Answer:
The rational explanations of doctors related to folk explanations concerning the properties of some foods began in the early days of ancient civilizations, when medicine was not yet a definable subject and folk explanations were the only ones who brought knowledge to bear on the field of health, and "try, taste and wait for the end of the process", was the only way to find out the food´s properties.
Explanation:
The ancient Greeks civilization, seeking for logic got curious about folk´s explanations about existence and the whies paving the road for important developments the rational explanations in medicine and the relationship with food propierties.
The set up medical schools leaving the informatily of folk explanations hidden in the darkness, to open a path to the scientific observations of patients who were sick, although many of them were philosophers, they investigated on nutrition as possoble causes for illness, even though many folk traditions already practiced on certain foods to get healthier or to get health maintenance.
Doctor´s observations on folks´ remedies like using olive oil to increase temperature in the body, were the base for them to develop techniques, which could become sophisticated medicine procedures.
This theory remained popular in Western Europe until the 17th century. However, while the ancient Greeks pushed medicine forward in many ways, the theory of humors posed an obstacle to advances in medical practice. But many of the folk´s natural remedies are similar to some home remedies practiced today.
Folks´ natural cures have doctors become herbalists treatment specialist, turning natural remedies into rational treatments using foods as the barley soup plus vinegar and honey to cough up phlegms; purging a person with food laxatives, diuretics or emetics to restore body´s balance; taking celery, to relieve inflamation; and in general rationalizing the concept of eating healthy foods, so the basis of modern medicine comes from the folk´s knowledge on food properties.