On The Shelf
Johanna Taylor Katroscik, PharmD
Although supplement sales have skyrocketed since the beginning of the pandemic, there is no scientific evidence that immune-boosting supplements can cure or prevent COVID-19 infection. So, what does the science say about whether or not these same supplements can play a supportive role? To help health professionals navigate some of these questions, NIH has published an online fact sheet, “Dietary supplements in the time of COVID-19,” that contains information regarding 15 different supplements and the research that has (or has not) been conducted.
Supplements with supportive data
Andrographis is an herbal supplement native to Southeast Asia that is used for symptom management of cold, flu, and other respiratory infections. Data suggest that andrographis might reduce the severity of respiratory tract infections.
Elderberry extract is derived from the Sambucus nigra plant and contains a number of compounds (e.g., flavanols, anthocyanins) that are believed to have antiviral, anti-inflammatory, and immune-stimulating effects. In small clinical trials, elderberry has been shown to reduce both the severity and the length of cold and flu infection. Researchers also speculate that it might have similar effects on COVID-19 infections.
Vitamin C has a reputation for being an immune-boosting champion. It plays a critical role in both innate and adaptive immunity and is believed to help prevent viral infections. Regular dietary intake of vitamin C is recommended for all individuals. Because vitamin C is crucial for immune system function, a deficiency in vitamin C may decrease the immune system’s ability to fight pathogens. The recommended daily intake for most healthy adults is approximately 75 mg per day for women and 95 mg per day for men.
Zinc is a mineral that the body uses for a variety of functions. It has antiinflammatory and antiviral properties, and people who have a zinc deficiency may be at increased risk of viral infections. Treatment of the common cold with zinc lozenges has been associated with a shorter duration of symptoms and illness; researchers believe that this may also be true for COVID-19 symptoms. Additionally, zinc is necessary for both smell and taste and studies are being done to see if zinc supplementation can help resolve loss of smell or taste from COVID-19.
What to tell your patients
While none of the supplements listed above have been recommended to be taken or avoided for the prevention or treatment of COVID-19, they may be beneficial to patients who have mild to moderate symptoms. Most of these supplements are theorized to work by supporting specific parts of the body’s natural immune function (see Table for details).
As with all new medications or supplements, patients should consult with a pharmacist or other health care professional prior to ingestion to ensure that the supplements don’t interact with medications they are currently taking. Because these medications may affect or modulate the immune system, it is especially important for patients who are taking immune-modulating prescription medications to talk with their health care providers prior to initiating a supplement.
Working to prevent and slow the spread of COVID-19 is one of the most important precautions that people can take. In addition to getting vaccinated, maintaining social distance, and proper hand hygiene, the Institute for Functional Medicine offers other lifestyle recommendations that people can take to help maintain or strengthen a healthy immune system. The recommendations predominantly have to do with leading a healthy lifestyle—eating a healthy and well-balanced diet, getting adequate amounts of sleep, and exercising regularly.
They also offer recommendations to help alleviate symptoms associated with respiratory infections—these vary based on the targeted symptom (e.g., honey and/or soothing tea for sore throat, humidifier or steam for congestion, etc.) and their overall recommendations are to drink plenty of fluids and rest as much as possible. While there is no magic bullet to cure COVID-19 or other respiratory infections, there are a number of interventions that may be helpful for symptom management. ■
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Vitamin/mineral/supplement
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Theorized mechanism of action against COVID-19
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Data/clinical trials to date
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Adverse effects or drug–drug interactions
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Andrographis
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Active component is andrographolide. Andrographolide and its derivatives are believed to have antiviral, anti-inflammatory, and immune-stimulating properties.
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One small clinical trial conducted in Thailand with only 12 participants showed promising results when given to patients with COVID—this prompted several more clinical trials to be conducted in Thailand and Georgia, which are both still underway.
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In the clinical trials performed, adverse effects included nausea, vomiting, vertigo, skin rashes, diarrhea, and fatigue.
May decrease blood pressure and inhibit platelet aggregation. Monitor closely if patient is taking anti-hypertensive or anticoagulant medications.
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Elderberry
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Elderberry is believed to inhibit viruses from binding to host cells.
It is also believed to have anti-inflammatory and antiviral properties.
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Small clinical trials have investigated whether elderberry can prevent or cure cold or influenza viruses. These trials had somewhat inconclusive results but patients who were enrolled and taking elderberry supplements tended to have a shorter duration of flu or cold symptoms.
There have been no clinical trials to date focused on the effect of elderberry on patients with COVID-19.
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It is important to note that elderberry is a plant and consuming any part of the plant in its raw form has the potential for severe toxicity.
May affect glucose or insulin metabolism. It should be used with caution in patients with diabetes.
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Vitamin C
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Vitamin C is important for innate and adaptive immunity. Has antioxidant, antimicrobial, and antiviral properties.
It enhances B-cell and T-cell differentiation and proliferation.
Because of the function of vitamin C in the immune system, a deficiency is believed to put people at a higher risk of viral infection.
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One small retrospective study looked at patients with COVID-19 who required mechanical ventilation. Patients given vitamin C had lower mortality rates than patients who did not receive vitamin C.
Another study looked at patients in critical care units with COVID-19 and did not show any difference in mortality between patients who received vitamin C compared to those who did not.
Other small clinical trials researched the effect of vitamin C on patients with COVID-19—at this point, the data are still inconclusive.
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Vitamin C is generally well-tolerated, but if taken in higher doses can cause diarrhea, nausea, and stomach cramping.
Vitamin C may decrease efficacy of certain radiation and chemotherapy treatments. Patients undergoing these treatments should consult with their provider prior to supplementation.
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Zinc
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Zinc deficiency is thought to impair numerous aspects of a fully functioning immune system (e.g., reduced formation, maturation, and activation of lymphocytes).
Zinc deficiency is also associated with an increased risk of respiratory infection.
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Several small case studies suggested that zinc supplementation may reduce severity and/or duration of illness.Other studies showed no difference in severity, duration, or clinical outcomes between patients who did and did not receive zinc supplementation.
Several clinical trials are in progress examining benefits of using zinc in patients with COVID-19.
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Zinc is generally well-tolerated, but if taken in higher doses zinc can cause nausea, vomiting, diarrhea, headaches, and loss of appetite.
Zinc can reduce the absorption of some antibiotics and penicillamine.
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