Characteristics of included studies

First author [ref.], yearCountryStudy designTotal subjectsAge of participants yearsHow COPD was diagnosedOutcomes of interestFactors adjusted for in analysisDietary patterns investigated
Ardestani [22], 2017IranCase–control164Mean 57Spirometric (FEV1/FVC <0.70 or FEV1 <80% pred)OR, FEV1, FVC, FEV1/FVCUnadjustedDASH (H)
Brigham [62], 2018USACohort15 256Mean 54.2Spirometric (FEV1 and FEV1/FVC <LLN)PR, FEV1, FVC, FEV1/FVCAge, sex, race, education, study location, smoking (status and pack-years), physical activity, total energy intake, BMIWestern (U), prudent (H)
Fischer [36], 2019SwedenCase–control1802Mean 55Doctor diagnosisORHigher education, living alone, number of daily cigarettesMediterranean (H)
Maisonneuve [20], 2016ItalyCohort4336Median 57Radiological (CT)ORAge, sex, smoking duration, smoking intensity, years of smoking cessation, asbestos exposure, total energyMediterranean (H)
McKeever [19], 2010NetherlandsCross-sectional12 648Range 20–59Spirometric (GOLD stage ≥2)ORAge, sex, age squared, height, age×height, smoking status, pack-years, BMI, educational levelCosmopolitan (H), traditional (U), refined-foods (U)
Ogunmoroti [18], 2016USACohort6506Mean 62.0Doctor diagnosis (discerned through ICD-9 codes)HRAge, sex, race/ethnicity, education, incomeAHA criteria (H)
Shaheen [21], 2010UKCohort2942Mean 65.7 males, 66.6 femalesSpirometric (FEV1/FVC <LLN)ORAge, height, smoking status, pack-years, smoke in home, age left education, home ownership, number of rooms, cars, social class, fat mass, activity score, energy intake, alcohol, dietary supplement use, birth weight, father's social class at birth, inhaled or oral steroid use, paracetamol usePrudent (H)
Steinemann [63], 2018SwitzerlandCohort2178Mean 58.6Spirometric (FEV1/FVC<0.70)ORStudy site, sex, age, height, smoking status, pack-years, number of daily cigarettes, exposure to passive smoking in the last 12 months, parental smoking in childhood, educational level, civil status, employment status, physical activity, total energy intake, BMIPrudent (H), high-carbohydrate (U), Western (U)
Varasso [16], 2007USACohort42 917Range 40–75Doctor diagnosis and spirometry or radiology (CXR or CT)RRAge, energy intake, smoking status, pack-years, race/ethnicity, physician visits, US region, BMI, physical activity, multivitamin usePrudent (H), Western (U)
Varasso [37], 2007USACohort72 043Range 30–55Doctor diagnosis and spirometry or radiology (CXR or CT)RRAge, smoking status, pack-years, exposure to second-hand tobacco smoke, menopausal status, race/ethnicity, spouse's educational attainment, physician visits, US region, physical activity, multivitamin use, energy intakePrudent (H), Western (U)
Varasso [17], 2015USACohort120 254Range 40–75 males, 30–55 femalesDoctor diagnosis and spirometry or radiology (CXR or CT)HRAge, physical activity, BMI, total energy intake, smoking status, pack-years, second-hand tobacco exposure, race/ethnicity, physician visits, US region, spouse, highest educational attainment, menopausal statusAlternate Healthy Eating Index (H)
Voortman [38], 2017NetherlandsCohort9701Median 64.1Spirometric (FEV1/FVC <0.70) or doctor diagnosisHRAge, subcohort, sex, smoking status, education level, employment status, total energy intake, physical activity, BMIDutch Dietary Guidelines (H)

FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; LLN: lower limit of normal; CT: computed tomography; GOLD: Global Initiative for Chronic Obstructive Lung Disease; ICD-9: International Classification of Diseases, ninth revision; CXR: chest radiography; PR: prevalence ratio; HR: hazard ratio; RR: risk ratio; BMI: body mass index; DASH: Dietary Approaches to Stop Hypertension; H: healthy; U: unhealthy; AHA: American Heart Association; AHEI: Alternative Healthy Eating Index.