The Evidence for Herbal Supplements for Immunity and Stress During COVID-19
By Gary Deng, MD, PhD, and Eugenie Spiguel, MSN, ANP-BC
As the world embarks on unprecedented research efforts to prevent and treat the COVID-19 coronavirus, patients with cancer and healthcare providers alike may be interested in using herbal products to boost their immune system or relieve anxiety and stress. However, finding accurate information is challenging: no herbs have been scientifically proven to prevent or treat COVID-19, and some may even cause harm.
The following evidence-based information on popular herbs used for immunity and to relieve anxiety and stress is adapted from the Memorial Sloan-Kettering Cancer Center’s About Herbs (https://www.mskcc.org/cancer-care/diagnosis-treatment/symptom-management/integrative-medicine/herbs) website. The links will take you to the full monographs to learn more about adverse effects and herb-drug interactions.
Herbs and Supplements for Immunity
- Echinacea (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/echinacea) is widely used to stimulate the immune system and prevent and treat the common cold and influenza. Clinical data (https://www.ncbi.nlm.nih.gov/pubmed/24877712) suggest that it may help improve immune function, but findings on cold prevention (https://www.ncbi.nlm.nih.gov/pubmed/25668266) are not definitive.
- Ginger (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/ginger) is commonly used in culinary preparations, and it’s used in traditional medicine for cold, fevers, headache, and gastrointestinal disorders. However, no clinical evidence supports antiviral effects.
- Zinc (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/zinc) is used to treat the common cold, diabetes, and rheumatoid arthritis. It has been shown (https://www.ncbi.nlm.nih.gov/pubmed/23775705) to help reduce the symptoms and duration of the common cold, but only when taken within 24 hours after symptoms appear.
- Garlic (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/garlic) is a mainstay of many cuisines around the world. Clinical studies show that it stimulates the immune system (https://www.ncbi.nlm.nih.gov/pubmed/26764326) and may prevent the common cold (https://www.ncbi.nlm.nih.gov/pubmed/22419312), but robust data are lacking.
Herbs and Supplements for Anxiety and Stress
- Ashwagandha (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/ashwagandha), referred to as “Indian ginseng,” is widely used in Ayurvedic medicine to relieve anxiety (https://www.ncbi.nlm.nih.gov/pubmed/19718255) and stress (https://www.ncbi.nlm.nih.gov/pubmed/31517876). Clinical studies indicate that it may help alleviate anxiety and stress and improve sleep (https://www.ncbi.nlm.nih.gov/pubmed/31728244) in patients with insomnia.
- Chamomile (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/chamomile-german) is a popular relaxant that’s shown modest benefits for chronic insomnia and anxiety. It was also reported useful for improving sleep quality (https://www.ncbi.nlm.nih.gov/pubmed/29154054), fatigue (https://www.ncbi.nlm.nih.gov/pubmed/21939549), and depression (https://www.ncbi.nlm.nih.gov/pubmed/22894890).
- Valerian (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/valerian) is known for its calming effects, but current evidence is insufficient (https://www.ncbi.nlm.nih.gov/pubmed/23653088) to support its use for reducing anxiety.
- L-theanine (https://www.mskcc.org/cancer-care/integrative-medicine/herbs/l-theanine) is an amino acid in green tea that’s known for its relaxant effects. It was shown to be safe in improving depressive symptoms and anxiety (https://www.ncbi.nlm.nih.gov/pubmed/27396868) in patients with major depressive disorder.
Oncology nurses have an important role in informing patients that no herbs can cure COVID-19, that indiscriminate use of herbal supplements is unsafe, and that supplements have the potential to interact with prescription medications. The best way to prevent or treat COVID-19 is to follow advice from healthcare authorities and clinicians, not self-medicating with herbs and supplements.