (i.e., germ free) or those orally treated with antibiotics (broad spectrum or targeted antibiotics such as neomycin, metronidazole or vancomycin) have impaired responses to systemic and respiratory infections.” Antibiotics’ disturbance of gut ecology weakens the host’s innate and adaptive defenses against influenza and respiratory syncytial virus (RSV), for example.

By contrast, the researchers say, a high-fiber diet has an immune-stimulating effect, and fiber-rich diets that are fermented by beneficial gut bacteria have been shown to positively impact influenza and RSV infection.2 

Fermentable fibers favored by gut bacteria include inulin found in green bananas and legumes, pectin found in fruit like apples and ß-glucans found in oats and barley.

Free as sunshine

Much of the time, vitamin D isn’t just cheap, it’s free. Most of the vitamin D we get—and specifically the most bioactive form, vitamin D3 (see box, page 31)—is manufactured when UV rays from sunlight shine on our skin. We can get small amounts from other sources like eggs and fortified milk, for example, but these come nowhere near what the body produces from sunshine. According to one study, just 30 minutes of midsummer midday “whole skin surface” sun exposure in Oslo, Norway produces the equivalent of taking between 10,000 and 20,000 IU vitamin D orally.20  

For those who can’t sunbathe naked, wearing shorts and a t-shirt for a half-hour exposure in high sun still provides a good dose. At high latitudes, however, the sun provides no vitamin D in winter, and oral supplementing is necessary to maintain high levels, which may be the reason for the seasonality of flus (and Covid), which surge just as vitamin D levels plummet.  

Researchers from the University of Liverpool, England, Trinity College and St. James Hospital in Ireland, looked at Covid mortality data and saw a clear pattern. “When mortality per million is plotted against latitude, it can be seen that all countries that lie below 35 degrees North have relatively low mortality,” they observed. “Vitamin D deficiency has also been shown to correlate with hypertension, diabetes, obesity and ethnicity—all features associated with increased risk of severe Covid-19.”21 

Dosing vitamin D

While public health agencies still warn about the dangers of supplemental vitamin D and cap doses at bare minimum levels of 400 to 800 IU per day, doctors like Roger Seheult advise that most people could safely take “bolus” doses as high as 50,000 IU of vitamin D3 for the first seven days if they have not been taking vitamin D before, and then switching down to a maintenance dose of 4,000 to 5,000 IU daily in the absence of sunshine exposure. 

He cites a Mayo clinic 10-year study of over 20,000 people in which only one individual developed vitamin D toxicity after supplementing with vitamin D, and that was after taking a staggering 50,000 IU daily for three months in addition to taking a calcium supplement .22

Neurosurgeon and nutrition author Russell Blaylock has advised that pregnant women should supplement with at least 2,000 IU of vitamin D3 throughout their pregnancy and during breastfeeding and that even newborns can be given at least 500 IU of vitamin D3 and small children can take 1,000 IU a day.23 

A few people with rare disorders linked to excess levels of calcium in the body, such as sarcoidosis or Williams syndrome, should not supplement with vitamin D at all. For those concerned about excess vitamin D, blood testing is a safeguard.

Cofactors for vitamin D

A growing medical literature supports supplementation with vitamin K to augment vitamin D’s activity,24 but as with vitamin D, dosing is still a question.

 Some companies offer supplements in fixed ratios of vitamin D3 and K2. The public health nonprofit GrassrootsHealth Nutrient Research Institute
( recommends 90 mcg of vitamin K for women and 120 mcg for men daily. Vitamin K promotes blood clotting and shouldn’t be taken with blood thinners such as warfarin.

Magnesium is another critical factor needed for optimal immune system function,25 and research going back decades has shown how it works in tandem with vitamin D.26  “Magnesium deficiency is associated with decreased immune cell activity and increased inflammation, including of IL-6, central to the pathology of the cytokine storm associated with Covid-19,” according to a recent paper written by researchers at the University of Melbourne and United Arab Emirates University.27

Foods including leafy dark green vegetables, berries, brown rice and chocolate are sources of magnesium, but it’s very difficult to eat your way out of a deficiency and many people, especially the elderly, are magnesium deficient. The Alliance for Natural Health International recommends taking 500–750 mg of magnesium daily if you are supplementing with 4,000 IU or more of vitamin D.

Vitamin C

More than 60,000 published scientific articles point to the protective benefit of vitamin C in infectious disease. Vitamin C supports respiratory defense mechanisms, prevents viral infections and reduces their duration and severity, and has anti-histamine effects that can improve flu-like symptoms. Vitamin C has also been shown to slow telomere shortening in cells.28

As with vitamin D, patients with acute respiratory infections such as pneumonia often have decreased plasma vitamin C concentrations, and some studies have reported that their symptoms improve more quickly when they are given vitamin C.27 

Vitamin C’s potent antiviral, anti-inflammatory and antioxidant properties make it a target of special interest in Covid-19.29 High IV doses have been used to squelch severe Covid infections,30 and more than 50 clinical trials of vitamin C for the treatment of Covid-19 are underway.31 The usual recommended maintenance dose is 1–2 grams per day. 


Essential mineral zinc has gotten a lot more attention as a result of the pandemic. It affects hundreds of enzymatic processes in the body and is critical to immune function and wound healing. It is a well-documented respiratory antiviral that clears mucous from airways and has anti-inflammatory and immune system-balancing properties.32 

Zinc can also affect our sense of smell and taste, which is curious since loss of both has been linked to early Covid-19 infection.  It’s thought that the drug hydroxychloroquine’s reported reduction of viral load may be due to the fact that it appears to increase zinc transport into cells.33 This may also be why there have been such promising results from the anti-parasitic drug, ivermectin.34

Worldwide, roughly 20 percent of people are deficient in zinc,31 especially the elderly and vegetarians/vegans since it is highest in meats (especially lamb) and shellfish, but it’s also in nuts, seeds and cocoa powder.

Taking too much zinc is as bad as taking too little, however, according to Dr Verkerk of the Alliance for Natural Health, who recommends taking 25 mg of zinc per day for average-weight individuals and up to 50 mg. It’s better to take zinc between meals, and especially without foods containing phytic acid such as nuts, seeds, whole grains and legumes. Lozenges are a good delivery form for anti-mucosal effects. 


Quercetin, a polyphenol found in onions, broccoli, fruits (apples, berries and grapes), green tea and wine, is known for its antioxidant, antiviral and anti-allergic properties, all characterized by immune system stimulation. Quercetin suppresses pro-inflammatory cytokines and balances the immune system’s overall cytokine response, and it’s used as an allergy and asthma treatment.35

Research has shown that quercetin inhibits influenza infection, and now it’s being considered as a suppressant of Covid-19 infection too.36

Among more than 8,000 drugs, natural products and other small molecules that were screened, quercetin ranked among the top five for its predicted ability to bind to the pandemic virus’s infamous spike protein receptor.37 It’s also been predicted to block the binding of the coronavirus to human cell receptors.38

There are no randomized, controlled studies of quercetin for the treatment of Covid-19, but it has been found safe in doses up to 1,000 mg a day for as long as 12 weeks, except during pregnancy, where questions of safety remain and research in mice suggests it may have adverse effects for the developing baby.39 

Green tea

If in doubt, sip green tea. Not only does it contain quercetin and other immune-boosting polyphenols, but elderly Chinese men (not women) who drank three cups of green tea daily were found to have longer telomeres, translating into five extra years of life.40

N-acetyl-cysteine (NAC)

This nutrient bolsters cell levels of glutathione, a potent antioxidant, anticancer, antiviral and antiaging molecule, which is significantly reduced in a number of diseases. NAC has been shown to bolster immune function41 and to reduce inflammation in lung disease.42 Test-tube studies have shown it suppresses viral replication of severe influenza and reduces inflammation.43 A clinical study of NAC at 600 mg twice a day during flu season found that NAC supplementation reduced the rate of symptomatic infection from 79 percent to 25 percent, reduced symptoms by 70 percent and cut patients’ recovery time.44    

Nitric oxide—natural hand sanitizer for the nose?

A group of researchers from Vancouver are promoting a natural nitric oxide nasal spray that kills 99.9 percent of the coronavirus that causes Covid-19 within two minutes.

Dr Gilly Regev, an Israeli physician who cofounded SaNOtize Research and Development Corp. based in Vancouver, Canada, told Jewish News, “If you use it daily, I really believe you won’t be affected by Covid-19. We have shown in the clinical trials that the people who used it did not get infected.”

The SaNOtize Nitric Oxide Nasal Spray (NONS) kills covid virus on contact in the upper airways and prevents it from taking hold traveling to the lungs. Earlier studies showed it prevented infection with Covid, and UK clinical trials began this week. NONS is currently in phase II clinical trials in Canada ( 

Nitric oxide (NO) is a molecule that relays messages between cells and has been described as “one of the most versatile players in the immune system.”1 It is known for its potent anti-inflammatory effects and to dilate blood vessels to increase blood flow, as well as for its antiviral action.

A 2005 study showed that it inhibited viral replication in cells infected with SARS-CoV-1—the related predecessor of SARS-Cov-2, the Covid-19 pandemic virus.2 A recent review described the potential for harnessing the immune-boosting power of NO against Covid-19.3

There are supplements on the market, like beetroot powder, that rev up natural NO production, but Regev believes that if NONS makes it to market it will be a “game changer.”4




wwtyhfdaqwertyuioplkjhgfdsszxcvbnmw Rep, 2020; 7: 1448–58


Glob Health J, 2020; 4: 146–52


Alliance for Natural Health International, Oct 28, 2020


Centre for Evidence-Based Medicine,


Int J Mol Med, 2019; 44: 218–26


Aging (Albany NY), 2021; 13: 1–15


MedCram medical lectures, Jan 2, 2021,


Arch Intern Med, 2009; 169: 384–90


J Leukoc Biol, 2012; 91: 829–38


Mech Ageing Dev, 2017; 164: 61–6


Aging Clin Exp Res, 2020; 32: 1195–8


J Clin Endocrinol Metab, 2020; dgaa733


BMJ, 2017; 356: i6583


Nutrients, 2020; 12: 3799; Postgrad Med J, 2020; 139065

15; search terms Covid19, vitamin D


Queen Mary University of London, press release Oct 13, 2020,


The Times, Oct 28, 2020,


The Connexion, Nov 5, 2020;


US Department of Justice, Jan 8, 2021


Anticancer Res, 2009; 29: 3495–500


Aliment Pharmacol Ther, 2020; 51: 1434–7


Mayo Clin Proc, 2015; 90: 577–86



Int J Endocrinol, 2017; 2017: 7454376


Eur J Clin Nutr, 2003; 57: 1193–7


Magnes Res, 1996; 9: 185–203


Maturitas, 2021; 143: 1–9


J Cell Biochem, 2004; 93: 588–97


Aging Dis, 2021; 12: 14–26


PharmaNutrition, 2020; 12: 100190

31, search terms Covid19, vitamin C


Adv Nutr, 2019; 10: 696–710


PLoS One, 2014; 9: e109180.


Naunyn Schmiedebergs Arch Pharmacol, 2020; 393: 1153–6


Molecules, 2016; 21: 623


Biomolecules, 2021; 11: 10; 3 Biotech, 2021; 11: 67


ChemRxiv, 2020 doi: 10.26434/chemrxiv.11871402.v3


ChemRxiv, 2020 doi: 10.26434/chemrxiv.12181404


Toxicology, 2011; 290: 350–8


Br J Nutr, 2010; 103: 107–13


Proc Nutr Soc, 2000; 59: 595–600


Proc Natl Acad Sci U S A, 2006; 103: 4628–33


Biochem Pharmacol, 2010; 79: 413–20


Eur Respir J, 1997; 10: 1535–41


Microbes and immune health



Annu Rev Immunol, 2015; 33: 227–56


Mucosal Immunol, 2021; 1–9


Nitric oxide—natural hand sanitizer for the nose?


Indian J Biochem Biophys, 2007; 44: 310–9


J Virol, 2005; 79: 1966–9


Nitric Oxide, 2020; 103: 4–8


Jewish News, Jan 13, 2021

What do you think? Start a conversation over on the... WDDTY Community

Article Topics: immune system, Vitamin D
  • Recent Posts

  • Copyright © 1989 - 2024 WDDTY
    Publishing Registered Office Address: Hill Place House, 55a High Street Wimbledon, London SW19 5BA
    Skip to content