The Role of UV-Exposed Mushrooms in Combating Vitamin D Deficiency

Vitamin D deficiency is a major public health problem worldwide. According to the CDC, over 20% of the global population may have vitamin D levels below the threshold, which prevents vitamin D deficiency-related bone disease. This deficiency poses significant health risks, impacting everything from bone integrity to immune function and increasing susceptibility to a range of chronic illnesses. Unfortunately, maintaining adequate levels of this vital nutrient can be challenging due to limited natural food sources and restricted sun exposure. 

Recent research has shown that when exposed to ultraviolet light, certain types of mushrooms can produce substantial amounts of vitamin D, presenting a food-based approach to mitigating vitamin D deficiency. 

Why is vitamin D important?

Unlike other vitamins, vitamin D acts similarly to a hormone, and receptors for it are found in virtually every cell throughout the body. The primary function of vitamin D is to assist the gut in absorbing calcium, which is needed to maintain bone health and function. But vitamin D also affects immune health, muscle function, and brain cell activity. Moreover, emerging research has indicated that vitamin D levels can impact mood and mental health. Low levels of this vitamin have been linked to depression, likely because of how vitamin D impacts the hormones and neurotransmitters that are responsible for mood regulation (1).

To treat vitamin D deficiency, doctors typically recommend supplements or more time outside, but in more extreme cases, they may prescribe intramuscular injections to ensure it is quickly absorbed into the body. 

Yet, enhancing dietary intake and preventing deficiencies through everyday food choices is a more sustainable approach to long-term health. Since there are very limited natural sources of vitamin D, researchers and nutritionists are seeking innovative ways to incorporate it into the diet beyond the traditional fortified foods and supplements.

Mushrooms as a source of vitamin D

Mushrooms contain a substance called ergosterol, which converts into vitamin D2 when exposed to UV light. This process is similar to how the human skin produces vitamin D from sunlight. Researchers have found that common mushrooms, such as the button mushroom, can have vitamin D2 contents that significantly exceed the daily recommendations when grown under UV light. For instance, just 100 grams of UV-exposed mushrooms can provide over 100% of the daily recommended vitamin D intake, making them an exceptionally rich plant-based source of this nutrient. 

As a result, UV-treated mushrooms stand out as a viable alternative to traditional sources of vitamin D, like fatty fish and fortified cereals or milk. Although fatty fish like salmon and sardines can provide a substantial amount of vitamin D, they may not be accessible to everyone because of dietary preferences, allergies, or economic factors. UV-exposed mushrooms can provide a comparable, if not superior, level of vitamin D while still being suitable for vegan and vegetarian diets. Furthermore, UV-exposed mushrooms are a more sustainable vitamin D source due to the low environmental impact of mushroom cultivation (2).

Implications for dietary guidelines

UV-exposed mushrooms are currently not recognized as a vitamin D source within worldwide dietary modeling approaches. However, given the substantial vitamin D content found in these mushrooms, growing research makes a compelling case for their inclusion in global dietary guidelines. Scientists believe that UV-exposed mushrooms should be recommended as part of a healthy diet, and dietary guidelines should be updated to reflect their high vitamin D content. This recognition could offer a more sustainable, accessible, and effective solution to prevent and address widespread vitamin D deficiency.

References

1. Akpınar, Şerife, and Makbule Gezmen Karadağ. 2022. “Is Vitamin D Important in Anxiety or Depression? What Is the Truth?” Current Nutrition Reports 11 (4). https://doi.org/10.1007/s13668-022-00441-0.
2. Starck, Carlene, Tim Cassettari, Jutta Wright, Peter Petocz, Emma Beckett, and Flavia Fayet-Moore. 2024. “Mushrooms: A Food-Based Solution to Vitamin D Deficiency to Include in Dietary Guidelines.” Frontiers in Nutrition 11 (April). https://doi.org/10.3389/fnut.2024.1384273.