Hypothesis

In the context of poverty in infancy, an adverse environmental situation conditions the gut and, paradoxically, acts as a protective factor against subsequent digestive diseases in adulthood.

One of the major differences in disease patterns between adult African and Western populations is the relative paucity of digestive diseases such as cancers (except for oesophageal cancer), adenomatous polyps, diverticular disease, inflammatory bowel disease, and appendicitis.1-5 This situation prevails despite the presence of environmental factors which favour increases in their occurrences. In contrast, their incidence is high in Western populations, although they were very much lower at the turn of the last century.6-11 Urbanisation of Africans is accompanied by changes in environmental factors and lifestyles. The significance of these changes is the subject of this paper.

Diet

In African countries, considerable changes in diet have occurred and are continuing, with falls in the intake of plant foods but rises in those of animal origin. In South Africa, among rural Africans a generation ago, of the total energy intake, protein supplied 10–11%, fat 15–20%, and carbohydrate 70–75%. Dietary fibre intake averaged 30–35 g daily.12 ,13 Later, in an urban area in the Cape Peninsula, the corresponding proportions were 13%, 25%, and 60%. Mean fibre intake was much lower (17 g daily).14 In Johannesburg, a recent study showed that the proportions of nutrients supplying energy were protein 14%, fat 30%, and carbohydrates 55%. Mean total daily energy intake was 2150 kcal, with 82 g of protein, 74 g of fat, 250 g of carbohydrate, and 14 g of fibre. Maize meal (previously and still the case in many families) is the staple food but is being replaced by bread, mainly white bread. Consumption of fruit, vegetables, and meat is low because of their cost. Of major significance, the marked reduction in …