Thinking about trying adaptogenic mushrooms? Read this nutritionist's advice first

Think beyond the button, chestnut and portobellos in your local store – the key players in this field include lion’s mane, turkey tail, reishi and cordyceps. Big claims are made that these complex organisms could be the antidote to the high levels of stress, poor diet and disruptive sleep patterns that dominate our modern lifestyles.

What are mushrooms?

Often considered a vegetable, mushrooms are neither plant nor animal – they are the fruiting body of a network of strands that form a mycelium, and as a fungus, they form their own kingdom within nature. There are thousands of different mushrooms, with more than 2,000 being edible. From a health perspective, certain mushrooms are often referred to as functional, and are divided into ‘medicinal’ and ‘adaptogenic’.

Why all the fuss?

Every mushroom has a unique nutritional profile, while sharing some common traits: they're packed with bioactive compounds, including natural antibiotics; prebiotics that feed our gut bacteria; polysaccharides, including alpha and beta glucans; as well as aromatic compounds, like terpenoids. These unique properties, combined with the belief that certain mushrooms have medicinal powers, has meant researchers have turned the spotlight on fungi and the health sector has responded with big claims and products to match.

Some of these compounds, like beta-glucans, help modify our biological responses, and mushrooms rich in these are often referred to as adaptogenic. This means they help our bodies adapt to the demands placed upon them by normalising our response to stress and optimising other bodily functions, all while keeping the body in balance. Mushroom varieties referred to as ‘medicinal’ boast other health benefits, including claims that they may be useful in our fight against heart disease, autoimmune conditions, metabolic disorders and potentially cancer.

What do mushrooms do?

Mushrooms, such as those you buy from your local store, are low in calories and a useful source of protein, fibre and protective plant compounds, including polyphenols that support gut health. They also contain high amounts of two important antioxidant compounds called glutathione and ergothioneine. Leave these shop-bought mushrooms on your kitchen counter in full sunlight and, like us, they'll convert a compound called ergosterol (similar to our cholesterol) to vitamin D. They are also one of only a few vegan sources of vitamin B12.

As impressive as this all sounds, the mushrooms receiving all of the attention are not your regular supermarket variety. Specific varieties of ‘medicinal’ mushroom, many of which you wouldn’t choose to eat because of their bitter, woody texture, contain compounds that potentially facilitate 130 medicinal activities that include modulating the immune system, protecting the heart, enhancing bone health and fighting cancer.

These medicinal mushrooms, which include maitake, shiitake and chaga, may also accelerate the metabolism, help fight obesity and slow the aging process thanks to their high antioxidant content.

Other varieties like reishi, cordyceps and lion’s mane are also famed for their adaptogenic properties, by which they mediate our stress response, help normalise how we react and as a result, improve our resistance so we cope better with life’s ups and downs.

It’s worth saying that functional mushrooms (whether medicinal or adaptogenic) are not the same as ‘magic’ mushrooms – the latter contain a compound called psilocybin, which is reputed for its psychoactive effects. More recent scientific interest is examining psilocybin’s potential for treating depression, anxiety and other mental health conditions.

Some common types of functional mushrooms:

• Chaga – not a true mushroom, but a mass of mycelia that grow on tree trunks, chaga is said to enhance learning and memory, keep you looking young and potentially support heart health and immunity.
• Cordyceps – popular in the sport and fitness community for its ability to support recovery and stamina, improve breathing and immune health.
• Lion’s mane – studies suggest benefits for the brain, including thinking more clearly, sharper focus and improved memory.
• Maitake – an edible mushroom that grows on trees, may help manage blood pressure, reduce cholesterol and support artery health.
• Reishi – known as the ‘mushroom of immortality,’ reishi mushrooms are said to reduce stress, balance hormones and increase energy. They contain a combination of polysaccharides that are thought to modulate the immune system and potentially help fight cancer.
• Shiitake – an edible mushroom that contains a type of beta-glucans called lentinan, may support immunity, reduce inflammation and support the effects of chemotherapy.
• Turkey tail – contains a compound called polysaccharide-K (PSK), that may modulate the immune system, improve gut health and potentially be useful for those with certain forms of cancer.

Should I take mushrooms?

Impressive claims would have us think there’s a medicinal mushroom for most modern ills, but sadly the evidence, although evolving, is simply not there yet. Over the years, there have been thousands of studies, but until recently, most of these have been performed on animals or using laboratory tests designed to emulate our cells and their reactions (in vitro), with the many human studies conducted being largely observational. Add to this the diversity of the many mushroom species and the large number of bioactive substances, and it’s clear there is still much for us to discover. As a result, more human trials over longer time periods are needed before we can make claim to many of the touted health benefits.

If despite this you choose to supplement, be sure to buy from a reputable company and look for one that guarantees the highest concentration of active ingredients, such as beta-glucans or terpenoids. If you supplement, you should be aware that the bioactive compounds found in mushrooms may potentially limit the absorption of other nutrients, including vitamins and minerals.

Hot mushroom beverages like tea or coffee are growing in popularity, and if this is your chosen product, you can be assured that brewing your drink in water heated to 85-90C will not harm the active constituents. In fact, many mushroom extracts are made this way, using hot water extraction to gently release the bioactive compounds without denaturing them.

Are there any dangers to taking mushrooms?

Shop-bought mushrooms are generally safe for most people, as long as you do not have an allergy or an allergy to moulds. However, there are many mushroom varieties that are unsafe to eat, so if you enjoy foraging, only eat those that you can positively identify, or forage with an expert.

Certain groups should avoid supplementation, including pregnant and breastfeeding women, and children. Those diagnosed with diabetes should be aware that some varieties, like lion’s mane and chaga, may lower blood glucose levels. Certain supplements may also be unsuitable for coeliacs, because the mushrooms may have been grown on a cereal substrate – if this is relevant to you, look for mushrooms and their derivatives that have been grown on wood.

It is important to remember that there is still a lot for us to learn about the active constituents in mushrooms, as many may present dangers as well as benefits. For example, one report suggested a higher risk of kidney stones when supplementing with chaga, due to its high oxalate levels.

If you are on prescribed medication or have a health condition, refer to your GP or other medical practitioner before taking mushroom supplements, especially if you are prescribed any of the following:

• Anticoagulants
• Antidepressants
• Blood pressure and/or diabetes medication
• Chemotherapy

A nutritionist’s verdict

Medicinal mushrooms are famed for their potential to modulate immunity, regulate metabolism and prevent many diseases. Packed with polysaccharides, polyphenols, amino acids and vitamins, they are a valuable source of biologically active compounds that may contribute to maintaining the health and well-being of the body. However, at this time, further research is needed to validate these benefits, determine optimal dosages and safety profiles, and fully quantify the potential risks and side effects.

That said, mushrooms remain a nutritious addition to your diet and, fortunately, we can still enjoy the many health benefits from culinary mushrooms, including button, oyster and chestnut. In fact, one study suggested that eating just 18g – that’s about one chestnut mushroom per day – may lead to a 45% reduction in overall cancer risk. The reason behind this is thought to be the mushroom's high antioxidant content, including being the richest food source of ergothioneine, with oyster and shiitake offering impressive amounts.

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Kerry Torrens BSc. (Hons) PgCert MBANT is a BANT Registered Nutritionist® with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Olive.