Mushrooms and cancer

Many websites discuss using mushrooms to treat cancer. From time to time this also comes up in the media. There is currently no evidence that any type of mushroom or mushroom extract can prevent or cure cancer.

There are many different types of mushroom. Mushrooms are part of the fungus family. In some countries such as Japan, China and Korea particular types of mushroom form a large part of the diet. In recent years, there has been research into different types of mushroom and mushroom extracts or compounds. Studies have looked at whether mushrooms can prevent cancer, stop the growth of cancer cells, reduce cancer treatment side effects, or help people with advanced cancer to live longer.

UK mushrooms

Button mushrooms and flat mushrooms are eaten commonly in the UK. They are very nutritious as food because they contain all the essential amino acids and are an excellent source of vitamins. But there is no evidence that they can prevent or treat cancer.

Exotic mushrooms

Exotic mushrooms are found in areas such as Japan, Korea and China. They include varieties such as the shiitake, enoke and oyster mushroom. More than 100 species of mushroom are documented by Chinese medicine practitioners as treatments for a wide range of illnesses. There are different ways of taking these mushrooms. They can be eaten fresh or dried. Or extracts can be taken as food supplements.

In China, Japan and Korea purified compounds are used alongside chemotherapy and radiotherapy. In the UK, powdered reishi, shiitake and maitaki mushrooms are available. Elixirs of their juice are also sometimes available. These can be bought from health food shops. There is nothing in the mushrooms or compounds that would be harmful as far as we know. But we don’t currently know how helpful they are in cancer care and we need more research.

In 2000, a report published by Cancer Research UK and the University of Strathclyde looked at different types of mushroom in relation to cancer. The review found some Japanese studies that used a particular type of exotic mushroom extract a week before people started cancer treatment. The extract appeared to reduce the side effects of both chemotherapy and radiotherapy, including sickness and hair loss.

Some studies seemed to show that these mushrooms could stimulate the immune system to fight disease. There is some evidence from a Japanese study that people who eat a particular type of mushroom all their lives have a lower risk of getting cancer. In some people mushrooms did seem to affect their cancer. But we have to be very cautious about the results because most of these early trials were not randomised or controlled. So, there was no proper comparison made between patients having the mushrooms and similar patients not being treated with mushrooms or drugs developed from mushrooms. So the studies can’t really show whether the mushrooms helped or not.

Research has since been carried out into some particular mushrooms and their extracts. This includes shiitake mushroom and their extracs, agaricus sylvaticus mushroom,  maitake mushroom extract, phellinus linteus mushroom extracts.

Shiitake mushrooms and their extracts

Shiitake mushrooms are native to East Asia but are grown worldwide for their supposed health benefits. They are valued in some cultures as an anti cancer agent. The fresh and dried forms of the mushroom are commonly used in East Asian cooking. Extracts from the mushroom, and sometimes the whole dried mushroom, are used in herbal remedies.

One shiitake extract called lentinan is a beta glucan. This is a type of complex sugar compound. Beta glucan is believed to stimulate the immune system and trigger certain cells and proteins in the body to attack cancer cells. In laboratory studies, it seems to slow the growth of cancer in some cell cultures.

In mice, lentinan has been shown to stop the growth of bowel cancer cells. In laboratory tests, the protein part of lentinan (lentin) can stop the growth of some fungal cells. It can also stop leukaemic cells dividing.

Some Japanese researchers give lentinan along with chemotherapy to treat patients with lung, nose, throat, and stomach cancers. A recent clinical trial didn’t show that it helped to treat prostate cancer. Some doctors in Japan use another shiitake extract called eritadenine.

There is limited evidence that lentinan, given alongside chemotherapy, could help some patients with advanced stomach cancer. But we need larger scale studies before we will know how shiitake extracts can help people with cancer. More clinical trials are currently under way to understand which compounds in shiitake mushrooms might work as cancer treatments.

Maitake mushrooms and maitake extracts

Maitake mushrooms and the maitake D-fraction prepared from them contain the sugar compound called beta glucan (sometimes called beta glycan).

Japanese studies using an injectable type of maitake-D have found that it boosted the immune system and slowed or stopped the spread of breast and liver cancer in animal studies. A phase 1 study is currently being carried out in the USA to see whether beta glucan can help a biological therapy called rituximab to work better. It is for young patients with lymphoma or leukemia that has come back after previous treatment. Another trial is looking at whether maitake extract has any effect on breast cancer.

A US study tested another complex sugar compound from maitake mushrooms called grifola frondosa in breast cancer patients. The study aimed to find out if the extract affected the immune system. Patients took the extract by mouth for 3 weeks. The researchers took blood tests to measure any effects. One patient stopped taking the extract because of sickness and joint swelling. Another stopped because of a rash and itching. The researchers found that the extract stimulated some immune functions but depressed others. So we don’t yet know whether this compound can help the immune system to fight cancer.

Agaricus sylvaticus mushroom

A Brazilian study gave patients agaricus sylvaticus mushrooms as part of their diet after bowel cancer surgery. It found that patients who had the mushrooms had a better quality of life compared to patients who did not have the mushrooms. The benefits included

  • More ability to do physical exercise
  • Less feeling sick
  • Better mood
  • Fewer aches and pains
  • Better sleep
  • Better appetite
  • Less abdominal pain, especially after eating
  • Fewer bowel problems such as constipation, diarrhoea, and wind

Phellinus linteus mushroom extracts

Used for centuries in Eastern Ancient medicine, this extract is believed to refresh bodies and extend life. Phellinus linteus is known as song gen in Chinese medicine, sang-hwang in Korean and meshimakobu in Japanese. Recent studies have shown that this type of mushroom extract slows the growth of breast cancer cells in the laboratory. It has also been shown to have anti cancer effects on skin, lung and prostate cancer cells.

One study showed that when used in combination with the chemotherapy drug doxorubicin, the extract increased the number of prostate cancer cells killed. We have to be cautious about such early research though. Substances that can kill cells in laboratory conditions don’t necessarily turn out to be useful treatments in people.

Safety of mushroom and mushroom extracts

There are no known side effects from eating normal amounts of mushrooms in our diet. Mushroom extracts are classed as dietary supplements. Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements.

Shiitake mushroom extracts are generally considered safe, although there are some reports of diarrhoea or bloating. With other types of mushroom there are some reports of allergic reactions affecting the skin, nose, throat, or lungs.


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