What is Vitamin D
Vitamin D is an essential vitamin that supports our immune system and metabolism and helps to build strong bones by promoting calcium absorption. It may reduce the risk of cardiovascular disease, respiratory infections, certain cancers, and even Alzheimer’s and dementia. On the flip side, vitamin D deficiency is associated with autoimmune diseases, osteoporosis, influenza, and Parkinson’s. So how much vitamin D is enough, where can we get it, and are there any ways to enhance vitamin D in our food?
Recommended Vitamin D Per Day
Daily vitamin D requirements vary by age and medical conditions. The National Institutes of Health (NIH) states that adults 19-70 years need 15 micrograms (600 International Units) whereas adults 71 years and older need 20 micrograms (800 International Units). But these values are controversial and many sources suggest even greater requirements.
Sources of Vitamin D
The sun is considered one of the best sources for vitamin D. When sunlight hits your skin, your body works to synthesize vitamin D. But for those of us that live in cloudy climates or are concerned about skin cancer, the sun isn’t the best option for vitamin D. Dietary supplements can also provided vitamin D but what are some of the best natural sources of vitamin D?
What Foods Have Vitamin D?
Unfortunately, few foods contain vitamin D in sufficient quantities to meet daily nutritional requirements. Cod liver oil, trout, salmon, sardines, eggs, and beef liver are some of the best natural sources of vitamin D according to the NIH. But these foods are often expensive, unpalatable, or excluded in a vegetarian or vegan diet. Could mushrooms be another viable source of vitamin D?
Mushrooms and Vitamin D
Mushrooms are the only item in the produce department that contain vitamin D, naturally. This means that mushrooms are the best vegan source of vitamin D! But while wild mushrooms can be particularly high in vitamin D, this is not the case for traditionally cultivated mushrooms. This is because commercially grown mushrooms are often produced in the dark to save on energy and, like humans, mushrooms can synthesize vitamin D from the sun. Does that mean that exposing mushrooms to sunlight could improve their vitamin D content?
UV Exposed Mushroom
Mushrooms contain a compound called ergosterol that, when exposed to UV light, converts to vitamin D. This means that you can increase your vitamin D intake by simply placing mushrooms in sunlight prior to eating! The effect is so dramatic that a review on the topic suggests that vitamin D-enhanced mushrooms could help alleviate the global health issue of vitamin D deficiency. And commercial mushroom farms have already caught on; many farms are now exposing their harvests to UV radiation and branding them as vitamin D fortified. But you don’t need to pay a premium for these products.
How to Soak Your Mushroom in Sunlight
There are many methods for increasing the vitamin D content in mushrooms with UV radiation; you can even use a UV lamp. We recommend the easiest: simply place your mushrooms in direct sunlight for 30-60 minutes anytime between 10am-4pm (depending on your location). It’s best to slice your mushrooms first in order to increase the surface area exposed to the sunlight. You should avoid placing the mushrooms behind a window as glass filters out UV -B radiation necessary for vitamin D synthesis (so be mindful of bugs and hungry critters when placing your mushrooms outside). Cook in your favorite recipe and enjoy!
