Mushrooms are an important source of vitamin D
Humans and wild mushrooms have (at least) one thing in common - they both produce vitamin D when the sun shines on them. A new research project is looking into which factors are important for producing vitamin D in commercial mushroom cultivation.
The wintertime is nutritionally poor for us humans when it comes to vitamin D. With weak rays of sun our skin cannot produce vitamin D as well as during the summer. Most Danes therefore lack vitamin D during the winter unless we eat the right food or take vitamin pills.
Wild mushrooms are the same. They also produce vitamin D when the sun shines on them and they are actually our only non-animal food source of vitamin D. According to studies in other countries, wild mushrooms can increase the content of vitamin D in the blood as well as vitamin D ingested as a dietary supplement.
- The fact of the matter is that just about all mushrooms sold in Denmark are grown in the dark and therefore do not contain vitamin D. In a new research project we will be investigating if cultivated mushrooms can be treated in a way during their growth period that allows them to produce the vital vitamin D, says senior scientist Hanne L. Kristensen from the Faculty of Agricultural Sciences, Aarhus University.
Let there be light…
Earlier studies from abroad have shown that you can get cultivated mushrooms to produce vitamin D by subjecting them to a certain part of the light spectrum, so-called UV-B light, when they are on the packaging belt. The vitamin that is produced is stable for several days in cool storage and is only slightly destroyed by cooking.
Scientists from the Faculty of Agricultural Sciences will get the mushrooms to produce vitamin D even earlier in the production process.
- Our aim is to integrate the lighting in the actual growing process so the mushrooms can still be the same pure product as the one we know from Danish production today, says Hanne L. Kristensen.
- What we would like to investigate is which factors in the growing process are important for production of the desired vitamin D. The mushrooms will not be subjected to UV-B light on the packaging line after harvest, as is the case in studies from other countries, but during their cultivation, she explains.
The scientists will build on the results from the foreign studies by investigating the correlations between the biology of the mushrooms and their vitamin D production. They will also investigate other effects of UV-B light on the nutrient content of the mushrooms.
The levels of vitamin D achieved in American and Chinese studies with UV-B light are so high that even using a small portion of mushrooms in the diet can cover the recommended daily vitamin D requirement for most people.
Vitamin D is vital
Danes do not get enough vitamin D and that is bad for their health. Vitamin D is important for the bones. Studies indicate that the risk of developing cancer, diabetes and several other diseases is increased when you are deficient in vitamin D, and that immunity and muscle strength are weakened.
Even worse is the fact that Danes, in general, do not get enough vitamin D. At particular risk are people over 50 years, people who are dark-skinned or people who avoid the sun, but healthy Danish school children also have a low vitamin D status.
During the winter, the diet is the only source of vitamin D, but the choices are few if you want to put vitamin D-rich food in your shopping trolley. Fatty types of fish such as salmon have a high vitamin D content. Other animal products such as eggs, meat and dairy products have only a limited content of vitamin D, while fruit and vegetables have none.
- I hope the project will provide a basis for developing novel fresh mushroom products with a high natural content of vitamin D for consumers who wish to promote their health through a varied and natural diet, says Hanne L. Kristensen.
The research project, which Hanne L. Kristensen is the leader of, has just been started at the largest mushroom grower in the Nordic countries, Egehøj Champignon A/S. It will be carried out in collaboration with the National Food Institute at the Technical University of Denmark and is financed by the Danish Food Industry Agency under the Ministry of Food, Agriculture and Fisheries, the marketing agency for fruit and vegetables (Gartneriets Afsætningsudvalg) and the project participants.