The investigation by Stiftung Warentest was:
“Vitamin D-Pilze: Halten diese Champignons, was sie versprechen?”
Vitamin D Mushrooms: Do these mushrooms deliver what they promise?
Stiftung Warentest is a non-profit German consumer organisation which investigates and compares goods and services of different providers on behalf of the state.
Stiftung Warentest determined the vitamin D content of the mushrooms in seven different packs. Main result: The Boosting process works – the average vitamin D content is 9.6 µg/100 g and thus significantly higher than that of normal cultivated mushrooms.