Causes of Diverticulosis (Diverticular Disease)
Primary Etiological Factors
Diverticulosis develops through a multifactorial process involving dietary deficiency, structural alterations of the colonic wall, abnormal colonic motility, and genetic predisposition. 1, 2, 3
Dietary Factors
- Low dietary fiber intake is the cornerstone environmental risk factor, with Western diets particularly implicated in the development of diverticula 1, 4, 3
- A prudent dietary pattern high in fiber from fruits, vegetables, whole grains, and legumes is protective, while diets high in red meat and sweets increase risk 1
- The epidemiological evidence is compelling: diverticulosis was rare in rural Africa (prevalence 1.85% in 1989) but common in Western populations, with this gap narrowing as African populations adopt Western dietary patterns 5, 4
Structural and Anatomical Factors
- Diverticula form as pseudodiverticula (outpouchings of mucosa and submucosa only) through preformed weak points in the colonic wall where the vasa recta penetrate the circular muscle layer to supply the mucosa 6, 2, 3
- Alterations in connective tissue composition—including changes in collagen, elastin, and overall connective tissue integrity—weaken these exit sites and reduce bowel wall flexibility 2, 3
- The diverticula typically occur along the mesenteric side of the antimesenteric taeniae in parallel rows 6
Functional and Motility Disorders
- Abnormal colonic motility patterns with increased intraluminal pressure promote diverticula formation through the weakened areas of the bowel wall 4, 2, 3
- Intestinal innervation disorders and structural alterations of the musculature induce these abnormal contractile patterns 2
- Increased intraluminal pressure is exerted on the colonic wall, causing outpouching at the three areas where vessels enter 4
Genetic Predisposition
- Approximately 40-50% of the risk for diverticular disease is attributable to genetic factors, making this one of the most important risk determinants 1
- The risk is three times higher for siblings of affected individuals compared to the general population, and higher in monozygotic twins than dizygotic twins 1
- Genome-wide association studies have identified over 30 susceptibility loci, with genes important for immunity, cell adhesion, connective tissue integrity, membrane transport, and smooth muscle function 1
- Congenital connective tissue diseases also predispose to diverticular formation 2
Secondary Risk Factors
Age-Related Changes
- Aging is a key factor, with prevalence increasing from 32.6% in patients aged 50-59 years to 71.4% in those aged 80+ years in Western populations 5, 2
- Approximately 70% of the Western population develops diverticulosis by age 80 7
Lifestyle and Behavioral Factors
- Obesity, particularly central obesity, and weight gain significantly increase risk 1
- Smoking is an independent risk factor 1
- Physical inactivity increases risk, while vigorous physical activity is protective 1
- Alcoholism (not moderate alcohol consumption) increases risk 1, 8
Medication-Related Factors
- Regular NSAID use increases risk, with non-aspirin NSAIDs carrying greater risk than aspirin 1
- Opiate analgesics and corticosteroids are associated with both diverticulitis development and perforation risk 1, 3
- Menopausal hormone therapy increases risk independent of dose or duration 1
Other Medical Factors
- High meat consumption is associated with increased risk 2
- Pronounced overweight (high BMI) is a risk factor 2