Bidirectional associations between diet and body composition measures from 2 to 15 years: Longitudinal Study of Australian Children

This study investigates how dietary patterns and scores are associated with subsequent BMI and waist:height ratio (WHtR), and how BMI and WHtR are associated with subsequent dietary patterns or scores, from 2-3 to 10-11 and 4-5 to 14-15 years of age. In the Longitudinal Study of Australian Children, height, weight and waist circumference were measured biennially in children, yielding BMI z-score and WHtR. Parents, latterly children, reported frequency of child consumption of 12-16 food/drink items during the previous 24 h. At each wave, we empirically derived dietary patterns using factor analyses, and dietary scores based on the 2013 Australian Dietary Guidelines. We used structural-equation modelling to investigate cross-lagged associations (n 1972-2882) between diet and body composition measures in univariable and multivariable analyses. Dietary scores/patterns did not consistently predict WHtR and BMI z-score in the next wave, nor did BMI z-score and WHtR consistently predict diet in the next wave. The few associations seen were weak and often in the opposite direction to that hypothesised. The largest effect, associated with each standard deviation increase in BMI in wave 5 of the K cohort (age 12-13 years), was a 0·06 standard deviation estimated mean increase in dietary score (higher quality diet) in the subsequent wave (95 % CI 0·02, 0·11, P=0·003). Associations between dietary patterns/scores and body composition were not strongly evident in either direction. Better quantitative childhood dietary tools feasible for large-scale administration are needed to quantify how dietary patterns, energy intake and anthropometry co-develop.

Associations between energy density of meals and snacks and overall diet quality and adiposity measures in British children and adolescents: the National Diet and Nutrition Survey

This cross-sectional study examined how energy density (ED) of meals and snacks are associated with overall diet quality and adiposity measures in 1617 British children aged 4-18 years from the 1997 National Diet and Nutrition Survey. On the basis of data from 7-d weighed dietary record, all eating occasions were divided into meals or snacks on the basis of time (meals: 06.00-09.00, 12.00-14.00 and 17.00-20.00 hours; snacks: all others) or contribution to energy intake (EI) (meals: ≥15 %; snacks: <15 %). ED of meals and snacks was calculated on the basis of food only. Overall diet quality was assessed using the Mediterranean diet score (range 0-8). Irrespective of the definition of meals and snacks, ≥67 % of EI was derived from meals, whereas ED of meals was lower than ED of snacks (mean: 8·50-8·75 v. 9·69-10·52 kJ/g). Both ED of meals and ED of snacks were inversely associated with total intakes of vegetables, fruits, dietary fibre and overall diet quality and positively associated with total intakes of fat. However, the associations were stronger for ED of meals. The change in the Mediterranean diet score with a 1-unit increase of ED (kJ/g) was -0·35 to -0·30 for ED of meals and -0·09 to -0·06 for ED of snacks (all P<0·0001). After adjustment for potential confounders, all measures of ED of meals and snacks did not show positive associations with adiposity measures. In conclusion, although both ED of meals and ED of snacks were associated with adverse profiles of overall diet quality (but not adiposity measures), stronger associations were observed for ED of meals.

Oxidative stress and nitric oxide are increased in obese children and correlate with cardiometabolic risk and renal function

Oxidative stress and nitric oxide (NO) appear to represent important links between obesity and cardiovascular, metabolic and/or renal disease. We investigated whether oxidative stress and NO production/metabolism are increased in overweight and obese prepubertal children and correlate with cardiometabolic risk and renal function. We performed a cross-sectional evaluation of 313 children aged 8-9 years. Anthropometrics, 24-h ambulatory blood pressure, pulse wave velocity (PWV), insulin resistance (homoeostasis model assessment index (HOMA-IR)), inflammatory/metabolic biomarkers, estimated glomerular filtration rate (eGFR), plasma total antioxidant status (TAS), plasma and urinary isoprostanes (P-Isop, U-Isop), urinary hydrogen peroxide (U-H2O2), and plasma and urinary nitrates and nitrites (P-NOx, U-NOx) were compared among normal weight, overweight and obese groups, according to WHO BMI z-score reference. U-Isop were increased in the obese group, whereas U-NOx were increased in both overweight and obese children. U-Isop were positively correlated with U-H2O2, myeloperoxidase (MPO), high-sensitivity C-reactive protein, HOMA-IR and TAG. TAS correlated negatively with U-Isop and MPO and positively with PWV. HOMA-IR and U-H2O2 were associated with higher U-Isop, independently of BMI and eGFR, and total cholesterol and U-H2O2 were associated with U-NOx, independently of BMI, eGFR values and P-NOx concentration. In overweight and obese children, eGFR decreased across P-NOx tertiles (median: 139·3 (25th, 75th percentile 128·0, 146·5), 128·0 (25th, 75th percentile 121·5, 140·4), 129·5 (25th, 75th percentile 119·4, 138·3), P for linear trend=0·003). We conclude that oxidant status and NO are increased in relation to fat accumulation and, even in young children, they translate into higher values of cardiometabolic risk markers and affect renal function.

Decreasing the number of small eating occasions (<15 % of total energy intake) regardless of the time of day may be important to improve diet quality but not adiposity: a cross-sectional study in British children and adolescents

Evidence of associations between meal frequency (MF) and snack frequency (SF) and diet and obesity in young populations is limited. This cross-sectional study examined MF and SF in relation to dietary intake and adiposity measures in British children aged 4-10 years (n 818) and adolescents aged 11-18 years (n 818). Based on data from a 7-d weighed dietary record, all eating occasions were divided into meals or snacks on the basis of contribution to energy intake (≥15 or <15 %) or time (06.00-10.00, 12.00-15.00 and 18.00-21.00 hours or others). All measures of MF and SF showed positive associations with energy intake, except for MF based on energy contribution in children. Irrespective of the definition of snacks, SF was associated with higher intakes of soft drinks, confectionery and total sugar, lower intakes of cereals, fish, meat, protein, PUFA, starch and dietary fibre, and a lower diet quality (assessed by the Mediterranean diet score, except for SF based on energy contribution in adolescents). MF based on time, but not based on energy contribution, was associated with higher intakes of confectionery and total sugar, lower intakes of fish, protein, PUFA and starch, and, only in children, a lower diet quality. All measures of MF and SF showed no association with adiposity measures. In conclusion, this cross-sectional study in British children and adolescents suggests that decreasing the number of small eating occasions (<15 % of total energy intake) regardless of the time of day may be important to improve diet quality but not adiposity.