Resolution of age-dependent reference intervals: polynomial regression methodology with applicability to plasma zinc levels in a childhood population

Red meat and a fortified manufactured toddler milk drink increase dietary zinc intakes without affecting zinc status of New Zealand toddlers

Evidence suggests that New Zealand (NZ) children are mildly zinc deficient and may respond to dietary change. A 20-wk randomized intervention trial was therefore conducted to determine whether an increased intake of red meat or consumption of a fortified manufactured toddler milk drink (FTMD, fortified with zinc and other micronutrients) would increase dietary zinc intakes and improve the biochemical zinc status of 12- to 20-mo-old NZ toddlers. Toddlers were randomized to a red meat intervention (n = 90), FTMD intervention (n = 45), or nonfortified milk placebo (n = 90). Study foods were provided. Adherence was assessed via monthly 7-d meat or milk recording diaries. Hair and serum zinc concentrations, and length and weight were measured at baseline and postintervention. Nutrient intakes were assessed via 3-d weighed food records at baseline, wk 4, and wk 18. At baseline, 38% of participants had low serum zinc concentrations despite seemingly adequate dietary zinc intakes (<4% below the Estimated Average Requirement). Dietary zinc intakes significantly increased by 0.8 mg/d (95% CI: 0.5, 1.1) in the meat group and 0.7 mg/d (95% CI: 0.2, 1.1) in the FTMD group compared with a decrease of -0.5 (95% CI: -0.8, -0.2) mg/d in the placebo group. No corresponding increases in serum or hair zinc concentrations were observed. Dietary zinc intakes achievable via interventions based on red meat or a FTMD are unlikely to improve biochemical zinc status in NZ toddlers. These results also question cutoffs used to define zinc deficiency in toddlers.

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 Children's 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. Anthropometriczscores 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 (n395); 11·9 (95 % CI 11·4, 12·4) and 12·0 (95 % CI 11·4, 12·5) μmol/l in Māori children (n379); and 11·5 (95 % CI 11·1, 11·9) and 11·4 (95 % CI 11·1, 11·8) μmol/l in Pacific children (n589). 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-agez-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.

Serum trace elements and fat-soluble vitamins A and E in healthy pre-school children from a Venezuelan rural community

Zn (SZn), Cu (SCu), Fe (SFe), vitamin A (SVA) and vitamin E (SVE) were measured in blood serum samples of 85 healthy pre-school children aged 2-6 yr. from the rural community of Canaguá, Mérida State, Venezuela. The relationship between these biochemical indexes was also investigated. The mean serum concentrations of zinc, copper, iron, vitamin A and vitamin E were 0.74 +/- 0.25, 1.18 +/- 0.30, 0.76 +/- 0.20, 0.30 +/- 0.15 and 5.87 +/- 0.43 mg/L, respectively. There was a tendency for SZn to increase with age, whereas SCu and SVA decreased. There was no significant difference in serum trace elements and fat-soluble vitamin concentration between males and females in the different age groups. SFe tended to be lower than that reported in the literature. However, the age groups studied showed no statistically significant sex- and age-related differences. The present study shows that there is a complex interaction between SZn, SCu, SFe, SVA, SVE and age of the children. Multiple regression analysis showed serum zinc was strongly related to serum copper, and serum iron. Serum vitamin A was strongly related to serum zinc and serum vitamin E, whereas serum vitamin E was strongly related to serum zinc, serum copper, and serum vitamin A. On the other hand, our observations also suggest that more detailed studies of these metals and fat-soluble vitamins should be carried out, and that the study should include nutritional surveys, metabolic balances and associations between SZn, SCu, SFe, SVA and SVE and anthropometric variables (height, weight, body mass index and skinfold thickness).

Determination of a reference range for whole blood serotonin in a pediatric population using high pressure liquid chromatography with electrochemical detection

Whole blood serotonin (5HT) concentrations were measured in a group of children and adolescents to determine a reference range for this population. Blood was collected after at least a 6-hour fast, mixed with ascorbic acid and EDTA, and frozen at -70 degrees C until analysis. 5HT was determined by HPLC with electrochemical detection. Matrix-matched whole blood standards and controls were used to determine 5HT concentrations, and monitor performance of the assay. 5HT concentrations in boys ranged from 0.53 to 3.13 mumol/L (mean = 1.27, SD = 0.47) while the range for girls was 0.63 to 2.46 mumol/L (mean = 1.21, SD = 0.47). There was no significant difference in 5HT concentrations between boys and girls, nor was there any significant change in 5HT concentration with age. The nonparametric central 95 percent reference range for boys and girls was determined to be 0.64-2.45 mumol/L.