Chronic Obstructive Pulmonary Disease (COPD)
Conditions
Keywords
COPD, Ketogenic Diet, Nutritional Ketosis, Pulmonary Function, Body Composition
Brief summary
Chronic obstructive pulmonary disease (COPD) is associated with persistent airflow limitation, systemic inflammation, reduced exercise capacity, and unfavorable changes in body composition. Nutritional interventions may represent a complementary strategy to improve clinical outcomes in individuals with COPD. This pilot randomized controlled trial evaluates the feasibility, safety, and preliminary effectiveness of an 8-week ketogenic dietary intervention in men with mild-to-moderate COPD. Participants are randomly assigned to either a supervised ketogenic diet or a control group receiving standard dietary advice. The ketogenic diet restricts carbohydrate intake and promotes nutritional ketosis, which is monitored using blood beta-hydroxybutyrate measurements. The primary outcome is change in the FEV1/FVC ratio. Secondary outcomes include systemic inflammation assessed by C-reactive protein (CRP), phase angle measured by bioelectrical impedance analysis, functional exercise capacity assessed by the 6-minute walk test, estimated aerobic capacity, body composition, and selected biochemical safety markers. The study aims to provide preliminary evidence regarding whether a ketogenic dietary approach may improve inflammatory status, functional capacity, and physiological outcomes in individuals with COPD.
Detailed description
Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder characterized by persistent airflow limitation, chronic inflammation, exercise intolerance, and alterations in body composition. In addition to pulmonary impairment, systemic manifestations such as increased inflammatory burden, skeletal muscle dysfunction, and adverse metabolic changes contribute substantially to morbidity and reduced quality of life. Nutritional interventions have therefore emerged as potential adjunctive strategies in COPD management. Ketogenic diets are characterized by marked carbohydrate restriction, moderate protein intake, and increased dietary fat consumption, resulting in nutritional ketosis. Potential mechanisms relevant to COPD include reductions in systemic inflammation, changes in substrate utilization, reductions in adiposity, and alterations in respiratory gas exchange. However, randomized controlled studies investigating ketogenic dietary interventions in COPD remain limited. This study is an 8-week, single-center, parallel-group pilot randomized controlled trial conducted in clinically stable men with GOLD stage I-II COPD. Participants are randomly allocated in a 1:1 ratio to either a ketogenic dietary intervention or a control group receiving standard dietary advice. The ketogenic diet is individually prescribed by a dietitian and aims to provide approximately 60-70% of total energy from fat, 15-20% from protein, and 5-10% from carbohydrates, with carbohydrate intake restricted to less than 50 g/day. Nutritional ketosis is monitored using capillary beta-hydroxybutyrate measurements obtained throughout the intervention period. Pulmonary function is assessed using spirometry. Body composition and phase angle are measured using multifrequency bioelectrical impedance analysis. Functional exercise capacity is evaluated using the 6-minute walk test, and estimated aerobic capacity is derived from walking performance. Blood samples are collected to assess inflammatory and safety-related biomarkers, including C-reactive protein, lipid parameters, alanine aminotransferase, and creatinine. The primary objective is to determine whether an 8-week ketogenic dietary intervention improves FEV1/FVC compared with standard dietary advice. Secondary objectives are to evaluate effects on systemic inflammation, phase angle, exercise capacity, body composition, and biochemical safety outcomes. As a pilot trial, the study is designed to generate effect-size estimates, assess feasibility and adherence, and inform the design of future larger multicenter randomized controlled trials.
Interventions
BEHAVIORALKetogenic diet
Participants received an individualized ketogenic dietary intervention for 8 weeks. The dietary prescription provided approximately 60-70% of total energy from fat, 15-20% from protein, and 5-10% from carbohydrates, with carbohydrate intake restricted to less than 50 g/day. Nutritional ketosis was monitored using blood beta-hydroxybutyrate measurements throughout the intervention period.
BEHAVIORALStandard Dietary Advice
Participants received standard dietary recommendations for chronic obstructive pulmonary disease and were instructed to maintain their habitual dietary patterns during the 8-week study period.
Sponsors
Agri Ibrahim Cecen University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Masking description
Blinding was not feasible because of the nature of the dietary intervention.
Intervention model description
Participants were randomized in a 1:1 ratio to either a supervised ketogenic dietary intervention or a control group receiving standard dietary advice. Outcomes were assessed at baseline and after 8 weeks.
Eligibility
Sex/Gender
MALE
Age
40 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* Male sex * Age between 40 and 75 years * Clinically stable chronic obstructive pulmonary disease (COPD) * GOLD stage I or II COPD * No acute COPD exacerbation within the previous 3 months * Stable pharmacological treatment for at least 4 weeks before enrollment * Ability to complete study assessments and comply with dietary instructions * Provision of written informed consent
Exclusion criteria
* GOLD stage III or IV COPD * Uncontrolled cardiovascular disease * Chronic kidney disease * Severe hepatic dysfunction * Active malignancy * Insulin-dependent diabetes mellitus * Participation in another dietary intervention program within the previous 3 months * Inability to complete study assessments * Contraindications to dietary carbohydrate restriction * Refusal or inability to provide informed consent
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| FEV1/FVC Ratio | Change in the ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC), assessed by spirometry after 8 weeks of intervention. | Baseline and Week 8 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| C-Reactive Protein (CRP) | Baseline and Week 8 | Serum C-reactive protein concentration (mg/L) measured as a marker of systemic inflammation. |
| Phase Angle | Baseline and Week 8 | Change in phase angle measured by multifrequency bioelectrical impedance analysis. |
| 6-Minute Walk Distance | Baseline and Week 8 | Change in functional exercise capacity assessed by the 6-minute walk test. |
| Body Mass Index | Baseline and Week 8 | Baseline and Week 8Change in body mass index calculated as weight divided by height squared. |
| Fat Mass | Baseline and Week 8 | Baseline and Week 8Change in body fat mass measured by bioelectrical impedance analysis. |
| Estimated VO2max | Baseline and Week 8 | Baseline and Week 8Change in estimated maximal oxygen uptake derived from 6-minute walk performance. |
Countries
Turkey (Türkiye)
Contacts
STUDY_CHAIRDursun Alper YILMAZ
Ağrı İbrahim Çeçen Üniversitesi
Outcome results
None listed