You do bring up some interesting points... dependent upon constitution, background, diet etc. we may be plus or minus in any one or many minerals causing an imbalance. This means that we all must find what works for ourselves, on our own, unless we are fortunate enough to have the tools and understand how to monitor.
I would be willing to bet that we would all eventually be able to "tune" into our bodies in order to recognize our needs, and then chose foods that would fill them, if we worked hard enough to listen to and understand our own unique body response to certain\any foods.
What has moved us away from being able to naturally recognize negative\positive physical responses to foods, is all the external distractions AND the OTCs sold and marketed to deal with, what would be a normal body response (digestive, and\or elimination issues) to something we should not have eaten in the first place.