Childhood dietary patterns and cardiovascular risk factors in adolescence:results from the ALSPAC cohort

OBJECTIVE: To investigate the prospective associations between dietary patterns in childhood and CVD risk in adolescence. DESIGN: Prospective cohort study. Exposures were dietary patterns at age 7, 10 and 13 years derived by cluster analysis. Outcomes were physiological and biochemical cardiovascular risk markers. SETTING: Avon Longitudinal Study of Parents and Children (ALSPAC), UK. SUBJECTS: Children (n 2311, 44.1 % male) with complete data available. RESULTS: After adjustment for known confounders, we observed an association between being in the ‘Processed’ and ‘Packed lunch’ dietary pattern clusters at age 7 and BMI at age 17. Compared with the ‘healthy’ cluster, the OR (95 % CI) for being in the top 10 % for BMI was 1·60 (1·01, 2·55; P=0·05) for the ‘Processed’ cluster and 1·96 (1·22, 3·13; P=0·005) for the ‘Packed lunch’ cluster. However, no association was observed between BMI and dietary patterns at age 10 and 13. Longitudinal analyses showed that being in either the ‘Processed’ or ‘Packed lunch’ cluster at age 7 was associated with increased risk of being in the top 10 % for BMI regardless of subsequent cluster membership. No associations between other cardiovascular risk measures and dietary patterns were robust to adjustment for confounders. CONCLUSIONS: We did not find any consistent evidence to support an association between dietary patterns in childhood and cardiovascular risk factors in adolescence, with the exception of BMI and dietary pattern at age 7 only. However, the importance of dietary intake in childhood upon health later in life requires further investigation and we would encourage the adoption of a healthy diet as early in life as possible

Is the growth of the child of a smoking mother influenced by the father's prenatal exposure to tobacco? A hypothesis generating longitudinal study

OBJECTIVES: Transgenerational effects of different environmental exposures are of major interest, with rodent experiments focusing on epigenetic mechanisms. Previously, we have shown that if the study mother is a non-smoker, there is increased mean birth weight, length and body mass index (BMI) in her sons if she herself had been exposed prenatally to her mother's smoking. The aim of this study was to determine whether the prenatal smoke exposure of either parent influenced the growth of the fetus of a smoking woman, and whether any effects were dependent on the fetal sex. DESIGN: Population-based prebirth cohort study. SETTING: Avon Longitudinal Study of Parents and Children. PARTICIPANTS: Participants were residents of a geographic area with expected date of delivery between April 1991 and December 1992. Among pregnancies of mothers who smoked during pregnancy, data were available concerning maternal and paternal prenatal exposures to their own mother smoking for 3502 and 2354, respectively. PRIMARY AND SECONDARY OUTCOME MEASURES: Birth weight, length, BMI and head circumference. RESULTS: After controlling for confounders, there were no associations with birth weight, length or BMI. There was a strong adjusted association of birth head circumference among boys whose fathers had been exposed prenatally (mean difference −0.35 cm; 95% CI −0.57 to −0.14; p=0.001). There was no such association with girls (interaction p=0.006). Similar associations were found when primiparae and multiparae were analysed separately. In order to determine whether this was reflected in child development, we examined the relationships with IQ; we found that the boys born to exposed fathers had lower IQ scores on average, and that this was particularly due to the verbal component (mean difference in verbal IQ −3.65 points; 95% CI −6.60 to −0.70). CONCLUSIONS: Head size differences concerning paternal fetal exposure to smoking were unexpected and, as such, should be regarded as hypothesis generating

Visual Perceptual Difficulties and Under-Achievement at School in a Large Community-Based Sample of Children

Difficulties with visual perception (VP) are often described in children with neurological or developmental problems. However, there are few data regarding the range of visual perceptual abilities in populations of normal children, or on the impact of these abilities on children's day-to-day functioning. Methods Data were obtained for 4512 participants in an ongoing birth cohort study (Avon Longitudinal Study of Parents and Children; ALSPAC). The children's mothers responded to questions designed to elicit indications of visual perceptual difficulties or immaturity, when their children were aged 13 years. We examined associations with standardised school test results in reading and in mathematics at age 1314 years (SATS-KS3), accounting for potential confounders including IQ. Results Three underlying factors explained half the variance in the VP question responses. These correlated best with questions on interpreting cluttered scenes; guidance of movement and face recognition. The adjusted parameter estimates (95% CI) for the cluttered-scenes factor (0.05; 0.02 to 0.08; p<0.001) suggested positive associations with the reading test results whilst that for the guidance-of-movement factor (0.03; 0.00 to 0.06; p = 0.026) suggested positive association with the mathematics results. The raw scores were associated with both test results. Discussion VP abilities were widely distributed in this sample of 13-year old children. Lower levels of VP function were associated with under-achievement in reading and in mathematics. Simple interventions can help children with VP difficulties, so research is needed into practicable, cost-effective strategies for identification and assessment, so that support can be targeted appropriately

Dietary patterns in pregnancy and associations with nutrient intakes

Despite the recent popularity in the use of dietary patterns to investigate diet-disease associations, the associations between dietary patterns and nutrient intakes have not been fully explored. This paper determines the linear and non-linear associations between estimated nutrient intake (considered as both absolute and relative intake) and distinct dietary patterns, obtained during the third trimester of pregnancy using principal components analysis (PCA). It also examines the proportion of variability explained by the patterns in food and nutrient intakes. Pregnant women were asked to record the frequency of consumption of a variety of food items as part of regular self-completion questionnaires, the primary source of data collection in the Avon Longitudinal Study of Parents and Children, 12 035 cases were available. Individual dietary components were identified using PCA and scores on these components were related to estimated nutrient intakes. Five individual dietary patterns were established to best describe the types of diet being consumed in pregnancy. Scores on the ‘processed’ and ‘confectionery’ patterns were negatively related to the estimated intake of most nutrients with the exception of energy, fats and sugars, which increased with higher scores. Scores on the ‘health-conscious’ and ‘traditional’ components showed positive linear relationships with all nutrients. The results presented here suggest that dietary patterns adequately characterize dietary intake. There is, therefore, potential for dietary patterns to be used as a valid tool in assessing the relationship between diet and health outcomes, and dietary pattern scores could be used as covariates in specific nutrient-disease studies

Picky eating in preschool children:associations with dietary fibre intakes and stool hardness

It has been suggested that constipation may be associated with picky eating. Constipation is a common condition in childhood and a low intake of dietary fibre may be a risk factor. Differences in fibre intake between picky and non-picky children and its relation to stool consistency is currently not well-understood. Children enrolled in the Avon Longitudinal Study of Parents and Children identified as picky eaters (PE) were compared with non-picky eaters (NPE): (1) to determine dietary fibre intake at 38 months; (2) to investigate whether any difference in dietary fibre intake was predictive of usual stool hardness at 42 months. PE was identified from questionnaires at 24 and 38 months. Usual stool hardness was identified from a questionnaire at 42 months. Dietary intake was assessed at 38 months with a food frequency questionnaire. Dietary fibre intake was lower in PE than NPE (mean difference –1.4 (95% CI –1.6, –1.2) g/day, p<0.001). PE was strongly associated with dietary fibre intake (adjusted regression model; unstandardised B –1.44 (95% CI –1.62, –1.24) g/day, p<0.001). PE had a lower percentage of fibre from vegetables compared with NPE (8.9% vs 15.7%, respectively, p<0.001). There was an association between PE and usually having hard stools (adjusted multinomial model; OR 1.31, 95% CI 1.07, 1.61; p=0.010). This was attenuated when dietary fibre was included in the model, suggesting that fibre intake mediated the association (OR 1.16, 95% CI 0.94, 1.43, p=0.180). Picky eating in 3-year-old children was associated with an increased prevalence of usually having hard stools. This association was mediated by low dietary fibre intake, particularly from vegetables, in PE. For children with PE, dietary advice aimed at increasing fibre intake may help avoid hard stools

Using Instruments for Selection to Adjust for Selection Bias in Mendelian Randomization

Selection bias is a common concern in epidemiologic studies. In the literature, selection bias is often viewed as a missing data problem. Popular approaches to adjust for bias due to missing data, such as inverse probability weighting, rely on the assumption that data are missing at random and can yield biased results if this assumption is violated. In observational studies with outcome data missing not at random, Heckman's sample selection model can be used to adjust for bias due to missing data. In this paper, we review Heckman's method and a similar approach proposed by Tchetgen Tchetgen and Wirth (2017). We then discuss how to apply these methods to Mendelian randomization analyses using individual-level data, with missing data for either the exposure or outcome or both. We explore whether genetic variants associated with participation can be used as instruments for selection. We then describe how to obtain missingness-adjusted Wald ratio, two-stage least squares and inverse variance weighted estimates. The two methods are evaluated and compared in simulations, with results suggesting that they can both mitigate selection bias but may yield parameter estimates with large standard errors in some settings. In an illustrative real-data application, we investigate the effects of body mass index on smoking using data from the Avon Longitudinal Study of Parents and Children.Comment: Main part: 27 pages, 3 figures, 4 tables. Supplement: 20 pages, 5 figures, 10 tables. Paper currently under revie