Clinical Bottom Line

This large prospective cohort study effectively challenges and refutes the historical dogma that patients with diverticular disease must avoid nuts, corn, and popcorn to prevent complications. The data demonstrate no association between the consumption of these foods and an increased risk of diverticulitis or diverticular bleeding. Conversely, the study found a statistically significant inverse association (protective effect) between higher intake of nuts and popcorn and the risk of diverticulitis. While observational designs cannot strictly prove causation, these findings strongly support discontinuing the routine recommendation to avoid these foods in patients with diverticular disease.

Results in Context

Main Results The study analyzed 47,228 men over 18 years of follow-up. The associations were adjusted for potential confounders including age, physical activity, and total fiber intake.

• Nuts and Diverticulitis: Men with the highest intake (at least twice/week) had a Hazard Ratio (HR) of 0.80 (95% CI, 0.63-1.01; P for trend = .04) compared to men with the lowest intake (<1/month).

• Popcorn and Diverticulitis: Men with the highest intake had an HR of 0.72 (95% CI, 0.56-0.92; P for trend = .007) compared to the lowest intake.

• Corn and Diverticulitis: No significant association was found (HR 1.13; 95% CI 0.83-1.54).

• Diverticular Bleeding: No significant associations were found for nuts, corn, or popcorn consumption.

• Uncomplicated Diverticulosis: No significant association was found between the consumption of these foods and the presence of uncomplicated diverticulosis.

Definitions

• Hazard Ratio (HR): A measure of how often a particular event happens in one group compared to another over time. An HR of 0.80 implies a 20% relative reduction in the risk of the event in the exposed group compared to the unexposed group.

• P for Trend: This tests whether there is a linear relationship between increasing levels of exposure (e.g., eating more nuts) and the outcome. A significant value (<.05) suggests a dose-response relationship.

Participants

• Total Cohort: 47,228 US male health professionals aged 40 to 75 years.

• Cases: 801 incident cases of diverticulitis and 383 incident cases of diverticular bleeding identified during follow-up.

Assertive Critical Appraisal

Limitations & Bias (STROBE Framework)

• Recall and Measurement Bias: Diet was assessed via self-administered Food Frequency Questionnaires (FFQ). While validated, self-reporting is subject to error. However, the authors note that any random misclassification would likely bias results toward the null (weakening the association), making the finding of a protective effect more robust.

• Reverse Causality: A major concern in dietary studies is whether patients stopped eating nuts because they had early symptoms (protopathic bias). The authors assertively addressed this using a “time-lag” analysis (ignoring recent diet and looking at baseline diet). The protective association for nuts persisted (HR 0.76), strengthening the conclusion that the nuts were not avoided due to pre-existing disease.

• Residual Confounding: Although the authors adjusted for key factors like total fiber, red meat, and physical activity, observational studies can never fully rule out unmeasured confounders (e.g., men who eat nuts might have other unmeasured healthy behaviors).

• Selection Bias: The cohort consisted entirely of male health professionals. While this limits generalizability regarding sex and socioeconomic status, the authors argue that the biological mechanism of diverticular injury (luminal trauma) is unlikely to differ by sex or profession.

Reporting Quality Assessment (STROBE)

• Confounding Variables: The reporting quality regarding confounding is high. The authors clearly described their efforts to address potential sources of confounding, adjusting for total energy-adjusted fat and fiber intake, which is critical given the high-fiber nature of the foods studied. This helps isolate the specific effect of the “particulate” nature of nuts/corn from their fiber content.

• Seed Assessment: A limitation in reporting/scope is that the study could not specifically assess the intake of small seeds (e.g., sesame, poppy) or fruit seeds (except specifically strawberries and blueberries, which showed no risk). Clinicians should be aware the data strictly exonerates nuts, corn, and popcorn, though extrapolation to seeds is biologically plausible.

Applicability These findings are highly applicable to general practice. The study addresses a specific, prevalent clinical question with a clear answer that contradicts older “expert opinion” guidelines. The definition of diverticulitis used was rigorous (requiring antibiotics, hospitalization, or surgery), ensuring the study tracked clinically significant disease rather than just abdominal pain.

Research Objective

The objective was to determine whether nut, corn, or popcorn consumption is associated with the incidence of diverticulitis and diverticular bleeding.

Study Design

• Design: Prospective cohort study (The Health Professionals Follow-up Study).

• Methods:

  • Dietary Assessment: Validated semiquantitative food-frequency questionnaire administered every 4 years.

  • Outcome Assessment: Self-reported diagnosis on biennial questionnaires, followed by supplemental questionnaires and medical record review for confirmation (97% confirmation rate).

  • Follow-up: 1986 to 2004 (18 years).

Setting and Participants

• Setting: United States (Health Professionals Follow-up Study).

• Population: 47,228 men aged 40-75 years at baseline (1986).

• Inclusion: Dentists, veterinarians, pharmacists, optometrists, osteopathic physicians, and podiatrists.

• Exclusion: Men with baseline diverticulosis, cancer, or inflammatory bowel disease were excluded to prevent bias.

Bibliographic Data

• Title: Nut, Corn, and Popcorn Consumption and the Incidence of Diverticular Disease

• Authors: Lisa L. Strate, MD, MPH; Yan L. Liu, MS; Sapna Syngal, MD, MPH; Walid H. Aldoori, MD, MPA, ScD; Edward L. Giovannucci, MD, ScD

• Journal: JAMA

• Year: 2008

• DOI: Included in text as JAMA. 2008;300(8):907-914

Mandatory Disclaimer: This AI-generated analysis is for informational and research purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition.