The Best Source of Vitamin D2: An In-Depth Guide

October 28, 2025 •

3 min read

According to the NIH, few foods naturally contain significant amounts of vitamin D, making it a critical nutrient to monitor. Understanding what is the best source of vitamin D2 is particularly important for those following a plant-based diet, as its primary natural sources are fungi and fortified foods.

Quick Summary

This guide examines the top dietary sources of vitamin D2, focusing on naturally occurring options like UV-exposed mushrooms and common fortified products. It also discusses the benefits and differences between D2 and D3, aiding consumers in making informed decisions about their nutritional intake and supplementation.

Key Points

UV-Exposed Mushrooms: The best natural food source of vitamin D2 is fungi, particularly varieties like button, portabella, and shiitake that have been exposed to ultraviolet light.
Fortified Plant Milks: Vegan alternatives like soy, almond, and oat milk are reliably fortified with vitamin D2 and widely available.
Fortified Cereals and Juices: Many breakfast cereals and orange juice products are enhanced with vitamin D2, offering a convenient dietary source.
Supplements for Targeted Needs: Ergocalciferol (D2) supplements provide a reliable, high dose for addressing vitamin D deficiencies, especially for those on plant-based diets.
Consider D2 vs. D3 Potency: While D2 is effective, some studies suggest vitamin D3 is slightly more potent at raising blood vitamin D levels over the long term.
Check Product Labels: For fortified products, always check the nutritional label to confirm the presence and amount of vitamin D2 added, as concentrations vary by brand.
Consult a Professional: Discussing your dietary choices and potential need for supplementation with a healthcare provider is the safest approach to ensure adequate intake.

Mushrooms: The Premier Natural Source of Vitamin D2

For anyone on a plant-based diet, mushrooms are undeniably the most significant and reliable natural source of vitamin D2. While most commercially cultivated mushrooms are grown in the dark and have very little vitamin D content, they have a unique ability to produce high levels of vitamin D2 when exposed to ultraviolet (UV) light. This process mimics how human skin produces vitamin D3 from sunlight.

How to Maximize Vitamin D2 in Mushrooms

To increase the vitamin D2 content in mushrooms, you can expose them to sunlight or a UV lamp. Slicing the mushrooms before exposure dramatically increases their surface area and, consequently, their vitamin D2 concentration. Research has shown that just 15-120 minutes of midday sunlight can significantly boost vitamin D2 levels. When purchasing, look for mushrooms specifically labeled as 'UV-exposed' or 'high in vitamin D' to ensure a potent source.

Common UV-exposed varieties include:

White button mushrooms
Portabella mushrooms
Maitake mushrooms
Shiitake mushrooms

Fortified Foods: A Convenient Source

For many, fortified foods provide a simple and consistent way to incorporate vitamin D2 into their diet. The fortification process adds vitamin D2 to products that don't naturally contain it, offering a reliable intake with minimal effort. This is especially useful in regions with limited sunlight or for those with dietary restrictions.

Examples of Fortified Foods Containing Vitamin D2

Plant-based milks: Soy, almond, and oat milks are commonly fortified with vitamin D2.
Breakfast cereals: Many cereals have added vitamin D, often D2, to help consumers meet daily requirements.
Orange juice: Fortified orange juice offers another common way to consume vitamin D2.
Margarine and tofu: These products can also be fortified with vitamin D2, making them suitable for vegan diets.

Supplements: When to Consider Ergocalciferol

For individuals with a diagnosed vitamin D deficiency or those who cannot meet their needs through food alone, supplements are a safe and effective option. Vitamin D supplements are available in both D2 (ergocalciferol) and D3 (cholecalciferol) forms. D2 is typically plant-derived, making it a good choice for vegans, while D3 often comes from animal sources, though vegan D3 from lichen is also available.

Vitamin D2 vs. D3 for Supplementation

While both forms can effectively raise blood vitamin D levels, some research suggests that vitamin D3 is more potent and maintains these levels for a longer duration. However, D2 is equally effective at treating vitamin D deficiency, especially at higher prescription-strength doses. The choice between D2 and D3 depends on personal dietary preferences and a discussion with a healthcare provider.

Comparison of Vitamin D2 Sources


Source	Natural or Fortified	Primary Benefit	Ideal For	Drawback(s)
UV-Exposed Mushrooms	Natural	Exceptionally high, plant-based vitamin D2 content	Vegans, vegetarians, and those preferring whole foods	Content can vary based on exposure method; must seek out specifically labeled products
Fortified Plant Milks	Fortified	Consistent, measured dosage, and widely available	Everyday dietary addition for plant-based diets	Can contain added sugars; dosage is lower than supplements
Fortified Cereals	Fortified	Easy way to add vitamin D to a daily routine	Kids and adults who eat breakfast cereal regularly	Can be high in sugar; dosage is generally low
D2 Supplements (Ergocalciferol)	Supplement	Provides a targeted, reliable, and high dose	Treating diagnosed deficiency or consistent intake	May be slightly less potent than D3 over the long term

Conclusion: Choosing Your Best Source of Vitamin D2

The best source of vitamin D2 ultimately depends on individual dietary needs and preferences. For those seeking a whole-food, naturally derived source, UV-exposed mushrooms offer an exceptionally high concentration of the vitamin and are a potent addition to a vegan or vegetarian diet. Fortified foods provide a simple and consistent way to boost intake, integrating seamlessly into a daily routine. Finally, supplements are available for those needing a more targeted approach, offering a reliable method to address deficiency. Regardless of the source, maintaining adequate vitamin D levels is crucial for bone health and overall well-being. For personalized advice, it is always best to consult a healthcare professional. For additional nutritional information, you can reference the NIH Office of Dietary Supplements fact sheet on Vitamin D: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

Frequently Asked Questions

UV-exposed mushrooms, particularly varieties like maitake, portabella, and button mushrooms, are the most significant natural food source of vitamin D2. Wild-grown mushrooms also contain D2 due to natural sun exposure.

While both vitamin D2 and D3 can effectively raise blood vitamin D levels, some research indicates that D3 may be more potent and maintain levels longer. However, D2 is a suitable vegan option and effectively treats deficiency, especially in higher doses.

You can increase the vitamin D2 content of mushrooms by exposing them to direct sunlight. Slicing them first maximizes the surface area, and leaving them in midday sun for 15-120 minutes is effective.

Yes, fortified plant-based milks and other foods offer a consistent and convenient source of vitamin D2. However, the dosage is often lower than in supplements, and concentrations can vary between brands, so always check the label.

For most vegans, getting enough vitamin D2 from diet alone is challenging due to limited natural sources. Including UV-exposed mushrooms and fortified foods can help, but supplementation is often necessary to meet optimal levels.

No, cooking does not completely destroy vitamin D2 in mushrooms. Studies have shown high retention rates (85-88%) after cooking methods like frying, boiling, or baking, though some loss may occur.

Ergocalciferol is the scientific name for vitamin D2, the form of vitamin D that is derived from plants and fungi, such as UV-irradiated mushrooms and fortified foods.