UV-treated vitamin D mushrooms can make a meaningful contribution to your daily intake—but the amount depends on the product, and ordinary mushrooms often contain very little. Check the nutrition label for vitamin D per serving: the words “UV-treated” alone do not tell you exactly how much you will get.
How UV Light Changes Vitamin D In Mushrooms
Mushrooms contain ergosterol, a compound that UV light can convert into vitamin D2. Sunlight can trigger this process, as can UV lamps used during commercial processing. Most cultivated mushrooms are grown with little UV exposure, so untreated button mushrooms typically have low vitamin D. Treatment can raise their levels substantially.
This is why mushroom and vitamin D figures can look so different from one product to another. Species matters, but so do the UV wavelength and dose, how long the mushrooms are exposed, and whether the light reaches the caps, stems or sliced surfaces.
Vitamin D Mushrooms: What A Serving Can Provide
In a USDA food-analysis project, mushrooms were collected from retail outlets in 12 US cities; some UV-treated samples came directly from growers. The analysis found 11.2 micrograms (µg) of D2 per 100 grams (g) of treated portabella mushrooms on average. Samples from two producers ranged from 3.5 to 18.8 µg per 100 g. That spread shows why one product’s result cannot stand in for every UV-treated mushroom.
Wild species can differ too. Morels and chanterelles have shown higher amounts than many untreated retail mushrooms, while a high figure for maitake mushroom vitamin D may reflect a particular growing or UV-treatment method—not a reliable value for all maitake. Regular white button, cremini and shiitake mushrooms are not automatically high in vitamin D; look for a stated amount on the package.
For context, reference intakes vary by region and age: the UK figure summarized in a 2018 review is 10 µg (400 IU) a day for adults; the European Union reference is 15 µg (600 IU); and US recommendations are 15–20 µg (600–800 IU), depending on age. Australia and New Zealand figures vary by age as well. A 100 g serving that provides 10 µg would supply the full UK amount, about two-thirds of the EU reference, or half to two-thirds of the US amount. A 75 g serving would provide three-quarters as much. These comparisons show potential contribution, not that a particular product meets your needs; use its label and your local guidance.
What Storage And Cooking Do To D2
Some vitamin D2 can be lost during storage or cooking, but the size of the change is not fixed. A 2018 review by Glenn Cardwell and colleagues concluded that UV-exposed mushrooms eaten before their best-before date were likely to retain more than 10 µg per 100 g. That is a review-level estimate, not a guarantee for every brand, species or storage history.
A more specific result came from a 2020 laboratory study in Iran. Sarina Salemi and colleagues tested UV-treated white button mushrooms and measured D2 after storage and cooking. Levels were nearly stable after a day at room temperature and after cooking, but fell by about half after seven days of refrigerated storage. The study used one mushroom type and a controlled treatment, so it cannot predict the exact retention in every shop-bought product. Other research summarized in the 2018 review reports losses with storage and cooking, too. Follow the package’s storage directions and, if vitamin D is your reason for buying them, avoid assuming that a laboratory result applies unchanged to your own product.
Food Is Not The Same As A Supplement
UV-treated mushrooms are a food source of D2, and a serving with a substantial labeled amount can help increase dietary intake. They are not interchangeable with a supplement in practical terms: supplements provide a stated dose in a concentrated form, while mushroom amounts vary by product and serving size. A small human study summarized by Raphael-John Keegan and colleagues found that 2,000 IU of D2 from mushrooms raised and maintained a blood vitamin D marker similarly to the same dose of D2 or D3 supplements. That comparison involved a specific dose and does not establish that an ordinary serving has the same effect.
If you are choosing mushrooms, compare the vitamin D amount per serving rather than relying only on species or UV-treatment claims. If you are concerned about your vitamin D intake or considering supplements, a clinician can help you interpret what is appropriate for your circumstances.