What Causes Diverticulosis?
Diverticulosis results from complex interactions among aging, low dietary fiber intake, altered colonic structure and motility, genetic factors, and lifestyle factors including obesity, physical inactivity, and smoking. 1, 2, 3, 4
Primary Pathophysiologic Mechanisms
The formation of colonic diverticula involves multiple interconnected factors:
Dietary fiber deficiency is the cornerstone mechanism originally proposed by Burkitt and Painter and remains the most established causative factor, with low intake of vegetables, fruits, whole grains, seeds, and nuts increasing risk 5, 2, 6
Age-related structural changes in the colon wall are fundamental, with prevalence increasing dramatically from 10% in patients under 50 years to 33% in those 60-69 years old, and up to 71.4% by age 80 in Western populations 7, 1
Genetic predisposition accounts for approximately 50% of diverticulitis risk, including variants in the TNFSF15 gene 1, 3
Altered colonic motility and structure from involutional changes in the gastrointestinal tract contribute to outpouching formation, particularly where the colon wall is weakest 5, 4
Modifiable Risk Factors
Several lifestyle and dietary factors directly increase diverticulosis risk:
Obesity (BMI ≥30) is a significant independent risk factor 2, 3
Red meat consumption increases risk, while vegetarian diets and increased vegetable intake are protective 2
Physical inactivity increases risk, whereas regular exercise appears protective 5, 2
Certain medications including opioids, steroids, and NSAIDs (except aspirin for cardiovascular prevention) increase risk 3
Medical Comorbidities
Specific conditions predispose to diverticular disease:
Connective tissue disorders such as polycystic kidney disease, Marfan syndrome, and Ehlers-Danlos syndrome 3
Hypertension and type 2 diabetes are associated risk factors 3
Geographic and Anatomic Patterns
Western populations predominantly develop left-sided (sigmoid) diverticulosis in 90% of cases, while Asian and African populations more commonly have right-sided disease (70-74% of cases) 7, 1
The sigmoid colon is the most common site in Western societies due to its smaller diameter and higher intraluminal pressures 1
Important Clinical Context
A critical distinction: while up to two-thirds of individuals in Western countries develop diverticulosis by age 85, only 1-4% will develop acute diverticulitis in their lifetime, and only 10-25% will ever manifest any clinical symptoms 1, 2, 3. The progression from asymptomatic diverticulosis to symptomatic disease likely involves changes in intestinal microflora, low-grade inflammation, and additional environmental triggers that remain inadequately understood 4.