BACKGROUND: Patients with diverticulitis often attempt to control their diet with a particular focus on avoiding nuts and seeds. However, whether dietary patterns or dietary intake of nuts and seeds are associated with diverticulitis risk is poorly studied, particularly in women. OBJECTIVE: To determine whether select diets affect incident diverticulitis risk in women. DESIGN: Prospective cohort study. SETTING: Cohort study in the United States and Puerto Rico. PARTICIPANTS: Women aged 35 to 74 years at enrollment who responded to food frequency and diverticulitis questionnaires and had no history of inflammatory bowel disease, cancer, or diverticulitis (n = 29 916). INTERVENTION: Food frequency questionnaires were used to calculate dietary index scores and to assess intake of nuts, seeds, and corn. MEASUREMENTS: Cox proportional hazards regression was used to estimate adjusted hazard ratios (aHRs) and 95% CIs for the associations between each dietary component or dietary index and diverticulitis risk. RESULTS: 1531 cases of incident diverticulitis for 415 103 person-years of follow-up were identified. Intake of peanuts, nuts, and seeds (aHR,1.07 [95% CI, 0.91 to 1.25]) and fresh fruits with edible seeds (aHR,1.06 [CI, 0.90 to 1.24]) was not associated with incident diverticulitis. There was a reduced risk for incident diverticulitis in women in the highest quartile of healthy diets compared with the lowest quartile: the Dietary Approaches to Stop Hypertension diet (aHR, 0.77 [CI, 0.65 to 0.90]), the Healthy Eating Index (aHR, 0.78 [CI, 0.66 to 0.91]), the Alternative Healthy Eating Index (aHR, 0.81 [CI, 0.69 to 0.95]), and the Alternative Mediterranean diet (aHR, 0.91 [CI, 0.78 to 1.06]). LIMITATION: Confounding, selection bias, and measurement bias are possible. CONCLUSION: Healthy diets were associated with a reduced risk for incident diverticulitis in women. Consumption of nuts and seeds was not associated with diverticulitis risk. PRIMARY FUNDING SOURCE: National Institutes of Health.