Are Nuts Safe in Diverticulosis? A Mixed-Methods Systematic Review of Available Evidence

Background: Diverticulosis is defined as the presence of diverticula in the intestinal tract. While asymptomatic in most cases, severe complications can arise. The precise etiology of diverticulosis is still being investigated, but its correlation to dietary exposures has been proven. While certain diet recommendations have cemented themselves throughout the years, others seem to be always disputed. Nut consumption has been highly questioned among researchers and clinicians alike for decades. Objectives: This review aims to examine all available data regarding nut consumption and diverticulosis. Methods: We performed a systematic literature review from various databases (PubMed, Web of Science, Embase, and the Cochrane Library). We followed a multi-modal approach, incorporating both qualitative and quantitative techniques to assess and evaluate studies that investigated nut exposure and diverticulosis. Results: Nine observational studies encompassing over two million person-years were included. The qualitative synthesis and risk-of-bias assessments align with a neutral to modestly protective effect of moderate nut intake. Analysis of nut-specific cohorts revealed no significant increase in diverticulitis risk (HR 0.89, 95% CI 0.71–1.12). A sensitivity analysis including a prudent dietary pattern yielded a significant risk reduction (HR 0.75, 0.58–0.97). Dose–response modelling indicated a linear 5% reduction in risk per additional weekly serving. Robustness checks (leave-one-out analysis, tripping point analysis, etc.) confirmed the stability of these findings, with no single study unduly influencing the pooled estimates. Conclusions: Although limitations are present, current evidence suggests that moderate nut consumption is safe and may be protective against diverticulosis, while showing no adverse effect on diverticulitis incidence.