Diverticulitis most often affects middle-aged and elderly persons, though it can strike younger patients as well. Abdominal obesity may be associated with diverticulitis in younger patients, with some being as young as 20 years old.

In Western countries, diverticular disease most commonly involves the sigmoid colon (95% of patients). The prevalence of diverticular disease has increased from an estimated 10% in the 1920s to between 35 and 50% by the late 1960s. 65% of those currently 85 years of age and older can be expected to have some form of diverticular disease of the colon. Less than 5% of those aged 40 years and younger may also be affected by diverticular disease.

Left-sided diverticular disease (involving the sigmoid colon) is most common in the West, while right-sided diverticular disease is more prevalent in Asia and Africa.

Among patients with diverticulosis, 10-25% patients will go on to develop diverticulitis within their lifetimes.

Peanuts and seeds may aggravate diverticulitis.

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