[echoangle]

The only relevant thing I could find was the „Schlager Süßtafel“ ( https://www.t-online.de/leben/essen-und-trinken/id_100228748... ) which seems to have been made with milk from cows fed with fishmeal, which made it taste weird.

[k__]

Ah, yes.

People in the time said it was in the food, but it was "just" used to feed the animals that produced the food.