Need a little more vitamin D in your diet? Why not try mushrooms, both wild and store bought. In this article we’ll cover which mushrooms are high in vitamin D.
We’ll also show you how to easily increase Vitamin D levels in store-bought mushrooms using a simply UV-B reptile lamp.
Note: If you click some of the links in this article we may earn a small commission at no additional cost to you.
Ideal Vitamin D Levels for People
Button mushrooms exposed to mid-day sunlight have 10 micrograms (ug) of Vitamin D2 per 100 grams of mushrooms (1).
According to the National Institutes of Health (NIH), the Recommended Daily Allowance (RDA) of Vitamin D is 15 micrograms (2). If you eat 150 grams (about 5 ounces or 4 to 5 mushrooms) of light-exposed button mushrooms daily you’ll get 15 micrograms of vitamin D.
The typical store-bought back of mushrooms from the grocery store is 8 ounces for about $3. Store-bought mushrooms are grown in darkness and have only 1 ug of Vitamin D per 100 grams of mushrooms. You’d need to eat 1500 grams (over six 8 oz packs) of store-bought mushrooms to get the 15 ug of Vitamin D required daily.
If you had access to sun-exposed button mushrooms you’d need a lot less. Two 8 oz packs of sun-exposed mushrooms every 3 days and you’d hit your ideal daily Vitamin D intake.
Mushrooms with the Highest Vitamin D Ranked From Most to Least
Oyster mushrooms that underwent UV-B light exposure had the highest concentrations of Vitamin D2 followed by Shiitake then button mushrooms.
Penny bun mushrooms naturally had the highest levels of Vitamin D2 followed by chanterelles.
Fresh mushrooms like store-bought button, oyster, and shiitake mushrooms had the least Vitamin D2.
How to Increase Vitamin D in Mushrooms
Expose them to sunlight mid-day in summer! This study ran that experiment on many types of common mushrooms (button, shiitake, oyster) (1).
Most of those mushrooms start at 1 ug vitamin D2 per 100 grams of mushrooms. When exposed to either strong summer sun or to UV lamps they D2 levels shot up to around 10 ug/100g.
That same study found you could even exposed dried mushrooms to UV lamps and it would increase their Vitamin D2 content.
According to the study you need about 60 to 90 minutes of exposure to UV-B radiation at 1.14 W/m2 at 28 °C (1). The example reptile light shown below uses 3 watts of power to give off 1.3 W/m2 of uv-B.
How do you do this at home?
- Get some fresh or dried mushrooms – the study was conducted on button, shiitake, and oyster mushrooms.
- Get a UV lamp with UV-B rays. UV-B was found to increase Vitamin D2 more than UV-A or UV-C.
- Slice the mushrooms and place them on a tray
- Expose sliced mushrooms to UV-B light for 60 minutes
- Enjoy your fresh vitamin D2!
What Kind of Vitamin D is in Mushrooms?
Mushrooms and other fungi and yeast contain the D2 form of vitamin D (1). Animals contain the D3 form.
The best source of vitamin D comes from oily fish. They also contain the D3 and D4 forms.
How Mushrooms Become High in Vitamin D
Vitamin D status in mushrooms increase when growing mushrooms are exposed to mid-day sunlight (1). They can also be increased by sun drying mushrooms after harvesting.
What Is the Best Form of Vitamin D for People?
Both Vitamin D2 (mushrooms) and Vitamin D3 (animal foods or sunlight on human skin) have been shown to prevent rickets (2). Therefore they are seen by the NIH as functionally the same. Both forms have enough bioavailability to raise blood concentrations of Vitamin D to ideal levels.
How are Vitamin D2 and Vitamin D3 Different?
Vitamin D2 and D3 molecules have different side chains in their chemical makeup. D2 comes from mushroom and yeast sources. D3 comes from animal sources, mainly fatty fish. D3 is also the form produced when your skin is exposed to sunlight.
As described above, both D2 and D3 raise blood levels of Vitamin D and both have been shown to prevent rickets. Therefore the NIH considers them both as adequate sources of Vitamin D.
Mushroom Vitamin D vs Vitamin D Supplement – Which is Better?
Vitamin D supplements contain both the D2 and D3 forms. Better safe than sorry!
Mushroom Vitamin D only comes in the D2 form. Again, as described before the NIH considers both D2 and D3 the same. Both raise blood levels of Vitamin D to prevent rickets and other signs of Vitamin D status deficiencies.
Note – You can thank Dr. Michael Holick for our desire to increase our Vitamin D levels. He’s written books on the subject, helped shape the Vitamin D guidelines, and even refuses to wear sunscreen when he goes outside!
Signs of Vitamin D Deficiency
The main problem with vitamin D deficiency is the development of rickets in children (2). This also occurs in young pets and animals that are fed diets without Vitamin D. This was primarily overcome by requiring milk and milk products to be fortified with Vitamin D.
Rickets results in soft bones and bone deformities. It can cripple your child.
For adults, signs of low levels of Vitamin D include the following (2):
- Weak bones (osteomalacia)
- Bone pain
- Muscle weakness
How to Find Vitamin D Mushrooms in the Wild
Vitamin D will be highest in wild mushrooms exposed to sunlight. Even though chanterelles grow in the understory of forests, they still had relatively high levesl of Vitamin D.
We’d expect, but don’t have research to back it, that full sun mushrooms like Giant Puffballs should have lots of vitamin D.
This guess is based on the studies done on store-bought mushrooms. Button, shiitake, and oyster mushrooms and exploded with vitamin D after being exposed to 60 to 90 minutes of UV-B radiation.
According to the USDA database, morel mushrooms have 5 ug/100 g of Vitamin D. Not great but it’s still five times higher than store bought white, shiitake, or oyster mushrooms. Morels in the store are usually wild-crafted.
We have an entire article on finding morel mushrooms in the wild.
How to Check if Mushrooms Contain Vitamin D
There’s no quick and easy way to test vitamin D levels in your food or mushrooms. The USDA has published Vitamin D levels in various foods (3).
You can also send your UV-B lamp exposed mushrooms to a lab to check that it’s working. Eurofins Lab offers food testing services.