Diet quality across early childhood and adiposity at 6 years: the Southampton Women's Survey

BACKGROUND: Poor diet quality in early childhood is inconsistently linked to obesity risk. Understanding may be limited by the use of cross-sectional data and the use of body mass index (BMI) to define adiposity in childhood. OBJECTIVE: The objective of this study is to examine the effects of continued exposure to diets of varying quality across early childhood in relation to adiposity at 6 years. METHODS: One thousand and eighteen children from a prospective UK birth cohort were studied. Diet was assessed using food frequency questionnaires when the children were aged 6 and 12 months, and 3 and 6 years; diet quality was determined according to scores for a principal component analysis-defined dietary pattern at each age (characterized by frequent consumption of fruits, vegetables and fish). At each age, children were allocated a value of 0/1/2 according to third of the distribution (bottom/middle/top) their diet quality score was in; values were summed to calculate an overall diet quality index (DQI) for early childhood (range 0-8). Obesity outcomes considered at 6 years were dual-energy X-ray absorptiometry-assessed fat mass and BMI. RESULTS: One hundred and seven (11%) children had a DQI = 0, indicating a consistently low diet quality, 339 (33%) had a DQI = 1-3, 378 (37%) had a DQI = 4-6 and 194 (19%) had a DQI = 7-8. There was a strong association between lower DQI and higher fat mass z-score at 6 years that was robust to adjustment for confounders (fat mass s.d. per 1-unit DQI increase: beta = -0.05 (95% confidence interval (CI): -0.09, -0.01), P = 0.01). In comparison with children who had the highest diet quality (DQI = 7-8), this amounted to a difference in fat mass of 14% (95% CI: 2%, 28%) at 6 years for children with the poorest diets (DQI = 0). In contrast, no independent associations were observed between DQI and BMI. CONCLUSIONS: Continued exposure to diets of low quality across early childhood is linked to adiposity at the age of 6 years.