How are mushrooms like humans? We can both convert sunlight to vitamin D in our skin!
So if you eat mushrooms, you can get all the Vitamin D you need!
Method 1: Sun Exposure
Key fact to know: Not all sunlight is the right wavelength to create Vitamin D. Sometimes the sun is out, but no Vitamin D synthesis can happen, either because it's too early/late in the day, or during the "Vitamin D winter" between around November - February (in the Chicago area).
So Method 1 only works when the sun is high in the sky in the full sun hours of the day (between around 10 am- 4 pm), between April and November (for folks as far north as Chicago).
Mushrooms can convert sun to Vitamin D AFTER THEY ARE HARVESTED. So you can buy regular, packaged or unpackaged mushrooms in the store (any kind my friends!) and this will work.
Simply spread them out on a tray and put them in full sun. I do it on my window ledge. Leave them for as long as you can/want-- 30 minutes, 2 hours, 6 hours, you name it.
If they are cut, great--that increases surface area for Vitamin D conversion. If they are not cut, put them GILLS UP.
The longer you leave them out, the higher the Vitamin D will rise. Even 30 minutes is worth it!
Method 2: UVB Light
You can't make Vitamin D on days when it rains. Or at 10 pm. Or in December in Chicago. But you CAN make Vitamin D from mushrooms any time, day or night, if you have a UVB light!
Lizards need UVB light exposure. You can take advantage of this to buy a UVB lizard light to use on your mushrooms. They come in all sizes and shapes.
You could attach one to something in your kitchen and create a permanent "mushroom irradiation" station. I couldn't find a good spot in my kitchen, so I decided to buy the absolute smallest UVB light I could find, keep it in a drawer, and take it out three/four times a week to shine on my mushrooms. This is what I bought on Amazon:
Reptile T5HO 12″ Standard Fixture & Reflector
Zoo Med 26396 Reptisun 15W 10.0 T5-Ho Uvb Fluorescent Lamp, 12″
Note: You can purchase cheaper fixtures and lights. I wanted something extremely small and compact, so I was willing to pay extra for it.
Note: If you have never attached a UVB light into a UVB fixture, you have to TURN the ends of the light to click in to the fixture. Don't break the light. This video showed me how.
I shine it right over my mushrooms at a distance of about 4-5″ for five minutes. I prop it up on tissue boxes to position it over my mushrooms. Super easy!
Want more info? Google "Vitamin D mushrooms" for links like these:
Final note: some people say the Vitamin D you get from mushrooms, Vitamin D2, in inferior to Vitamin D3, which you get from your own skin. So perhaps try to get as much Vitamin D from the sun as you can, and when you can't...use mushrooms!