Discussion of which foods are healthy and which are not has been going on for years. Rows of cookery-books and numerous columns in magazines tell us how to keep our physique in shape (or to bring it into shape) by a diet which is nourishing, and carefully selected and adapted, often with a preference for products of the health–food industry. Calories are not popular, but diets are no longer solely slimming diets: they are also recommended prophylactically and even prescribed therapeutically. In short, the interest in the medical aspects of our food keeps the (rich) world intensively busy, scientifically and commercially.

These are modern problems, but they have very ancient ancestors.

In Classical Antiquity medicine already had the double aim of conserving as well as restoring one's health: ‘Medicina est conservatio sanitatis et curatio aegritudinis’ (Medicine is the art whereby health is conserved and the art whereby it is restored, after being lost). In both medical fields, food played an important part: the ‘ingredients’ or simplicia, just like the ‘preparations’ or composita, belonged to the field of polypharmacopoeia.

A large number of medical treatises containing modes of life, viz. regimens and diets, arise from this point of view. The distinction between the two categories is based on the division in medicine: the diet includes mainly curative eating prescriptions and has, therefore, highly variable contents. The regimen, on the other hand, consists of preventive rules for people's health.