Mushrooms And Vitamin D3: What's The Link?

Mushrooms are a potential source of vitamin D, an essential nutrient that can be hard to obtain from diet alone. While vitamin D is typically derived from sun exposure, mushrooms exposed to ultraviolet (UV) radiation or sunlight can generate vitamin D. The vitamin D content in mushrooms varies by species and cultivation method, with wild mushrooms historically containing higher amounts than commercially grown ones. Shiitake mushrooms contain vitamins D2, D3, and D4, while white button mushrooms have lower levels. Consuming mushrooms is one way to increase vitamin D intake, especially for those who cannot access sunlight or follow animal-based diets.

Mushrooms are a source of vitamin D2, D3 and D4

Mushrooms are a source of vitamin D2, D3, and D4. Vitamin D is predominantly derived from exposure to the sun, but mushrooms exposed to sunlight or UV radiation are a potential source of vitamin D. The most common form of vitamin D in mushrooms is D2, with lesser amounts of vitamins D3 and D4. Vitamin D3 is the most common form in animal foods.

When exposed to UV light, mushrooms can produce vitamin D2. Vitamin D3 is formed in animals from 7-dehydrocholesterol, whereas ergosterol (provitamin D2) in mushrooms is converted to pre-vitamin D2 under UV light, with heat required for full conversion to ergocalciferol (vitamin D2). Vitamin D-enhanced mushrooms are the only non-animal food product with substantial amounts of bioavailable vitamin D and can be an important source for vegans and vegetarians.

Edible mushrooms such as Agaricus bisporus can produce over 100% of the recommended daily vitamin D intake (10 μg/day) per 75g serve when exposed to UV light. Similarly, placing white button mushrooms in the midday sun for 15–20 minutes can help them form 10μg/100g, which would give the recommended daily dose of vitamin D. Chopping mushrooms and placing them gill-side up forms more vitamin D than leaving them whole and placing them gill-side down.

Vitamin D2 from mushrooms has been found to be as effective as supplemental vitamin D2 in raising and maintaining serum 25(OH)D2 concentrations. However, the efficacy of vitamin D2 compared to vitamin D3 in increasing vitamin D status is not yet fully understood. While vitamin D3 is more effective than vitamin D2 in increasing total vitamin D status, these relationships are modified by BMI and baseline vitamin D status.

Sunlight exposure increases vitamin D content in mushrooms

Mushrooms are a source of vitamin D, which is an essential vitamin that plays a vital role in boosting the immune system and human metabolism. The two main dietary forms of vitamin D are D2, found in fungi and yeast, and D3, found in animals. Mushrooms contain vitamin D2, with lesser amounts of vitamins D3 and D4.

When exposed to sunlight, mushrooms can increase their vitamin D content. This is because mushrooms, when exposed to ultraviolet (UV) light, specifically UVB radiation, can produce vitamin D. This process mimics how humans and other animals synthesize vitamin D in their skin when exposed to sunlight. Mushrooms convert a compound called ergosterol into ergocalciferol, also known as vitamin D2.

The vitamin D content in mushrooms can be increased by exposing them to sunlight or artificial UV light. However, the idea that simply placing mushrooms under sunlight at home will significantly increase their vitamin D content is somewhat misleading. The process of vitamin D synthesis in mushrooms requires specific conditions, including the right intensity and duration of UV exposure. Sunlight intensity and UVB radiation levels vary depending on factors such as time of day, season, geographical location, and weather conditions. Additionally, the duration of exposure required to achieve significant vitamin D synthesis may not be practical for home settings.

In a controlled environment, specific mushrooms under UV light can optimize vitamin D synthesis. Commercial mushroom producers may utilize artificial UV light to enhance vitamin D synthesis in mushrooms. For example, a study found that exposing shiitake mushrooms to sunlight for two days, six hours per day, with their gills facing upwards, resulted in a significant increase in vitamin D levels, from 100 IU/100 grams to nearly 46,000 IU/100 grams. Another study published in the Journal of Nutrition & Food Sciences found that exposing mushrooms to sunlight or UV light for as little as 15 minutes consistently increased vitamin D2 by at least 25% of the DRI (150 IU) per 70 g serving and more than 100% of the DRI (>600 IU) in many cases.

Vitamin D2 from mushrooms is as effective as supplements

Mushrooms exposed to ultraviolet (UV) radiation, such as sunlight or a UV lamp, can generate nutritionally relevant amounts of vitamin D. The most common form of vitamin D in mushrooms is vitamin D2, with lesser amounts of vitamins D3 and D4. Vitamin D3 is the most common form in animal foods.

A study of 30 healthy adults who were randomised to receive 2000 IU (50 μg) of supplemental vitamin D2, mushroom vitamin D2, or vitamin D3 for three months found that vitamin D2 from mushrooms was as effective as supplemental vitamin D2 in raising and maintaining serum 25(OH)D2 concentrations. Similarly, a five-week study in adults with low serum 25(OH)D concentrations showed that vitamin D2 from soup made with UV-B irradiated mushrooms improved vitamin D status as effectively as supplemental vitamin D2.

However, it is important to note that vitamin D3 is typically more effective than vitamin D2 in raising the concentration of circulating 25(OH)D. Additionally, vitamin D2 has a shorter half-life than vitamin D3, and there may be differences in the rate of hydroxylation, affinity for the vitamin D binding protein, and binding to the vitamin D receptor. Nevertheless, vitamin D-enhanced mushrooms can be a valuable source of vitamin D, especially for those who are deficient or insufficient, those with limited sun exposure, and those with limited intake of animal sources of vitamin D.

Agaricus bisporus, a commonly consumed mushroom species, can produce over 100% of the recommended daily intake of vitamin D (10 μg/day) per 75 g serve (18 μg) when exposed to UV-light. Four servings per week of UV-exposed button mushrooms can help most Australian adults meet their recommended vitamin D intake. Vitamin D2 from mushrooms is generally stable during cooking and processing, but it is important to store mushrooms in dry, dark conditions to retain their vitamin D2 content.

Wild mushrooms have higher vitamin D content than commercially grown mushrooms

Mushrooms are a source of vitamin D, which is essential for health. The two main dietary forms of vitamin D are D2, found in fungi and yeast, and D3, found in animals. Vitamin D2 is produced by mushrooms under the right conditions, and vitamin D3 is the most common form in animal foods.

Wild mushrooms are an excellent source of vitamin D2 due to their exposure to UV light from the sun. Commercially grown mushrooms, on the other hand, are often grown in the dark and contain very little vitamin D2. This is because they are usually grown in darkness, and the only time they are exposed to light is during picking under fluorescent lights, which emit little to no UV radiation. As a result, the vitamin D2 content of fresh button mushrooms sold worldwide is typically less than 1 μg/100 g FW.

In contrast, wild edible Finnish mushrooms, such as the funnel chanterelle (Cantharellus tubaeformis), sampled in late summer and early autumn, provided 3–30 μg D2/100 g fresh weight (FW). Large amounts of vitamin D2 have also been found in other wild mushrooms, such as funnel chanterelles (21.1 μg D2/100 g FW), Cantharellus cibarius (10.7 μg D2/100 g FW), and Boletus edulis (58.7 μg D2/100 g FW).

While some commercially grown mushrooms are treated with ultraviolet (UV) light to boost their vitamin D content, wild mushrooms naturally have higher vitamin D content due to their exposure to sunlight. This makes them a potentially important source of dietary vitamin D for vegans and vegetarians, as vitamin D-enhanced mushrooms are the only non-animal food product with substantial amounts of bioavailable vitamin D.

Mushrooms are a good source of vitamin D for vegans and vegetarians

The vitamin D content in mushrooms can be increased by exposing them to UV-B light. In fact, farmers using UV-B light can generate up to 40μg/1g of dried mushrooms, providing four-fifths of the daily recommended dosage in a single gram. Similarly, placing white button mushrooms in the midday sun for 15–20 minutes can help them form 10μg/100g, which is the recommended daily dose of vitamin D.

The most common form of vitamin D in mushrooms is D2, with lesser amounts of vitamins D3 and D4. Vitamin D3 is the most common form in animal foods, while vitamin D2 is found in fungi and yeast. Vitamin D2 from mushrooms has been shown to be as effective as supplemental vitamin D2 in raising and maintaining serum 25(OH)D2 concentrations.

While the efficacy of vitamin D2 compared to D3 for increasing vitamin D status is still being studied, mushrooms are a viable option for vegans and vegetarians to obtain their recommended daily dose of vitamin D. Four servings per week of UV-exposed button mushrooms can help most Australian adults meet their vitamin D recommendations. Additionally, vitamin D-enriched mushrooms are readily available for purchase in the US and Australia, providing 100% of the IOM EAR per 85g serving.

Frequently asked questions