MUSHROOMS + SUNLIGHT = x100 VITAMIN D
the vitamin D
COPYRIGHT JAMES WONG 2017
Doing one simple thing to your shop-bought mushrooms could transform them from containing virtually zero Vitamin D to one of nature's richest food sources in as little as an hour or two, according to Penn State University. Popped on a sunny windowsill, the mushrooms (which are commercially grown in near total darkness) will react to the UV light, churning out loads more antioxidant Vitamin D to defend themselves from damage from solar radiation.
The Penn State team found that a serving of white button mushrooms exposed to UV lamps for just 1 second could go from containing essentially no Vitamin D, to an astonishing 824% of your daily value.
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When they tried the same thing with shiitake and oyster mushrooms, their vitamin D content skyrocketed way over 1000 times what you need to consume each day. In the world of food science this really is as close as you can get to alchemy, all for very little effort.
With such tiny amounts of UV light needed to create such an enormous impact, it doesnt have to be a blazingly hot day either. Simply lay your mushrooms out on a windowsill for an hour or two anytime between 10am and 3pm and their levels should rise significantly. As the gill tissue (the brown underside of the caps) is more sensitive to light, placing these with their gills facing up will trigger the strongest spike.
National Univeristy of Singapore
A SCIENTIST'S GUIDE TO THE WONDERS OF PLANTS
But what about the glass?
One potential critique of the idea that putting mushrooms on windowsills can up their vitamin D content is that some of this research has come from experiments testing only the UV-B wavelength of light. Yet as most, if not all, UV-B is filtered out by glass, does the window have to be open for this trick to work?
Well, in fact there are a range of studies that show that another wavelength called UV-A, which does pass through glass, can also boost the vitamin D2 content of a range of mushrooms. This was first tested in 2004 by a team at the National University of Singapore, just 6 years after the phenomenon was 1st established by a team of Taiwanese scientists using UV-B.
Yet, perhaps surprisingly, in the exhaustive literature review I conducted for the book it appears only two studies actually set out to compare the effect of different UV wavelengths on a range of mushrooms to see which one is more effective.
Between these two, only one directly compared UV-A & UV-B, the wavelengths that reach the Earth's surface. It was also the only study to use the full wavelength of UV-A as is found in sunlight, as opposed to single wavelength produced by lab lamps. Science can be complex!
This study was conducted by the same Singaporean team mentioned earlier and found that while in each case UV-A was less effective than UV-B light, both resulted in a significant spike in vitamin D2 levels, producing more than enough to meet daily requirements. Hurrah!
But what does that mean to you at home? Based on the best research available to date, exposure to UV-A light on a closed windowsill should significantly boost the vitamin D in your mushrooms. Opening your window to allow more UV-B light in, however, may help even more. A simple swap that won't cost you anything and could give you more of the good stuff.