Crystal Nelson
Vitamin D deficiency is a widespread disease – every fifth person in Germany suffers from an undersupply of the vitamin. Dietary supplements can help. But is there a plant-based alternative? Is there – mushrooms can store a very high dose of this important vitamin and are therefore the ideal source of vitamins, especially in the dark season.
Vitamin D is absorbed through our skin and direct sunlight. We get the rest of it through our food. This is not a problem in summer, but in winter the sun is not intense enough and is too low to meet our daily vitamin D needs. Unfortunately, there are only a few foods that contain natural vitamin D. This includes fish, but also eggs and mushrooms. Salmon and wild salmon as well as mackerel, tuna, eel, and sardines are among the best sources of vitamin D among fish. Salmon contains 640 IU of vitamin per 100 grams, measured against the required daily amount of vitamin D of 800 IU, the problem becomes obvious; we can hardly eat enough to cover our vitamin D budget. A solution must be found – and it comes unexpectedly in the form of mushrooms. The small lamellar plants turn out to be true miracle stores of important vitamins.
Vitamin D deficiency – what is it anyway?
The vitamin D status is determined by measuring the concentration of 25 (OH) D in the blood serum. A guideline value of less than 20 ng of vitamin D per milliliter is medically referred to as a vitamin D deficit; a value of less than 10 is a severe insufficiency. For a sufficient supply of the vitamin, the value should be at least 30.
If we are not exposed to direct sunlight often enough or if we use sun protection, the risk of a deficiency is high. Anyone who also eats a vegetarian or vegan diet cannot even fall back on fish as a possible source of vitamin D.
Mushrooms as vitamin D stores
Mushrooms unexpectedly come up with the solution. The lamellar plants can not only produce a large amount of the vitamin but also store it for one year. This means that they can serve us permanently as a vitamin D supplier. Particularly useful when we are entering the dark season and the number of hours of sunshine is falling to its annual minimum and we are struggling to absorb and produce enough vitamin D naturally.
Researchers have found that mushrooms exposed to direct sunlight for six hours a day over two days have significantly higher levels of vitamin D. The highest level was in shiitake mushrooms from 100 IU (International Units) per 100 grams to 46,000 IU per 100 grams. The recommended daily vitamin D value for an adult is around 800 IU. The fungus is thus becoming an excellent source of vitamin D and is at the top of the list of foods that ensure our supply.
Mushrooms as vitamin D suppliers: how does it work?
Mushrooms naturally contain ergosterol, a precursor to vitamin D. Vitamin D2 is formed when exposed to direct sunlight. To achieve the highest possible concentration of vitamin D in the mushrooms, they should be cut and placed evenly on a flat surface in the sun with the lamellae pointing upwards. On two consecutive days, the mushrooms are exposed to direct light for six hours – if this period is exceeded, the vitamin D content falls again due to too much exposure to the sun. The mushrooms should then be dried completely and stored airtight. Even a small amount of about 10 grams per day covers the human body’s daily vitamin D requirement. The dried mushrooms can simply be used as an ingredient during cooking and do not require any special treatment.
Vitamin D2 or Vitamin D3?
The vitamin formed in the mushrooms is vitamin D2. Vitamin D3 is found in oily fish and also in dietary supplements. An important difference? Not for our bodies. Our metabolism can convert both types into active vitamin D with the help of enzymes. The biggest difference between the two vitamins is longevity and the amount of time they stay in the bloodstream. Vitamin D3 stays in our bloodstream for several months, while vitamin D2 is broken down over a few days. A particular advantage of one vitamin over the other could not be determined so far.
