Why eating mushrooms is good for your brain – they may ward off effects of Alzheimer’s disease
Studies show mushrooms can adjust the body’s immune response and boost brain cells, but Hong Kong experts warn some contain toxins; seven varieties to add to your diet for better health
Cases of dementia, Alzheimer’s and other neurodegenerative diseases are projected to hit 42 million by 2020, according to the World Health Organisation. Scientists are researching alternative treatments through nutraceuticals, including mushrooms.
Mushrooms and their extracts appear able to tweak the body’s immune response and a number of edible mushrooms contain rare and exotic compounds that positively affect brain cells.
In the study “Edible and Medicinal Mushrooms: Emerging Brain Food for the Mitigation of Neurodegenerative Diseases”, Chia Wei Phan, Pamela David, and Vikineswary Sabaratnam from the University of Malaya, Kuala Lumpur, found encouraging signs as they collated mushroom research findings.
Denise Fair, a dietitian at Central Health Medical Practice in Hong Kong, admits there are potential benefits, but says most mushroom studies have been conducted on rats. “Also, these rats weren’t eating just mushrooms but were being fed mushroom extracts,” she says. “So the study shows that there is something positive going on that needs to be researched further and the potential is there, but we are a bit far from making any health claims at this point. But it is promising.”
Mushrooms are a good source of dietary fibre, protein and complex carbohydrates, they are high in copper, phosphorus, vitamins D, B2 and B3, and contain high amounts of selenium, an antioxidant that helps protect cells against damage. According to dietitian Karen Chong, at Matilda International Hospital in Hong Kong, mushrooms have a low GI (glycaemic index), and are low in fat and calories. “Mushrooms such as the caterpillar fungus and lingzhi have been widely used among the Chinese population and quite a few studies have reviewed their potency in treating various diseases.”
Since mushrooms are naturally rich in purines, chemicals that the body converts into uric acid, they aren’t recommended for people with gout or kidney stones.
In Chinese medicine nutrition studies, mushrooms don’t suit those with excessive dampness in the body – a condition associated with poor digestion and absorption. Mushrooms can be difficult to digest and cause bloating if not properly cooked.
Raymond Chung Tsz Man, a nutritionist at Mineralysis and Albert Place Practice in Hong Kong’s Central district, cautions against harvesting or eating unknown mushrooms. Non-edible varieties contain different mycotoxins which can cause hallucinations, intestinal upsets, acute liver, kidney failure and death.
“It’s advisable to consume a variety of mushrooms bought from reliable suppliers,” he says. “This will help maximise health benefits [as they all have a slightly different composition] and broaden the spectrum of phytonutrient intake.”
Fair warns that some dried mushrooms contain the heavy metal cadmium and Japanese mushrooms have had higher levels of radioactive caesium, a mildly toxic metal. She advises soaking mushrooms for 15 to 30 minutes before cooking to help remove pesticides and other debris, but that will not remove heavy metals or toxins.
According to the Centre for Food Safety Hong Kong, mushroom toxins produced naturally by the fungi can be neutralised by cooking, canning, freezing or other processing.
Organic varieties are seen as the best option because mushrooms are very porous and easily absorb chemicals from soil. Hong Kong nutritionist Michelle Lau, an educator at Nutrilicious, says it’s best to buy them from local farmer’s markets.
“Try to include some mushrooms in your diet a couple of times a week. A serving of mushrooms can be counted as one of your daily servings of vegetables. What’s more, it can meet your daily vitamin B12 needs – this is especially important for vegetarians and vegans.”
Large mushrooms such as portobellos can be baked and still hold their firm texture, but others such as shiitakes and white buttons are best fried. Mushrooms absorb a lot of liquid at first and release their water, so avoid drowning them in sauce or oil.
Seven mushrooms worth including in your diet
Monkey head mushroom (Hericium erinaceus)
This has long been used in traditional Chinese medicine. Studies have shown it to have antioxidant effects, regulate blood lipid levels and reduce blood glucose levels. Pills of this mushroom are used in the treatment of gastric ulcers. Scientists around the world are investigating possible anti-dementia properties.
Bamboo fungus (Phallus indusiatus)
Believed to help reduce “bad” cholesterol and excessive acid in the body fluids and boost overall immunity.
Maitake (Grifola frondosa)
This Japanese mushroom has anti-cancer, anti-viral, and immunity enhancing effects and can also help control high blood pressure and regulate blood sugar levels.
Snow fungus (Tremella fuciformis)
Used by Chinese and Japanese herbalists for more than 2,000 years who believe this translucent parasitic yeast “increases bodily fluids and alleviates dry coughs and palpitations”.
Cordyceps (Cordyceps – several species)
A fungus considered to act as a gentle stimulant, an invigorating tonic and a restorative used to increase energy and reduce fatigue. You can add it to soups and stews, or drink tea made from powdered cordyceps, but it’s more convenient to get cordyceps extracts in liquid or capsule form.
Lingzhi (Ganoderma – several species)
This species can improve immune function and inhibit the growth of some malignant tumours. It also has anti-inflammatory effects, helps reduce allergic responses, and protects the liver. These mushrooms can be eaten raw or cooked. Dried and powdered forms of the mushroom are often used to make tea in traditional and alternative Chinese medicine.
Shiitake (Lentinula edodes)
This Japanese variety contains a substance called eritadenine, which helps lower circulating blood cholesterol. Shiitake also has antiviral and antioxidant properties.