Improve immunity and prevent cancer with a little help from medicinal mushrooms, says Pamela Allardice. Here are four fungi you need to know about.

For centuries, traditional Chinese medicine (TCM) has prescribed certain mushrooms — shiitake, maitake, reishi and turkey tail — for their health-promoting effects. Along with other common mushrooms, like button and Portobello, they are rich in vitamin D, B-group vitamins and the minerals iron, potassium and selenium.

However, Asian mushrooms have additional effects, including boosting immunity, fighting infection, lowering cholesterol and acting as an anticoagulant, thanks to three substances. These are beta-glucan, a fibre with cardiovascular benefits; terpenoids, which are antiviral, antibiotic and anti-inflammatory; and polysaccharides, sugars which bolster the immune system by increasing the number and effectiveness of natural killer (NK) cells, and so support the body's fight against infection and cancer.

In some cases, this improved immune response appears to slow and suppress the growth of breast and prostate cancer cells.

For general health and immune support, you can add these mushrooms to soups, stews, stir-fries and pasta dishes. Or, ask your local TCM practitioner for a blend that may be boiled in water and drunk as a tea. For a more concentrated dose, take them as supplements, in liquid extract, powder or capsule form.

• SHIITAKE (Lentinus edodes)

  This mushroom contains a polysaccharide called lentinan, which promotes production of NK cells that destroy cancerous cells. Lentinan's potential in helping people with AIDS and HIV, who have weakened immune systems, is currently being studied. Shiitake also contains interferon, an antiviral substance, and eritadenine, which reduces cholesterol. Extracts are even starting to appear in skincare products, because shiitake contains a lightening agent called kojic acid, which counters pigmentation.

• MAITAKE (Grifola frondosa)

  Traditionally prescribed as an overall immune booster, maitake also has cholesterol-lowering, anti-diabetes and cancer-fighting effects. It was traditionally used as an adaptogen, which is a substance that helps the body adapt to stress. Studies show that maitake mushrooms fight heart disease by lowering blood pressure and cholesterol, and slowing the blood's tendency to clot. In Japan, they are used to strengthen the immune systems of cancer patients undergoing chemotherapy and protect healthy cells from damage.

• REISHI (Ganoderma lucidum)

  Nicknames like 'immortality elixir' and 'the king of herbs' hint at this mushroom's many benefits; in Japan it is also used to protect against the effects of radiation treatment. It is a potent anti-inflammatory and is used in TCM to relieve bronchitis and coughs as well as arthritis.

• TURKEY TAIL (Coriolus versicolor)

  This mushroom has been used in China and Japan for centuries to boost immunity and fight disease. Modern studies have found that two polysaccharides it contains – polysaccharide-K (PSK) and polysaccharopeptide – help restore immunity in people undergoing conventional cancer treatments and may possibly improve survival rates in cancer patients.

  Note: Consult your doctor before using mushrooms for any condition, especially if you are pregnant or breast-feeding. Don't forage for wild mushrooms: it's easy to mistake a deadly fungus for an edible one.