The Real Science Behind Zinc and Elderberry Supplementation for Viral Infections

Dr. Stengler’s News and Breakthroughs

The Real Science Behind Zinc and Elderberry Supplementation for
Viral Infections

There have been some myths circulating on the Internet in regards to nutritional supplements and their role in viral infections and especially COVID-19. In this article, I will address claims made about the mineral zinc and the herb elderberry.

Let me begin by noting that is that there is no published research demonstrating that any nutritional supplement cures COVID-19. I know most of you are aware of that, but for those of you reading my materials for the first time, you will find that I focus on the scientific and clinical experience when making recommendations. There is a lot of nutritional gurus who in their passion for nutritional therapies make claims that range from the exaggerated to complete fabrications. Yet on the other end of the spectrum are those who refuse to believe there is any validity to nutritional and holistic therapies. They too, are unscientific and guilty of misleading people away from valid therapies. Without a doubt, there is good scientific evidence that certain foods, lifestyles, and several nutritional supplements are proven to support a healthy immune response and have antiviral effects.

False Claim #1

Zinc must be used in the lozenge form to have an antiviral effect

Some people claim that zinc must be used in the lozenge form to have an antiviral effect such as the common cold or even possibly COVID-19. They state that zinc must come in contact with the virus as it enters the respiratory system for it to be effective.

It is important to note that zinc plays a role by supporting both the innate (activating immune cells that directly kill viruses) and adaptive (antibody production) parts of the immune system. Also, when it gets into the cell (intracellular), it has a virucidal (antiviral) effects. Zinc can be transported via special proteins intracellularly from food and supplement sources into the cell.

Researchers from Oregon State University state: “adequate zinc intake is essential in maintaining the integrity of the immune system,” and “zinc-deficient individuals experience an increased susceptibility to a variety of infectious agents.” They also note that one of the microbe killing effects of zinc occurs when microbes are exposed to macrophages (immune cells) that attack the infectious agent with zinc.

In studies done with the common cold, it appears zinc has a direct antiviral effect when in contact with the virus at the mucosal sites in the respiratory tract. However, the antiviral effects of zinc go beyond this with its internal immune system benefits as well as intracellular effects.

Zinc lozenges have indeed been shown in older studies to be helpful in the treatment of the common cold (rhinovirus). A review of 14 studies on zinc treatment for the common cold, including lozenges, tablets, and syrups, concluded that people who took these supplements for five months or longer experienced fewer colds.  The most recent study published in 2020 did not find zinc acetate lozenges to be effective in the treatment of the common cold.

Positive studies for the treatment of the common cold and zinc have tended to use daily doses of greater than 75 mg daily and used earlier in the course of the infection. Long term use of 60 mg or more of zinc daily should be accompanied by copper supplementation. Do note that most zinc lozenge studies and the common cold have been with active infections and not used for preventative purposes. Recommending zinc lozenges in smaller doses (less than 75 mg) for the prevention or treatment of the common cold (or any other viral infection) is unproven. Also, there are no studies using zinc lozenges for COVID-19 treatment.

Zinc ion transport intracellularly may be improved by dietary polyphenols such as quercetin. Some researchers, such as my colleague Dr. Michael Murray, recommend supplementation of highly absorb-able quercetin along with zinc supplementation to improve the transport of zinc into the cell.

Whether one can apply zinc therapy to the COVID-19 pandemic is theoretical but reasonable. I have found only one study on Coronavirus and zinc treatment in vitro (test-tube), where zinc ions appear to inhibit Coronavirus (SARS-CoV) intracellularly.

Yet we do know that zinc is essential for a healthy immune system and has antiviral effects. The Recommended Dietary Allowance for zinc is 8 mg for adult females and 11 mg for adult males. These are minimal dosing recommendations by the government and considered by nutritionally oriented doctors such as myself to be inadequate for optimal health and immunity. Supplementing zinc at 20 mg to 25 mg daily with a meal is very reasonable. People that are more prone to zinc deficiency should definitely consider zinc supplementation. Examples of individuals at risk for zinc deficiency include:

Children and adolescents

Pregnant and lactating women

Those with digestive problems such as Crohn’s disease and ulcerative colitis


Adults over the age of 65


Those taking certain medications such as anticonvulsants, diuretics, and certain antibiotics

False Claim #2  

Elderberry can worsen the cytokine storm of COVID-19

Elderberry (Sambucus nigra) has been shown to reduce the common cold duration and severity in overseas travelers. Also, it reduces the length and severity of the flu when given at the onset of the infection.

Cytokines are substances released by the immune system during an infection as part of a normal response. The COVID-19 disease is problematic for some people, especially seniors since it results in an excessive cytokine response, also termed “cytokine storm.” This over-reaction by the immune system can cause lung damage, respiratory distress, and in a limited number of cases, death. However, it is a mistake to think of cytokine production during infection as a bad thing since it is a necessary part of a healthy immune response. Cytokines summon other immune cells to come to the infected and inflamed area to target and destroy the infectious agent. Some authors have taken a small 2001 in vitro (test tube study) out of context where it was shown to increase specific inflammatory cytokines as part of a natural inflammatory/immune process.

There is no research I know of that shows it would be problematic in the initiation or worsening of a cytokine storm. Elderberry has multiple beneficial effects for a healthy immune response, which involves several cytokines. Keep in mind that elderberry extract is effective in reducing flu symptoms and the duration of the illness when given early in the treatment. These benefits have been documented without any indication of cytokine storm induction. If cytokine overstimulation were problematic, then one would not expect a reduction in the intensity of flu symptoms or a shortened duration of the illness with Elderberry supplementation. Therefore, the published human studies on Elderberry refute the hypothesis that Elderberry is problematic with cytokine storm induction.



Barak, V., Halperin, T., & Kalickman, I. (2001). The Effect of Sambucol, a Black Elderberry-Based, Natural Product, on the Production of Human Cytokines: I. Inflammatory Cytokines. Eu Cytokine Netw, 12(2).

Dabbagh-Bazarbachi, H., Clergeaud, G., Quesada, I., Ortiz, M., O’Sullivan, C., & Fernández-Larrea, J. (2014). Zinc Ionophore Activity of Quercetin and Epigallocatechin-gallate: From Hepa 1-6 Cells to a Liposome Model. Journal Of Agricultural And Food Chemistry, 62(32), 8085-8093.

Daneshkhah, A., Agrawal, V., Eshein, A., Subramanian, H., Roy, H., & Backman, V. (2020). The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients.

Hemilä, H., Haukka, J., Alho, M., Vahtera, J., & Kivimäki, M. (2020). Zinc acetate lozenges for the treatment of the common cold: a randomised controlled trial. BMJ Open, 10(1), e031662.

Marks, R. (2020). Unveiling How Coronavirus Hijacks Our Cells to Help Rush New Drugs to Patients. Unveiling How Coronavirus Hijacks Our Cells to Help Rush New Drugs to Patients | UC San Francisco. Retrieved 14 May 2020, from

Meneghetti, A. (2018). What is the role of oral zinc in the treatment of upper respiratory tract infection (URI)?. Retrieved 14 May 2020, from

Read SA, Obeid S, Ahlenstiel C, Ahlenstiel G. The Role of Zinc in Antiviral Immunity. Adv Nutr. 2019;10(4):696‐710. doi:10.1093/advances/nmz013

Zinc. Linus Pauling Institute. (2020). Retrieved 15 May 2020, from