Which Plant Has the Most Vitamin D? Unlocking the Power of UV-Exposed Mushrooms

December 28, 2025 •

2 min read

According to data from the USDA, certain mushrooms exposed to ultraviolet (UV) light can contain over 300% of the recommended daily value for vitamin D. This fact positions them as the most potent plant-based source and provides a crucial answer to the question, which plant has the most vitamin D?

Quick Summary

Mushrooms, particularly those exposed to UV light, are the most significant natural plant-based source of vitamin D. They synthesize vitamin D2, making them a key dietary component for those on vegan diets seeking natural vitamin D.

Key Points

Mushrooms Lead the Way: UV-exposed mushrooms, technically fungi, contain the most potent naturally occurring vitamin D (D2) among plant-based food sources.
Fortification is Common: Fortified plant-based milks, cereals, and juices are the most consistent and reliable sources of vitamin D2 for vegan and vegetarian diets.
Common Plants Fall Short: Most common fruits and vegetables, including leafy greens, contain negligible or no detectable amounts of vitamin D.
DIY Sun Exposure: You can significantly increase the vitamin D content of store-bought mushrooms by exposing them to direct sunlight for a short period.
D2 vs. D3 Efficacy: While mushrooms provide vitamin D2 and animal products provide D3, studies suggest D2 is also effective at increasing and maintaining vitamin D levels, especially for those who are deficient.
Natural Production vs. Fortification: Mushrooms offer a natural, whole-food way to get vitamin D, whereas fortified foods rely on added synthetic or extracted vitamins.

The Fungal Anomaly: Why Mushrooms Dominate the Plant-Based Market

When exploring which plant has the most vitamin D, mushrooms emerge as the leading plant-based source, though they are technically fungi. Unlike most plants, mushrooms contain ergosterol, a compound converted to vitamin D2 (ergocalciferol) upon exposure to ultraviolet (UV) light. This conversion is similar to how human skin produces vitamin D3 from sunlight.

How Mushrooms Synthesize Vitamin D

Mushrooms efficiently synthesize vitamin D2 when their ergosterol is exposed to UVB light. While many commercially grown mushrooms lack significant vitamin D due to being grown in darkness, some producers use UV light exposure to increase the vitamin D content, a process called biofortification.

Maximize Vitamin D in Your Home-Grown Mushrooms

You can boost the vitamin D in mushrooms at home by placing sliced mushrooms, gill-side up, in direct sunlight for 15 minutes to an hour. This simple method significantly increases vitamin D levels, which remain stable during cooking.

Comparison of Plant-Based Vitamin D Sources


Source	Primary Vitamin D Form	Biofortification Potential	Typical Vitamin D Content (IU)	Best For	Consistency
UV-Exposed Mushrooms	Vitamin D2	High (via sunlight/lamps)	400 - >1,000 per 1/2 cup serving	Potent, natural vegan source	Variable (depends on UV exposure)
Fortified Plant Milks (Soy, Almond)	Vitamin D2	High (added)	100-144 per cup	Consistent, daily intake	Very consistent (added)
Fortified Cereal	Vitamin D2	High (added)	~80 per serving	Breakfast staple, easy dose	Very consistent (added)
Wild Mushrooms	Vitamin D2	Variable (natural sun)	0 - 1,200 (species dependent)	Foraging enthusiasts	Inconsistent (unpredictable)
Common Vegetables/Fruits	Mostly None	Low/None	Negligible	Other nutrients only	N/A

Fortified Foods: The Consistent Alternative

For a reliable source of vitamin D in a plant-based diet, fortified foods are a key option, as most common plants contain minimal to no vitamin D.

Plant-Based Milks: Many soy, almond, and oat milks are fortified to provide comparable vitamin D levels to dairy milk.
Cereals and Juices: Fortified breakfast cereals and some orange juices also offer a convenient way to consume vitamin D.
Tofu: Select tofu products are fortified, adding another nutrient-rich option to vegan meals.

The Negligible Role of Other Plants

Common plants like spinach and broccoli contain no vitamin D. Aside from fungi and some microalgae, the plant kingdom generally does not offer significant vitamin D. Relying on typical produce for vitamin D needs is not effective and can lead to deficiency.

Conclusion: Harnessing Nature's Vegan Vitamin D

The answer to which plant has the most vitamin D is clear: mushrooms. Their unique ability to produce vitamin D2 through UV exposure makes them an excellent natural source for plant-based diets. Fortified foods offer a consistent alternative. For more detailed information on vitamin D sources, the Office of Dietary Supplements at the National Institutes of Health is a valuable resource. Incorporating UV-exposed mushrooms or fortified foods is crucial for maintaining adequate vitamin D levels.

Frequently Asked Questions

While UV-exposed mushrooms are the highest plant-based source, animal products like cod liver oil and fatty fish, such as trout and salmon, contain significantly higher levels of vitamin D3.

No. Most commercially grown mushrooms are cultivated in the dark and contain very little vitamin D. Only those explicitly labeled as 'UV-exposed' or 'high in vitamin D,' or those you expose to sunlight yourself, will have significant levels.

For maximum conversion of ergosterol to vitamin D, exposing sliced mushrooms gill-side up to direct sun between 10 a.m. and 3 p.m. for 15 minutes to an hour is effective.

Research has shown that vitamin D2 from mushrooms is effective at raising and maintaining total vitamin D levels, particularly in deficient individuals. While some studies suggest D3 may be more potent, D2 is still a valuable and bioavailable form.

Besides mushrooms and some lichens, there are very few edible plants that naturally contain significant vitamin D. Most common fruits and vegetables have negligible amounts.

Yes, fortified foods like plant-based milks, cereals, and orange juice are a very reliable and consistent way to get a daily dose of vitamin D, especially for vegans and vegetarians.

No, cooking does not significantly affect the vitamin D content in mushrooms, so you can cook them normally after sun-exposing them without losing the benefit.