Anne-Louise M. Heath

Serum prohepcidin concentration: no association with iron absorption in healthy men; and no relationship with iron status in men carrying HFE mutations, hereditary haemochromatosis patients undergoing phlebotomy treatment, or pregnant women.

Hepcidin plays a major role in iron homeostasis, but understanding its role has been hampered by the absence of analytical methods for quantification in blood. A commercial ELISA has been developed for serum prohepcidin, a hepcidin precursor, and there is interest in its potential use in the clinical and research arena. We investigated the association between serum prohepcidin concentration and iron absorption in healthy men, and its relationship with iron status in men carrying HFE mutations, hereditary haemochromatosis patients, and pregnant women. Iron absorption was determined in thirty healthy men (fifteen wild-type, fifteen C282Y heterozygote) using the stable isotope red cell incorporation technique. Iron status was measured in 138 healthy men (ninety-one wild-type, forty-seven C282Y heterozygote), six hereditary haemochromatosis patients, and thirteen pregnant women. Mean serum prohepcidin concentrations were 214 (SD 118) ng/ml [208 (SD 122) ng/ml in wild-type and 225 (SD 109) ng/ml in C282Y heterozygotes] in healthy men, 177 (SD 36) ng/ml in haemochromatosis patients, and 159 (SD 59) ng/ml in pregnant women. There was no relationship between serum prohepcidin concentration and serum ferritin in any subject groups, nor was it associated with efficiency of iron absorption. Serum prohepcidin is not a useful biomarker for clinical or research purposes.

The role of blood loss and diet in the aetiology of mild iron deficiency in premenopausal adult New Zealand women

OBJECTIVE To investigate the role of blood loss and diet in the aetiology of mild iron deficiency (MID) in premenopausal New Zealand women. Mild iron deficiency was defined as low, but not necessarily exhausted, iron stores (i.e. serum ferritin <20 microg/L) in the absence of anaemia (i.e. haemoglobin > or =120 g/L). DESIGN Cross-sectional study of a volunteer sample of premenopausal adult women. Information on habitual dietary intakes (using a specially designed and validated computerised iron food frequency questionnaire), health and demographic status, sources of blood loss (including menstrual blood loss estimated using a validated menstrual recall method), contraceptive use, height and weight, haemoglobin, serum ferritin and C-reactive protein were collected. SETTING Dunedin, New Zealand during 1996/1997. PARTICIPANTS Three hundred and eighty-four women aged 18-40 years. RESULTS The characteristics that were associated with an increased risk of MID were: low meat/fish/poultry intake, high menstrual blood loss, recent blood donation, nose bleeds, and low body mass index. The protective factors included shorter duration of menstrual bleeding, and multivitamin-mineral supplement use in the past year. CONCLUSIONS There are a number of potentially modifiable factors that appear to influence risk of MID. Women with low menstrual blood loss may be able to decrease their risk of MID by increasing their meat/fish/poultry intake, while those with a higher menstrual blood loss may be able to decrease their risk by decreasing their menstrual blood loss, perhaps by changing their method of contraception. Women should be encouraged to maintain a healthy body weight, and those who choose to donate blood, or who experience nose bleeds, should have their iron stores monitored.

Can dietary treatment of non-anemic iron deficiency improve iron status?

Objective: To investigate the efficacy of, first, a dietary regimen involving increased consumption of iron-rich foods and enhancers of iron absorption and decreased consumption of inhibitors of iron absorption and, second, a low dose iron chelate iron supplement, for increasing iron stores in young adult New Zealand women with mild iron deficiency (MID). Methods: The study was a 16 week randomized placebo-controlled intervention. Seventy-five women aged 18 to 40 years with MID (serum ferritin <20 μg/L and hemoglobin ≥120 g/L) were assigned to one of three groups: Placebo, Supplement (50 mg iron/day as amino acid chelate) or Diet. Participants in the Diet Group were given individual dietary counseling to increase the intake and bioavailability of dietary iron. Dietary changes were monitored by a previously validated computer-administered iron food frequency questionnaire. Results: Diet Group members significantly increased their intake of flesh foods, heme iron, vitamin C and foods cooked using cast-iron cookware and significantly decreased their phytate and calcium intakes. Serum ferritin increased in the Supplement and Diet Groups by 59% (p=0.001) and 26% (p=0.068), respectively, in comparison to the Placebo Group. The serum transferrin receptor:serum ferritin ratio decreased by 51% in the Supplement Group (p=0.0001), and there was a non-significant decrease of 22% (p=0.1232) in the Diet Group. Conclusions: This study is the first, to our knowledge, to demonstrate that an intensive dietary program has the potential to improve the iron status of women with iron deficiency.

A Longitudinal Study of Breastfeeding and Weaning Practices During the First Year of Life in Dunedin, New Zealand

OBJECTIVE To investigate infant feeding practices during the first year of life in a group of white infants in Dunedin, New Zealand. DESIGN Prospective study of infants from birth to 12 months of age. PARTICIPANTS A self-selected sample of 74 white mothers and their infants born in Dunedin, New Zealand, between October 1995 and May 1996. Statistical analyses Regression analyses were performed to determine factors associated with successful breastfeeding initiation and duration. RESULTS Among mothers, 88% (n=65) initiated breastfeeding, 42% (n=31) were exclusively breastfeeding at 3 months, and 34% (n=25) were partially breastfeeding at 12 months. Intention to breastfeed increased the likelihood of successful breastfeeding initiation. Mothers who reported that they did not have enough breastmilk tended to exclusively breastfeed for a shorter period of time. Tertiary education and exclusively breastfeeding at 1 month were associated with a longer duration of breastfeeding. Perception of breastfeeding in public as embarrassing was associated with a shorter duration of breastfeeding. Among infants, 45% (n=33) were given nonmilk foods before 4 months of age, and 69% (n=51) were given unmodified cows milk as a beverage before 12 months. APPLICATIONS Breastfeeding rates in this study, although higher than in many Western countries, were still lower than current recommendations. Our findings suggest that women should be taught how to increase their breastmilk supply. Parents should also be informed of the importance of delaying the introduction of nonmilk foods until their infant is 4 to 6 months of age and cows milk until they are 12 months of age. Society also needs to address the social issue of embarrassment many mothers feel when breastfeeding in public.

How Feasible Is Baby-Led Weaning as an Approach to Infant Feeding? A Review of the Evidence

Baby-Led Weaning (BLW) is an alternative method for introducing complementary foods to infants in which the infant feeds themselves hand-held foods instead of being spoon-fed by an adult. The BLW infant also shares family food and mealtimes and is offered milk (ideally breast milk) on demand until they self-wean. Anecdotal evidence suggests that many parents are choosing this method instead of conventional spoon-feeding of purées. Observational studies suggest that BLW may encourage improved eating patterns and lead to a healthier body weight, although it is not yet clear whether these associations are causal. This review evaluates the literature with respect to the prerequisites for BLW, which we have defined as beginning complementary foods at six months (for safety reasons), and exclusive breastfeeding to six months (to align with WHO infant feeding guidelines); the gross and oral motor skills required for successful and safe self-feeding of whole foods from six months; and the practicalities of family meals and continued breastfeeding on demand. Baby-Led Weaning will not suit all infants and families, but it is probably achievable for most. However, ultimately, the feasibility of BLW as an approach to infant feeding can only be determined in a randomized controlled trial. Given the popularity of BLW amongst parents, such a study is urgently needed.

Predictors of vitamin D status and its association with parathyroid hormone in young New Zealand children

BACKGROUND Despite increased awareness of the adverse health effects of low vitamin D status, few studies have evaluated 25-hydroxyvitamin D [25(OH)D] status in young children. OBJECTIVES We aimed to assess vitamin D status on the basis of 25(OH)D and its relation with parathyroid hormone (PTH) and to identify possible predictors of 25(OH)D status in young children living in a country with minimal vitamin D fortification. DESIGN Serum 25(OH)D and PTH concentrations were measured in a cross-sectional sample of children aged 12-22 mo [n = 193 for 25(OH)D, n = 144 for PTH] living in Dunedin, New Zealand (latitude: 45 degrees S). Anthropometric, dietary, and sociodemographic data were collected. RESULTS The majority of children sampled in the summer (94%; 47 of 50) had 25(OH)D >50 nmol/L; however, nearly 80% of children sampled in the winter (43 of 55) had serum concentrations < or =50 nmol/L. In season-adjusted multivariate analysis, breastfeeding and higher levels of education were independently associated with lower 25(OH)D concentrations, whereas male sex and cigarette-smoke exposure were positively associated with 25(OH)D (all P < 0.05). Fractional polynomial regression was used to describe the nonlinear relation between serum PTH and 25(OH)D (P < 0.001). When 25(OH)D concentrations were >60-65 nmol/L, a plateau in PTH was evident. CONCLUSIONS Seasonal variation in 25(OH)D concentration implies that postsummer vitamin D stores were insufficient to maintain status >50 nmol/L year-round. Examination of the predictors of 25(OH)D in our model shows few modifiable risk factors, and thus effective dietary strategies may be required if future research determines that children with 25(OH)D concentrations <50 nmol/L are at significant health risk. This trial was registered at www.actr.org.au as ACTRN12605000487617.

Are changes in food consumption patterns associated with lower biochemical zinc status among women from Dunedin, New Zealand?

Reductions in red meat and increases in cereals in the diet may compromise the intake and bioavailability of Zn. In this cross-sectional study of 330 premenopausal New Zealand women aged 18--40 years, we have assessed the inter-relationships among dietary intakes (via computer-administered food-frequency questionnaire), biochemical Zn status, and anthropometric indices, and compared our results with earlier data. Fasting serum (12.00 (sd 1.36) micromol/l) and hair Zn (2.71 (sd 0.36) micromol/g) were lower than those for young Dunedin, New Zealand, women in 1973 (non-fasting serum Zn 18.6 (sd 4.6) micromol/l, hair Zn 2.99 (sd 0.35) micromol/g). Further, our mean serum Zn was at the 25th percentile of the US National Health and Nutrition Examination Survey (NHANES) (1976--1980) reference sample for women aged 20--44 years. Meat-poultry-fish contributed only 28 % total Zn in the present study, a level comparable with that from cereals-nuts-legumes (27 %), compared to about 40 % in 1989. Significant negative correlations existed between serum Zn and dietary [phytate]:[Zn] molar ratios (r -0.163, 35 % had diets with [phytate]:[Zn] >15, a level said to compromise Zn status. Mean serum Zn of a subgroup of non-oral contraceptive users free of infection was higher in the red-meat eaters (n 149) compared with non-red-meat eaters (n 48) (12.2 v. 11.8 micromol/g, In contrast, serum Zn was lower in those with dietary [phytate]:[Zn] ratios >15 v. <15 (i.e. 11.9 v. 12.3 micromol/l, We postulate that the lower biochemical Zn status of these New Zealand women may be associated in part with changes in food selection patterns, which have led to a reduction in the bioavailability of dietary Zn.

Vitamin D-Fortified Milk Achieves the Targeted Serum 25-Hydroxyvitamin D Concentration without Affecting That of Parathyroid Hormone in New Zealand Toddlers

For young children, the level of vitamin D required to ensure that most achieve targeted serum 25-hydroxyvitamin D [25(OH)D] ≥50 nmol/L has not been studied. We aimed to investigate the effect of vitamin D-fortified milk on serum 25(OH)D and parathyroid hormone (PTH) concentrations and to examine the dose-response relationship between vitamin D intake from study milks and serum 25(OH)D concentrations in healthy toddlers aged 12-20 mo living in Dunedin, New Zealand (latitude 46°S). Data from a 20-wk, partially blinded, randomized trial that investigated the effect of providing red meat or fortified toddler milk on the iron, zinc, iodine, and vitamin D status in young New Zealand children (n = 181; mean age 17 mo) were used. Adherence to the intervention was assessed by 7-d weighed diaries at wk 2, 7, 11, 15, and 19. Serum 25(OH)D concentration was measured at baseline and wk 20. Mean vitamin D intake provided by fortified milk was 3.7 μg/d (range, 0-10.4 μg/d). After 20 wk, serum 25(OH)D concentrations but not PTH were significantly different in the milk groups. The prevalence of having a serum 25(OH)D <50 nmol/L remained relatively unchanged at 43% in the meat group, whereas it significantly decreased to between 11 and 15% in those consuming fortified study milk. In New Zealand, vitamin D intake in young children is minimal. Our findings indicate that habitual consumption of vitamin D-fortified milk providing a mean intake of nearly 4 μg/d was effective in achieving adequate year-round serum 25(OH)D for most children.

Is iron and zinc nutrition a concern for vegetarian infants and young children in industrialized countries

Well-planned vegetarian diets are considered adequate for all stages of the life cycle, despite limited data on the zinc status of vegetarians during early childhood. The bioavailability of iron and zinc in vegetarian diets is poor because of their higher content of absorption inhibitors such as phytate and polyphenols and the absence of flesh foods. Consequently, children as well as adult vegetarians often have lower serum ferritin concentrations than omnivores, which is indicative of reduced iron stores, despite comparable intakes of total iron; hemoglobin differences are small and rarely associated with anemia. However, data on serum zinc concentrations, the recommended biomarker for identifying population groups at elevated risk of zinc deficiency, are sparse and difficult to interpret because recommended collection and analytic procedures have not always been followed. Existing data indicate no differences in serum zinc or growth between young vegetarian and omnivorous children, although there is some evidence of low serum zinc concentrations in vegetarian adolescents. Some vegetarian immigrants from underprivileged households may be predisposed to iron and zinc deficiency because of nondietary factors such as chronic inflammation, parasitic infections, overweight, and genetic hemoglobin disorders. To reduce the risk of deficiency, the content and bioavailability of iron and zinc should be enhanced in vegetarian diets by consumption of fortified cereals and milk, by consumption of leavened whole grains, by soaking dried legumes before cooking and discarding the soaking water, and by replacing tea and coffee at meals with vitamin C-rich drinks, fruit, or vegetables. Additional recommended practices include using fermented soy foods and sprouting at least some of the legumes consumed. Fortified foods can reduce iron deficiency, but whether they can also reduce zinc deficiency is less certain. Supplements may be necessary for vegetarian children following very restricted vegan diets.

Parent-led or baby-led? Associations between complementary feeding practices and health-related behaviours in a survey of New Zealand families

Objective To determine feeding practices and selected health-related behaviours in New Zealand families following a ‘baby-led’ or more traditional ‘parent-led’ method for introducing complementary foods. Design, setting and participants 199 mothers completed an online survey about introducing complementary foods to their infant. Participants were classified into one of four groups: ‘adherent baby-led weaning (BLW)’, the infant mostly or entirely fed themselves at 6–7 months; ‘self-identified BLW’, mothers reported following BLW at 6–7 months but were using spoon-feeding at least half the time; ‘parent-led feeding’, the mother reported not having tried BLW; and ‘unclassified method’, the mother reported they were not following BLW at 6–7 months but reported the infant mostly or entirely fed themselves at 6–7 months. Results 8% were following ‘adherent BLW’, 21% ‘self-identified BLW’ and 0% were following the ‘unclassified method’. Compared with ‘self-identified BLW’ and ‘parent-led feeding’, a higher proportion of the ‘adherent BLW’ met the WHO recommendations to exclusively breastfeed for 6 months and to introduce complementary foods at 6 months. The ‘adherent BLW’ group was more likely to have family foods (p=0.018), and less likely (p=0.002) to have commercially prepared baby food. Both BLW groups were more likely to share meals with the family compared with ‘parent-led feeding’. In contrast to ‘self-identified BLW’ and ‘parent-led feeding’, the ‘adherent BLW’ group did not offer iron-fortified cereal as a first food. Conclusions This study suggests that although many parents consider they follow BLW, a very few are following it strictly. The extent to which BLW was followed was associated with potential benefits (eg, sharing family meals) and risks (eg, low iron first foods) highlighting the importance for health professionals and researchers of accurately determining the extent of adherence to BLW.