PhD student, Karolinska Institutet
The importance of adequate nutrition during pregnancy and early childhood for mental development
My research concerns the impact of heavy metals and essential minerals, commonly present in our environment, on children's health and development. More specifically, I study the effects of exposure to heavy metals like arsenic and cadmium, which can be found naturally at elevated levels in food and drinking water in many places of the world, on child development and health. My main focus is on the impact of adequate or inadequate intake of essential elements, in particular selenium, on children's mental development. Selenium deficiency is very common world-wide due to low concentrations in food (the main source), and it has been estimated that up to 1 billion people are selenium deficient. Since the discovery that selenium is essential for human life, the main focus has been on health effect such as cancer, cardiovascular disease, diabetes, and other areas. However, most studies are evaluating effects in adults or in elderly, and few have assessed the impact of selenium deficiency on child health. In more recent years, selenium has been suggested to be important for cognitive function in elderly, and therefore, the main focus of my PhD projects is to elucidate whether adequate selenium status is of importance also for children's cognitive development (e.g. IQ). In particular, my studies concern selenium status during pregnancy and in early childhood, and they are indeed suggesting that selenium is of important for cognitive function also in children. However, selenium can be toxic at high concentrations, and the interval in which the beneficial effects can be seen is rather narrow. Therefore, my research also aims to evaluate at what levels the beneficial effects disappear and turn into harmful effects. Finally, it is commonly believed that some of the beneficial effects of selenium are occurring through protection against harmful effects caused by arsenic. Therefore, I also investigate the effect of combined exposure to toxic and essential elements on child health and development. To estimate the natural exposure to metals and minerals we also try to find good biomarkers, which may be e.g. concentrations in blood, urine or hair. We recently found that hair was a good marker for selenium status also in children, and we now use this to estimate how many children are selenium deficient, and the impact of this on their IQ, in a population of 10-year old children in Bangladesh.
Abstract: Exposure to lead, a common environmental pollutant, is known to cause cardiovascular and nephrotoxic effects in adults. Potential effects of early-life lead exposure on these functions are, however, less well characterized.To assess blood pressure and kidney function in preschool-aged children in relation to prenatal lead exposure.This prospective study in rural Bangladesh measured children's systolic and diastolic blood pressure in triplicate at the follow-up at 4.5±0.11 years. Their kidney function was assessed by the estimated glomerular filtration rate (eGFR), calculated based on serum cystatin C concentrations, and by kidney volume, measured by sonography. Exposure to lead was assessed by concentrations in the mothers' blood (erythrocyte fraction; Ery-Pb) in gestational weeks (GW) 14 and 30, the effects of which were evaluated separately in multivariable-adjusted linear regression analyses.We found no associations between maternal exposure to lead [n~1500 for GW14 and 700 for GW30] and children's blood pressure or eGFR. However, we found an inverse association between late gestation lead and kidney volume, although the sample size was limited (n=117), but not with early gestation lead (n=573). An increase of 85µg/kg in Ery-Pb (median concentration at GW30) was associated with a 6.0cm(3)/m(2) decrease in kidney volume (=0.4SD; p=0.041). After stratifying on gender, there seemed to be a somewhat stronger association in girls.Prenatal lead exposure may cause long-lasting effects on the kidney. This warrants follow-up studies in older children, as well as additional studies in other populations.
Pub.: 10 Sep '16, Pinned: 25 Aug '17
Abstract: Hair is a commonly used exposure biomarker for metals and other trace elements, but concern has been raised regarding its appropriateness for assessing the internal dose.The aim of the present study was to evaluate children's hair as biomarker of internal dose for toxic (As, Mn, Cd, Pb) and essential elements (Mg, Ca, Fe, Co, Cu, Zn, Se, Mo).In 207 children (9-10 years of age), originating from a population-based cohort in rural Bangladesh, we measured concentrations of the selected elements in hair ( closest to the scalp) using ICP-MS. We compared these with previously measured concentrations in erythrocytes, urine, and water. For a subset of children (), we analyzed four consecutive pieces of hair.There were strong associations between hair As and the other biomarkers (erythrocytes: , ; urine: , ); and water (, ); and there were significant correlations between Se in hair and erythrocytes (overall , ), and urine (, ). Hair Co and Mo showed weak correlations with concentrations in erythrocytes. Hair Mn was not associated with Mn in erythrocytes, urine, or water, and the geometric mean concentration increased almost five times from the closest to the head to the (). Also Mg, Ca, Co, Cd, and Pb increased from the scalp outward ( higher in compared with , ).Hair was found to be a useful exposure biomarker of absorbed As and Se only. Of all measured elements, hair Mn seemed the least reflective of internal dose. https://doi.org/10.1289/EHP1239.
Pub.: 04 Jul '17, Pinned: 25 Aug '17
Abstract: Selenium deficiency has been shown to affect the neurological development in animals, but human research in this area is scarce. We aimed to assess the impact of selenium status during pregnancy on child development at 1.5 years of age.This prospective cohort study was nested into a food and micronutrient supplementation trial (MINIMat) conducted in rural Bangladesh. Using inductively coupled plasma mass spectrometry, we measured selenium concentrations in erythrocyte fraction of blood collected from 750 mothers at gestational week 30, and calculated μg per g hemoglobin. A revised version of Bayley Scales of Infant Development was used to assess children's mental and psychomotor development. A Bangladeshi version of MacArthur's Communicative Development Inventory was used to assess language comprehension and expression. Linear regression analyses adjusted for multiple covariates were used to assess the associations.Maternal erythrocyte selenium concentrations varied considerably, from 0.19 to 0.87 μg/g hemoglobin (median 0.46 μg/g hemoglobin), and were associated with developmental measures. An increase in erythrocyte selenium by 0.50 μg/g hemoglobin was associated with an increase in children's language comprehension by 3.7 points (0.5 standard deviations; 95% confidence interval: 0.40, 7.1; p = 0.028). The same increase in erythrocyte selenium corresponded to an increase in the girls' psychomotor development by 12 points (0.9 standard deviation; 95% confidence interval: 4.3, 19; p = 0.002), but much less in boys.Low prenatal selenium status seems to be disadvantageous for children's psychomotor and language development. Further studies are needed to elucidate the underlying mechanisms of these effects.
Pub.: 03 Dec '14, Pinned: 25 Aug '17
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