Iron status, energy intake, and nutritional status of healthy young Asian children

An assessment of methods used in the investigation of iron status: findings in a population of young British South Asian children

AIMS

To assess the value of laboratory tests available for the investigation of iron status in a population of young British South Asian children.

METHODS

Blood count, red cell distribution width (RDW), percentage hypochromic red cells (%hypo), concentrations of C-reactive protein (CRP), zinc protoporphyrin (ZPP), ferritin, soluble transferrin receptor, plasma iron measurements and incidence of deletional forms of α-thalassaemia were determined.

RESULTS

Haemoglobin, mean cell haemoglobin (MCH), ferritin and CRP values classified iron status in 151/205 (73.6%) consecutive children aged 4-43 months. Fifty-four could not be classified: 12 were anaemic with findings, other than normal CRP values, indistinguishable from those with anaemia of inflammation and 42 were non-anaemic with reduced MCH values. All 42 had normal ferritin concentration and 8 of 36 successfully tested had deletional α-thalassaemia trait. Despite apparent iron sufficiency the RDW, %hypo and ZPP values of these 42 were not significantly different from the 32 children classified with iron-deficient erythropoiesis. The gene frequency of deletional α-thalassaemia trait in the entire group was 8.6%.

CONCLUSIONS

Among 205 British South Asian children aged 4-43 months with high incidences of anaemia, iron deficiency, infection and α-thalassaemia, 151 (73.6%) were classified using haemoglobin, MCH, ferritin and CRP values. In 42 non-anaemic, iron-sufficient children with subnormal MCH values, that is with a phenotype of α-thalassaemia trait, RDW, %hypo and ZPP values did not differ significantly from those with iron-deficient erythropoiesis. Raised RDW, %hypo and ZPP values should be interpreted with caution in non-anaemic young British South Asian children with microcytosis.

Associations of iron status with dietary and other factors in 6-year-old children

OBJECTIVE

To investigate the associations of iron status at 6 years of age with dietary and other factors.

DESIGN

In a cross-sectional study, children's dietary intakes (3-day weighed food record) were recorded, body size was measured and blood samples were taken near their sixth birthday.

SUBJECTS

A sample of 188 children, from two previous studies (cohorts 1 and 2), was contacted, and 139 (74%) agreed to participate.

RESULTS

Multiple regression analyses with dietary and other factors showed that meat and fish consumption, multivitamin/mineral supplement intake (both positively) and cow's milk product consumption (negatively) were associated with log serum ferritin (SF) (adjusted R (2)=0.125; P=0.028; n=129), and juices and residence (rural>urban) with haemoglobin (Hb) (adjusted R (2)=0.085; P=0.034; n=127). Of 21 multivitamin/mineral consumers, none had depleted iron stores compared to 21 iron-depleted of 108 non-consumers (P=0.024). Children living in rural areas (<10,000 inhabitants) (n=33) had higher mean corpuscular volume (MCV) (83.3+/-2.3 fl) than those living in urban areas (>10,000 inhabitants) (82.1+/-3.2 fl; n=103) (P=0.048). Multiple regression analyses with dietary and other factors and growth showed in cohort 1 that residence (rural>urban), weight gain 0-1years (negatively), and meat and fish intake (positively) were associated with Hb (adjusted R (2)=0.323; P=0.030; n=51), meat and fish (positively) with both log SF (adjusted R (2)=0.069; P=0.035; n=52) and MCV (adjusted R (2)=0.064; P=0.035; n=52), and in cohort 2 cow's milk product consumption (negatively) was associated with log SF (adjusted R (2)=0.119; P=0.017; n=41) and residence (rural>urban) with MCV (adjusted R (2)=0.102; P=0.025; n=41).

CONCLUSIONS

Consumption of meat and fish and possibly also juices, as well as multivitamin/mineral intake might affect iron status in 6-year-old children positively, whereas cow's milk product consumption might affect iron status negatively. Slower growth in the first year of life and rural residence are positively related to iron status of 6-year-olds.

Haemoglobin and ferritin concentrations in children aged 12 and 18 months. ALSPAC Children in Focus Study Team

AIMS

To define the normal ranges and investigate associated factors for haemoglobin and ferritin in British children at 12 and 18 months of age, and to estimate correlations between both haemoglobin and ferritin concentrations at 8, 12, and 18 months of age.

SUBJECTS AND METHODS

Subjects were part of the "children in focus" sample, randomly selected from the Avon longitudinal study of pregnancy and childhood. Capillary blood samples were taken from 940 children at 12 months and 827 children at 18 months of age.

RESULTS

Haemoglobin was distributed normally and ferritin was distributed log normally at 12 and 18 months of age. Ninety five per cent reference ranges were established from empirical centiles of haemoglobin and ferritin. Haemoglobin concentrations at 18 months were associated with sex and maternal education. Concentrations of ferritin at 12 and 18 months of age were associated with birth weight and current weight. Girls at 12 months, but not at 18 months, had 8% higher ferritin concentrations than boys. Haemoglobin and ferritin concentrations were significantly correlated over time (8-12 months: rHb = 0.26, rFer = 0.46; 12-18 months: rHb = 0.37, rFer = 0.34; 8-18 months: rHb = 0.22, rFer = 0.24).

CONCLUSION

Iron stores are depleted by rapid growth in infancy. A definition of anaemia based on the fifth centile gives cut off points at 12 and 18 months of age of haemoglobin < 100 g/l, and for iron deficiency of ferritin < 16 micrograms/l and < 12 micrograms/l, respectively. Because children below the fifth centile at one time point differ from those six months later, it is unclear whether screening would be effective.

Iron supplementation

Iron deficiency affects approx. 20% of the world population. Due to predominantly vegetarian diets that reduce the bioavailability of food iron drastically, deficiency states are most widely distributed in developing countries. In addition, iron demand is increased by blood losses and by fast growth which increases the risk of iron deficiency in infants, young adolescents, and in menstruating and pregnant women. The symptoms of iron deficiency include impaired physical and intellectual performance. Iron supplementation may help to break the vicious cycle between inadequate nutrition and poverty. Fortification programs have to consider social and health aspects, including provision against iron overload. Excess iron stores may promote cancer and increase the cardiovascular risk, though the latter is a subject of current debate. The best approach to control such risks is individual iron supplementation geared to the demand by adequate laboratory controls. However, this approach is too costly for general application in developing countries. Food-iron fortification has successfully reduced iron deficiency in many trials and, in comparison, is much cheaper. As iron deficiency is widely distributed in most developing countries, the risk of inducing iron overload in the general population is low. Genetically determined diseases that may lead to siderosis, such as hereditary haemochromatosis or thalassaemia major, show a limited geographic and ethnic distribution. Such subgroups can be largely avoided by targeting food-iron fortification to infants, young adolescents, or pregnant women. Food vehicle and iron compound have to be matched in order to optimise iron bioavailability and to avoid rancidity in food, spoiling its taste and odour. The fortification of salt, sugar and spice mixtures or of bakery products with a short shelf-life are valid approaches to this end. Alternatively, haem iron can be used to fortify cereal-based food staples in developing countries such as tortillas or chappaties. Thus, a variety of options is available to solve the technical problems of food iron fortification. However, optimal solutions have to be tailored to the individual situation in each country.

A longitudinal study of iron status in children at 12, 24 and 36 months

OBJECTIVES

To assess iron status in a sample of clinically well, Caucasian children and explore the complex factors which contribute to iron deficiency during infancy.

DESIGN

Infants recruited at birth and followed longitudinally at 1, 2, 3, 4, 5, 6, 9, 12, 24 and 36 months; feeding practices and socioeconomic data recorded. Iron status assessed using venous blood at 12, 24 and 36 months.

SETTING

Baseline data recorded in the maternity unit. Follow-up visits took place in the infants' homes and blood sampling in a paediatric hospital.

SUBJECTS

Subjects comprised a mixed socioeconomic group of healthy children (n = 121). Blood samples taken from 85, 72 and 67% at 12, 24 and 36 months, respectively.

RESULTS

Prevalence of anaemia (Hb < 110 g l(-1)) in the longitudinal sample (n = 76) increased from 2.6% at age 12 months to 9.2% at 24 months, and at age 36 months (n = 70) was 8%. The most significant finding was that at age 12 months, cows' milk consumption was negatively associated with iron status. Other variables also had an influence. At both 24 and 36 months the most significant predictor of iron status was earlier iron status.

CONCLUSIONS

Infants born to anaemic mothers or mothers who smoke and infants who consume cows' milk during infancy are at increased risk of developing anaemia. Breast milk is the ideal, but for the infant who is not breast fed an iron fortified formula should be used. Advice to mothers should focus on the importance of introducing nutrient dense complementary foods, such as meat, which contains readily absorbable iron.

Iron status of Asian children aged 2 years living in England

Haemoglobin and ferritin values were analysed in blood from 1057 children, aged 2 years, of Asian parents living in England. Children who had thalassaemia trait or a current/recent infection were excluded. Twenty nine per cent of Pakistani, 25% of Bangladeshi, and 20% of Indian children had haemoglobin < 110.0 g/l. The recent national diet and nutrition survey of preschool children found a prevalence of 12% of 2 year olds with haemoglobin < 110.0 g/l. No single factor accounted for more than a small proportion of the variance in haemoglobin and ferritin values, but the most significant factors that had a negative effect on iron status included the amount of cows' milk consumed, the use of a baby bottle, and mother's place of birth being outside of the UK. Taking vitamin or iron supplements was positively associated with iron status in one or more of the three groups.

Iron status and anaemia in preschool children in Sydney

The purpose of this study was to determine the iron status of preschool children in Sydney. We assessed 678 children aged 9 to 62 months living in 32 randomly selected census collection districts in central and southern Sydney for iron status using plasma ferritin; of these 678 children, 542 had zinc protoporphyrin tests, red cell indices and haemoglobin tests. Risk factors for iron deficiency were assessed by an administered questionnaire. Overall, the prevalence of iron depletion was 10.5 per cent, iron deficiency 2.8 per cent and iron deficiency anaemia 1.1 per cent. The 24-to-35-month age group (176 children) had the highest prevalence of iron deficiency anaemia of 3.0 per cent although iron depletion (18.7 per cent) and iron deficiency (5.4 per cent) were highest among the 9-to-23-month age group (182 children). Low iron status was related to age of under 24 months (odds ratio (OR) 2.86,95 per cent confidence interval (CI) 1.72 to 4.76). After adjustment for this age effect, the consumption of red meat fewer than four times a week was significantly associated with iron depletion (OR 2.27, CI 1.25 to 4.17) and there was a tendency for children who were being given a vitamin supplement to be less likely to be iron depleted (OR 4.00, CI 0.95 to 16.67). Iron deficiency and iron deficiency anaemia do not represent a major public health problem in preschool children in Sydney. However, for children in the age range of 12 to 36 months there is scope for interventions to further reduce the prevalence of iron deficiency anaemia.

The growth and nutritional status of healthy Asian children aged 4-40 months living in Sheffield

Detailed anthropometric measurements were made on 169 healthy children aged between 4 and 40 months during a comprehensive study of the diet and nutritional status of Asian children (of Pakistani and Bangladeshi origin) living in Sheffield. These measurements were used to describe the growth profile of these apparently healthy children and to compare this with both international and UK reference data. The distribution of values for most anthropometric measurements was close to the UK reference data although both boys and girls tended to be slight of build, and girls tended to have relatively smaller head circumferences. Nevertheless, it was concluded that their growth and nutritional status over this age range can be evaluated using standard (UK) growth charts.

Prevention of anaemia in inner city toddlers by an iron supplemented cows' milk formula

There are few data to support the use of follow-on formulas in infants from the age of 6 months. In a prospective trial in a deprived inner city area of Birmingham 100 infants who were already receiving pasteurised cows' milk by 6 months of age were enrolled and randomised either to receive a follow-on formula or to continue on cows' milk from 6 months until 18 months. At 18 months of age the follow-on formula group returned to cows' milk and both groups were followed up until 24 months. Iron status, growth, and nutritional status were analysed at intervals of six months. At enrollment, no differences in haematological status were evident. However, by 12 months of age, 31% of the cows' milk group were anaemic (haemoglobin concentration < 110 g/l) compared with only 3% of those receiving follow-on formulas. At 18 months, 33% of the cows' milk group were anaemic compared with only 2% of the follow-on formula group and by 24 months of age none of the follow-on formula group was anaemic, whereas 26% in the cows' milk group still had a haemoglobin of < 110 g/l. Mean corpuscular volume was significantly smaller and ferritin significantly lower in the cows' milk group at 12, 18, and 24 months. Dietary iron intake was higher in the follow-on formula group at 12 and 18 months but not at 24 months, when both groups were back on cows' milk. Infants and toddlers at high risk of iron deficiency are therefore unlikely to become anaemic if receiving a follow-on formula, although the relative merits of follow-on formula compared with an ordinary infant formula remain uncertain.

Haemoglobin and ferritin concentrations in infants at 8 months of age

AIM

To identify the optimum age to screen for iron deficiency, the normal distribution of haemoglobin and ferritin in a representative population sample was investigated.

METHODS

Normal values for haemoglobin and ferritin were measured from heel prick capillary samples obtained from a representative cohort of 1175 infants at 8 months old who were randomly selected from children taking part in the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC).

RESULTS

Haemoglobin was normally distributed: mean (SD) 117 (11) milligrams, 95% confidence interval (CI) 116 to 118, and range 72-153 milligrams. Ferritin was log normally distributed: geometric mean 38.5 micrograms/l, 95% CI 37.0 to 39.9, range 7.1-224 micrograms/l. The 5th centile for haemoglobin was 97 milligrams and for ferritin 16.9 micrograms/l. No correlation was found between haemoglobin and ferritin. Multiple regression analysis showed ferritin concentrations to be positively related to birth weight (p < 0.0001) and the sex of the child (girls with higher concentrations) (p < 0.0001) but negatively with the child's weight at 8 months (p < 0.0001). Haemoglobin concentrations were positively related to the child's weight at 8 months (p = 0.04). Neither haemoglobin nor ferritin concentrations were related to social class as measured by maternal education level.

CONCLUSION

These data define the normal range for haemoglobin and ferritin in capillary samples in the UK population, and suggest that anaemia is common in infancy. Using current recommendations, 23% of infants would be identified as anaemic. For British infants at 8 months of age, a more representative 'cut off' for anaemia would be haemoglobin concentration < 97 milligrams and for iron deficiency ferritin < 16 micrograms/l.

Serum total cholesterol and ferritin and blood haemoglobin concentrations in primary schoolchildren

Serum total cholesterol and ferritin and haemoglobin concentrations were measured in blood samples obtained by venepuncture in 378 of 593 children aged 5-6 or 8-9 years from seven primary schools in Canterbury. This study formed part of an investigation to assess the feasibility of including a venepuncture procedure for monitoring purposes in primary schoolchildren. Although only one child had a very low haemoglobin concentration of 61 g/l, a large percentage, 25% in the rising 6 years and 7% in the rising 9 years, had concentrations between 100 and 115 g/l--that is, less than the reference fifth centile. Eight per cent had a serum ferritin concentration less than 8 micrograms/l. Cholesterol concentrations higher than 5.2 mmol/l were found in 20% of the 5-6 year olds and 23% of the 8-9 year olds, and in 19% of boys and 25% of girls. About 5% of children had cholesterol concentrations above 6 mmol/l. The number of children with anaemia, iron deficiency, and high cholesterol raises serious concerns about the nutritional and coronary heart disease risk of British children.

Nutrition-related diseases and dietary change among Third World immigrants in northern Europe

Immigrants from the third world are more prone to acquire nutritional deficiency diseases, such as rickets, osteomalacia and iron deficiency anemia than the rest of the population in the recipient countries. Lately, evidence is also emerging that some immigrant groups are particularly susceptible to diseases related to overnutrition, such as coronary heart disease and non-insulin dependent diabetes. The purpose of this review article is to give a holistic view of the nutrition related diseases and disorders among immigrants. It deals with the prevalence of these diseases among immigrants in Northern European countries, and looks into some of the hypotheses, which have been put forward to explain why immigrant groups are more prone to acquire these diseases than the rest of the population. The focus of this part of the paper is the process of dietary change after migration. The practical implications of the findings from the literature review are then discussed.