Mushrooms

food source · 1

• →Vitamin D

  Ergosterol in the cell membranes of mushrooms turns into vitamin D2 under ultraviolet light. Mushrooms grown in the dark have little vitamin D; only those that have been in the sun or treated with UV light count as a vitamin D source.

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  Mechanism · 2

  Mechanism · Mushrooms make vitamin D in sunlight

  Ultraviolet light striking ergosterol in fungal cell membranes turns it into vitamin D2, the same kind of light-driven reaction by which sunlight turns 7-dehydrocholesterol in human skin into vitamin D3. The D2 you eat is still raw material that the liver and then the kidney have to process.

  In practice · Look for UV treatment on the label

  Mushrooms grown in the dark have little vitamin D, so unless the label says they were UV-treated or sun-dried, do not count them as a vitamin D food. Mushrooms exposed to sun or UV light can raise blood vitamin D levels, which is especially useful for people who eat no animal foods, though D2 does this less well than D3, which is why supplements usually use D3.

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