15/06/2026
Your mushrooms can make Vitamin D! ☀️
Yes, the ones sitting in your fridge right now.
Here is what the research shows. Mushrooms contain ergosterol, a compound that converts to Vitamin D2 when exposed to UV light. Place them gill-side up on a sunny windowsill for 30 to 60 minutes before cooking, and the Vitamin D content can increase significantly.
In winter, when sun exposure drops and Vitamin D levels in women crash, this is a small intervention that actually moves the needle.
But the story does not end there.
Mushrooms also contain beta-glucans, a type of fiber that feeds the bacteria in your gut, supporting microbiome diversity and immune resilience through the colder months when most of us catch something.
And then there is ergothioneine. An antioxidant found almost exclusively in mushrooms, linked to cellular protection and slower biological aging in emerging research.
How I recommend using them through winter:
→ Sauté shiitake or button mushrooms in olive oil with garlic, low and slow, to release the umami and break down the chitin (which raw mushrooms hold, and your gut struggles to digest)
→ Roast portobello or oyster mushrooms at high heat for that deep caramelisation, perfect tossed into warm winter bowls
→ Blend cooked mushrooms into bone broth or a slow soup for a gut-soothing, mineral-rich meal
→ Always cook them. Raw mushrooms are somewhat suboptimal for the gut, and the nutrients are far less bioavailable
One small note. Wild and supermarket varieties differ in their nutrient profile, and not all UV exposure is equal. But even basic white button mushrooms respond to that windowsill trick.
This is the kind of foundational shift I love. Cheap. Evidence-based. Quietly powerful through a long winter.
Try the windowsill experiment this week, and notice how you feel by the end of the month.
NOTE: 🍄 Mushrooms are NOT a replacement for adequate sun exposure or supplementation when deficiency is present, but they're a simple way to boost vitamin D intake while also providing fibre, antioxidants, potassium, and umami flavour.