There are no dietary supplements that will cure or prevent disease. With the 2019 coronavirus COVID-19 pandemic, it’s especially important to understand that no supplement, diet, or other lifestyle modification other than physical distancing, also known as social distancing, and proper hygiene practices can protect you from COVID-19.

There is no research to support the use of any dietary supplement to protect against COVID-19. No supplement may claim to diagnose, prevent, treat or cure COVID-19. Consumers and retailers should avoid products that suggest they do.1, 2

Dietary Supplements in the United States

The Dietary Supplement Health and Education Act of 1994 (Public Law 103-417, DSHEA), authorized the establishment of the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH). The ODS was created in 1995 within the Office of Disease Prevention (ODP).

The mission of ODS is to 

Strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating, and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the U.S. population.3

One of the purposes in creating the ODS was to promote scientific research in dietary supplements. In the United States, these ingredients are usually defined as including plant extracts, enzymes, vitamins, minerals, amino acids, and hormonal products that are available without prescription and are consumed in addition to the regular diet. Although vitamin and mineral supplements have been available for decades, their health effects have been the subject of detailed scientific research only within the last 15–20 years.4 

As part of the mission of the NIH, information about current clinical research using pharmaceuticals and/or dietary supplements that are being evaluated for a wide range of pathologies affecting humans is provided on the website Here professionals and consumers can search any pathology using a variety of filters to narrow their search.

Dietary Supplement Sales in the United States

Revenue from vitamin and nutritional supplement production reached nearly $31 billion in the United States in 2018. The industry is set to add over a $1 billion more in revenue in 2019.5 U.S. sales data for 2020 were not available (as of June 1, 2020) from multiple online industry sources.

Vitamins: A Brief Overview

Although vitamins have been in existence forever, “vitamins” by definition have been labeled as such since 1912. They are a group of substances that are needed for normal cell function, growth, and development. Semba6 provides an excellent review of the discovery of vitamins.

MedLine PLUS identified 13 essential vitamins.7 Each vitamin’s function in the body is also described on the MedLinePLUS website and will not be reviewed here. The vitamins are labeled alphabetically but with no vitamin F, G, H, I and J (these vitamins were later included with other vitamin groupings). The current list includes: Vitamin A, B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6, B7 (biotin), B9 (folate/folic acid), B12 (cyanocobalamin), C, D, E, and K.

The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid play important and complementary roles in supporting the immune system. 

The authors concluded that (1) supplementation with the above micronutrients and omega-3 fatty acids is a safe, effective, and low-cost strategy to help support optimal immune function; (2) supplementation above the Recommended Dietary Allowance (RDA), but within recommended upper safety limits, for specific nutrients such as vitamins C and D is warranted; and (3) public health officials are encouraged to include nutritional strategies in their recommendations to improve public health.8

The Role of the Food and Drug Administration

Several supplement companies looking to cash in on the COVID-19 pandemic were cited by the U.S. Food and Drug Administration as early as February/March after the pandemic for selling fraudulent products (teas, essential oils, tinctures and colloidal silver).9 These products are unapproved drugs that posed significant risks to patient health (especially colloidial silver) and violate federal law.

If a consumer experiences and adverse side effect using a dietary supplement, nutraceutical or essential oil, the FDA encourages health care professionals and consumers to report adverse events or quality problems experienced with the use of [non-prescription, over-the-counter] COVID-19 products to the FDA’s MedWatch Adverse Event Reporting Program. NOTE: This is the same program professionals can use to report an adverse event from a pharmaceutical). 

More than 170 Fact Sheets are available from the National Institutes of Health’s Office of Dietary Supplements10 for those interested in learning more about dietary supplements. 

The Role of the Federal Trade Commission (FTC)

One of the many missions of the FTC (established in 1914) is to protect consumers from false or deceptive advertising.11

In April 2020, over 20 companies were warned by the FTC concerning false and deceptive advertising about their products and COVID-19. Many of the warning letters focused on questionable representations for high doses of vitamins), intravenous treatments (vitamin C), ozone, and purported stem cell therapies.12 

Just one month later, another 45 companies received warnings about their product claims for COVID-19 treatment/intervention. Ten companies touted vitamin C (two oral and six intravenous) and one vitamin D for this infection.13

Dietary Supplements For COVID-19 Treatment: Part 1

The research review for this section of the report, used the following filters on May 21, 2020, at

  • Recruitment: Recruiting
  • Eligibility Criteria: All Ages
  • Sex: All
  • Study Type: Interventional (Clinical Trials)
  • Study Results: All
  • Study Phase: Early Phase 1, Phase 1, Phase 2, and Phase 3
  • Funder: All Funders
  • Study Documents: Blank

The website identified no current research using the search term “coronavirus.” 

When using the search term “COVID-19” one study was identified using vitamin D with hydroxychloroquine.14 The study will be evaluating approximately 1,700 subjects over the age of 18 years. This research is being conducted by Sanford Health is Sioux Falls, South Dakota. The estimated completion date is 2023.

DiSogra15 provides a review of the ototoxic effects of hydroxychloroquine in the treatment of COVID-19 survivors.

Dietary Supplements For COVID-19 Treatment: Part 2

1. Vitamin C for COVID-19 Intervention

Vitamin C (which has high antioxidant properties) was the most often referenced vitamin in reviewing the FTC complaint documents. 

Cheng16 proposed high dosages of vitamin C (oral or IV) for acute respiratory distress syndrome (ARDS) but concluded that “well-designed clinical studies are absolutely needed to develop standard protocols for bedside use.”

At the present time, reports that there are two clinical trials underway using intravenous vitamin C. The first is in Wuhan, China, titled: Vitamin C Infusion for the Treatment of Severe 2019-nCoV Infected Pneumonia: a Prospective Randomized Clinical Trial. The second trial is recruiting subjects in the US titled: Administration of Intravenous Vitamin C in Novel Coronavirus Infection and Decreased Oxygenation (AVoCaDO): A Phase I/II Safety, Tolerability, and Efficacy Clinical Trial. Details can be found at the clinical trials website.

Finally, as of May 21, 2020, the FTC had received a total of 52,458 complaints with an estimated cost to the consumers at $38.58 million with an average cost of $470.00 per person.17

2. Vitamin D for COVID-19 Intervention

The first proposed use of vitamin D for COVID-19 intervention appeared in April 2020.18

A subsequent study19 suggested that vitamin D supplementation could reduce the risk of influenza and COVID-19 infections and deaths. Despite their extensive review of vitamin D as a therapy for respiratory disorders “the hypothesis that vitamin D supplementation can reduce the risk of influenza and COVID-19 incidence and death should be investigated in trials to determine the appropriate doses, serum 25(OH) D concentrations, and the presence of any safety issues.”

In another study20 the authors examined vitamins C, D, zinc and elderberry as treatment options for COVID-19 patients. They concluded that because of a lack of evidence in COVID-19 patients, healthcare providers and patients should not rely on dietary supplements to prevent or treat COVID-19.

3. Zinc for COVID-19 Intervention

Zinc is a component of many enzymes and transcription factors in cells all over the body, and inadequate zinc levels limit the individual’s ability to mount an adequate immune response to infections.21 Oral zinc supplementation reduces the incidence rate of acute respiratory infections by 35 percent, shortens the duration of flu-like symptoms by approximately two days, and improves the rate of recovery.22,23 

The dose of zinc in these studies ranged from 20 mg/week to 92 mg/day. Dose does not appear to be the main driver of the effectiveness of zinc supplementation.24

Also, zinc can enhance innate and adaptive immunity in the course of a viral infection. The effectiveness of zinc can be enhanced by using chloroquine as an ionophore while zinc inside the infected cell can stop SARS-CoV-2 replication.25

Skalny, et al26 reported that zinc may possess protective effect as preventive and adjuvant therapy of COVID 19 through reducing inflammation, improvement of mucociliary clearance, prevention of ventilator induced lung injury, modulation of antiviral and antibacterial immunity. However, the authors concluded that further clinical and experimental studies are required.

4. Elderberry for COVID-19 Intervention

Rahman25 reported that elderberry extracts may help to prevent the early stage of corona virus infections, which includes COVID-19. Elderberry contains compounds that decrease the ability of viruses to infect cells.27 PubMed had no published research to support those claims. See also Adams et al.20

Role of the Audiologist

The role of the audiologist is quite clear: Patients should be advised about the inefficacy and unknown safety issues of dietary supplements for COVID-19 management. Also, patients should be advised that no federal health agency (i.e., FDA, CDC) recommends the use of a dietary supplement for any part of the COVID-19 management process. User testimonials that appear in any advertisements are not a substitute for evidence-based research findings.


Vitamins, dietary supplements, and nutraceuticals have been researched for a variety of medical conditions as a preventive and a treatment. The COVID-19 pandemic that is part of our lives at this time has been under the watchful eye and strictly management of the Centers for Disease Control and Prevention

Over-the-counter/mail-order supplements are classified by the FDA as food; therefore, they are exempt from the rigors of acquiring evidence-based research to back up their health claims. User testimonials are not a substitute for evidence-based research showing efficacy and safety.

Unfortunately, because of loose federal regulations, unscrupulous companies have already been marketing the use of dietary supplements and a preventive, treatment, or management strategy for COVID-19. The FDA and FTC remain vigilant to maintain consumer safety.

Along with other professionals, audiologists must also be vigilant in their patient care – especially during their case history review – to counsel their patients about the extremely limited safety and efficacy information about dietary supplements as it pertains to COVID-19. 


1Council for Responsible Nutrition. Accessed online 5/27/2020.

2Kubala J. The 15 best supplements to boost your immune system right now. Accessed online 5/27/2020.

3National Institutes of Health, Office of Dietary Supplements. Accessed online 5/21/2020.

4National Institutes of Health, Office of Dietary Supplements. Accessed online 5/21/2020.

5Shabandeh M. U.S. sales of vitamins and nutritional supplements manufacturing 2018–2019. Statista ( August 2019. Accessed online 5/22/2020.

6Semba RD. (2012) The discovery of the vitamins. Int J Vitam Nutr Res 82(5):310–315.

7U.S. National Library, MedLine Plus. Accessed online 5/21/2020.

8 Calder PC, Carr CC, Gombart AF, Eggersdorfer M. (2020) Optimal nutritional status for a well-functioning immune system is an important factor to protect against viral infections. Nutrients 12(4):1181.

9U.S. Food and Drug Administration. Coronavirus update: FDA and FTC warn seven companies selling fraudulent products that claim to treat or prevent COVID-19. March 9, 2020. ( Accessed online 5/22/2020.

10National Institutes of Health, Office of Dietary Supplements. Accessed online 5/22/2020.

11U.S. Federal Trade Commission. ( Accessed online 5/22/2020.

12U.S. Federal Trade Commission. ( Accessed online 5/22/2020.

13U.S. Federal Trade Commission. ( Accessed online 5/22/2020 Randomized, double-blind, controlled trial of hydroxychloroquine vs placebo as post-exposure prophylaxis against COVID-19 infection

15DiSogra RM. Audiological management of COVID-19 survivors treated with hydroxychloroquine and azithromycin, Audiol Today May/June 2020. Accessed online 5/22/2020 (

16Cheng, RZ. Can early and high intravenous dose of vitamin C prevent and treat coronavirus disease 2019 (COVID-19)? Med Drug Discov 2020 Mar; 5: 100028. Published online 2020 Mar 26. Accessed online 5/22/2020

17U.S. Federal Trade Commission. Accessed online 5/22/2020.

18Wimalawansa, S.J. Global epidemic of coronavirus - COVID-19: What we can do to minimize risks. Eur J Biomed Pharm Sci. 2020, 7, 432–438.

19Grant WB, Lahore, H, McDonnell SL, Baggerly CA, French CB, Aliano JL, Bhattoa HP. (2020) Evidence that vitamin D supplementation could reduce risk of influenza and COVID-19 infections and deaths. Nutrients 12(4):988. Accessed online 5/22/2020. 

20Adams, KK, Baker WL, Sobieraj. Myth busters: dietary supplements and COVID-19. Ann Pharmacother (2020) May 12. Accessed online ahead of print 5/27/2020.

21Read SA, Obeid S, Ahlenstiel C, Ahlenstiel G. The role of zinc in antiviral immunity. Adv Nutr. 2019 Jul 1;10(4):696-710.

22Hemilä H, Fitzgerald JT, Petrus EJ, Prasad A. Zinc acetate lozenges may improve the recovery rate of common cold patients: an individual patient data meta-analysis. Open Forum Infect Dis 2017 April, 4(2):1-6.

23Roth DE, Richard SA, Black RE. Zinc supplementation for the prevention of acute lower respiratory infection in children in developing countries: meta-analysis and meta-regression of randomized trials. Int J Epidem. 2010 Jun 1;39(3):795-808.

24Harvard School of Public Health. Ask the Expert: The role of diet and nutritional supplements during COVID-19. Accessed online 5/27/2020.

25Rahman MT, Idid, SZ. Can zinc be a critical element in COVID-19 treatment? Biol Trace Elem Res 2020 May 26. Accessed online ahead of print 5/27/2020. 

26Skalny AV, Rink L,  Ajsuvakova OP, Aschner M, Gritsenko VA, Alekseenko SI, Svistunov AA, Petrakis D, Spandidos DA, Aaseth J, Tsatsakis A, Tinkov AA. Zinc and respiratory tract infections: perspectives for COVID 19 (Review). Int J Mol Med 2020 Apr 14. Accessed online ahead of print 5/27/2020.

27Andrew Weil Center for Inegrative Medicine. COVID-19 FAQ. Accessed online 5/28/2020.

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