Mushrooms in sunlight

Sundried mushrooms are a provitamin D2 source

Mushrooms are a largely unknown, significant, plant source of provitamin D2 when purposefully exposed to sunlight

• Mushrooms need to be exposed to sulight for two days - Commercially supplied mushrooms are usually grown in the dark and contain no vitamin D. However, they do contain a rich potential source of vitamin D2 - the vitamin D2 precursor ergosterol. This can be converted to ergocalciferols (i.e. provitamin D2) when exposed to UV-B light (wavelength 290- 315 nm)
• Can be exposed to sun even after picking - the best time to do this is June through September
• Vitamin D levels are retained for at least a year in dried, sun-exposed mushrooms
• Can be used as a good supplemental source when sunlight is scarce -eating a handful of mushrooms every other day can bring serum D to a healthy level during non-summer months if living in the northern hemisphere

Use any kind of edible mushrooms  E.g. shiitake, maitake, button

Mushrooms contain several health beneficial nutrients -including:

• Beta glucans -for boosting immune system
• Ergothioneine, amino acid aminly found in mushrooms -has antioxidant properties; used as a medicine for liver damage, cataracts, Alzheimer's disease, diabetes, heart disease and topically for wrinkles;
• Nerve growth stimulators -to help brain function
• Antimicrobial properties
  
  

How to obtain the highest vitamin D2 content from mushrooms

Exposure to UV-B ultraviolet light increases D content several-fold.  Robert Beelman at Penn State University found that when mushrooms are dried, pulverized and exposed to pulsed beams of UV-B light, their vitamin D is increased several times more than just exposing the mushrooms to sunlight. Consequently, UV-exposed white button mushrooms are becoming available in grocery stores. Additionally the mushroom surface is sterilized as an added bonus.

Slicing the mushrooms before sun-exposure exponentially increases vitamin D content by increasing exposed surface area

Drying the mushrooms after slicing and indoor UV-B significantly affects D2 content.   In Paul Stamet's article: Place Mushrooms in Sunlight to Get Your Vitamin D. Posted 08/06/2012, he refers to an experiment he did comparing drying the mushrooms in the sun for 2 days with the gills facing the sun and indoor UV-B exposure.

(1 IU is equal to 40 micrograms).

Paul Stamets noted that:

• Stems produced only about 900 IU of vitamin D2 probably due to over-exposure to UV
• The 14 hr indoor UVB exposure was more intense than sun exposure and the mushrooms were also sliced.   IU's would likely also be higher in sun-exposed mushrooms if they were first sliced.

This author is going to conservatively estimate a D2 content of 100,000 IU / 100g for Sun-exposed, SLICED mushrooms

This would yield 10,000 IU of D2 / 10g (a handful) of sundried mushrooms

10 grams (~ .35 ounces) of sun exposed, dried shiitake mushrooms

Photo Source: Place Mushrooms in Sunlight to Get Your Vitamin D

How to produce vitamin D2 in mushrooms

Instructions gleaned from Paul Stamet's online article Place Mushrooms in Sunlight to Get Your Vitamin D

1. Use fresh Organic shiitake, maitake, button, or other mushrooms
2. On a sunny day, slice the fresh mushrooms and place them evenly on a tray exposed directly to the sun from 10 am to 4 pm (6 hours)
3. Before nightfall, cover the mushrooms with a layer of cardboard to block moisture from dewfall.
4. The next clear day repeat exposure to the sun from 10 am to 4 pm.
5. Remove the mushrooms and if necessary finish drying in a food dehydrator until they are crispy.
6. When thoroughly dry, store in a glass jar or sealed container - Add a tablespoon of uncooked rice as a moisture absorber.
7. The mushrooms retain a good amount of D2 for a year or more, depending upon conditions.
8. Take 10 grams (~1/3 oz) daily per person, about a small handful. Rehydrate in water for one hour. The mushrooms will swell. Then cook as desired. E.g. in a soup or cream sauce

This British author's personal favorite mushroom recipe is creamed mushrooms on toast

(Creamed mushrooms cooked with onions, garlic, butter, cream, salt and white pepper)

Does vitamin D2 from mushrooms make it into blood stream?

According to Paul Stamet, a Frieburg University Medical Center Study (in Germany) compared 26 people who took a vitamin D2 supplement to 26 others ingesting 120 g (a handful = ~1/4 lb) of UV light vitamin D-enriched mushrooms (containing ~24,000 IU of D2) in soup four times per week for five weeks. The study found that similar levels of vitamin D were absorbed into the blood in both groups and at the end of the study, both groups'serum vitamin D levels had increased to ~50 nmol/L (considered a healthy baseline level).