Relationship between vitamin D, iron, and hepcidin in premenopausal females, potentially confounded by ethnicity.

PURPOSE: To investigate the associations between vitamin D, hepcidin, and iron status in premenopausal females of different ethnic cohorts residing in Auckland, New Zealand (NZ). METHODS: A total of 160 females aged 18-45 years participated in a cross-sectional study. Demographics, body composition, serum 25(OH)D, inflammatory markers (C-reactive protein and interleukin-6, IL-6), and iron biomarkers (serum ferritin, haemoglobin, soluble transferrin receptor, and hepcidin) were measured. Comparisons between parametric, non-parametric, and categorical variables were completed by using one-way ANOVA, Kruskal-Wallis, and Chi-squared tests, respectively. ANCOVA was used to compare serum 25(OH)D across iron parameter categories. RESULTS: Of the 160 participants, 60 were NZ European, 67 were South Asian, and 33 were from the 'other' ethnic groups. South Asians had significantly higher body fat percentage (BF%) and IL-6 concentration (38.34% and 1.66 pg·mL-1, respectively), compared to NZ Europeans (27.49% and 0.63 pg·mL-1, respectively, p < 0.001). South Asians had significantly lower 25(OH)D concentrations compared to NZ Europeans (33.59 nmol·L-1 vs 74.84 nmol·L-1, p < 0.001). In NZ Europeans, higher 25(OH)D concentration was seen in those with lower (≤ 3.5 nM) hepcidin concentration, p = 0.0046. In South Asians, higher 25(OH)D concentration was seen in those with higher (> 3.5 nM) hepcidin concentrations, p = 0.038. There were no associations between serum 25(OH)D and serum ferritin. CONCLUSION: Within South Asian women, an unexpected positive relationship between 25(OH)D and hepcidin concentration was observed which may be due to significantly higher IL-6 concentrations, BF%, and lower 25(OH)D concentrations. Future research is required to confirm these observations in this ethnic cohort.

Iron deficiency and risk factors in pre-menopausal females living in Auckland, New Zealand.

BACKGROUND AND OBJECTIVES: Iron deficiency is prevalent in New Zealand, with low dietary haem intake and blood loss previously identified as risk factors. However, the influence of the hormone hepcidin on iron status has not been investigated. METHODS AND STUDY DESIGN: Females (n=170) aged 18-45 residing in Auckland participated in a cross-sectional study. Iron status and inflammation were assessed with serum biomarkers including; serum ferritin, haemoglobin, soluble transferrin receptor, hepcidin, C-reactive protein and interleukin-6. Lifestyle factors were assessed using a series of validated questionnaires, including an iron food frequency questionnaire. Potential determinants of serum ferritin were identified using multiple linear regression analysis. RESULTS: Iron insufficiency was confirmed in 55.8% of participants (Serum ferritin <30 µg·L-1). Hepcidin levels were higher in those who were iron sufficient (Serum ferritin ≥30 µg·L-1) (6.62 nM vs 1.17 nM, p<0.001). South Asian females had higher hepcidin (8.78 nM) levels, compared to New Zealand Europeans (6.28 nM) (p=0.018), a result likely due to South Asians presenting with higher interleukin-6 (1.66 vs 0.63 pg·mL-1, p<0.001). Hepcidin (ß=0.082, p<0.001) and frequency of meat intake (ß=0.058, p=0.001) were identified as significant predictors of serum ferritin in New Zealand Europeans, while hepcidin was the only identified predictor in South Asians (ß=0.138, p<0.001) and those of other ethnicities (ß=0.117, p<0.002). CONCLUSIONS: This is the first study in New Zealand to show that hepcidin levels strongly predict serum ferritin in premenopausal females. Additionally, frequency of meat intake appears to be an important determinant of iron status in New Zealand Europeans.

Characterizing patterns of dietary exposure using metabolomic profiles of human biospecimens: a systematic review.

CONTEXT: Establishing diet-disease associations requires reliable assessment of dietary intake. With the rapid advancement of metabolomics, its use in identifying objective biomarkers of dietary exposure has substantially increased. OBJECTIVE: The aim of our review was to systematically combine all observational studies linking dietary intake patterns with metabolomic profiles of human biospecimens. DATA SOURCES: Five databases were searched - MEDLINE, Embase, Scopus, Web of Science, and Cochrane CENTRAL - to March 2020. DATA EXTRACTION: Of the 14 328 studies initially screened, 35 observational studies that met the specified inclusion criteria were included. DATA ANALYSIS: All reviewed studies indicated that metabolomic measures were significantly correlated with dietary patterns, demonstrating the potential for using objective metabolomic measures to characterize individuals' dietary intake. However, similar dietary patterns did not always result in similar metabolomic profiles across different study populations. CONCLUSION: Metabolomic profiles reflect a multitude of factors, including diet, genetic, phenotypic, and environmental influences, thereby providing a more comprehensive picture of the impact of diet on metabolism and health outcomes. Further exploration of dietary patterns and metabolomic profiles across different population groups is warranted.

Evaluating a novel dietary diversity questionnaire to assess dietary diversity and adequacy of New Zealand women.

OBJECTIVES: We sought to develop and evaluate the relative validity of a dietary diversity questionnaire (DDQ) that reflects food-group diversity, food variety, and micronutrient adequacy among New Zealand women. METHODS: A cross-sectional study included New Zealand women (Auckland based; ages 16-45 y, n = 101), completing a 7-d DDQ and 4-d weighed food record (reference method). The relative validity of the DDQ was evaluated by correlating nutritious and discretionary dietary diversity scores (DDSs; number of food groups) and food-variety scores (number of foods), calculated from both methods. The dietary mean adequacy ratio (MAR; micronutrient intakes relative to estimated average requirements) was calculated from the weighed food record and correlated to dietary diversity and food-variety scores from the DDQ to assess construct validity. Cross-tabulation was used to explore dietary diversity measures versus adequacy ratios. Significance was set at P < 0.05. RESULTS: The median (interquartile range) DDSs (maximum 25) from the DDQ-23 (21-23)-and the weighed food record-18 (17-19)-were significantly correlated (rs = 0.33, P < 0.001), as were the food-variety scores (maximum 237)-respectively, 75 (61-87) and 45 (37-52) (rs = 0.22, P < 0.03). A mean (± SD) MAR of 0.94 ± 0.04 suggested a near-adequate diet, but one-third of foods consumed were from discretionary sources. Nutritious DDS was significantly correlated with MAR for micronutrients (rs = 0.20, P ≤ 0.05). An inverse trend was observed between discretionary DDS and MAR. CONCLUSIONS: The DDQ is a quick, low-burden tool for describing nutritious and discretionary dietary diversity reflecting micronutrient adequacy in high-income settings. It requires further validation across different time frames, population groups, and settings.

Factors affecting optimal nutrition and hydration for people living in specialised dementia care units: A qualitative study of staff caregivers' perceptions.

AIM: To explore the perceptions of staff caregivers regarding factors affecting optimal nutrition and hydration for individuals living in Specialised Dementia Care Units in New Zealand. METHODS: Qualitative descriptive study using a semi-structured interview approach with 11 staff caregivers at two Specialised Dementia Care Units. Data were analysed using a general inductive approach. RESULTS: Two main themes were identified. The first theme 'It's about the individual' encompassed individual factors such as appetite, food appeal, and cognitive and functional abilities. The second theme 'It's about the environment' encompassed factors relating to the dining environment, the social aspects to dining and the provision of support with mealtime activities. CONCLUSIONS: Factors affecting nutrition and hydration in people living with dementia are complex and inter-related. Organisations providing specialised dementia care, their staff and foodservice providers should focus on both the individual and environment to ensure optimal nutrition and hydration for the people in their care.