No one knows, because it doesn't. Any reports are anecdotal, not scientific.Does anyone know WHY this works?
It seems some people who have heard this, do so when they get impatient. The feeding of the hot peppers coincides with point of lay and they are convinced. The pullets would have started to lay with or without the capsacin.
It is a shame when people start grasping at straws and ultimately perpetuate an old wives tale.
It certainly won't hurt them and may very well be nutritionally beneficial but to kick start egg production? Not!