Sunbake your ‘Shrooms for Vitamin D
When we think of vitamin D, we often think of sunshine and maybe a supplement or two, but did you know your humble mushroom can also be a powerful source of this vital nutrient?
It turns out, mushrooms are one of the only plant-based sources of vitamin D and the magic happens when you give them a little time in the sun.
How Does It Work?
Like humans, mushrooms naturally produce vitamin D when they’re exposed to sunlight. Specifically, they contain a compound called ergosterol, which converts into vitamin D2 when exposed to UV rays. While D2 isn’t quite as potent as the D3 we make in our skin, it still contributes meaningfully to your daily intake, especially if you follow a plant-based diet or don’t get much sun exposure.
How to Sun-Bake Your Mushrooms
It’s super simple and only takes about 15–30 minutes.
Slice your mushrooms (button, portobello, or shiitake work well) and lay them out on a plate or tray, gill side up.
Place them in direct sunlight, ideally during peak UV hours (between 10am–2pm).
Leave them for 15–30 minutes. Even a short exposure time can dramatically increase their vitamin D content.
Cook or store as usual. You can use them straight away or keep them in the fridge for a few days.
Fun fact: Studies show that just 100g of mushrooms exposed to sunlight can provide over 100% of the recommended daily intake of vitamin D!
When Is This Helpful?
During winter months when sun exposure is lower
For people following vegan or vegetarian diets
If you’re limiting sun exposure for skin health
When trying to support immune function or bone health naturally
Tips to Get the Most Out of It
Expose mushrooms after purchase, not while growing
Use fresh mushrooms, older ones may not produce as much vitamin D
Even cloudy days work… UV still gets through
No need to overdo it, a short sun session is plenty.
A Natural Top-Up for Your Plate
Next time you grab a bag or punnet of mushrooms, try sunbaking them before you cook. It’s a simple, ‘food as medicine’ way to support your bone health, immune system, and mood, especially during low-sunshine seasons.
And the best part? Your pasta, stir-fry or risotto just became a little more nourishing, naturally.
Have you tried Regi’s Immune Boosting Mushroom Soup yet? Get the recipe here.
References:
Bechraki, L, van den Heuvel, E, de Groot, L & Groenendijk, I 2023, ‘The Nutritional Benefit of UV-Exposed Mushrooms for the Dutch Population: Modelling the Addition of UV-Exposed Mushrooms to the Diet’, Current Developments in Nutrition, vol. 7, Elsevier BV, no. 12, pp. 102039–102039.
Cardwell, G, Bornman, J, James, A & Black, L 2018, ‘A Review of Mushrooms as a Potential Source of Dietary Vitamin D’, Nutrients, vol. 10, no. 10, p. 1498.
Keegan, R-JH, Lu, Z, Bogusz, JM, Williams, JE & Holick, MF 2013, ‘Photobiology of vitamin D in mushrooms and its bioavailability in humans’, Dermato-Endocrinology, vol. 5, no. 1, pp. 165–176.
Starck, C, Cassettari, T, Wright, J, Petocz, P, Beckett, E & Fayet-Moore, F 2024, ‘Mushrooms: a food-based solution to vitamin D deficiency to include in dietary guidelines’, Frontiers in nutrition, vol. 11, Frontiers Media.