Ganoderma lucidum/“Lingzhi” (soul/spirit) mushroom, commonly known as “Reishi mushroom”, is a potent fungus that has been used for thousands of years in traditional Chinese medicine. Proponents claim it is especially good at modifying the immune system by increasing it when weakened, or lowering it when it is too active .
It has 400 different bioactive compounds reported to have a number of potential effects including modification of the immune system, anti-inflammatory, anti-tumor, antibacterial, antiviral, anti-diabetic, and anti-oxidative .
This article is for informational purposes only. The current coronavirus outbreak is an ongoing event and certain details may change as new information comes to light. No effective or FDA-approved products are currently available for the treatment of the new coronavirus (also known as SARS-CoV-2 or 2019-nCoV), although research is still ongoing. For now, the best preventive measures you can take against COVID-19 are standard precautions, including social distancing, hand washing, and avoiding touching your face.
To date, there have been no direct studies on Reishi and COVID-19 or the new coronavirus in any of the areas discussed. We are simply providing information about Reishi’s health effects in areas that are of interest to people concerned about COVID-19. However, we can’t draw any conclusions related to COVID-19 given that there is no direct research.
Reishi’s Effect on the Immune System & Inflammation
Boosting the Immune System
Most people have heard about reishi for balancing immunity. Studies have identified high amounts of compounds that may strengthen the immune cells and improve general immune system health .
Strong immunity, especially in the beginning of an infection, can be important for overcoming coronavirus and for reducing complication.
Two clinical trials on 75 people with advanced-stage cancer showed that both reishi mushroom extract and complex carbohydrates isolated from this fungus increased the counts of several immune cells (CD3+, CD4+, CD8+, and CD56+) and the blood levels of several cytokines (IL-2, IL-6, IFN-gamma), but decreased IL-1 and TNF-alpha [3, 4].
In a clinical trial on 40 male soccer players on a training program to improve endurance performance (‘living high-training low’), reishi mushroom helped correct the reduction in the CD4+/CD8+ ratio caused by the training. The authors suggested this may help the players fight infections .
Reducing Inflammation and Oxidative Damage
During later stages of COVID-19, antiinflammatory substances may be beneficial in preventing a cytokine storm.
Studies have shown that reishi may reduce inflammation in rheumatism, asthma, and pink eye without notable side effects .
14 days of reishi increased anti-inflammatory/antioxidant markers and protected the blood from oxidative damage in mice. It decreased the levels of an oxidant (malondialdehyde) while increasing several antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione S-transferase) .
The extracts of reishi and other mushrooms showed anti-inflammatory and antioxidant activity in cells. Among them, reishi was the most effective at inhibiting nitric oxide production in response to bacterial carbohydrates (LPS) [10, 1].
In a clinical trial on 61 people infected with a virus that causes warts (HPV/human papillomavirus), a combination of reishi and Turkey tail mushroom (Trametes versicolor) cleared the infection in 88% of the patients .
An herbal formula with reishi mushroom and other extracts decreased herpes zoster pain in 5 people with shingles. The same mixture sped up symptom relief in a small trial on 15 people with cold sores or genital herpes [12, 13].
Reishi mushroom extract improved malaria and prevented the resulting liver damage in infected mice .
Two triterpenoids from Ganoderma lucidum prevented enterovirus 71 infection in a cell-based study, possibly by blocking its attachment to the cells .
In cells, a terpenoid from Ganoderma lucidum (ganoderic acid) prevented the replication of the hepatitis B virus  and protein-bound polysaccharides had the same effect on the herpes simplex viruses 1 and 2 .
Enzymatic assays identified several compounds from Ganoderma lucidum capable of inhibiting the protease needed by the HIV-1 virus to produce infective particles [24, 25] and the neuraminidase used by the Newcastle disease virus to infect cells .
In addition, two triterpenoids from this mushroom inhibited the enzyme required by the avian influenza H5N1 virus to infect cells (neuraminidase) . This approach also identified its compound hesperetin as an inhibitor of the protease used by the dengue virus to produce infectious particles [28, 29].
COVID-19 is particularly hard on the lungs, and people often need oxygen and ventilators. In addition, preconditions like asthma may increase the fatality of COVID-19.
A commercial herbal formula with Ganoderma lucidum and two herbs used in Chinese medicine (Chinese licorice and Sophora flavescens) improved lung function (although less than prednisone) in a clinical trial on 91 asthmatic people and a study in mice. The complex was well tolerated and caused no adverse effects in another trial on 20 people [30, 31, 32].
In a clinical trial on 96 healthy people, a supplement combining Ganoderma lucidum and Cordyceps failed to improve different exercise capacity parameters .
In rats, its polysaccharides protected against lung tissue scarring .
Caution: Due to their small size and allergen content, Ganoderma lucidum’s airborne spores can trigger respiratory allergies if they enter the lower respiratory tract of sensitive people [38, 39, 40, 41].
Heart disease can significantly increase the risk of death from COVID-19.
An active compound isolated from reishi mushroom (beta-D-glucan) reduced the risk of narrowed arteries (atherosclerosis) in 71 people with chest pain by acting as an antioxidant .
Reishi extract also reduced damage to the cells that line blood vessels in a small trial on 14 people with kidney damage, thus reducing the risk of heart attacks .
In a clinical trial on 26 people with diabetes, reishi helped reduce both blood cholesterol and insulin resistance. However, a similar trial on 84 people found reishi ineffective to reduce cardiovascular risk factors in diabetics [43, 44].
A protein-rich extract of this mushroom lowered blood pressure, with the effects lasting up to 8 hours, in hypertensive rats .
Because reishi mushroom is not approved for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. They normally recommend taking 1-2 caps per day of the extract.
Reishi shows promise of improving general health in ways that may lessen the severity of COVID-19. Unfortunately, no direct evidence exists that Reishi can help COVID-19.