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During the summer, our bodies produce their own vitamin D when exposed to the sun, and store it for winter, when many don’t get enough sun exposure to make all the vitamin D they need. This naturally intelligent process of the body is important as vitamin D is essential for bone health and immune system functions. Low levels of it can cause osteoporosis and osteomalacia.

Against this background, one has to bear in mind that there are few foods besides fish and eggs that supply humans with vitamin D through nutrition. However, there is now a nutritional source of vitamin D available which also should appeal to vegetarians: “fungous vitamin D” or “mushroom vitamin D.”

Pilzland, one of the biggest mushroom producers in Germany, veered toward engaging in this novel food last year after it had successfully entered the Dutch market. It started breeding mushrooms by applying an innovative process to them, that is, an imitation of the previously noted process that takes place in our own bodies. Called photolysis, the growing mushrooms get exposed to UV light to gain high levels of vitamin D. Depending on the UV spectrum, the irradiation dose, the moisture content of the mushrooms, and their alignment toward the UV light, ergosterol (an important component of the cell membrane in mushrooms as well as a pre-stage of vitamin D) converts alongside a thermic isomerization to vitamin D. Paul Urbain, the researcher who invented the process, said that “mushroom vitamin D” is of equal value to the vitamin D produced in the human body. (https://www.nature.com/articles/ejcn201153.pdf)

As a result, Pilzland has been able to offer vitamin D mushrooms that, he said, contain 30 times more of the sunshine vitamin than conventionally grown mushrooms. Interestingly, the claim was proven right by various tests which show that exposing mushrooms to UV light works: 100 grams of the novel mushrooms contain on average 9.6 micrograms (mcg) of vitamin D. In contrast, 100 grams of conventional mushrooms only have 0.3 mcg of vitamin D. And to compare: 100 grams of salmon have 16 mcg of vitamin D, 100 grams of egg yolk have 5.6 mcg and 100 grams mackerel, 4.0 mcg.

However, it also was found that the amount of vitamin D varied from package to package. The lowest amount of vitamin D was 5.3 mcg per 100 grams, in comparison, the highest went far over the maximum content of 10 mcg per 100 grams — as is laid down by the Novel Food Law of the European Union (EU) — namely 15.1 micrograms. Technically speaking, the new method would even allow vitamin D values as high as 700 mcg per 100 grams of mushrooms. The EU´s Novel Food legislation from 2015, which came into force in January 2018, requires that 100 grams of vitamin D mushrooms contain 10 mcg and be labelled “Agaricus bisporus.”

The law goes back to 1997 when the first regulation on novel food came into force. It defines food that had not been consumed to a significant degree by humans in the EU before May 15, 1997. Today, “Novel Food” can be newly developed, innovative food; food produced using new technologies and production processes; and/or food which is or has been traditionally eaten outside of the EU. The principles underpinning Novel Food in the European Union are that they must:

  • Be safe for consumers.
  • Be properly labelled, so as not to mislead consumers.
  • If intended to replace another food, not differ in a way that its consumption would be nutritionally disadvantageous for the consumer.
  • Have pre-market authorization on the basis of an evaluation in line with the defined principles.

Urbain stresses that even the conventional way of drying mushrooms in the sun increases their vitamin D content; however, exposing them to UV light during the process of growing is a lot more effective. The costs of adding UV light to the production of mushrooms are not high. Apart from investing in a UV light system and considering continuous quality controls, the running production costs remain low and the finishing of mushrooms with UV light does not collide with the guidelines of organic farming. Additionally, “mushroom vitamin D” is less toxic than an unintended overdose of the human vitamin D would be.