Years ago, it was shown that vitamin D isn’t just the sunshine vitamin for us, but for mushrooms as well. You take some mushrooms, put them under a sun lamp for an hour, and they’ll make vitamin D just like we do lounging at the pool.
Now most mushrooms you buy at the store don’t have any vitamin D because they’re grown in the dark, but now there are sun-bathed varieties on the market that boast significant levels. Some mushrooms grown out in the wild have vitamin D as well, but only about 12% of one’s recommended daily allowance per cup.
But is the vitamin D in mushrooms bioavailable? In 2008 there was a case report of a dark skinned individual living in England in the winter who–like the other 9 out of 10 South Asians living in the UK–was vitamin D deficient. His physician prescribed a vitamin D supplement, but after doing his own research this patient decided to self-treat. He bought a UV bulb from a local hardware shop and proceeded to shine this directly onto 2 cups of regular mushrooms a day before stir-frying and consuming them. He repeated this on a daily basis for 3 months, and indeed his vitamin D levels shot up and he was cured. So it’s reasonable to assume that such mushrooms may be able to provide a source of vitamin D for those at risk for deficiency. This was just one person though, so further studies were necessary, and finally those studies have been done.
In the above video I profile a study entitled “Bioavailability of Vitamin D from Ultraviolet Light Irradiated Button Mushrooms in Healthy Adults Deficient in Serum 25-Hydroxyvitamin D: A Randomized Controlled Trial.” They compared the mushrooms to vitamin D supplements and placebo, and both the mushrooms and the supplements were equally effective in raising vitamin D levels compared to the placebo.
The type of D made by mushrooms is vitamin D2, which is typically derived from yeast and is the form traditionally prescribed by doctors to cure D deficiency. Most supplements, though, are D3, which is the type found in plants and animals, typically derived from sheep’s wool. Back in 2008 it was established that vitamin D2 was as effective as D3 in maintaining one’s vitamin D levels at standard daily dosing levels. As you can see in the video, whether folks were given D3, D2, or a combo of half D3 and D2, it didn’t seem to matter much in terms of improving vitamin D levels in the bloodstream. But that was 5 years ago–what’s the update? Is vitamin D2 better than vitamin D3? It depends how you take it and what your starting levels are. Watch the video for the latest details.
Here are my vitamin D recommendations for those in the Northern Hemisphere:
That’s not what the Institute of Medicine says though. I justify my recommendation in this video series: