A recent prospective cohort study published in the Nutrition Journal examined data from 95,612 American adults to investigate whether a sulfur microbial diet score correlates with lung cancer incidence and mortality. Researchers evaluated 25 food groups linked to sulfur-metabolizing gut bacteria, revealing a modest increase in risk among individuals with high adherence scores.
Habitual diet has increasingly drawn focus as a modifiable risk factor in oncology, particularly given the heterogeneous risk observed among ever-smokers and never-smokers alike. While smoking remains the dominant driver of lung malignancies—which maintain a U.S. five-year survival rate hovering near 25%—investigators sought to determine if gut microbial patterns tied to dietary sulfur intake influence systemic health outcomes via the gut-lung axis. The study, drawing from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, utilized dietary questionnaires to map out how specific food combinations interact with intestinal microbes.
Decoding the Sulfur Microbial Dietary Pattern and Clinical Markers
To analyze dietary impacts without direct stool sequencing data, researchers utilized a food-based sulfur microbial diet score. This metric relies on 25 standardized, weighted food-group components calculated from a 124-item questionnaire administered at a median of three years post-randomization. Higher scores reflect diets rich in red and processed meats, French fries, and high-fat dairy, coupled with lower consumption of whole grains, fruits, and yellow vegetables.
At elevated concentrations, hydrogen sulfide can impair epithelial barrier function, provoke local DNA damage, and elevate systemic inflammation. Although the study could not directly measure microbial populations or metabolite concentrations, the dietary score served as a dietary proxy.
The analytic cohort encompassed 95,612 participants with a mean age of 65.5 years, 52 percent women. Over extended follow-up periods spanning from initial questionnaire completion through December 2009 for incidence and December 2018 for mortality, investigators documented 1,561 lung cancer cases and 2,109 lung cancer-related deaths. Crude incidence rates climbed from 1.20 per 1,000 person-years in the lowest quintile to 3.03 per 1,000 in the highest quintile.
| Sulfur Microbial Diet Quintile | Mean Participant Characteristics | Observed Lung Cancer Incidence Rate | Observed Lung Cancer Mortality Rate |
|---|---|---|---|
| Quintile 1 (Lowest Adherence) | Older, male, higher BMI, higher rates of smoking, diabetes, and hypertension | 1.20 per 1,000 person-years | Similar increase across quintiles |
| Quintile 5 (Highest Adherence) | Younger, higher BMI, higher red/processed meat and high-fat dairy intake | 3.03 per 1,000 person-years | Similar increase across quintiles |
Evaluating Hazard Ratios, Smoking Interplay, and Histologic Subtypes
After adjusting for demographic factors, health status, lifestyle, and dietary covariates through sequentially structured Cox proportional hazards models, the absolute risk elevation narrowed considerably. Individuals falling into the top quintile showed an estimated 23% greater hazard for developing lung cancer and a 19% greater estimated hazard of lung cancer mortality relative to participants in the bottom quintile.
Investigators noted that residual confounding from smoking exposure and the observational design limit definitive causal inferences.
Contraindications & When to Consult a Doctor
While observational nutrition studies highlight broad population-level dietary trends, they do not prescribe immediate individual treatment alterations or serve as diagnostic tools. Patients should never use dietary scoring models to self-diagnose oncological risks or manage existing pulmonary conditions. Individuals presenting with persistent respiratory symptoms must seek prompt evaluation by a qualified physician or pulmonologist. Smokers and former smokers should prioritize evidence-based cessation programs and clinical screening protocols as recommended by healthcare providers.
References
- Luo, Y., Xiao, Y., Yang, J., et al. (2026). Association of sulfur microbial diet with lung cancer incidence and lung cancer-related mortality in 95,612 American adults: a prospective cohort study from the PLCO trial. Nutrition Journal. DOI:10.1186/s12937-026-01406-7
