Shiitake mushrooms, like most fungus foods, aren't much to look at. But try to get past their odd form and texture, because their nutritional benefits are extraordinary.

Once only cultivated in Japan, shiitakes are now grown worldwide, and comprise 25 percent of earth's total annual mushroom cultivation.

Shiitakes contain many of the same amino acids as meat, but their big secret ingredients are the polysaccharides, terpenoids, sterols and lipids linked to immune-boosting, cholesterol-controlling and anti-cancer effects.  

One study indicated that the heart-healthy shiitakes could lower blood pressure; others pointed to their eritadenine and sterol molecules for their ability to inhibit and otherwise control cholesterol production in the body. Another study in lab rats fed a high-fat diet found that those given shiitake mushrooms developed less fat in their livers, less plaque on their artery walls and had lower cholesterol levels than those who didn’t get any mushroom supplement.

Recent studies have shown the eating shiitakes can give your immune system a significant boost. A 2015 study saw people eating around two dried shiitakes daily for a month. Not only did their their immune markers improve, also had less inflammation than before the study began. Even more interesting was the mouse study that showed how a supplement derived from shiitakes helped reverse some of the age-related decline in immune function. If anyone ever concocts a youth potion, it's likely to contain a lot of shiitake essence!

Shiitake mushrooms fight cancer from a number of different directions. The polysaccharide lentinan found in the 'shroom helps fight tumors by activating the immune system, and has been been shown to inhibit the growth and spread of leukemia cells. In fact, an injectable form of lentinan is used alongside chemotherapy and other major cancer treatments in China and Japan to improve immune function and quality of life in people with gastric cancer.

Multiple compounds found in shiitakes contain antibacterial, antiviral and (ironically!) antifungal effects.

There are some caveats (aren't there always?). A skin condition known as “shiitake dermatitis” is believed to be caused by lentinan, and occurs in some people who handle shiitakes. Gout sufferers should probably steer clear of shiitakes, due to their high purine content. Exposure to powdered shiitake extract can not only cause shiitake dermatitis, but also upset stomach and a sensitivity to sunlight.