Table 1

Study characteristics of published cross-sectional and cohort studies on soft drinks and asthma

References	Study design	Country	Study period	Age	Cases/(total) subjects	Outcome	Comparison	Adjusted risk estimate (95% CI)	Quality	Adjustment variables
Adulthood exposure
Ibrahim et al 34	CS	Qatar	2012–2018	≥20 years	65/986	Self-report of doctor’s diagnosis of asthma	Soft drinks: None Less than or once/week 1–6 times/week ≥7 times/week	Ref 1.21 (0.53 to 2.75) 1.29 (0.59 to 2.84) 2.64 (1.10 to 6.36)	7/10	Age, sex, smoking, education, leisure time physical activity, fruit and vegetables, BMI
DeChristopher and Tucker16	Cohort	USA	1984–2001	24–72 years	363/2696	Self-reported asthma	Non-diet soft drinks Less than or once/week 2–4 times/week 5–7 times/week More than once/day Diet soft drinks Less than or once/week 2–4 times/week 5–7 times/week More than once/day	Ref 0.99 (0.73 to 1.34) 1.48 (1.09 to 2.01) 0.94 (0.68 to 1.31) Ref 1.00 (0.72 to 1.40) 0.83 (0.57 to 1.21) 0.94 (0.73 to 1.21)	7/9	Sex, age, ever smoked, education level and time-varying covariates such as BMI, smoking, total energy intake
Park et al 33	CS	USA	2013	≥18 years	Not reported/ 146 990	Self-report of doctor’s diagnosis of asthma (BRFSS data)	Sugar-sweetened drinks (non-obese adults): None >0–<1 time/day 1–<2 times/day ≥2 times/day Sugar-sweetened drinks (obese adults): None >0–<1 time/day 1–<2 times/day ≥2 times/day	Ref 1.13 (1.00 to 1.28) 1.08 (0.91 to 1.28) 1.66 (1.39 to 1.99) Ref 0.99 (0.85 to 1.16) 0.96 (0.79 to 1.17) 1.13 (0.91 to 1.38)	8/10	Age, sex, race/ethnicity, education level and smoking status
Shi e t al 13	CS	Australia	2008–2010	≥16 years	2118/16 907	Self-reported doctor-diagnosed asthma, with experience of symptoms or use of prescribed medication for asthma in the past 12 months	Soft drinks: 0 L/day 0.1–0.5 L/day ≥0.5 L/day	Ref 1.24 (1.03 to 1.49) 1.26 (1.01 to 1.58)	7/10	Age, gender, education, income, area of residence, smoking, alcohol consumption, physical activity, being overweight, intake of fruit and vegetables, intake of water and juice
Takaoka and Norback15	CS	Japan	2005–2006	Mean 21 years	24/153	Self-reported wheeze (ECRHS questionnaire)	Soft drinks: Undefined in article: high vs low or any vs none	1.02 (0.66 to 1.57)	6/10	Age, current smoking and parental asthma/allergy
Priftanji et al 32	CS	Tirana, Albania	1995–1996	20–44 years	234/2653	Self-reported asthma-like symptoms and positive skin tests (ECRHS questionnaire)	Carbonated drinks: <1 time a week ≥1 time a week	Ref 1.59 (0.97 to 2.60)	6/10	Age, sex, smoking, family history of asthma, allergy to animals
Childhood exposure
Han e t al 24	CS	USA	2009–2011	Grades 9–12	3222/24 612	Self-report of doctor’s diagnosis of asthma	Regular soft drinks Never 1–6 times/week ≥7 times	Ref 1.11 (0.96 to 1.27) 1.27 (1.11 to 1.47)	8/10	Age, sex, race, health risk behaviours (except physical activity) and psychosocial stressors
Malaeb e t al 25	CS	Lebanon	2017	Grades 1–9	107/1000	Parental reports of doctor’s diagnosis of asthma (ISAAC questionnaire)	Carbonated drinks: Never Occasional >3 times per week Daily	Ref 0.25 (0.10 to 0.61) 0.03 (0.01 to 0.10) 0.77 (0.23 to 2.52)	6/10	Not explicit
Wright et al 31	Cohort	USA	1999–2002	Median=7.7 years	924	Mother report of asthma (ISAAC questionnaire)	Sugar-sweetened drinks: Quartile 1 Quartile 2 Quartile 3 Quartile 4	Ref 0.96 (0.58 to 1.61) 0.73 (0.41 to 1.29) 1.20 (0.74 to 1.94)	7/9	Maternal education, smoking and sugar-sweetened beverage intake during pregnancy and pre-pregnancy BMI; family income; child age, sex, BMI and race/ethnicity
Melo et al 30	CS	Brazil	2012	Grade 9	16 280/109 104	Self-report of asthma	Soft drinks: 0–2 days/week 3–4 days/week ≥5 days/week	Ref 1.04 (0.96 to 1.13) 1.13 (1.05 to 1.22)	7/10	Sex, age, mother’s education level, parents as smokers, smoking, alcohol, school type, geographical region and municipality of residence
Berentzen et al 14	CS	The Netherlands	2009	1–12 years	139/2406	Parental reports of 2 out of 3 of the following: wheezing in the past 12 months, prescription of inhaled corticosteroid in the past 12 months and a doctor’s diagnosis of asthma ever (GA²LEN definition)	Sugar-sweetened drinks: <4 glasses/week 4–9 glasses/week ≥10 glasses/week Artificially sweetened drinks: 2 glasses/week ≥2 glasses/week	Ref 1.17 (0.71 to 1.80) 1.56 (0.95 to 2.56) Ref 1.08 (0.74 to 1.59)	8/10	Age, gender, breastfeeding, maternal education, parental allergy, smoking indoors, fruit and vegetable consumption and BMI
DeChristopher et al 36	CS	USA	2014	2–9 years	229/1961	Self-report of doctor’s diagnosis of asthma (NHANES data)	Sugar-sweetened drinks: ≤1 time/month 2–3 times/month 1–4 times/week ≥5 times/week	Ref 0.85 (0.40 to 1.83) 0.82 (0.39 to 1.70) 1.00 (0.43 to 2.32)	7/10	Age, sex, race/ethnicity, BMI and energy intake
Saadeh et al 26	CS	France	2000–2001	9–11 years	Not reported /7432	Parental report of asthma (ISAAC questionnaire)	Soft drinks: Never/occasionally 1–2 times/week ≥3 times/week	Ref 1.07 (0.82 to 1.40) 1.03 (0.77 to 1.37)	7/10	Age, gender, place of residence, parental atopic disease, the number of siblings, maternal education, parental ethnic origins, breastfeeding, daycare centre or nursery, obesity and current exposure to environmental tobacco smoke
Park et al 12	CS	USA	2009	Grades 9–12	1724/15 960	Self-report of doctor’s diagnosis of asthma (YRBS data)	Sugar-sweetened drinks: 0 time/day 1 time/day 2 times/day ≥3 times/day	Ref 1.28 (0.99 to 1.66) 1.28 (1.02 to 1.62) 1.64 (1.25 to 2.16)	7/10	Age, sex, race/ethnicity, weight and smoking
Nagel et al 5	CS	20 countries	1995–2005	8–12 years	Not reported /50 004	Parental report of asthma (ISAAC)	Carbonated drinks: Never/occasionally 1–2 times/week ≥3 times/week	Ref 1.00 (0.85 to 1.16) 1.03 (0.91 to 1.16)	8/10	Age, sex, environmental tobacco smoke, parental atopy, exercise and number of siblings
Tsai and Tsai27	CS	Taipei, Taiwan	2004	11–12 years	574/2218	Two or more wheezing-associated non-exercise-induced respiratory symptoms OR self-report of doctor-diagnosed asthma	Sugar-sweetened drinks: Consumption level not specified	1.08 (1.03 to 1.13)	6/10	Residential districts, gender, physician-diagnosed allergy
Wickens et al 28	CS	Hastings, New Zealand	2000	10.1–12.5 years	468/1321	Parental report of asthma (ISAAC questionnaire)	Carbonated drinks: Never Less than once a week ≥1 time a week	Ref 1.16 (0.79 to 1.68) 1.32 (0.91 to 1.93)	7/10	Gender, BMI, family history of allergic disease, family size, birth weight, current smoking in the home, father’s education, fast food and vegetable intake, exercise, ethnicity and year born
Corbo et al 29	CS	Italy	2005	6–7 years	3297/19 995	Parental report of asthma	Carbonated drinks: Never 1–2 times/week 3–4 times/week ≥5 times/week	Ref 1.07 (0.9 to 1.12) 1.29 (1.1 to 1.5) 1.31 (1.0 to 1.7)	6/10	Age, gender, residence, education, season when data collected, person filling the questionnaire, being the only child, active smoking in the house, family history of asthma
Prenatal exposure
Wright et al 31	Cohort	USA	1999–2002	Median=7.7 years	1053	Mother report of asthma (ISAAC questionnaire)	Sugar-sweetened drinks: Quartile 1 Quartile 2 Quartile 3 Quartile 4	Ref 1.02 (0.63 to 1.66) 0.96 (0.59 to 1.56) 1.68 (1.07 to 2.65)	7/9	maternal education, smoking during pregnancy and pre-pregnancy BMI; family income; child age, sex, BMI and race/ethnicity
Maslova et al 35	Cohort	Denmark	1996–2002	18 months and 7 years	9164/60 466	Parental report of asthma at 7 years (ISAAC questionnaire)	Artificially sweetened carbonated soft drinks: Never <1 serve/week weekly ≥1 serve/day Artificially sweetened non-carbonated soft drinks: Never <1 serve/week weekly ≥1 serve/day Sugar-sweetened carbonated soft drinks: Never <1 serve/week weekly ≥1 serve/day Sugar-sweetened non-carbonated soft drinks: Never <1 serve/week weekly ≥1 serve/day	Ref 0.91 (0.74 to 1.12) 1.04 (0.87 to 1.23) 1.18 (0.87 to 1.59) Ref 0.98 (0.76 to 1.27) 0.94 (0.77 to 1.14) 1.0 (0.82 to 1.22) Ref 1.16 (0.95 to 1.43) 1.04 (0.86 to 1.26) 1.20 (0.93 to 1.56) Ref 1.03 (0.85 to 1.26) 0.97 (0.82 to 1.15) 1.07 (0.90 to 1.28)	7/9	Maternal age, smoking, parity, pre-pregnancy BMI, physical activity, breastfeeding, socioeconomic position, child sex, parental history of asthma and allergies and energy intake

BMI, body mass index; CS, cross-sectional; ECRHS, European Community Respiratory; GA²LEN, Global Allergy and Asthma European Network consortium; ISAAC, International Study of Asthma and Allergies in Childhood; NHANES, National Health and Nutrition Examination Survey; Ref, Reference category; YRBS, Youth Risk Behaviour Survey.