Nutrition is considered to be one of the key components in the development of most chronic degenerative diseases so that medical nutrition therapy has become important in their primary prevention. Food-based dietary guidelines provide the following values: the Lowest Threshold Intake (LTI), the Average Requirement (AR) and the Population Reference Intake (PRI) or Recommended Dietary Allowance (RDA). RDA indicates the quantity of a nutrient that must be present in the food supply if the dietary requirements of most of the population are to be met. Contrary to the established optimistic belief about Mediterranean diet, we have repeatedly documented widespread unhealthy dietary behaviours in adult subjects living in Pisa. The distribution of energy sources was incorrect and fibre consumption did not match general guidelines. Moreover, mild to moderate combined element (calcium) and vitamin (vitamin B1, folates, vitamin D, and vitamin E) deficient intakes were observed. The finding of essential nutrient deficiencies in otherwise over-nourished adults prompted us to reconsider the variety and abundance of foods required to guarantee the reference requirements for those substances and which are the historical, environmental, and contingent factors able to prevent the adequacy of food supplies in meeting physiological needs.