Which mushroom has the highest vitamin D content?

November 28, 2025 •

3 min read

Vitamin D content varies greatly among mushrooms, with some offering significant amounts when exposed to UV light. Understanding which mushroom has the highest vitamin D content is key to using fungi as a plant-based source of this essential nutrient.

Quick Summary

Vitamin D levels in mushrooms depend on UV light exposure. Maitake and Portobello, when treated with UV light, can provide high amounts, similar to fortified foods. Wild mushrooms also contain variable amounts due to natural sun exposure.

Key Points

UV Exposure is Key: The vitamin D content in any mushroom is almost entirely dependent on its exposure to UV light, not its species alone.
Maitake and Portobello: Among commercially available varieties, UV-treated Maitake and Portobello mushrooms can contain exceptionally high amounts of vitamin D.
Sunlight is Effective: You can increase the vitamin D in store-bought mushrooms by exposing them to midday sunlight for just 15-60 minutes.
Wild vs. Cultivated: Wild mushrooms often have naturally higher vitamin D levels due to sun exposure, while cultivated ones require artificial UV treatment or home sunning.
Bioavailability: Vitamin D2 from mushrooms is effectively absorbed and utilized by the body, offering a viable alternative to animal-based vitamin D3 for vegetarians and vegans.
Maximize Absorption: Slicing mushrooms before sunning increases surface area for more vitamin D production, and cooking methods like grilling help preserve it best.

The Surprising Science of Mushroom Vitamin D

Mushrooms are unique because they are the only non-animal, unfortified source of vitamin D, specifically vitamin D2. This happens through a process similar to how human skin produces vitamin D3 from sunlight. A substance called ergosterol, found in mushroom cell walls, is converted into vitamin D2 (ergocalciferol) when exposed to ultraviolet (UV) light. For this reason, the vitamin D content can vary dramatically depending on the mushroom's growing conditions and post-harvest treatment.

Wild vs. Commercially Grown Mushrooms

Most commercially produced mushrooms, like basic white button, are grown indoors in dark, controlled environments and contain very little vitamin D. In contrast, wild mushrooms that grow in sunlight can contain naturally high levels. However, some commercial producers now intentionally expose mushrooms to UV light using specialized lamps to create a vitamin D-enhanced product. The result is a simple, effective, and vegan-friendly way to boost your vitamin D intake.

Factors Influencing Vitamin D Levels

To get the most vitamin D from mushrooms, consider these factors:

UV Exposure: The single most important factor. Mushrooms grown in darkness contain minimal vitamin D, while those exposed to sunlight or UV lamps develop high concentrations.
Surface Area: Slicing mushrooms before sun exposure increases the surface area, allowing more ergosterol to convert into vitamin D2.
Exposure Time: Just 15 to 60 minutes of midday sunlight can significantly boost vitamin D levels in mushrooms. Commercial UV lamp treatment can be even faster, sometimes taking only seconds.
Storage: The vitamin D content in UV-treated mushrooms is relatively stable during storage and cooking, though slight degradation can occur over time. For best results, consume within a week of purchase.
Cooking Method: Cooking, particularly oil-based frying, can cause some fat-soluble vitamin D to leach out. Grilling or sautéing with minimal fat can help retain more nutrients.

Leading Mushrooms and Their Vitamin D Potential

While UV exposure is the primary determinant, certain mushroom types are more prone to high vitamin D content. Maitake mushrooms are notable for producing high levels naturally, and some commercial brands have proprietary growing methods to enhance this. Similarly, wild chanterelles and portobellos, especially when UV-treated, can become excellent sources.

Comparison of Vitamin D Content in Mushrooms


Mushroom Type	Typical Growing Condition	Potential Vitamin D (per 100g)
Maitake	UV-Enhanced / Wild	Up to 2242 IU (56µg)
Portobello	UV-Treated	Up to 752 IU (18.8µg)
Wild Chanterelle	Wild, sun-exposed	Up to 212 IU (5.3µg)
Button (Cultivated)	Grown in darkness	Less than 40 IU (<1µg)
Shiitake (Cultivated)	Grown in darkness	Less than 40 IU (<1µg)

How to Maximize Vitamin D from Your Mushrooms

To maximize vitamin D intake from fungi, the most reliable method is to buy intentionally UV-treated mushrooms. Look for labels specifically stating "UV-treated" or "high in vitamin D." You can also fortify mushrooms at home with sunlight.

Here’s how:

Select Your Mushrooms: Any edible mushroom, including button, portobello, and cremini, will work. Slicing them can help increase the surface area.
Lay Them Out: Place the mushrooms, gill-side up, on a tray or plate in direct sunlight.
Time It: Expose them to midday sun for about 15 to 60 minutes. The longer the exposure, the higher the vitamin D content, though this is also affected by factors like cloud cover and season.
Refrigerate: After sun exposure, you can cook them immediately or store them in the refrigerator for up to a week.

This is a simple, cost-effective way to turn a standard mushroom into a nutritional powerhouse.

Conclusion: Which Mushroom Delivers the Most Vitamin D?

To pinpoint which mushroom has the highest vitamin D content, the growing method is more important than the species itself. While some wild mushrooms naturally absorb UV rays, commercially available UV-enhanced varieties, particularly Maitake and Portobello, offer the most consistently high levels. For home cooks, even basic cultivated mushrooms can become a potent vitamin D source by simply placing them in direct sunlight. This technique empowers consumers, especially vegans and vegetarians, to naturally increase their intake of this vital nutrient. Ultimately, the mushroom with the highest vitamin D is the one that has been deliberately exposed to a UV source, whether by sunlight or specialized lamps, rather than one specific species grown in the dark.

Explore More with Mushroom Health Science Australia

For more in-depth information about the health benefits of mushrooms and their role in providing vitamin D, visit the Mushroom Health Science Australia website.

Frequently Asked Questions

No, not all mushrooms are naturally a good source of vitamin D. Their vitamin D content is dependent on exposure to ultraviolet (UV) light. Many commercially grown mushrooms are cultivated in the dark and contain very little, while wild or specially treated mushrooms can be an excellent source.

You can increase the vitamin D content by exposing fresh mushrooms to direct sunlight. Lay them gill-side up on a tray for 15 minutes to an hour around midday. Slicing them first will increase the surface area and enhance the effect.

Some vitamin D can be lost during cooking, especially during oil-based frying, as vitamin D is fat-soluble and can leach into the oil. Methods like grilling or sautéing with minimal fat help retain more of the nutrient.

Mushrooms produce vitamin D2 (ergocalciferol), while the form commonly found in animals and some supplements is vitamin D3 (cholecalciferol). Both forms can effectively raise vitamin D levels in the blood, and mushroom-derived D2 has been shown to be bioavailable.

Maitake mushrooms, particularly those that are wild-harvested or UV-enhanced, can offer very high levels of vitamin D. Other varieties like Portobello and wild chanterelles also become potent sources when exposed to UV light.

Look for labels on the packaging that state “UV-treated,” “high in vitamin D,” or indicate the specific amount of vitamin D the mushrooms contain. If no label is present, it's safer to assume they have low vitamin D content.

Ergosterol is a precursor compound found in mushrooms that, upon exposure to UV light, converts into vitamin D2. It is analogous to the 7-dehydrocholesterol in human skin that converts to vitamin D3. The amount of ergosterol varies between mushroom species.