Mushrooms are widely regarded as plants or vegetables, but they are species of the kingdom fungi, which also includes, yeast, rusts, mildews and moulds. Fungi have been with us for a long, long time; probably over a billion years. They survived the meteor strike that destroyed the dinosaurs and established their dominance on the forest floor. 1

While humans initially ate mushrooms for food; the healing powers of mushrooms were recognised in ancient Chinese and Greek cultures. The oldest reference to medicinal mushrooms in traditional Chinese medicine dates to 2,000 years BC, with a list of hundreds of different species. Hippocrates used the amadou mushroom to heal wounds, and as an anti-inflammatory medicine. 2

Modern, intelligent humans, in their quest for chemical medicines, forgot about mushrooms, but we are now seeing a resurgence of scientific interest in these dear old friends. In evolutionary terms, we humans are more closely related to fungi than to plants and this relationship may be linked to the health benefits of mushrooms. 2

What useful nutrients do mushrooms contain?

Mushrooms are a rich source of protein, fiber, minerals, vitamins and antioxidants. 3 They are also lauded for what they do not contain; no gluten, a miniscule amount of polyunsaturated fat and they are low in sugars and sodium. As they contain very low sugar levels and are highly nutritious, mushrooms are an excellent part of a keto diet.

The fiber in mushrooms is rich in β-glucans, xylans and galactans, which is an excellent prebiotic food for your gut bugs (gut microbiome). 4, 5 This is important for your health, as your gut bug colony is highly dependent on fiber. The secret to a healthy immune system, good mood, and healthy metabolism is

• (a) resilient gut bugs and
• (b) highly diversified gut bugs.

To achieve (a) and (b) we need to think fiber, fiber and fiber and low sugar, low sugar and low sugar. We also know that eating ultra-processed foods leads to the opposite.

The recommendations for daily fiber intake vary between 25-30g per day. But the reality is that dietary fiber intake is pitifully low, averaging 15g per day in the US and 18g in the UK. Low dietary fiber contributes to a host of diseases including cancer and lack of this vital nutrient alone, is partially responsible for many modern-day diseases. Adding two cups of mushrooms will provide you with between 3-6g of fiber. Every little bit helps when it comes to fiber!

Selenium is an important mineral in mushrooms and it supports your immune system. 6 This helps you to withstand and protect your body against damage from infection and free radicals. One cup of mushrooms provides you with a fifth of your daily selenium requirement. Selenium has also been linked with improvements regarding inflammation, heart disease, thyroid function, asthma, and dementia.

Your bone health and your immune system benefit from Vitamin D contained in mushrooms, without which, you could develop thinning of your bones, or osteoporosis. Mushrooms are one of the few non-animal sources of vitamin D, so they are particularly useful if you are a vegetarian or vegan.

Mushrooms contain powerful antioxidants; ergothioneine and glutathione. Your body can manufacture glutathione, but ergothioneine is only sourced from your food. These antioxidants reduce inflammation and oxidative stress, helping in the protection and repair of your DNA, which then reduces the risk of cancer and metabolic diseases.

Levels of ergothioneine decrease with age and this predisposes to age-related diseases. 7 As you get older, you may need to work harder to keep your ergothioneine levels up, as low levels are associated with heart and metabolic diseases. Ergothioneine is considered to have unique anti-cancer effects and it also protects your mitochondria. And mitochondria are the most important factor in ageing. Mushrooms are one of the most significant sources of ergothioneine, particularly speciality mushrooms such as shiitake, oyster and hen of the wood varieties.

Mushrooms as Medicine: Reducing Disease Risk

Cancer is one of the leading causes of death in high income countries and 1 in 3 people will develop cancer. Diet plays a significant part in the development of cancers. A healthy diet rich in plants including vegetables, fish, fewer processed meats, and whole grains reduces the risk of cancer. Damage due to free radicals contributes to cancer, and antioxidants derived from our food, help to counteract the harm caused by free radicals.

A recent review of the published work on cancer risk and mushroom consumption showed that people who eat mushrooms every day, have a reduced risk of cancer, particularly breast cancer, compared to those who never eat mushrooms. 8 Eating just 18g of mushrooms every day, reduces the risk of cancer by 45%. Previous studies have demonstrated that mushrooms have anti-cancer effects, but this is the largest study to date, confirming the link between mushroom consumption and a reduced risk of cancer.

Heart disease is one of the commonest causes of illness and death in the world. Risk factors include visceral fat and metabolic abnormalities such as high LDL, high blood pressure, high blood sugar and oxidative stress. Mushrooms contain β-glucans, a soluble dietary fiber that has been shown to lower cholesterol levels and boost heart health. There is evidence that mushrooms improve metabolism and lower LDL, blood pressure and inflammation; thus, potentially reducing the risk of cardiovascular disease. 4, 9

Dementia: The term, mild cognitive impairment, denotes minor problems with memory and thinking. Up to 20% of people over 65 have this condition and if you develop mild cognitive impairment, your risk of developing dementia goes up. Low levels of ergothioneine have been found in people with dementia. Mushrooms supply you with ergothioneine and studies have been carried out to assess if mushrooms may help to prevent mental deterioration.

A recent study looked at mushroom consumption and mild cognitive impairment. People who ate mushrooms twice per week, (about 150g twice per week) were 50% less likely to develop mild cognitive impairment. 10 Thus, science is now showing that there is indeed a relationship between eating mushrooms and poor brain function.

A word of caution here, these findings describe the association between eating mushrooms and protection from mild cognitive impairment; but it does not confirm that a diet low in mushrooms is* causing* cognitive impairment. Further research is needed to establish causation. But in the meantime, why wait for the results, why not try to protect yourself now? What’s the harm in eating mushrooms twice a week?

Mushroom Tips

• 150g of mushrooms = 5.3 ounces = ¾ cup
• Mushrooms are one of the few plant sources of vitamin D
• Deliquescence is the process of mushroom degradation, where liquefaction of the mushroom occurs
• Keep mushrooms in the fridge in paper bags, not plastic bags where they become slimy, due to mould growth. Fresh whole mushrooms will keep for up to 10 days
• Nutrients, such as vitamin D decline rapidly after harvesting mushrooms
• Recipe suggestions: Sautéed mushrooms and garlic, mushroom toast with fried egg, add mushrooms to bolognaise sauce, to quiches and substitute mushrooms for beef in stroganoff
• If you don’t care for the taste of mushrooms-they can be chopped and added to casseroles, salads and soups
• Based on the current scientific research, to gain the health benefits, choose to eat either one or two mushrooms ¾ cup twice a week