Mushrooms: Nature's Vitamin D Source

Mushrooms are a type of fungus that can be a good source of vitamin D. While vitamin D is essential for health, it can be hard to obtain sufficient amounts from one's diet alone. Mushrooms that are exposed to ultraviolet (UV) radiation, such as sunlight or a UV lamp, can generate nutritionally relevant amounts of vitamin D. The vitamin D content in mushrooms varies based on their exposure to UV light. Mushrooms contain vitamin D2, which is also found in fortified foods and supplements. The other main form of vitamin D is D3, found in animal foods like egg yolks and oily fish. Vitamin D2 in mushrooms remains stable during cooking, and cooking methods such as sautéing or simmering can help preserve nutrients.

Mushrooms are the only non-animal source of vitamin D

The two main dietary forms of vitamin D are D2, found in fungi and yeast, and D3, found in animals; lesser amounts of vitamin D3 and vitamin D4 are also found in fungi. Vitamin D2 from mushrooms can be part of a larger solution to increasing dietary vitamin D intakes, as well as an important focus for public health policy. Mushrooms exposed to UV light represent an important tool in the strategic toolkit for addressing vitamin D deficiency in Australia and globally.

When commonly consumed mushroom species are exposed to a source of ultraviolet (UV) radiation, such as sunlight or a UV lamp, they can generate nutritionally relevant amounts of vitamin D. The most common form of vitamin D in mushrooms is D2, with lesser amounts of vitamins D3 and D4, while vitamin D3 is the most common form in animal foods. Although the levels of vitamin D2 in UV-exposed mushrooms may decrease with storage and cooking, if they are consumed before the ‘best-before’ date, vitamin D2 levels are likely to remain above 10 μg/100 g fresh weight, which is higher than the level in most vitamin D-containing foods and similar to the daily requirement of vitamin D recommended internationally.

Edible mushrooms such as Agaricus bisporus can produce over 100% of vitamin D recommendations (10 μg/day, Institute of Medicine) per 75 g serve (18 μg) on exposure to UV light, with the vitamin D2 produced showing good stability during cooking and processing. Four servings per week of UV-exposed button mushrooms can support most Australian adults in meeting vitamin D recommendations.

Vitamin D2 is the form of vitamin D found in mushrooms

Mushrooms are a unique source of vitamin D, as they are the only food in the produce aisle that can increase their vitamin D levels through exposure to UV light or sunlight. This is because the penetrable tissue of mushrooms responds to light similarly to humans, by increasing vitamin D content when exposed to sunlight. The most common form of vitamin D in mushrooms is vitamin D2, with lesser amounts of vitamins D3 and D4. Vitamin D2 is also the form of vitamin D found in fungi and yeast.

Vitamin D is a highly impactful nutrient for people of all ages, helping to build and maintain strong bones by aiding the body in absorbing calcium. It can be hard to get enough vitamin D from your diet, and few foods naturally contain it. Mushrooms exposed to UV light represent an important tool in addressing vitamin D deficiency in Australia and globally. In Australia, approximately three-quarters of the adult population have suboptimal vitamin D status, and the rate of vitamin D deficiency is 31%.

When commonly consumed mushroom species are exposed to a source of UV radiation, they can generate nutritionally relevant amounts of vitamin D. The amount of vitamin D2 generated depends on the time of day, season, latitude, weather conditions, and exposure time. Sun-exposed sliced mushrooms produce more vitamin D2 than whole mushrooms from the same amount of UV radiation exposure. At midday in midsummer in Germany, the vitamin D2 content of sliced mushrooms was as high as 17.5 μg/100 g FW after 15 minutes of sun exposure and reached 32.5 μg/100 g FW after 60 minutes.

Mushrooms are the only non-animal, unfortified food source of vitamin D that can provide a substantial amount of vitamin D2 in a single serve. They are a natural, vegan, safe, and sustainable vitamin D food source. Four serves/week of UV-exposed button mushrooms can support most Australian adults in meeting vitamin D recommendations.

Sunlight and UV light exposure increases vitamin D in mushrooms

Mushrooms are a good source of vitamin D, especially for vegans and vegetarians. When exposed to sunlight or ultraviolet (UV) light, they can generate nutritionally relevant amounts of vitamin D. The vitamin D content in mushrooms is mostly in the form of vitamin D2, with smaller amounts of vitamins D3 and D4. Vitamin D3 is the most common form in animal foods.

Sunlight and UV light exposure can significantly increase the vitamin D content in mushrooms. For example, fresh button mushrooms exposed to midday sunlight for 15-20 minutes can produce vitamin D2 levels exceeding 10 μg/100 g FW, which is higher than the daily requirement in many countries. The amount of vitamin D2 generated depends on various factors, including the time of day, season, latitude, weather conditions, and exposure time. Sliced mushrooms have a higher surface area exposed to sunlight or UV light, resulting in increased vitamin D2 production compared to whole mushrooms.

In a study, shiitake mushrooms dried outdoors in the sunlight with their gills facing upwards for six hours a day over two days showed a remarkable increase in vitamin D levels, soaring from 100 IU/100 grams to nearly 46,000 IU/100 grams. Similarly, sliced button mushrooms exposed to midday summer sunlight in Germany for 15 minutes produced 17.5 μg/100 g FW of vitamin D2, while 60 minutes of exposure yielded 32.5 μg/100 g FW.

The use of UV lamps, particularly pulsed UV lamps, has also been explored to enhance the vitamin D content in mushrooms. Pulsed UV lamps emit high-intensity beams of UV light for short durations, typically 1-3 seconds, which is sufficient to increase the vitamin D2 concentration in mushrooms without causing significant discolouration. This method is cost-effective and commercially viable, as it can enhance the nutritional value of mushrooms while maintaining their aesthetic appeal.

Vitamin D2 in mushrooms is effective in boosting vitamin D in the body

Vitamin D is essential for health, but it can be challenging to obtain enough from one's diet. Vitamin D helps build and maintain strong bones by aiding the body in calcium absorption. It also plays a role in hormone production and is important for the nervous system.

Vitamin D2, also known as ergocalciferol, is one of the two main dietary forms of vitamin D, found in fungi and yeast. Mushrooms are the only significant source of vitamin D in the produce department, as no other fruits and vegetables contain enough of the nutrient to be considered beneficial. When exposed to sunlight or ultraviolet (UV) radiation, mushrooms can generate nutritionally relevant amounts of vitamin D2. The amount of vitamin D2 produced depends on factors such as time of day, season, latitude, weather conditions, and exposure time.

Sun-exposed sliced mushrooms produce more vitamin D2 than whole mushrooms due to their higher surface area to volume ratio. For example, at midday in midsummer in Germany, sliced mushrooms exposed to sunlight for 60 minutes can contain up to 32.5 μg/100 g FW of vitamin D2. Similarly, a study found that exposing button mushrooms to the midday winter sun in Sydney, Australia, for one hour resulted in a vitamin D2 content of 10 μg D2/100 g FW.

Vitamin D-enhanced mushrooms are the only non-animal food product with substantial amounts of bioavailable vitamin D. They can be an important source of vitamin D for vegans and vegetarians, who may otherwise rely on animal-based or synthetic sources. Research has shown that vitamin D2 from mushrooms can be effective in boosting vitamin D levels in the body. For instance, a study comparing vitamin D2 from mushrooms with vitamin D3 from supplements found that both forms were equally effective in raising blood levels of the biologically active form of vitamin D.

Furthermore, dietary modelling suggests that UV-exposed mushrooms can contribute meaningfully to vitamin D intakes, helping individuals meet their daily requirements. In Australia, where vitamin D deficiency is prevalent, studies have shown that consuming four servings of UV-exposed button mushrooms per week can help most adults meet the recommended vitamin D intake. Therefore, incorporating mushrooms into one's diet can be a safe and sustainable way to increase vitamin D intake and address vitamin D deficiency.

Mushrooms are a solution to vitamin D deficiency

Vitamin D is an essential nutrient for people of all ages. It helps build and maintain strong bones by aiding the body in absorbing calcium. However, it can be challenging to obtain sufficient amounts from one's diet. Vitamin D deficiency is a widespread issue, with rates as high as 47.9% globally and 31% in Australia. While supplementation and sun exposure can help, a food-based solution is often preferred.

Mushrooms are a unique and effective food-based solution to vitamin D deficiency. They are the only significant source of vitamin D in the produce department, as they can increase their vitamin D levels through exposure to UV light or sunlight. This is because the penetrable tissue of mushrooms responds to light similarly to humans, by boosting vitamin D content. The most common form of vitamin D in mushrooms is D2, with lesser amounts of D3 and D4. Vitamin D2 from mushrooms can be an important part of increasing dietary vitamin D intake, especially for vegans and vegetarians who may not have many other options.

When exposed to UV-B light, the conversion of ergosterol to vitamin D2 is most efficient, and sliced mushrooms produce more vitamin D2 than whole mushrooms due to their higher surface area. The amount of vitamin D2 generated depends on factors such as time of day, season, latitude, weather conditions, and exposure time. For example, at midday in midsummer in Germany, sliced mushrooms exposed to sunlight for 60 minutes can contain up to 32.5 μg/100 g FW of vitamin D2.

Consuming UV-exposed mushrooms has been found to increase vitamin D status in deficient individuals. Dietary modelling shows that four servings per week of UV-exposed button mushrooms can help most Australian adults meet their vitamin D recommendations. Additionally, mushrooms treated with UV light have shown good stability during cooking and processing, ensuring that the vitamin D content remains high even after preparation.

In conclusion, mushrooms are a viable and effective solution to vitamin D deficiency. By including UV-exposed mushrooms in their diet, individuals can increase their vitamin D intake and improve their overall health. This is especially beneficial for those who may not have access to other sources of vitamin D or prefer a food-based approach to supplementation.

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