Noela C. Wilson

Correlates of body mass index among a nationally representative sample of New Zealand children

OBJECTIVES To describe how nutrition behaviours and physical activity are associated with body mass index (BMI) among New Zealand children and to determine if these relationships vary by ethnicity. METHODS Data were collected during the 2002 National Childrens Nutrition Survey. 3250 children provided information about their eating and activity behaviours and anthropometric measurements. RESULTS Approximately 31% of New Zealand children aged 5 to 14 years were overweight/obese, with the highest prevalences of overweight/obesity among Pacific children (62%) and Mäori children (41%). Higher prevalences of obesity were also observed among females and children experiencing socioeconomic deprivation. Television use, buying school food from the dairy/takeaway shops, skipping breakfast, consumption of fruit drinks/soft drinks, and low physical activity were associated with BMI in analyses controlling for demographic characteristics among the total population. Buying school food from the dairy/takeaway (p=0.04) and skipping breakfast (p=0.007) retained significance when all nutrition behaviours and physical activity were analysed simultaneously. Significant interactions between ethnicity and bringing school food from home and buying school food from school were observed in relation to BMI. In most cases, the relationships were most significant for Pacific children. CONCLUSIONS Strategies to address childhood obesity among all New Zealand children should primarily include efforts to increase breakfast consumption and decrease food purchases away from home. Given the high rates of obesity between Pacific and Mäori children, targeted interventions are warranted and should include strategies to improve the school food environment.

Exploring the relationship between sugars and obesity.

OBJECTIVE Investigate the relationship between body mass index (BMI) and intake of sugars and fat in New Zealand adults and children. DESIGN Secondary analyses of National Nutrition Survey (1997) and Childrens Nutrition Survey (2002) data for the New Zealand population. BMI calculated from height and weight; fat, sugars and sucrose (used as a surrogate for added sugars) intakes estimated from 24-hour diet recall. Ethnic-specific analyses of childrens data. Relationships (using linear regression) between BMI and sugars/sucrose intakes; per cent total energy from fat; mean total energy intake from sucrose. Subjects classified into diet-type groups by levels of intake of fat and sucrose; relative proportions of overweight/obese children in each group compared with that of normal weight subjects using design-adjusted chi2 tests. SETTING New Zealand homes and schools. SUBJECTS 4379 adults (15+ years); 3049 children (5-14 years). RESULTS Sugars (but not sucrose) intake was significantly lower among obese compared to normal weight children. In adults and children, those with the lowest intake of sugars from foods were significantly more likely to be overweight/obese. Sucrose came predominantly from beverages; in children, 45% of this was from powdered drinks. Sucrose intake from sugary beverages was not related to BMI. Per cent total energy (%E) from sucrose was significantly inversely related to %E from fat among adults and children. Proportions of overweight/obese adults or children in each diet-type group did not differ from that of normal weight individuals. CONCLUSIONS Current sugars or sucrose intake is not associated with body weight status in the New Zealand population.

Serum selenium concentrations and dietary selenium intake of New Zealand children aged 5-14 years

Serum Se concentrations and dietary Se intakes have been determined in relation to age, sex, ethnicity, region and index of deprivation in a nationally representative sample of New Zealand children aged 5-14 years from the 2002 National Childrens Nutrition Survey. Dietary intake was assessed from computer-assisted, multiple-pass 24 h diet recall interviews (n 3275). Serum Se concentrations were obtained from a subset of urban-based children (n 1547). Mean (95 % CI) serum Se concentration in children was 0.96 (0.93, 1.00) micromol/l. Males (1.00 micromol/l) had higher serum Se levels than females (0.93 micromol/l; P = 0.027). Mäori children had lower serum Se than Pacific Islands children (P = 0.038) and New Zealand European and Other children (P = 0.005). Children in the Upper North Island (1.06 micromol/l) had higher mean serum Se values than those in the Lower North Island (0.98 micromol/l, P < 0.0005) and South Island (0.79 micromol/l, P < 0.0005), and serum Se in the Lower North Island was higher than that in the South Island (P < 0.0005). Mean dietary Se intake was 36 (34, 37) microg/d. The intakes of children aged 5-6 years (31 microg/d) were lower than those of children aged 7-10 and 11-14 years (35 and 38 microg/d, respectively; P < 0.00 005) and the intakes of 7-10-year-olds were lower than those of 11-14-year-olds (P = 0.002). Serum Se was associated with dietary Se after adjusting for all variables, including region (P = 0.006). The Se status of our children falls in the middle of the international range of serum Se concentrations, but that for children in the South Island is among the lowest values reported and may be a cause for concern.

Higher risk of zinc deficiency in New Zealand Pacific school children compared with their Māori and European counterparts: a New Zealand national survey.

Few multi-ethnic national surveys have examined Zn nutriture, despite its importance for optimal growth and development during childhood. We assessed the Zn status of urban and semi-urban children aged 5-15 years from three ethnic groups in New Zealand (NZ) in the 2002 Childrens National Nutrition Survey and investigated the factors predisposing them to Zn deficiency. In a 10-month cross-sectional survey, Pacific and Māori children were over-sampled permitting ethnic-specific analyses. Anthropometry, serum Zn and Zn intakes via 24 h recalls were measured. Anthropometric z scores were highest in Pacific children. Overall, mean adjusted serum Zn at 11 years was for males and females, respectively: 11·9 (95% CI 11·5, 12·3) and 12·5 (95% CI 12·0, 12·9) μmol/l in NZ European and Other (NZEO) children (n 395); 11·9 (95% CI 11·4, 12·4) and 12·0 (95% CI 11·4, 12·5) μmol/l in Māori children (n 379); and 11·5 (95% CI 11·1, 11·9) and 11·4 (95% CI 11·1, 11·8) μmol/l in Pacific children (n 589). The predictors of serum Zn were age, serum Se and sex for NZEO children; serum Se and age for Pacific children; and none for Māori children. Pacific children had the highest prevalence of low serum Zn (21 (95% CI 11, 30) %), followed by Māori children (16 (95% CI 12, 20) %) and NZEO children (15 (95% CI 9, 21) %). Prevalence of inadequate Zn intakes, although low, reached 8% for Pacific children who had the lowest Zn intake/kg body weight. Pacific boys but not girls with low serum Zn had a lower mean height-for-age z-score (P < 0·007) than those with normal serum Zn. We conclude that the biochemical risk of Zn deficiency in Pacific children indicates a public health problem. However, a lack of concordance with the risk of dietary Zn inadequacy suggests the need for better defined cut-offs in children.

Nutrients and foods consumed by New Zealand children on schooldays and non-schooldays.

OBJECTIVE To describe and compare food and nutrient intakes in New Zealand (NZ) children on schooldays and non-schooldays. DESIGN Secondary analysis of cross-sectional data from the NZ 2002 Childrens Nutrition Survey. Dietary intake was assessed using computer-assisted multi-pass 24 h dietary recalls in the home. Data were adjusted for survey weightings to be representative of the NZ population. The effect of day category on nutrient intake, and likelihood of consumption of food categories were determined using linear and logistic regression. SETTING NZ homes and schools. SUBJECTS A total of 2572 children (538 non-schooldays and 2034 schooldays) at the age of 5-14 years. RESULTS There were differences in the proportion consuming some food groups between schooldays and non-schooldays, although the majority of nutrient intakes including energy did not differ by day category. Mean cholesterol intake was higher on non-schooldays; dietary fibre and available carbohydrate, in particular sucrose and fructose, were higher on schooldays. Hot chips were twice as likely to be consumed on a non-schoolday. Soft drink consumption was higher on non-schooldays for Māori/New Zealand European and others and powdered drinks/cordial consumption did not vary by day category. More children consumed snack bars (normal weight, obese), fruit, sandwiches, biscuits/crackers and snack foods on schooldays. There was no difference in consumption of pies/sausage rolls by day category. CONCLUSIONS The proportion of consumers of a variety of foods differed significantly between non-schooldays and schooldays; few nutrient intakes differed. The present study indicates that family food, wherever it is consumed, is the mainstay of nutrition for NZ schoolchildren.

The Risk of Inadequate Zinc Intake in United States and New Zealand Adults.

A comparison of the 1997 New Zealand National Nutrition Survey and the US 1988-1994 National Health and Nutrition Examination Survey III showed that dietary zinc intakes for the New Zealand population, adjusted for intrasubject variation, were generally higher than those for the Unites States. Adult groups with the lowest percentage of adequate intakes of zinc were seniors aged >71 years in both surveys, followed by women aged 51 to 70 years in New Zealand, and females aged 11-18 years in the United States.

What children eat during afternoons and evenings: is it important?

OBJECTIVE To complete a description of the dietary intakes of New Zealand schoolchildren by describing afternoon and evening foods and nutrients. DESIGN Twenty-four hour dietary recall data from the 2002 Childrens Nutrition Survey were analysed to describe food and nutrient intakes during the afternoon (14.00 to 16.59 hours) and evening (17.00 to 23.59 hours). SETTING New Zealand homes and schools. SUBJECTS Children (n 2875) aged 5-14 years. RESULTS Most children consumed something during the afternoon (79 %) and evening (98 %). Children were less likely to consume something during non-school day afternoons; if 11-14 years of age; and when of Pacific ethnicity. Afternoon food consumers had higher daily intakes for most nutrients. Afternoon intake accounted for much of this difference. In the afternoon, children consumed fruit (26 %) and biscuits/crackers (21 %). Evening eating contributed to daily intakes of energy (40 %), fat (43 %), carbohydrate (35 %), sucrose (20 %), glucose (24 %), vitamin A (47 %), Ca (26 %) and Fe (40 %). Children aged 5-6 years consumed a lower proportion of their daily energy intake during the evening than older children. In the evening, just one-third of children consumed vegetables (45 % if including potato/kumara/taro), 19 % fruit and 17 % ate hot chips. Children were more likely to consume vegetables if they also consumed potato/kumara/taro. Twenty-three per cent of children had powdered drinks/cordials, 21 % had soft drinks and 19 % had milk. CONCLUSIONS Consuming foods/drinks in the afternoon positively influenced macronutrient distribution, increasing the carbohydrate proportion. During the evening 40 % of energy intake was consumed but less than one-half of children consumed vegetables; thus inclusion of vegetables in the evening is important, particularly in meals without potato/kumara/taro.