“Substitute substances” were commonplace in wartime Germany, motivated by limited access to farmland and coal/oil/energy supplies.
The Germans made gasoline from oil, developed synthetic wool and cotton, and a hundred other innovations.
Everything had to prioritized. Small children got first dibs, to include plenty of milk and good food. Factory workers and soldiers came next, then military and police and security personnel. Since unemployment was 0%, this pretty well took care of the German people.
Every German, still, had to manage on what they got on their ration cards or were able to grow in their own “victory garden.” German youths got precisely the number of calories they needed to grow up and be healthy; ditto for workers and soldiers. Not a calorie was wasted – even food refuse was recycled for farm animals.
Jews in work camps who were no longer able to work for their quota of food were at the end of the line.