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Vegan Vitamin D: Why Mushrooms are Your Best Whole Food Source

Vegan Vitamin D: Why Mushrooms are Your Best Whole Food Source cover
Written by Real Mushrooms - Updated: June 17, 2024

In this article, we will explain in depth how the human body processes sunlight into vitamin D and uses it to maintain its proper function. We’ll also analyze which populations have deficiency issues, why supplementation is of utmost importance, and finally, we will talk about how to find the best plant-based source of vegan vitamin D to optimize your health.

Did you know most sources of supplemental vitamin D come from lanolin, a wax found in sheep’s wool?

If you follow a plant-based diet, this might be something you want to avoid. To solve this dilemma, Real Mushrooms has created a vegan vitamin D out of, yup you guessed it, MUSHROOMS. This article will shine a light on everything you need to know.

In this article we’ll cover:

The information in this article has been reviewed by Dr. Mason Bresett, Naturopathic Doctor.

Vitamin D Supplements made from Lanolin
Most vitamin D supplements are synthesized from the Lanolin of sheep’s wool.

Overview of Vitamin D, Deficiency, & Sources

Vitamin D Deficiency

The human body requires many nutrients to run optimally every single day; some of these nutrients the body can miraculously produce on its own (non-essential), others need to be obtained from the diet (essential).

Essential nutrients are ones that cannot be synthesized by the body and, therefore, must be supplied from foods.

Since we get most of our vitamin D from the sun, most North Americans who experience the winter season are at risk for deficiency in vitamin D. During winter, the Northern Hemisphere leans away from the sun, there are fewer daylight hours, and the sun hits us at an angle; this makes it appear lower in the sky. This also means that the sun rays hitting the earth are not as strong; therefore we don’t have sufficient sun exposure to get the necessary amount of vitamin D from UV rays (ultraviolet radiation).

Vitamin D is a fat-soluble vitamin that helps your body absorb calcium and phosphorus. It appears in small quantities in a few foods such as oily fish, egg yolks, cheese, and fortified cereals. But, it generally needs to be taken as a supplement, especially for those living in less sunny regions.

How the Body Gets Vitamin D

It’s really quite amazing how the human body can translate sunlight into energy; here’s how it works: ultraviolet light stimulates the production of cholecalciferol (a vitamin D precursor), which the body absorbs from the skin and eventually transforms into active vitamin D3. Vitamin D obtained from sun exposure, food, and supplements is inactive when first presented in the body, so it must undergo two chemical processes for its activation.

The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol (1).

Both Vitamin D2 and D3 are formed through ultraviolet exposure of precursors: ergosterol for D2, and 7-dehydrocholesterol for D3. It is true that most forms of D3 are animal-based. The available non-animal forms (yeast, mushrooms) are actually based on the fungus kingdom and are primarily D2 (2). There is lichen-based D3 which is derived from an edible lichen (a complex life form made from a fungus and alga).

As you can see, the sun is a vital resource that maintains our health. We are continuously discovering how connected humans are to mother nature, and how the fungi kingdom is a key player in this interconnected web called life. As we work harmoniously with the earth, we are co-creating a sustainable planet for future generations.

Northern Hemisphere Vitamin D Deficiency
People living north of the 35th parallel often become vitamin D deficient in the winter, when sun exposure is more limited.

Available Vitamin D Supplement Sources

Now that you’re aware of our human requirement for vitamin D and understand how it’s synthesized, we’re going to discuss the sources being sold on the market.

Most of the vitamin D is sold to us in its D3 form, and it’s primarily made from irradiating sheep lanolin (a wax secreted by the sebaceous glands of wool-bearing animals). This may seem unattractive to some vegans out there who do not consume or use animal products. It also begs the question: are these highly processed in a mass production facility? What are the ethics and morals behind these agricultural farming practices? How were the animals treated?

It’s important to question everything and to trace back to the source of your food and supplements. Quality and sourcing are everything when it comes to the health of your body, mind, and spirit.

Vegan Vitamin D from Mushrooms

About 1 billion people worldwide have a Vitamin D deficiency or insufficiency (5). We understand the urgency for the population to get their bodies back up to healthy levels; that’s why we’re thrilled to bring you vegan vitamin D that is made purely from the highest quality mushrooms.

While many “mushroom” products sold on the market are just myceliated grain and do not contain any actual mushroom (fruiting body), our mushroom extracts are free from grains and fillers, and we use the whole mushroom, which contains many highly medicinal compounds such as beta-glucan (a polysaccharide found in the cell wall of mushrooms).

When using analytical testing methods to determine fungal content, ergosterol is measured; ergosterol is highest in mushrooms. It is a definitive marker for fungal presence and has been utilized for years by the grain industry as a test for fungal contamination.

Our whole-food, plant-based source of vitamin D is potent; we use 100% organic Agaricus and Shiitake mushroom for our capsules, and each one contains 1000 IU of vitamin D2. We recommend taking 1 capsule per day over a prolonged period of time.

For people aged 9-70: adequate intake is 600 IU/day; maximum safe upper level of intake, 4,000 IU/day (3).

Recent work from the Vitamin D, Skin, and Bone Research Laboratory at Boston University Medical Center evaluated a newer food source of Vitamin D - mushrooms exposed to UVB light, which provide a significant source of D2. In this study, it was determined that healthy adults who ingested 2000 IUs of Vitamin D2 from mushrooms daily for 3 months were able to raise and maintain their total 25(OH)D concentrations similarly to healthy adults who ingested supplements containing either 2000 IU of Vitamin D2 or D3. This study suggests that Vitamin D2 is equally able to help consumers meet their Vitamin D shortfall as Vitamin D3.

Shiitake Nammex Farm
Irradiated mushrooms are one of the few nature sources rich in vitamin D. These organic shiitake mushrooms form the basis of our vegan Vitamin D2 supplement.

Mushroom Exposure to UV Light & Vitamin D Production

Ultraviolet light exposure during the growing phase is essential to getting vitamin D from mushrooms. This is an important point that many articles touting mushrooms for vitamin D leave out. Without some sort of UV light exposure, most mushrooms have almost no vitamin D. For example, the common button mushroom has roughly 7 IU of vitamin D per 100 grams, which is nothing to celebrate.

But mushrooms have this incredible ability to absorb sunlight and convert it into vitamin D2. Small amounts of Vitamin D2 are found in wild mushrooms (2). However, D2 levels can be amplified with ultraviolet light exposure. Ergosterol (which is a fungal sterol similar to cholesterol in humans) needs to be converted into ergocalciferol (D2), and this is done by exposing cultivated mushrooms to UV light.

One study showed that vitamin D2 levels can be increased in any variety of mushrooms by exposing them to pulsed UV light. With each additional pulse, the mushrooms were exposed to increasing amounts of ultraviolet radiation and thus more energy was available for Vitamin D2 synthesis. The oyster and shiitake showed higher amounts of Vitamin D2 content after pulsed UV light exposure than other mushrooms tested (6).

UV Light Mushrooms Vitamin D
The more mushrooms are exposed to UV light, the higher their concentrations of Vitamin D.

What is the Difference Between Vitamin D3 and Vitamin D2?

There has been some debate on whether vitamin D3 is more effective than D2 (7). The two forms have traditionally been regarded as equivalent based on their ability to cure rickets (a skeletal disorder that is caused by a lack of vitamin D, calcium, or phosphate). Most steps involved in the metabolism and actions of vitamin D2 and vitamin D3 are identical. Both forms can raise serum 25(OH)D levels (1).

Vitamin D expert, medical doctor, author, and researcher Dr. Michael Hollick, uses a synthetic Vitamin D2 form in his clinic and his data suggests it is as efficient as Vitamin D3 (7). He did mention that you have to get a good quality source and dose.

While some past research publications suggested that D2 intake may decrease the construction of Vitamin D3 (4), Dr Hollick maintains that these studies dismantle the future use of Vitamin D2 for therapeutic purposes without substantiated evidence. He has conducted his own research around Vitamin D, performing 3 studies on Vitamin D2 and Vitamin D status. He confirmed that the kidneys are able to convert Vitamin D2 to the active form of Vitamin D (7).

Rest assured that you can supplement your vitamin D2 from an environmentally friendly and humane option: mushrooms! This is great news for vegans. The mysterious and miraculous mushroom comes to save the day, yet again!

Additional Mushroom Health Benefits

Taking mushroom extracts will help us sustain our Vitamin D2 levels. In general, mushroom benefits for health are numerous, so we also want to highlight other supportive compounds your body will receive as a bonus!

The great thing about medicinal mushrooms is that they are amazing allies for your immune system. The common threads between all medicinal varieties are their ability to a) support immunity, and b) promote a healthy inflammation response.

The cell wall of the mushroom (fruiting body) contains beta-glucans. These wonderful compounds can increase host immune defense by enhancing macrophage and natural killer cell function (9). Beta-glucans also mediate inflammation in the body by helping to regulate various inflammatory cytokines (8).

To go deeper into the power of fungi for overall wellness, check out our article about the 7 medicinal mushroom benefits for health.

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Picking the Right Vitamin D Mushroom Supplement

We’re truly on the precipice of global change; each one of us has the ability to make decisions that will greatly impact our health and the earth. Our vegan vitamin D supplement made from 100% organic mushrooms is sure to make your cells dance in celebration; after all, humans have evolved alongside fungi for thousands of years!

If you’re looking for even more immune system support on top of your vitamin D intake, consider taking our D2Z mushroom supplement which contains zinc in addition to vegan vitamin D.

Real Mushrooms’ products have the purest and most potent concentrations of mushrooms. We use only 100% mushrooms (fruiting bodies), so rest assured that no grain or fillers end up in your supplement.

Real Mushrooms Vitamin D Supplement
A mushroom-based Vitamin D supplement should be made from the fruiting-body (versus myceliated grain) to ensure potency and a full spectrum of bonus immune-system support.

Becoming informed about the contents and sources of any health supplement you are considering purchasing is crucial to getting effective health support.

Learn more about how to spot fungi supplements that contain grain fillers and little to no mushrooms at all, by reading our article about mushrooms versus mycelium.

Be sure to try our vegan vitamin D or our vegan D2Z vitamin D supplement with zinc and do let us know your thoughts! We’d love to hear from you and how it made you feel.

Fun Fact: You can enhance your store-bought mushrooms' vitamin D levels by slicing them and putting them out in the sun for 20 minutes!


  2. Cardwell, G., Bornman, J. F., James, A. P., & Black, L. J. (2018). A Review of Mushrooms as a Potential Source of Dietary Vitamin D. Nutrients, 10(10), 1498.
  3. Tripkovic, L., Lambert, H., Hart, K., Smith, C. P., Bucca, G., Penson, S., Chope, G., Hyppönen, E., Berry, J., Vieth, R., & Lanham-New, S. (2012). Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. The American journal of clinical nutrition, 95(6), 1357–1364.
  4. Trang, H. M., Cole, D. E., Rubin, L. A., Pierratos, A., Siu, S., & Vieth, R. (1998). Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. The American journal of clinical nutrition, 68(4), 854–858.
  5. Sizar O, Khare S, Goyal A, et al. Vitamin D Deficiency. [Updated 2021 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:
  6. Holick, M. F., & Chen, T. C. (2008). Vitamin D deficiency: a worldwide problem with health consequences. The American journal of clinical nutrition, 87(4), 1080S–6S.
  7. Holick, M. F., Biancuzzo, R. M., Chen, T. C., Klein, E. K., Young, A., Bibuld, D., Reitz, R., Salameh, W., Ameri, A., & Tannenbaum, A. D. (2008). Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. The Journal of clinical endocrinology and metabolism, 93(3), 677–681.
  8. Keegan, R. J., Lu, Z., Bogusz, J. M., Williams, J. E., & Holick, M. F. (2013). Photobiology of vitamin D in mushrooms and its bioavailability in humans. Dermato-endocrinology, 5(1), 165–176.
  9. Akramiene, D., Kondrotas, A., Didziapetriene, J., & Kevelaitis, E. (2007). Effects of beta-glucans on the immune system. Medicina (Kaunas, Lithuania), 43(8), 597–606.
  10. Du, B., Lin, C., Bian, Z., & Xu, B. (2015). An insight into anti-inflammatory effects of fungal beta-glucans. Trends in Food Science & Technology, 41(1), 49-59.

Real Mushrooms is the premier provider of organic mushroom extracts, verified for the beneficial medicinal compounds like beta-glucans and free from starchy fillers like grains. With over 40 years of mushroom growing experience, Real Mushrooms prides itself on providing a transparent source of functional mushrooms that you can trust. All the information provided on our blog has been reviewed by our science and medical team.

Disclaimer: The information or products mentioned in this article are provided as information resources only, and are not to be used or relied on to diagnose, treat, cure, or prevent any disease. This information does not create any patient-doctor relationship, and should not be used as a substitute for professional diagnosis and treatment. The information is intended for health care professionals only. The statements made in this article have not been evaluated by the Food and Drug Administration. Any products mentioned are not intended to diagnose, treat, cure, or prevent any disease. The information in this article is intended for educational purposes. The information is not intended to replace medical advice offered by licensed medical physicians. Please consult your doctor or health practitioner for any medical advice.