Introduction and description
Boletus edulis, commonly known as penny bun, porcino or cep, is a basidiomycete fungus, and the type species of the genus Boletus.
Widely distributed in the Northern Hemisphere across Europe, Asia, and North America, it does not occur naturally in the Southern Hemisphere, although it has been introduced to southern Africa, Australia and New Zealand.
And it has an impressive record of being able to heal.
The fruit body has a large brown cap which on occasion can reach 35 cm (14 in) in diameter and 3 kg (6.6 lb) in weight.
Like other boletes, it has tubes extending downward from the underside of the cap, rather than gills; spores escape at maturity through the tube openings, or pores.
The pore surface of the B. edulis fruit body is whitish when young, but ages to a greenish-yellow. The stout stipe, or stem, is white or yellowish in colour, up to 25 cm (10 in) tall and 10 cm (3.9 in) thick, and partially covered with a raised network pattern, or reticulations.
Cultivation and habitat
The fungus grows in deciduous and coniferous forests and tree plantations, forming symbiotic ectomycorrhizal associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue.
The fungus produces spore-bearing fruit bodies above ground in summer and autumn.
Although it is sold commercially, it is very difficult to cultivate. Available fresh in autumn in Central, Southern and Northern Europe, it is most often dried, packaged and distributed worldwide. Keeping its flavour after drying, it is then reconstituted and used in cooking. B. edulis is one of the few fungi sold pickled.
Medicinal and health
Although a great deal of time and well justified effort has been devoted to studying plants, such that, thanks to the work of people like Dr Duke, a vast database of information is now available on the health uses of plants, the area of fungi and their uses is still only just beginning to be explored.
There is no analysis of the porcini mushroom on the USDA Nutrients database, for example, nor is there one on Dr Duke and yet there is evidence that the porcini mushroom in particular has some very important properties.
Although often looked on as an Italian speciality, the porcini mushroom has been gathered all over Europe for food and health reasons for millenia, for example
Int J Circumpolar Health. 1998 Jan;57(1):40-55. Uses of mushrooms by Finns and Karelians. Härkönen M1. 1Department of Ecology and Systematics, University of Helsinki, Finland.
Finns have adopted two traditions of mushroom use: one, the old Roman tradition, came through France and Sweden to the educated, mostly Swedish speaking people of southwest Finland; the other came from the east via Karelia and was adopted by ordinary country folk.
This eastern tradition is still maintained among the Karelinas living in Tver government in Russia. Even the use of Amanita muscaria for killing flies is still utilized there.
The western tradition favoured chanterelles and Boletus edulis, the eastern acrid milk caps, the Lactarius species.
During the famines in the 1860's and after the World War II the government authorities tried to promote the use of wild mushrooms, but the real impulse to a more versatile mushroom use was initiated after the war when 400,000 evacuees from that part of Karelia conquered by the Soviet Union were resettled among farming families all over Finland.
In 1969 the National Board of Forestry began to train mushroom advisors, a programme which still continues.
In 1981 Finland passed a statute on edible mushrooms and drew up a list of commercial species.
Even today the largest percentage of marketed mushrooms comes from Eastern Finland and the Lactarius tivialis species sells best. Gyromitra esculenta, the false morel is considered a delicacy. Today picking mushrooms is a passionate hobby for many Finns. PMID: 9567575
The porcini mushroom is known to produce a variety of organic compounds with a diverse spectrum of biological activity, including antioxidants, and phytochelatins, which give the organism resistance to toxic heavy metals, but if found on toxin free ground, can act as chelators of us. Or to put this another way they are chelating agents.
Porcini mushrooms have also shown antiviral activity and there are an increasing number of papers on the various anti-cancer functions they have....
Proc Nutr Soc. 2006 May;65(2):190-7. Wild-gathered fungi for health and rural livelihoods.- de Román M1, Boa E, Woodward S. 1CABI Bioscience, UK.
Fungi are a good source of digestible proteins and fibre, are low in fat and energy and make a useful contribution to vitamin and mineral intake. In terms of current dietary advice, 80 g fungi represent one portion of vegetables. Dried fungi and concentrated extracts are also used as medicines and dietary supplements. Some species show strong anti-tumour and antioxidant activity by enhancing various immune system functions ……... PMID: 16672080
Unusual properties and uses
There are some other quite amazing uses being found for Porcini mushrooms. For example, pickles are popular in China and 'exhibit health-promoting effects'. However, the nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Researchers have found that the fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. Safe pickles!
One of their findings has a bearing on the overall health giving properties of porcini mushrooms. The ideal is to have them fresh, then they are at their most potent. I would like to be able to say that you have to gather them by the light of the full moon dressed only in a white smock and bedroom slippers - but there appears to be no supporting evidence that this has any effect at all on their potency.
Instead all the evidence seems to point to the fact that B. edulis fruiting bodies which have been oven-dried are devoid of any effect.
In contrast, the air-dried fruiting bodies have an effect which is slightly less potent than those produced by fresh and frozen fruiting bodies.
B. edulis fruiting bodies, regardless of whether they are fresh, previously stored frozen or air-dried at room temperature, were all capable of lowering nitrite level in pickles, though the effect produced by air-dried fruiting bodies was slightly inferior to the effects of fresh and frozen fruiting bodies. Fruiting bodies dried in an 60 °C oven were totally devoid of nitrite lowering activity.
One additional finding of this same group was that porcini mushrooms also appear to be able to reduce nitrite in animals - us – in vivo. We may not realise it but Nitrite is a natural constituent of the human diet and an approved food additive present not only in pickles, but also in many preserved foods and fermented foods. Effects on health are dose dependent. In Korea, kimchi is a daily favourite dish. However, nitrite is present in kimchi and may contribute to the high incidence of gastric carcinogenesis among Southwest Koreans. Some processed meat products, like sausage, salami and ham, also contain nitrite because of its use as a preservative. But add a few porcini mushrooms and you have a much safer meal. So the theory goes.
Boletus appears to also contain muscarine in trace amounts and this may be key to much of its activity. Muscarine, in trace amounts, is a promoter of the parasympathetic nervous system.
In order to understand the functions this may invoke you will need to turn to the section Muscarine and the muscarinic ligands, where a full description is available. From this you should be able to see that porcini mushroms are exceptionally important healers and the 'trace amounts' of muscarine are all that is needed.
You should also be able to see that oven dried or stale mushrooms are quite likely to have lost that essential muscarinic effect, which is why fresh [or frozen] is best.
"You pray for me and I'll dance naked in the forest for you"
The mushroom Boletus edulis is well known for being delicious and nutritious. The crispy fruiting bodies can be sliced and eaten raw, or cooked. They can be simply grilled with garlic or fried. When the mushroom is used to prepare soup, it gives off a pleasant fragrant smell.
Prized as an ingredient in various foods, B. edulis is an edible mushroom held in high regard in many cuisines, and is commonly prepared and eaten in pasta, polenta and risotto. It also goes well in stews as it keeps its shape well and preserves its taste.
References and further reading
- Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice - Weiwei Zhang, Guoting Tian, Shanshan Feng, Jack Ho Wong, Yongchang Zhao, Xiao Chen, Hexiang Wang & Tzi Bun Ng Scientific Reports 5, Article number: 14907 (2015) doi:10.1038/srep14907