news

The Functional Medicine Approach to COVID-19: Virus-Specific Nutraceutical and Botanical Agents

Content Reviewed on 09/05/23

Background and Introduction

Health professionals and the public must be well informed about the SARS-CoV-2 virus, the disease it causes (COVID-19), and how it spreads. This information is readily available and not within the scope of this document. At this time, there are no uniformly successful treatment for COVID-19. In this context of insufficient evidence, the scope of this document will be to assess the scientific plausibility of promising prevention approaches and therapeutic (nutraceutical and botanical) interventions and then to offer clinical recommendations. This article is part one of a series. Click here to view part two.

With respect to interventions, the practice of Functional Medicine emphasizes the primacy of safety, validity, and effectiveness. In the novel context of COVID-19, validity in the form of published evidence is lacking. Therefore, “validity” relies upon inferences from the mechanisms of action of individual agents and/or published outcomes data supporting their mitigating effects on illness from other viral strains. Likewise, data for the “effectiveness” of interventions targeting the viral mechanisms of COVID-19 are nascent and rapidly emerging. In this context, the following recommendations represent the Functional Medicine approach to the COVID-19 crisis:

  • Adherence to all current health recommendations from official sources to decrease viral transmission.
  • Optimizing modifiable lifestyle factors in order to improve overall immune function (an introductory document on boosting immunity is available here). This should reduce progression from colonization to illness.
  • Personalized consideration of therapeutic agents that may:
    • Favorably modulate cellular defense and repair mechanisms.
    • Favorably modulate viral-induced pathological cellular processes.
    • Promote viral eradication or inactivation.
    • Mitigate collateral damage from other therapeutic agents.
    • Promote resolution of collateral damage and restoration of function.
  • Treatment of confirmed COVID-19 illness (as per conventional standards and practice):
    • May reduce the severity and duration of acute symptoms and complications.
    • May support recovery and reduce long-term morbidity and sequelae.

Additional references are being collated and will be made available in the future.

Clinical Recommendations and Mechanisms of Action

Background and Mechanisms of Action

We encourage practitioners to learn about the mechanism of invasion, replication, and pathophysiology of the COVID-19 virus. Much of what we know has been extrapolated from basic science research on SARS-CoV-2. Excellent resources are available online, including the free YouTube lectures through Dr. Roger Seheult: 

This document discusses the mechanisms of action of a number of different botanical and nutraceutical agents. These agents can be considered as immunoadjuvants, defined as substances that act to accelerate, prolong, or enhance antigen-specific immune responses by potentiating or modulating the immune response.[1]

A coronavirus such as SARS-CoV-2 can be deadly because of its ability to stimulate a part of the innate immune response called the inflammasome, which can cause uncontrolled release of pro-inflammatory cytokines, leading to cytokine storm and severe, sometimes irreversible, damage to respiratory epithelium.[2] The SARS-CoV-2 virus has been shown to activate the NLRP3 inflammasome.[3,4] A 2016 review article[5] entitled “Natural compounds as regulators of NLRP3 inflammasome-mediated IL-beta production” notes that “resveratrol, curcumin, EGCG [epigallocatechin gallate], and quercetin are potent inhibitors of NLRP3 inflammasome-mediated IL-1beta production, typically acting at more than one element of the involved pathways. However, it should be noted that these polyphenols have an even much broader biological effect, as they influence a variety of pathways.” For example, these polyphenols modulate NF-kB upregulation, which is useful to counteract the COVID-19 ’hyper-inflammation.[6]

A preprint released on March 23, 2020, identified the ability of plant bioactive compounds to inhibit the COVID-19 main protease (Mpro),[7] which is necessary for viral replication. There is much excitement surrounding the recent identification of Mpro, and it is a current potential pharmaceutical drug target. Kaempferol, quercetin, luteolin-7-glucoside, demethoxycurcumin, naringenin, apigenin-7glucoside, oleuropein, curcumin, catechin, and epicatechin-gallate were the natural compounds that appeared to have the best potential to act as COVID-19 Mpro inhibitors. Though further research is necessary to prove their efficacy, this study provides the biologic plausibility and mechanistic support (SARS-CoV-2 protease inhibition) to justify their use.

For these reasons, we recommend the following compounds, at standard dosages, to prevent activation of the NLRP3 inflammasome, to decrease NF-kB activation, and to potentially inhibit SARS-CoV-2 replication. There is no literature to support a regimen of a single vs. multiple agents. Our recommendation is to use higher dosing and/or multiple agents when patient contextual factors (e.g., patient desire, pre-existing inflammation, multiple co-morbidities, higher risk, etc.) and/or therapeutic decision-making warrant such use.

Download COVID-19: Nutraceutical and Botanical Recommendations for PatientsDownload COVID-19: Nutraceutical and Botanical Recommendations for Patients

Recommended Interventions

ZINC

Zinc contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. There is also evidence that it suppresses viral attachment and replication. Zinc deficiency is common, especially in those populations most at risk for severe COVID-19 infections, and is challenging to accurately diagnosis with laboratory measures. Supplementation with zinc is supported by evidence that it both prevents viral infections and reduces their severity and duration. Moreover, it has been shown to reduce the risk of lower respiratory infection, which may be of particular significance in the context of COVID-19.

Intervention Zinc
Suggested dose 30–60 mg daily, in divided doses
Zinc acetate, citrate, picolinate, or glycinate orally
Zinc gluconate as lozenge
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate innate and adaptive immune system
Favorably modulate viral-induced pathological cellular processes, attachment, and replication
Outcomes data supporting their mitigating effects on illness from other viral strains Reduced severity of symptoms
Reduced duration of illness
Strength of evidence Strong
Risk of harm Minimal

ELDERBERRY

Elderberry (Sambucus nigra) is seen in many medicinal preparations and has widespread historical use as an anti-viral herb. Based on animal research, elderberry is likely most effective in the prevention of and early infection with respiratory viruses. 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. 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.

Intervention Elderberry
Suggested Dose 500 mg po qd (of USP standard of 17%
anthocyanosides) for up to 12 weeks
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate cellular defense and repair mechanisms
Favorably modulate viral-induced pathological cellular processes
Outcomes data supporting their mitigating
effects on illness from other viral strains		 Reduction and improvement in symptoms
Reduced incidence and duration
Strength of evidence Strong
Risk of harm Minimal

VITAMIN D

Activated vitamin D,1,25(OH) D, a steroid hormone, is an immune system modulator that reduces the expression of inflammatory cytokines and increases macrophage function. Vitamin D also stimulates the expression of potent antimicrobial peptides (AMPs), which exist in neutrophils, monocytes, natural killer cells, and epithelial cells of the respiratory tract. Vitamin D increases anti-pathogen peptides through defensins and has a dual effect due to suppressing superinfection. Evidence suggests vitamin D supplementation may prevent upper respiratory infections. However, there is some controversy as to whether it should be used and the laboratory value that should be achieved. Research suggests that concerns about vitamin D (increased IL-1beta in cell culture) are not seen clinically. The guidance we suggest is that a laboratory range of >50 and < 80ng/mL serum 25-hydroxy vitamin D may help to mitigate morbidity from COVID-19 infection.

Intervention Vitamin D
Suggested dose 5,000 IU po qd in the absence of serum levels
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate cellular defense and repair mechanisms:
•Activation of macrophages
•Stimulation of anti-microbial peptides
•Modulation of defensins
•Modulation of TH17 cells
Favorably modulate viral-induced pathological cellular processes:
•Reduction in cytokine expression
•Modulation of TGF beta
Outcomes data supporting their mitigating effects on illness from other viral strains Reduce progression from colonization to illness
Strength of evidence Strong for prevention
(conditional for treatment)
Risk of harm Minimal

VITAMIN A

Vitamin A is a micronutrient that is crucial for maintaining vision, promoting growth and development, and protecting epithelium and mucus integrity in the body. Vitamin A is known as an anti-inflammation vitamin because of its critical role in enhancing immune function. Vitamin A is involved in the development of the immune system and plays regulatory roles in cellular immune responses and humoral immune processes through the modulation of T helper cells, sIgA, and cytokine production. Vitamin A has demonstrated a therapeutic effect in the treatment of various infectious diseases.

Intervention Vitamin A
Suggested dose Up to 10,000-25,000 IU/d
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate cellular defense and repair mechanisms:
• Modulation of T helper cells
• Modulation of sIgA
Favorably modulate viral-induced pathological cellular processes:
• Modulation of cytokine production
Outcomes data supporting their mitigating effects on illness from other viral strains Reduction of symptom duration
Mortality reduction
Reduction of incidence of illness associated with viral strains
Strength of evidence Strong
Risk of harm Mild; only if dose is not exceeded
*Caution in pregnancy (high dietary intake of >10,000 IU/day of preformed vitamin A appears to be teratogenic)

VITAMIN C

Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing. Supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections. Vitamin C has been used in hospital ICUs to treat COVID-19 infection.

Intervention Vitamin C
Suggested dose 1-3 grams po qd
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate cellular defense and repair mechanisms
Favorably modulate viral-induced pathological cellular processes
Outcomes data supporting their mitigating effects on illness from other viral strains Reduced mortality with sepsis
Strength of evidence Moderate (for sepsis treatment)
Conditional (prevention)
Risk of harm Mild with suggested dose
Minimal (1–2 g po qd)

N-ACETYLCYSTEINE (NAC)

N-acetylcysteine promotes glutathione production, which has been shown to be protective in rodents infected with influenza. In a little-noticed six-month controlled clinical study enrolling 262 primarily elderly subjects, those receiving 600 mg NAC twice daily, as opposed to those receiving placebo, experienced significantly fewer influenza-like episodes and days of bed confinement.

Intervention N-acetylcysteine (NAC)
Suggested dose 600-900 mg po bid
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate cellular defense and repair mechanisms:
•Hypothetical: repletion of glutathione and cysteine
Outcomes data supporting their mitigating effects on illness from other viral strains Reduce progression from colonization to illness
Reduce the severity and duration of acute symptoms
Strength of evidence Limited
Risk of harm Minimal (with oral intake)

QUERCETIN

Quercetin has been shown to have antiviral effects against both RNA (e.g., influenza and coronavirus) and DNA viruses (e.g., herpesvirus). Quercetin has a pleiotropic role as an antioxidant and anti-inflammatory, modulating signaling pathways that are associated with post-transcriptional modulators affecting post-viral healing.

Intervention Quercetin
Suggested dose Regular: 1 gm po bid; phytosome: 500 mg, bid Suggested Duration: Up to 12 weeks
Mechanism(s) of action against non-COVID-19 viruses Promote viral eradication or inactivation:
•Inhibition of viral replication
Favorably modulate viral-induced pathological cellular processes:
•Modulation of NLRP3 inflammasome activation
Mechanistically promote resolution of collateral damage and restoration of function:
•Modulation of mast cell stabilization (anti-fibrotic)
Outcomes data supporting their mitigating effects on illness from other viral strains Reduction of symptoms
Strength of evidence Limited
Risk of harm Minimal (with suggested dose/duration)

EPIGALLOCATECHIN GALLATE (EGCG)

Green tea, in addition to modulating the NLRP3 inflammasome and, based on a preprint, potentially targeting the SARS-CoV-2 main protease (Mpro) to reduce viral replication, has also been shown to prevent influenza in healthcare workers.

Intervention Epigallocatechin gallate (EGCG)
Suggested dose 4 cups daily or 225 mg po qd
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate viral-induced pathological cellular processes:
•Modulation of NLRP3 inflammasome activation
Outcomes data supporting their mitigating effects on illness from other viral strains No data available
Strength of evidence Limited (for prevention)
Conditional (for treatment)
Risk of harm Minimal (mild for higher doses >800 mg where some temporary elevated liver enzymes are noted)

CURCUMIN

Curcumin has been shown to modulate the NLRP3 inflammasome, and a preprint suggests that curcumin can target the SARS-CoV-2 main protease to reduce viral replication.

Intervention Curcumin
Suggested dose 500-1,000 mg po bid (of absorption-enhanced curcumin)
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate viral-induced pathological cellular processes:
•Modulation of NLRP3 inflammasome activation
Outcomes data supporting their mitigating effects on illness from other viral strains No data available
Strength of evidence Conditional
Risk of harm Minimal

MELATONIN

Melatonin has been shown to have an inhibitory effect on the NLRP3 inflammasome. This has not gone unnoticed by the COVID-19 research community, with two recent published papers proposing the use of melatonin as a therapeutic agent in the treatment of patients with COVID-19.

Intervention Melatonin
Suggested dose 5-20 mg qd
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate viral-induced pathological cellular processes
• Modulation of NLRP3 inflammasome activation
Outcomes data supporting their mitigating effects on illness from other viral strains Research in progress
Strength of evidence Conditional
Risk of harm Minimal

RESVERATROL

Resveratrol, a naturally occurring polyphenol, shows many beneficial health effects. It has been shown to modulate the NLRP3 inflammasome. In addition, resveratrol was shown to have in vitro activity against MERS-CoV in an animal study.

Intervention Resveratrol
Suggested dose 100-150 mg po qd
Mechanism(s) of action against non-COVID-19 viruses Favorably modulate viral-induced pathological cellular processes
•Modulation of NLRP3 inflammasome activation
Outcomes data supporting their mitigating effects on illness from other viral strains No outcomes data available
Strength of evidence Conditional
Risk of harm Minimal

Evaluative Criteria

In the recommendations above, the following criteria are used to identify strength of evidence and risk of harm.

Strength of Evidence Risk of Harm
Strength of Evidence Conditional

Human trials with conflicting outcomes, or lack of published human trials. Must be supported by extensive historical experience of effectiveness, consensus of expert opinion, mechanistic plausibility, and compelling Functional Medicine model factors. In the absence of any one of these features, must be supported by compelling patient or clinical circumstances or contextual factors
Risk of Harm Minimal Risk of self-limited symptoms No risk of loss of function or corrective intervention anticipated; expected to resolve with discontinuation and observation
Strength of Evidence Limited One human study demonstrating correlation between intervention and outcome, or real world data/evidence demonstrating patient oriented outcome; Must be accompanied by compelling Functional Medicine model factors and/or patient contextual factors and mechanistic plausibility
Risk of Harm Mild Risk of self-limited symptoms. No risk of loss of function. Expected to resolve with discontinuation and minor evaluative and/or therapeutic intervention
Strength of Evidence Moderate Moderate Two independent human studies (one of which is LOE = 1 or 2) demonstrating correlation between intervention and patient oriented outcome; mechanistic plausibility required
Risk of Harm Significant Risk of temporary loss of function or quality of life Significant evaluative and/or therapeutic intervention necessary to resolve
Strength of Evidence Strong Strong Two independent human studies (both LOE = 1 or 2) demonstrating correlation between intervention and patient oriented outcome; mechanistic plausibility or one additional independent human study required
Risk of Harm Severe Risk of permanent symptoms, loss of function, quality of life, or death Long term evaluative and/or therapeutic intervention necessary to mitigate

*This resource is only intended to identify nutraceutical and botanical agents that may boost your immune system. It is not meant to recommend any treatments, nor have any of these been proven effective against COVID-19. None of these practices are intended to be used in lieu of other recommended treatments. Always consult your physician or healthcare provider prior to initiation. For up-to-date information on COVID-19, please consult the Centers for Disease Control and Prevention at www.cdc.gov.

SPECIAL THANKS
We would like to thank the IFM COVID-19 Task Force, members of the IFM staff, and consultants working with IFM for their contributions to this article.

Click here to see all references

COVID-19: Functional Medicine Resources