Diverticulosis is a condition that is associated with ageing. The older the individual the more likely they are to have diverticulosis, but this process is not necessarily inevitable. Diverticula are a herniation through the wall of the sigmoid colon and are likely to be a consequence of a weakness in the colonic wall or prolonged exposure to increased intracolonic pressure consequent on a low dietary fibre intake. The tensile strength of the colon declines with age and becomes least in the distal colon. Adult Africans living in Africa eat a high-fibre diet and are free from diverticulosis. Their colons are stronger, wider and thinner than those Scottish adults of the same age. The strength of the colon is in part dependent on collagen fibres and their diameter. The collagen fibrils on the left side of the colon are smaller and more tightly packed than those of the right side of the colon. Ageing and the presence of colonic diverticulosis are associated with smaller more-tightly-packed collagen fibrils. An animal model was established to investigate the effect of a lifelong high- and low-fibre diet on the development of colonic diverticulosis. The findings show that a high-fibre diet from birth, and preferably a maternal high-fibre diet, lessen the risk of diverticulosis with age.