In April 2015, the University of Florida Institute of Food and Agricultural Sciences published a study showing increased immunity in persons who ate cooked shiitake mushrooms every day for 4 weeks. Through blood tests before and after the experiment, researchers saw better functioning gamma delta T-cells and reductions in inflammatory proteins.
The shiitake mushroom is almost unique in its ability to either up-regulate or down-regulate the immune system. Several studies have demonstrated this potential, with one set of studies showing they prevent over activity of the immune system – helping to reduce inflammation and allergies. Another set of studies showed that shiitake can stimulate a poorly functioning immune system, helping to fight off viral infections – including tumour related growths. Whilst this dual regulatory action may seem contradictory, this type of adaptive regulation is exactly what the body needs to thrive.
Shiitake mushrooms also contain an extensively researched polysaccharide called “lentinan” – a compound which activates macrophage T-lymphocytes and other immune effector cells.
In addition to the above, shiitake mushrooms demonstrate strong anti-fungal, high in vitamin D and exhibit antibacterial effects.
Shiitake mushrooms contain 3 compounds that may help to lower cholesterol; Eritadenine - inhibits an enzyme involved in the production of cholesterol, Sterols – molecules that can help to block cholesterol absorption in the gut, and Beta-Glucans – a soluble fibre which dissolves in the digestive tract and creates a thick gel like paste, this binds with excess cholesterol to keep it from being absorbed.
Shiitake can also protect against atherosclerosis by reducing production of immune cell adhesion molecules, which make cells sticky and cause plaques on the arteries.
A fabulous food for healthy weight loss, shiitake is around 30% fibre which not only increases satiety, it is the kind of fibre that makes it difficult for the body to absorb fat. In a study conducted by the University of Wollongong, Australia, a research group fed four groups of rats a high fat diet along with a certain amount of shiitake supplements. The rats that received the highest amount of shiitake also had the lowest weight gain, around 1/3 less than rats fed the fatty diet without shiitake.
These findings, published in the “Journal of Obesity”, theorize that certain components in the mushrooms could increase the fat elimination, reduce certain fatty acids, and/or inhibit the release of triacylglycerol from the liver. Scientists are now using shiitake extracts as prebiotic agents and studying how this can help prevent obesity-related metabolic disorders.
Folklore and history
Indigenous to Japan, China and Korea, shiitake has a long history of cultivation, with one of the first historical records to mention shiitake dated 199 AD.
In China the cultivation of shiitake started around 1,000 years ago with a man called Wu San-Kwung. According to legend, Kwung was testing his axe on a log that had shiitake growing on it - swinging his axe he made several cuts in the log before leaving. He returned some days later to discover that more shiitake had grown exactly where the log had been chopped by his axe. Kwung continued to successfully experiment, becoming the pioneer of cultivated shiitake. In his quest to perfect his method of cultivation he became frustrated with one particular log that wouldn't fruit. After a long, hard, rainy day Kwung vented his frustration by beating and flinging the log around. Upon his return he discovered that the log he had beaten so vigorously was completely covered in mushrooms. Kwung had inadvertently discovered the ‘soak and beat’ method of mushroom cultivation which is still in use today. Kwung’s contribution to shiitake cultivation is commemorated in a temple situated in Qingyuan, where festivals are still celebrated in his name.
Possibly the most popular mushroom in the world after the button mushroom, shiitake has long been a favourite of the Chinese and Japanese. Traditional Chinese Medicine (TCM) uses this mycelium heavyweight as a stimulant to boost overall health, prevent strokes, relieve hunger, strengthen the immune system, stimulate “qi” (life force) and improve circulation. Most of these properties were pioneered by the Chinese in the “Ri Youg Ben Cao”, a Traditional Chinese Medicine compendium written in 1620.
Most commonly this mushroom is consumed as a food. In China and Japan it is also taken for its medical properties.
1-3 beta-glucans; polysaccharide KS-2; glycoproteins (LEM, LAP); eritadenine; iron, niacin, vitamins B1 and B2.