By Dr Ksanbok Makdoh & Dr Marvellous B Lynser
Mushrooms are seasonal fungi, occupying diverse niches in nature in the forest ecosystem and predominantly occurring during the rainy season. Mushrooms are in fact the fruiting bodies of the underground fungal mycelium. About 1.5 million species have been reported worldwide out of which more than 2,000 species are edible. In India, about 27,000 species are reported and about 300 of these are edible.
Wild edible mushrooms are valued for food and medicine and people have been known to consume them since time immemorial, probably because of their pleasant texture and flavour. Tribal communities across the world are known to possess immense ethno-mycological knowledge and use many wild mushroom species as food and in traditional medicines.
Wild edible mushrooms have high commercial value where fresh as well as dried mushrooms are commonly sold in local markets and along roadsides in villages and small towns of developing countries. Extensive and profound traditional mycological knowledge has also been noted to exist among most ethnic and indigenous groups in India.
In the North East, wild edible mushrooms are a highly coveted food item. A wide range of wild edible mushrooms used by the ethnic tribes of the region has been reported from Meghalaya, Assam, Manipur, Sikkim, Nagaland and Arunachal Pradesh. There are several wild mushrooms which grow in the forests of Meghalaya and the locals relish them.
The mushrooms are picked from the forest and they form an integral part of the diet during the monsoon months when these are abundantly available. It is also observed that women are mostly involved in the collection and selling of mushrooms in Khasi Hills.
Following are some of the species consumed by the Khasis — tit thylliej masi, tit stem, tit stem, tit eit masi, tit ball, tit kjat syiar, tit kjat syiar, tit kjat syiar, tit stem, tit khoh and tit tyndong. The elaborate list is a result of our survey in some of the villages and rural weekly markets, including the Iewduh market.
These mushrooms are collected mostly for self-consumption but some are also collected for sale in either fresh or dried forms. Tit sohpailen, tit tyngab, tit tyndong, tit kjat syiar, tit lbong hati, tit thylliej masi and tit tung are most abundantly sold. The market price of these mushrooms varies from species to species and depends on availability. During the peak season, a mixture of these mushrooms is sold at Rs 150-200/kg. Dried tit tung is sold at a minimum price of Rs 1,000/kg.
Nutritional & medicinal values
Wild mushrooms can be valuable in maintaining good health and boosting human immune system as many biochemical studies revealed that mushrooms are rich in nutrition and energy values with high content of proteins, carbohydrates, unsaturated fatty acids, phenolic compounds, tocopherols, ascorbic acid, carotenoids, fibres and trace elements from very low to zero cholesterol. They are useful sources of human dietary minerals like iron, magnesium and zinc and are very low in sodium.
Several studies have confirmed that mushroom make a useful contribution to vitamin intake, particularly the B, D and K vitamins and in some cases vitamins A and C.
The intake of mushroom has also been shown to be effective in cancer prevention. Several anti-tumour polysaccharides have been isolated, the most important of which is lentinan, a b-1,3-glucan isolated from Lentinula edodes (shiitake), which is used clinically in Japan.
Some medicinal species are widely used in traditional and alternative medicines to heal a broad range of diseases. The medicinal benefits derived from mushrooms like anti-fibrotic, anti-inflammatory, anti-diabetic, anti-microbial activities, anti-tumor, anti-HIV, anti-Alzheimer, anti-malarial, blood sugar lowering, cholesterol reducing, and liver protectant have been previously reported.
In addition to their medicinal importance, mushrooms have also been reported to exhibit significant antioxidant and free radical scavenging activities.
Cellular damage caused by reactive oxygen species has been implicated in several diseases, and hence the antioxidant properties of mushrooms may play an important role in human health. Among the anti-oxidant compounds, polyphenols and tocopherols have gained importance due to their large array of biological actions.
Limited data & deaths
In spite of the immense popularity of this food in the region, data regarding the nutritive value of wild edible mushrooms available in the region are meagre. A study by Agrahar-Murugkar and Subbulakshmi (2005) on nutritional values of seven wild edible mushrooms of Khasi Hills showed that they are rich sources of protein, fibre and minerals and have low amounts of fat.
Micronurients like calcium, phosphorus, iron and manganese are found in all the seven species and they are very rich in potassium and Vitamin C.
Mushroom toxicity has been known for millennia and is implicated in the death of several historical figures, including the Roman Emperor Claudius. Although the benefits of eating wild fungi are clear, there are safety concerns which have to be taken into consideration. It is clearly of great importance that poisonous species are not mistaken for edible ones.
Mushroom poisoning refers to harmful effects from ingestion of toxic substances present in a mushroom.
The symptoms of mushroom poisoning vary from mild to fatal. The toxins present are secondary metabolites produced by the fungus.
The most common reason for misidentification is close resemblance in terms of colour and general morphology of the toxic mushroom species with edible species. There are no morphological characteristics to differentiate between the edible and poisonous mushrooms. The edible ones are identified based on traditional knowledge, which is passed on orally from generation to generation.
Poisonous mushrooms contain a variety of different toxins that can differ markedly in toxicity. Symptoms of mushroom poisoning may vary from gastric upset to organ failure resulting in death.
Serious symptoms do not always occur immediately after eating, often not until the toxin attacks the kidney or liver, sometimes days or weeks later.
Most poisonous mushrooms contain gastrointestinal irritants that cause vomiting and diarrhoea but usually no long-term damage. However, there are a number of recognised mushroom toxins with specific, and sometimes deadly, effects. Some like alpha-amanitin and orellanine are deadly.
Mushroom poisoning resulting in illness and deaths among the local population of Meghalaya have been reported almost every year. Although a myth exists among people that mushroom poisoning can result from consuming mushrooms which have been spit upon by snakes and frogs or other poisonous insects, there is no scientific evidences to prove this.
We can clearly see that these incidences of mushroom poisoning reflect the degradation of the traditional ethno-mycological knowledge and lack of awareness on mushroom poisoning.
To avoid such fatality one has to be 100 per cent sure that the mushroom is edible.
More research is required on the nutritional and medicinal values and also on biological compounds or toxins present in these mushrooms which may have a long-term effect on human health.
(Dr Makdoh is assistant professor in the Department of Botany,
Lady Keane College, and Dr Lynser is assistant professor in the Department of Environmental Science, Shillong College)