Investigation into longitudinal dietary behaviours and household socio-economic indicators and their association with BMI Z-score and fat mass in South African adolescents: the Birth to Twenty (Bt20) cohort.
OBJECTIVE
The present study aimed to assess the relationship between dietary habits, change in socio-economic status and BMI Z-score and fat mass in a cohort of South African adolescents.


METHODS
In the longitudinal study, data were collected at ages 13, 15 and 17 years on a birth cohort who have been followed since 1990. Black participants with complete dietary habits data (breakfast consumption during the week and at weekends, snacking while watching television, eating main meal with family, lunchbox use, number of tuck shop purchases, fast-food consumption, confectionery consumption and sweetened beverage consumption) at all three ages and body composition data at age 17 years were included in the analyses. Generalized estimating equations were used to test the associations between individual longitudinal dietary habits and obesity (denoted by BMI Z-score and fat mass) with adjustments for change in socio-economic status between birth and age 12 years.


METHODS
Birth to Twenty (Bt20) study, Soweto-Johannesburg, South Africa.


METHODS
Adolescents (n 1298; 49·7 % male).


RESULTS
In males, the multivariable analyses showed that soft drink consumption was positively associated with both BMI Z-score and fat mass (P < 0·05). Furthermore, these relationships remained the same after adjustment for socio-economic indicators (P < 0·05). No associations were found in females.


CONCLUSIONS
Longitudinal soft drink consumption was associated with increased BMI Z-score and fat mass in males only. Fridge ownership at birth (a proxy for greater household disposable income in this cohort) was shown to be associated with both BMI Z-score and fat mass.
MRC/WITS Developmental Pathways for Health Research Unit, School of Medicine, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa. alison.feeley@gmail.com
Alison B
AB
Feeley
Eustasius
E
Musenge
John M
JM
Pettifor
Shane A
SA
Norris
D000273:Adipose Tissue / Q000378:metabolism*; D000293:Adolescent; D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D015331:Cohort Studies; D004032:Diet; D002149:Energy Intake; D005191:Family Characteristics; D057140:Fast Foods; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015999:Multivariate Analysis; D015596:Nutrition Assessment; D009765:Obesity / Q000453:epidemiology*; D012959:Socioeconomic Factors; D013019:South Africa / Q000453:epidemiology