Effects of Low-Carbohydrate and Low-Fat Diets on Morbidity and Mortality of COPD.

Purpose: Although low-carbohydrate and low-fat diets improve weight loss, cardiovascular disease, and diabetes, the relationship between these dietary patterns, highlighting macronutrient sources, and chronic obstructive pulmonary disease (COPD) remains unclear. This study aimed to assess the association between low-carbohydrate diets (LCDs) and low-fat diets (LFDs) and the odds of COPD and mortality among people with COPD in the National Health and Nutrition Examination Survey.

Patients and methods: Clinical data were extracted from the 2007-2008, 2009-2010, and 2011-2012 National Health and Nutrition Examination Survey (NHANES) cycles that met the inclusion criteria. Multivariable logistic regression was used to evaluate the associations between LCD and LFD scores and COPD, and multivariable Cox proportional hazards regression and restricted cubic spline (RCS) regression were used to assess the relationship between all-cause mortality and LCD and LFD scores.

Results: Comparing extreme tertiles, multivariable-adjusted odds ratio (OR) were 1 (reference), 1.09 (95% CI, 0.77-1.55), 1.84 (95% CI, 1.09-3.09) (P = 0.045 for trend) for unhealthy LFD scores. After multivariate adjustment, a per 5-point increase in unhealthy LCD score was associated with a 21% higher risk of total mortality (hazard ratio, 1.21; 95% CI, 1.03-1.43); while a per 5-point increase in healthy LFD scores was associated with a 21% lower risk of total mortality (HR, 0.79; 95% CI, 0.67-0.94).

Conclusion: Higher unhealthy LFD score was associated with an increased odds of COPD. Unhealthy LCD scores were significantly associated with higher total mortality, whereas healthy LFD scores were associated with lower total mortality in patients with COPD.