In Western populations a century ago diets consumed by the masses included a large amount of little refined cereal products. Intakes of vegetables (other than potatoes) and fruit, also foodstuffs of animal origin, tended to be low. Since then the situation changed conversely. There is now a third stage of change--authorities are urging reversion toward greater reliance on foods of plant origin, with increased intakes of less refined cereal products, legumes and vegetables and fruit. In developing countries, the first two stages are represented by rural traditional and urban partially Westernized diets. This paper provides details of intakes of diets generally, especially of dietary fibre, mineral salts and vitamins during the stages referred to, in both First and Third World populations, and discusses their bearing on the occurrences of nutrition-related diseases.