Vitamin D is essential for our metabolism and boosts our immune system. Paul Stamets, author of Growing Gourmet and Medicinal Mushrooms, showed that mushrooms, either store bought or home grown are a very effective source of vitamin D.
The widespread commercial sources of vitamin D are vitamin D3 that comes from animal skins and oily fish. Both mushrooms and animal skins create vitamin D when exposed to sunlight. However, getting vitamin D from animal skins such as pigskins can be quite gruesome and tedious. Besides, eating mushrooms packed with vitamin D confirms other health benefits. Mushrooms have several helpful nutrients, including beta glucans for immune enhancement, nerve growth stimulators for helping brain function, and antimicrobial compounds for limiting viruses.
There was a simple experiment done in Kamilche Point, Washinton. Several forms of organically-grown shiitake mushrooms, all from the same crop were compared in three sets. The first was grown and dried indoors. The second set was dried outdoors in the sunlight with their gills facing down. The third set of mushrooms was dried outdoors in the sunlight with their gills facing upward for full sun exposure. The most effective amount of vitamin D was found in shiitake dried with gills up that were exposed to sunlight for two days, six hours per day. The vitamin D levels in these mushrooms soared from 100 IU/100 grams to nearly 46,000 IU/100 grams. Their stems, though, produced very little vitamin D, only about 900 IU. Notably, vitamin D levels dropped on the third day, probably due to an excessive exposure of UV. In the experiment the mushrooms were tested a year after the exposure and they still preserved a significant amount of vitamin D2. This concluded that our bodies could get high levels of vitamin D from the tasty mushrooms throughout the fall, winter, and spring.
To read more visit: http://www.huffingtonpost.com/paul-stamets/mushrooms-vitamin-d_b_1635941.html
Growing Gourmet and Medicinal Mushrooms by Paul Stamets is available from Green Shopping
This is the most complete book ever written on mushroom cultivation! Everything from laboratory construction to recipes, and includes detailed growth requirements for 25 species.
A classic permaculture text.