A major advance in understanding diverticular disease occurred decades ago with the epidemiologic association between fiber intake and the development of diverticular disease. This association has been well documented with investigations into the emergence of diverticular disease in underdeveloped countries where the disease had been virtually unknown before the adoption of a westernized diet, low in fiber. The high frequency of right-sided diverticular disease in Asian countries diverges from what is seen in the West. The physiologic effects of insoluble fiber has been well examined as well, increasing bulk and decreasing transit time, with a deficiency contributing to the high pressures implicated in the physiology which leads to diverticular disease. However, at most, 10% to 25% of individuals with diverticular disease will develop diverticulitis. Risk factors for symptomatic diverticular have been increasingly described in recent years with obesity and red meat intake being of particular importance, in addition to age. However, the known factors poorly identify those at increased risk and the predisposing pathophysiology is incompletely understood as well. Insoluble fiber, but not soluble fiber, has been viewed as the principal component which has been deficient in western diets and is the culprit which leads to the establishment of diverticular disease and in turn, diverticulitis. Soluble fiber and its effect on the intestinal flora is proposed as having significant influence on the development of diverticulitis. This understanding, if demonstrated, would have important implications for the primary and secondary prevention of diverticulitis.