A comprehensive assessment of urinary iodine concentration and thyroid hormones in New Zealand schoolchildren: a cross-sectional study.

BACKGROUND: Insufficient iodine in children's diets is of concern because thyroid hormones are needed for normal growth and development, particularly of the brain. This study aimed to carry out a comprehensive assessment of the iodine status of New Zealand schoolchildren using a range of biochemical indices suitable for populations (i.e. urinary iodine concentration) and individuals (i.e. thyroid hormones). METHODS: The New Zealand National Children's Nutrition Survey was a cross-‒sectional survey of a representative sample of schoolchildren aged 5-‒14 years. Children were asked to provide a casual urine sample for the determination of urinary iodine concentration (UIC) and a blood sample for the determination of thyroglobulin (Tg), Thyroid Stimulating Hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3). RESULTS: The median UIC was 68 µg/L (n = 1153), which falls between 50-‒99 µg/L indicative of mild iodine deficiency. Furthermore, 29% of children had an UIC <50 µg/L and 82% had an UIC <100 µg/L. The median Tg concentration was 12.9 µg/L, which also falls between 10.0-‒19.9 µg/L indicative of mild iodine deficiency. The Tg concentration of children with an UIC <100 µg/L was 13.9 µg/L, higher than the 10.3 µg/L in children with an UIC >100 µg/L (P = 0.001). The mean TSH (1.7 mU/L), fT4 (14.9 pmol/L), and fT3 (6.0 pmol/L) concentrations for these mildly iodine deficient New Zealand children fell within normal reference ranges. CONCLUSIONS: The UIC and Tg concentration indicate that New Zealand schoolchildren were mildly iodine deficient according to WHO/UNICEF/ICCIDD, and both are suitable indices to assess iodine status in populations or groups. The normal concentrations of TSH, fT4 and fT3 of these children suggest that these thyroid hormones are not useful indices of mild iodine deficiency.

Through the eyes of young people: favourite places for physical activity.

INTRODUCTION: A decrease in physical activity amongst adolescents has been observed and it is well documented that low levels of activity are associated with poor health. In an attempt to understand factors that influence physical activity (PA) in young people research was undertaken with high school students in New Zealand to identify preferred places for PA and establish factors that they felt influenced levels of PA. METHODS: One hundred males and 73 females in year nine (aged 12-13) in health and physical education classes completed mapping exercises in which they delineated favourite and least favourite places for PA, where they went on a particular Sunday, how they got there and what they did, and chosen after-school activities and how they got there. RESULTS: Open public spaces were the most favoured places for PA with a nearby beach and park most frequently cited. Specific physical activities, having fun, and having friends to do an activity with were the most frequently cited reasons for liking these places. An industrial harbour area, other schools, and cemeteries were the least favoured places. Less than 2% biked somewhere on the Sunday surveyed and only 23% walked somewhere. The majority were driven to activities by car and a similar reliance on cars was observed for after-school activities. CONCLUSIONS: A combination of environmental and social factors is important in both encouraging and discouraging PA and should be taken into account when seeking to enhance PA of young people.

Higher risk of zinc deficiency in New Zealand Pacific school children compared with their Maori 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 Children's National Nutrition Survey and investigated the factors predisposing them to Zn deficiency. In a 10-month cross-sectional survey, Pacific and Maori 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 Maori 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 Maori children. Pacific children had the highest prevalence of low serum Zn (21 (95% CI 11, 30) %), followed by Maori 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 Children's 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 Maori/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.

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 Children's 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.

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 Children's 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 children's 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.

Ethnic differences in extreme obesity.

A nationwide representative survey of New Zealand schoolchildren showed a 2.7% incidence of extreme obesity (versus 4% in the United States) but revealed worrying ethnic differences in prevalence. Prevalence percentages (95% CI) were 0.8 (0.4 to 1.9), 5.1 (3.6 to 7.1), and 10.9 (8.9 to 13.3) in New Zealand European, Maori, and Pacific Island groups, respectively. These findings warrant remedial action.

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 Children's 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.

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 Children's 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.

The Dunedin Multidisciplinary Health and Development Study: are its findings consistent with the overall New Zealand population?

AIMS: To compare the health of the Dunedin Multidisciplinary Health and Development Study members with people of the same age in the nationally representative New Zealand Health and National Nutrition Surveys. METHOD: Where similar information was obtained, means or proportions and confidence intervals were generated for both the age 26 assessment of the Dunedin sample and for the 25-26 year old participants in the national surveys. The populations were considered to differ when confidence intervals did not overlap. RESULTS: For smoking habit, body mass index, waist-hip ratio, general practitioner and medical specialist consultations, and hospital admissions, the findings of the Dunedin Study were not significantly different to the nationally representative surveys. The Dunedin Study members also did not differ from their national counterparts on SF-36 subscales measuring physical functioning, bodily pain, general health, vitality, and mental health. They had better scores on the three interference subscales of the SF-36 compared to the national sample, and men in the Dunedin Study spent a little more time doing vigorous physical activity. DISCUSSION: For most outcomes, the Dunedin Study members were very similar to the nationally representative samples. There was little evidence that the repeated assessments in the Dunedin Study had significantly altered the Study members' health, either in terms of responses to questionnaires or on physiological measures of health status. Findings from the Dunedin Study are likely to be generalisable to most young New Zealanders. However, the Dunedin Study is under-representative of Maori and Pacific peoples, so these findings need to be interpreted with caution in this context. Implications for the proposed national Longitudinal Study of New Zealand Children and Families are discussed.

Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y.

New Zealand children, particularly those of Maori and Pacific ethnicity, may be at risk for low vitamin D status because of low vitamin D intakes, the country's latitude (35-46 degrees S), and skin color. The aim of this study was to determine 25-hydroxyvitamin D concentrations and their determinants in a national sample of New Zealand children aged 5-14 y. The 2002 National Children's Nutrition Survey was designed to survey New Zealand children, including oversampling of Maori and Pacific children to allow ethnic-specific analyses. A 2-stage recruitment process occurred using a random selection of schools, and children within each school. Serum 25-hydroxyvitamin D concentration [mean (99% CI) nmol/L] in Maori children (n = 456) was 43 (38,49), in Pacific (n = 646) 36 (31,42), and in New Zealand European and Others (NZEO) (n = 483) 53 (47,59). Among Maori, Pacific, and NZEO, the prevalence (%, 99% CI) of serum 25-hydroxyvitamin D deficiency (<17.5 nmol/L) was 5 (2,12), 8 (5,14), and 3 (1,7), respectively. The prevalence of insufficiency (<37.5 nmol/L) was 41 (29,53), 59 (42,75), and 25 (15,35), respectively. Multiple regression analysis found that 25-hydroxyvitamin D concentrations were lower in winter than summer [adjusted mean difference (99% CI) nmol/L; 15 (8,22)], lower in girls than boys [5 (1,10)], and lower in obese children than in those of "normal" weight [6 (1,11)]. Relative to NZEO, 25-hydroxyvitamin D concentrations were lower in Maori [9 (3,15)] and Pacific children [16 (10,22)]. Ethnicity and season are major determinants of serum 25-hydroxyvitamin D. There is a high prevalence of vitamin D insufficiency in New Zealand children, which may or may not contribute to increased risk of osteoporosis and other chronic disease. There is a pressing need for more convincing evidence concerning the health risks associated with the low vitamin D status in New Zealand children.

Implementation of a successful lifestyle intervention programme for New Zealand Maori to reduce the risk of type 2 diabetes and cardiovascular disease.

Lifestyle programmes have been shown to reduce the risk of type 2 diabetes in European populations. The participation of Maori in many mainstream health programmes is poor. This study evaluates a lifestyle intervention programme which is acceptable to Maori and which has objective outcome measures to determine the effectiveness of the programme. Thirty six Maori men and women were recruited for a 4 month programme involving modification of diet and exercise. Insulin sensitivity was measured using a euglycaemic insulin clamp, body composition using dual-energy-absorptiometry and fitness using a submaximal exercise test. Secondary outcome measures included anthropometry, blood pressure, fasting glucose and insulin levels, and lipid profiles. There was a 24% improvement in insulin sensitivity (from 5.1 to 6.3 G/mIU/L, P=0.03, N=29). This was associated with a reduction of 3.1 kg in weight (95%CI -4 to -2) and a reduction of 7 mmHg in systolic blood pressure (95%CI -13, -1). This approach successfully reduced risk for type 2 diabetes and cardiovascular disease in New Zealand Maori in the short term.

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.

Intensive lifestyle changes are necessary to improve insulin sensitivity: a randomized controlled trial.

OBJECTIVE: The extent to which lifestyle must be altered to improve insulin sensitivity has not been established. This study compares the effect on insulin sensitivity of current dietary and exercise recommendations with a more intensive intervention in normoglycemic insulin-resistant individuals. RESEARCH DESIGN AND METHODS: Seventy-nine normoglycemic insulin-resistant (determined by the euglycemic insulin clamp) men and women were randomized to either a control group or one of two combined dietary and exercise programs. One group (modest level) was based on current recommendations and the other on a more intensive dietary and exercise program. Insulin sensitivity was measured using a euglycemic insulin clamp, body composition was measured using dual-energy X-ray absorptiometry, and anthropometry and aerobic fitness were assessed before and after a 4-month intervention period. Four-day dietary intakes were recorded, and fasting glucose, insulin, and lipids were measured. RESULTS: Only the intensive group showed a significant improvement in insulin sensitivity (23% increase, P=0.006 vs. 9% in the modest group, P=0.23). This was associated with a significant improvement in aerobic fitness (11% increase in the intensive group, P=0.02 vs. 1% in the modest group, P=0.94) and a greater fiber intake, but no difference in reported total or saturated dietary fat. CONCLUSIONS: Current clinical dietary and exercise recommendations, even when vigorously implemented, did not significantly improve insulin sensitivity; however, a more intensive program did. Improved aerobic fitness appeared to be the major difference between the two intervention groups, although weight loss and diet composition may have also played an important role in determining insulin sensitivity.