Mushrooms and Vitamin D

When mushrooms are taken out of the dark and exposed to sunlight, they produce Vitamin D using a photochemical process rather than the biological process we depend on when we expose our skin to sunlight. The process is much faster and it really only takes a few minutes of exposure after they're harvested to produce large amounts of vitamin D.

This has all been documented in a recent study from Scandinavia, an area that, due to its high latitude, is very low on sunshine outside of the summer months. The study showed that mushrooms can produce significant amounts of vitamin D when exposed to ultraviolet light. It was published in 2012 in the Journal Food & Nutrition Research.

Associate Professor Hanne L. Kristensen, of Aarhus University, head of the research project said:

"It's actually quite hard to believe, but when mushrooms are exposed to ultraviolet light they start producing vitamin D naturally in large quantities - even after they're harvested."

According to the author, mushrooms contain higher vitamin D concentration than salmon. Kristensen and her group were able to get mushrooms to produce as much as 164 micrograms of vitamin D per 100 grams of mushrooms. Kristensen said:

"In comparison, salmon, which is often mentioned as one of the main sources of vitamin D, contains only around 30 micrograms of vitamin D per 100 grams."

So mushrooms produce over five times the concentration that salmon do. This happens because the mushrooms, when exposed to UV light, convert ergosterol (which is found in mushrooms) into vitamin D. It is similar to our process of converting cholesterol in the skin to Vitamin D. It requires the frequencies of UV light but, of course, those wave lengths are included in sunlight.

So you could actually take mushrooms you have harvested yourself (be sure you know what you are doing!) or take store-bought, common button, portabella or shiitake or other varieties and dry them in the sun. Or just leave them out for awhile - think of doing it longer in the weaker winter sun. You would do this with the gills positioned to receive full sun exposure. You could even do it with button mushrooms you have grown yourself - kits are available to help you do this easily. A person could even become self-sufficient in this very important nutrient. Mushrooms and vitamin D - enjoy them together.

For more information about Vitamin D, visit these pages:

The benefits of vitamin D.
Food sources of vitamin D.
A ready-made, vegan source.

Reference: Increase of vitamin D2 by UV-B exposure during the growth phase of white button mushroom (Agaricus bisporus) Hanne L. Kristensen, Eva Rosenqvist, Jette Jakobsen (Food & Nutrition Research 2012. 56: 7114)