Reishi mushroom

Reishi mushroom, also known as Ganoderma lucidum and Lingzhi, is a mushroom that grows in various warm and humid areas of Asia (1). This mushroom has long been a mainstay of traditional Eastern medicine (1, 2). The reishi mushroom contains several active compounds including triterpenoids, polysaccharides and peptidoglycans, which may be responsible for the health benefits attributed to it (3). Although the mushroom itself can be eaten fresh, the use of dried mushrooms in powder form or the use of extracts is also widespread. The different dosage forms have been investigated in cell studies, animal studies and human studies. The health benefits described in the following sections have been observed.

Possible health benefits of the reishi mushroom

Reishi could improve the function of the immune system

One of the most important effects of reishi is that this mushroom can improve the function of the immune system (4). Although some details remain unclear, test-tube studies have shown that reishi affects genes in white blood cells that are critical for immune system function. In addition, these studies have found that some forms of reishi may alter inflammatory pathways in white blood cells (5). Studies conducted with cancer patients have shown that molecules found in reishi mushroom can increase the activity of a type of white blood cell called natural killer cells (6). Natural killer cells fight infections and cancer in the body (7). Another study found that reishi can increase the number of other white blood cells (lymphocytes) in colon cancer patients (2).

Although most of the immune system benefits of reishi have been observed in sick people, there is also evidence that reishi may improve immune function in healthy people as well. In one study, the mushroom improved lymphocyte function in athletes exposed to stress, which helps fight infection and cancer (8, 9). However, other studies with healthy adults showed no improvement in immune function or inflammation levels after 4 weeks of taking reishi (10). All in all, it is clear that reishi affects white blood cells and immune function. However, further research is needed to determine the degree of benefits in healthy and sick people.

Reishi may have anti-cancer effects

Many people consume reishi mushroom for its potential anti-cancer effects (11, 12). In fact, a study of 4000 breast cancer survivors found that approximately 59% of subjects had consumed reishi mushroom (13). In addition to this, several studies conducted in test gas have shown that reishi can induce the death of cancer cells (14, 15, 16). However, the results of these cell studies are not necessarily transferable to animals or humans. Some studies have investigated whether reishi could be helpful in the treatment of prostate cancer due to its effects on the hormone testosterone (17, 18). While one case study showed that molecules found in reishi mushroom can reverse the development of prostate cancer in humans, a larger follow-up study did not support these results (19, 20).

Reishi has also been studied for its potential to fight or prevent colon cancer (2, 21). Some studies have shown that one year of treatment with reishi could reduce the number and size of tumors in the colon (21). In addition, a detailed report of several studies suggests that reishi mushroom can positively affect cancer patients (22). These benefits included an increase in white blood cell activity, which helps to fight cancer, and an improvement in the quality of life of cancer patients. However, the scientists pointed out that reishi should be used in combination with traditional cancer therapy and cannot replace it (22). It should also be noted that many of the studies on the effects of reishi on cancer were not of particularly high quality. Due to this fact, further studies are needed (11, 23).

Reishi could combat fatigue and depression

Although the benefits of reishi on the immune system are most often emphasized, reishi has a number of other potential benefits. These include reducing fatigue and depression, as well as improving quality of life. One study examined the effects of reishi in 132 people with neurasthenia, a poorly defined condition associated with pain, drowsiness, headaches and irritability (24). The researchers found that 8 weeks of reishi supplementation reduced fatigue and improved well-being.

Another study of 48 breast cancer survivors found that taking reishi powder for four weeks improved quality of life and reduced fatigue (25). In addition, the study participants experienced less anxiety and depression. However, while reishi mushroom shows promise for people with certain diseases or conditions, it is still unclear whether these benefits will also be seen in otherwise healthy individuals.

The effects of reishi on heart health are contradictory

A 12-week study of 26 subjects showed that reishi could increase levels of good HDL cholesterol and lower triglyceride levels (26). However, other studies with healthy adults showed no improvement in these risk factors for heart disease (10). In addition, a larger analysis of five different studies involving a total of around 400 people also showed no positive effects on heart health. The researchers found that consuming reishi for up to 18 weeks did not improve cholesterol levels (27). Further research is therefore needed into the effects of reishi on heart health.

The effects of reishi on blood sugar levels are inconsistent

Several studies suggest that molecules contained in reishi can lower blood glucose levels in animals (28, 29). Some initial studies in humans reported similar results (30). However, the majority of studies do not support these benefits. After studying hundreds of patients, scientists found no benefits in terms of fasting blood glucose levels (27). As for post-meal blood sugar levels, the study results are mixed. In some cases, reishi reduced blood sugar levels, but in other cases the results were worse than with a placebo. Further studies are needed here too.

Reishi could have antioxidant effects and reduce inflammation

Studies have shown that reishi can reduce inflammation in rheumatism, asthma and conjunctivitis without significant side effects (31). Active compounds isolated from reishi mushrooms acted as antioxidants in two clinical trials involving 42 and 71 subjects with chest pain (angina) (32, 33). 14 days of reishi supplementation increased anti-inflammatory and antioxidant markers in mice and protected the blood from oxidative damage. It reduced the levels of one oxidant (malondialdehyde) while increasing the levels of several antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathione S-transferase (34). The extracts of reishi and other mushrooms showed anti-inflammatory and antioxidant activities in cells. Of these mushrooms, reishi was the most effective in inhibiting nitric oxide production in response to bacterial carbohydrates (36, 36). However, several studies failed to observe changes in blood levels of two important antioxidant enzymes after consuming the mushroom for 4 to 12 weeks (10, 26).

Reishi could alleviate allergies

A commercial herbal formula containing reishi mushrooms and two other medicinal herbs used in Chinese medicine (Chinese licorice root and Sophora flavescens) improved lung function in a clinical trial with 91 asthma patients and in a study with mice - albeit to a lesser extent than prednisone (37, 38, 39). Other studies have shown that compounds found in reishi effectively inhibited the release of histamines from mast cells, which may explain the benefits of reishi in asthma (40, 41, 42).

Reishi could support liver and kidney function

In a small study of 14 people with proteinuria - a sign of kidney disease - reishi ended this condition and restored the balance of the immune system (43). In a clinical study of 42 healthy people, reishi extract enriched with triterpenoids and carbohydrates reduced oxidative damage to the liver and reversed mild fatty liver disease (32). In rats, reishi protected against liver damage caused by moderate daily alcohol consumption (44). In malaria-infected animals, reishi protected against liver damage while suppressing malaria infection (45).

Reishi could alleviate chronic pain

In a clinical study of 32 people with rheumatoid arthritis, a supplement containing reishi and a herbal mixture used in traditional Chinese medicine (San Miao San) reduced pain slightly and was also well tolerated. However, no antioxidant or anti-inflammatory effects could be demonstrated (46). Although the study did not evaluate pain reduction, taking reishi for 6 weeks improved athletic fitness in a clinical trial of 64 women suffering from fibromyalgia (47).

Reishi is probably inefficient in improving brain function Reishi improved brain function in alcohol-consuming rats by increasing energy delivery to the brain and reducing levels of inhibitory neurotransmitters (44). However, a reishi spore powder was ineffective in improving any symptoms of the disease in a pilot study of 42 Alzheimer's patients (48), and a commercial supplement containing reishi and another mushroom used in traditional Chinese medicine (Cordyceps sinensis) did not improve cognitive function in a clinical trial of 96 subjects (49). Taken together, these results suggest that reishi is ineffective in improving brain function in both healthy people and Alzheimer's patients.

Dosage

Dosage may depend on factors such as age, condition for which the mushroom is being used. Unlike other supplements, the dosage of reishi can vary substantially based on the type used (12).

The following dosages represent typical amounts used:

1.5 to 9 grams of the raw dried mushroom
1 to 1.5 grams of reishi powder
1 ml reishi solution

The highest dosages are observed when the mushroom itself is consumed. In these cases, the dosage can range from 25 to 100 grams (50, 51). Usually a dry extract of the mushroom is used instead. In these cases, the dose is about a factor of 10 lower than when consuming the mushroom in fresh form (10). 50 grams of fresh reishi mushroom is roughly comparable to 5 grams of the mushroom extract. Dosages of reishi extract typically range from 1.5 to 9 grams per day (27). In addition, some supplements use only certain parts of the extract. In these cases, the recommended dosage may be significantly lower than the amounts listed above.

Can reishi mushrooms be taken naturally with food?

Reishi mushroom is cultivated and sold as a food, but it can be tough and bitter. When used for health reasons, it is usually used in dried form or as an extract in the form of capsules, powder or a solution.

Risks and side effects

Side effects

If reishi mushroom is used over a period of 3 to 6 months, it can cause dryness around the mouth, throat and nose. It can also cause side effects such as itching, stomach problems, nosebleeds and bloody stools (22). Most studies report no noticeable changes in biological markers or subjective experiences (52, 53). One toxicity study showed no evidence of liver, kidney or DNA toxicity from reishi consumption (54).

In contrast, two case studies reported significant liver problems (55, 56). Both individuals in these case studies had previously consumed fresh reishi mushrooms without problems, but experienced side effects after switching to a reishi powder. This makes it difficult to determine whether the mushroom itself was responsible for the liver problems, or whether there were problems with the powder extract. Due to its effects on the immune system, reishi mushroom could exacerbate certain autoimmune or inflammatory diseases by activating/increasing the activity of an already overactive immune system.

Risks

Taking reishi mushroom may be riskier if you suffer from low blood pressure or are taking medication to increase blood pressure. Higher doses may increase the risk of bleeding in people who suffer from blood clotting disorders. Pregnant and breastfeeding women should avoid reishi mushrooms as there is insufficient research on safety during pregnancy and breastfeeding.

Interactions

You should discuss the use of reishi mushrooms with your doctor if you are taking medication that can inhibit blood clotting. These medications include aspirin and non-steroidal anti-inflammatory drugs. Reishi mushrooms can also interact with medication for high blood pressure. In addition, you should check with a doctor about possible interactions when using herbs or supplements that can inhibit blood clotting or lower blood pressure. Examples of such products are fish oil and ginkgo.

Conclusion

The reishi mushroom is a popular medicinal plant used in Eastern medicine. It can increase the function of the immune system through its effects on white blood cells, which is especially true for sick people. The mushroom may also be able to reduce the number and size of tumors in certain types of cancer, as well as improve the quality of life in some cancer patients. Most human studies have shown that reishi does not improve cholesterol levels, blood sugar levels or antioxidant status, but it may be effective in reducing fatigue or depression in some cases.