Quantitative estimation of mercury intake by toxicokinetic modelling based on total mercury levels in humans

Mercury is a toxic metal that can be disseminated into the environment from both natural and anthropogenic sources. Human exposure to the metal stems mainly from food, and more particularly from the consumption of fish and other seafoods. Examining dietary exposure and measuring mercury levels in body tissues are two ways of estimating exposure to mercury. In this study, we utilized a modelling system consisting of three linear toxicokinetic models for describing the fate of methyl mercury, inorganic mercury, and metallic mercury in the body, in order to estimate daily intake of mercury as measured through total mercury concentrations in the blood. We then compared the results stemming from our modelling system to those of the detailed semi-quantitative food frequency questionnaire (FFQ) of the Norwegian Fish and Game (NFG) Study, a project that focused on dietary mercury exposure. The results indicate that toxicokinetic modelling based on blood levels gave higher daily intake values of mercury compared to those of the FFQ. Furthermore, the former had a wider range of estimates than the latter. The properties of the toxicokinetic model or limitations in the dietary exposure assessment could be posited as reasons for the differences between the respective methods. Moreover, the results may have been influenced by sources of mercury exposure that cannot be described as dietary, such as amalgam fillings.

Arsenic in seafood is associated with increased thyroid-stimulating hormone (TSH) in healthy volunteers - A randomized controlled trial

BACKGROUND

Exposure to exogenous elements like arsenic (As) may influence thyroid enzymes, thyroid-stimulating hormone (TSH), and the two principal thyroid hormones, free thyroxine (FT4) and free triiodothyronine (FT3), but little is known about how this is related to organic arsenicals, the main form in seafood.

AIM

To investigate whether a high intake of dietary arsenic from seafood can impact thyroid function and thyroid hormones by examining possible associations with changes in TSH, FT4, FT3 and the FT4:FT3-ratio in plasma.

METHODS

Thirty-eight healthy subjects were randomized into four groups. During a 14-day semi-controlled dietary study, the subjects ingested daily portions of either 150g cod, salmon, blue mussels or potato (control). Plasma concentrations of total As, FT3, FT4, TSH and selenium (Se), and urinary concentrations of iodine were monitored.

RESULTS

Plasma concentrations of TSH increased significantly in all seafood groups. The change in plasma As, with different coefficients for each seafood group, was the dominant factor in the optimal multiple regression model for change in TSH (R²=0.47). Plasma Se and iodine were negative and positive factors, respectively. There were also indications of changes in FT4, FT3 and the FT4:FT3 ratio consistent with a net inhibiting effect of As on FT4 to FT3 conversion.

CONCLUSION

Ingestion of seafood rich in various organic As species was strongly associated with an increase of the TSH concentrations in plasma. Change in TSH was positively associated with total plasma As, but varied with the type of seafood ingested. These findings indicate that organic dietary As, apparently depending on chemical form, may influence thyroid hormones and function.

The impact of iron status and smoking on blood divalent metal concentrations in Norwegian women in the HUNT2 Study

Low iron (Fe) stores may result in increased absorption of divalent metals, in particular cadmium (Cd). We have previously shown that in non-smoking women participating in the Norwegian HUNT2 cohort study this also included other divalent metals, e.g. manganese (Mn) and cobalt (Co). The diet is the main source of metals in non-smoking individuals, whereas in smoking individuals tobacco smoke contributes significant amounts of Cd and lead (Pb). The aim of the present study was to investigate the impact of smoking on the relationship between low iron status and divalent metals. Blood concentrations of the divalent metals Cd, Mn, Co, Pb, copper (Cu) and zinc (Zn), determined using an Element 2 sector field mass spectrometer (ICP-MS), were investigated in smoking women of fertile age (range 21-55 years) (n=267) from the HUNT2 cohort. Among these, 82 were iron-deplete (serum ferritin<12μg/L) and 28 had iron deficiency anaemia (serum ferritin<12μg/L & Hb<120g/L). 150 (56%) women smoked 10 or more cigarettes daily, 101 (38%) had smoked for more than 20 years, and 107 (40%) had smoked for 11-20 years. Results from the smoking population were compared with results from our previous study in non-smoking women (n=448) of which 132 were previous smokers, all from the same cohort. Increasing concentrations of Cd in blood were observed for previous smokers, low-to-moderate smokers and high intensity smokers in all subgroups compared to never smokers, and according to age groups, education level, BMI and serum ferritin. Smokers had higher Pb concentrations than non-smokers in all subgroups, but less pronounced than for Cd. Smoking was not associated with Mn and Co concentrations in blood. In multiple regression models, low ferritin was associated with increased blood concentrations of Cd, Pb, Mn and Co. Ferritin was strongly associated with Cd at low smoking intensity, but was not a significant factor in heavy smokers, where intensity and duration of smoking emerged as main determinants. Ferritin associations with Co and Pb varied with tertiles of blood Cd. Ferritin emerged as the main determinant of blood Co and Mn, while for blood Pb, age and smoking intensity had higher impact. Cu and Zn remained within reference values and no significant associations with ferritin were found. Strong positive associations between blood concentrations of Pb, Mn, Cd and Co were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the divalent metals studied. Mild anaemia (110<Hb<120g/L) did not seem to have any effect independent of low ferritin. The results indicate that low serum ferritin facilitates absorption of certain divalent metal ions in female smokers as well as the previously shown effect in non-smokers. Even if smoking provides Pb and Cd, the mutual associations between Cd and other divalent metals in blood persisted in medium and heavy smokers. This indicates that the interrelationship between Cd and divalent metals not only reflect effects on the absorption, but possibly also on kinetic processes such as transportation in blood and other compartments, including excretion.

Maternal dietary exposure to dioxins and polychlorinated biphenyls (PCBs) is associated with language delay in 3year old Norwegian children

BACKGROUND

Prenatal exposure to dioxins and PCBs is potentially harmful to the developing fetus and may increase the risk of delayed or impaired neurodevelopment. Several studies have reported negative associations between prenatal exposure to these compounds and aspects of cognition related to language in early childhood.

OBJECTIVES

The aim was to examine the association between maternal low level dietary exposure to dioxins and PCB during pregnancy and language development in 3year old children in a large group of mother-child pairs participating in the Norwegian Mother and Child Cohort Study (MoBa).

METHODS

This study includes 44,092 children of women who were recruited to the Norwegian Mother and Child Cohort Study (MoBa) during the years 2002-2009. Maternal dietary exposure to dioxins and PCBs was estimated based on a validated food frequency questionnaire (FFQ) answered mid-pregnancy and a database of dioxin and PCB concentrations in Norwegian foods. Exposure to dioxins and dioxin-like PCBs (dl-compounds) was expressed in total toxic equivalents (TEQ), and PCB-153 was used as marker for non-dioxin-like PCBs (ndlPCBs). Children's language skills at age 3 were assessed by parental report including a Dale and Bishop grammar rating and questions about communication skills from the Ages and Stages Questionnaire (ASQ). Logistic regression models adjusted for confounders were used to examine the association between maternal dietary exposure to dl-compounds or PCB-153 and language development in children.

RESULTS

The maternal dietary exposure to dl-compounds and PCB-153 was generally low, and 98% of women had intakes of dl-compounds ≤14pg TEQ/kg bw/week, which is the tolerable weekly intake set by EU's Scientific Committee for Food (SCF). High maternal exposure (>14pg TEQ/kg bw/week of dl-compounds (median 2.6pg/kg bw/day, range 2-16) or >97.5-percentile intake of PCB-153 (median 11ng/kg bw/day, range 5-28) was associated with higher odds of incomplete grammar (in boys and girls, adjusted ORs 1.1 to 1.3) and severe language delay in girls, adjusted ORs 2.8 [95% CI 1.1, 7.1] for PCB-153 and 2.9 [95% CI 1.4, 5.9] for dl-compounds. Furthermore, high exposure to dl-compounds was associated with moderate language delay 1.4 [95% CI 1.0, 2.0] and lower communication score (ASQ), adjusted OR 1.4 [95% CI 1.1, 1.9] in girls.

CONCLUSIONS

The main findings of this study were: 1) Girls born to mothers who exceeded the tolerable weekly intake for dl-compounds or had a PCB-153 intake above the 97.5 percentile in early pregnancy may have increased risk of language delay at age 3years. 2) Negative associations with maternal exposure to dl-compounds or PCB-153 were observed for both boys and girls having incomplete grammar, which is a subtle reduction in language skills. This interesting finding should not be considered as deviant at this age.

Consumption of lead-shot cervid meat and blood lead concentrations in a group of adult Norwegians

Several recent investigations have reported high concentrations of lead in samples of minced cervid meat. This paper describes findings from a Norwegian study performed in 2012 among 147 adults with a wide range of cervid game consumption. The main aim was to assess whether high consumption of lead-shot cervid meat is associated with increased concentration of lead in blood. A second aim was to investigate to what extent factors apart from game consumption explain observed variability in blood lead levels. Median (5 and 95 percentile) blood concentration of lead was 16.6 µg/L (7.5 and 39 µg/L). An optimal multivariate linear regression model for log-transformed blood lead indicated that cervid game meat consumption once a month or more was associated with approximately 31% increase in blood lead concentrations. The increase seemed to be mostly associated with consumption of minced cervid meat, particularly purchased minced meat. However, many participants with high and long-lasting game meat intake had low blood lead concentrations. Cervid meat together with number of bullet shots per year, years with game consumption, self-assembly of bullets, wine consumption and smoking jointly accounted for approximately 25% of the variation in blood lead concentrations, while age and sex accounted for 27% of the variance. Blood lead concentrations increased approximately 18% per decade of age, and men had on average 30% higher blood lead concentrations than women. Hunters who assembled their own ammunition had 52% higher blood lead concentrations than persons not making ammunition. In conjunction with minced cervid meat, wine intake was significantly associated with increased blood lead. Our results indicate that hunting practices such as use of lead-based ammunition, self-assembling of lead containing bullets and inclusion of lead-contaminated meat for mincing to a large extent determine the exposure to lead from cervid game consumption.

Essential and toxic element concentrations in blood and urine and their associations with diet: results from a Norwegian population study including high-consumers of seafood and game

The first aim of the study was to evaluate calculated dietary intake and concentrations measured in blood or urine of essential and toxic elements in relation to nutritional and toxicological reference values. The second aim was to identify patterns of the element concentrations in blood and urine and to identify possible dietary determinants of the concentrations of these elements. Adults with a known high consumption of environmental contaminants (n=111), and a random sample of controls (n=76) answered a validated food frequency questionnaire (FFQ). Complete data on biological measures were available for 179 individuals. Blood and urine samples were analyzed for selenium, iodine, arsenic, mercury, cadmium and lead. Principal component analysis was used to identify underlying patterns of correlated blood and urine concentrations. The calculated intakes of selenium, iodine, inorganic arsenic and mercury were within guideline levels. For cadmium 24% of the high consumer group and 8% of the control group had intakes above the tolerable weekly intake. Concentrations of lead in blood exceeded the bench-mark dose lower confidence limits for some participants. However, overall, the examined exposures did not give rise to nutritional or toxicological concerns. Game consumption was associated with lead in blood (B(ln) 0.021; 95%CI:0.010, 0.031) and wine consumption. Seafood consumption was associated with urinary cadmium in non-smokers (B(ln) 0.009; 95%CI:0.003, 0.015). A novel finding was a distinct pattern of positively associated biological markers, comprising iodine, selenium, arsenic and mercury (eigenvalue 3.8), reflecting seafood intake (B 0.007; 95%CI:0.004, 0.010). The study clearly demonstrates the significance of seafood as a source of both essential nutrients and toxic elements simultaneously and shows that exposure to various essential and toxic elements can be intertwined.

Determinants of plasma concentrations of perfluoroalkyl substances in pregnant Norwegian women

BACKGROUND

Perfluoroalkyl substances (PFASs) are widespread pollutants that have been associated with adverse health effects although not on a consistent basis. Diet has been considered the main source of exposure. The aim of the present study was to identify determinants of four plasma PFASs in pregnant Norwegian women.

METHODS

This study is based in the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. Our sample included 487 women who enrolled in MoBa from 2003 to 2004. A questionnaire regarding sociodemographic, medical, and reproductive history was completed at 17 weeks of gestation and a dietary questionnaire was completed at 22 weeks of gestation. Maternal plasma samples were obtained around 17 weeks of gestation. Plasma concentrations of four PFASs (perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA)) were examined in relation to demographic, lifestyle, dietary, and pregnancy-related covariates. Predictors were identified by optimizing multiple linear regression models using Akaike's information criterion (AIC).

RESULTS

Parity was the determinant with the largest influence on plasma PFAS concentrations, with r(2) between 0.09 and 0.32 in simple regression models. In optimal multivariate models, when compared to nulliparous women, parous women had 46%, 70%, 19%, and 62% lower concentrations of PFOS, PFOA, PFHxS, and PFNA respectively (p<0.001 except for PFHxS, p<0.01). In all these models, duration of breastfeeding was associated with reduced PFAS levels. PFOA showed the largest reduction from breastfeeding, with a 2-3% reduction per month of breastfeeding in typical cases. Levels of PFOS, PFOA, and PFNA increased with time since most recent pregnancy. While pregnancy-related factors were the most important predictors, diet was a significant factor explaining up to 4% of the variance. One quartile increase in estimated dietary PFAS intake was associated with plasma PFOS, PFOA, PFHxS, and PFNA concentration increases of 7.2%, 3.3%, 5.8% and 9.8%, respectively, resulting in small, although non-trivial absolute changes in PFAS concentrations.

CONCLUSION

Previous pregnancies and breastfeeding duration were the most important determinants of PFASs in this sample of pregnant women.

Dietary mercury exposure in a population with a wide range of fish consumption--self-capture of fish and regional differences are important determinants of mercury in blood

Human, low level, chronic exposure to mercury (Hg) from fish is of concern because of potential neurodevelopmental and cardiovascular toxicity. The purpose of the study was to 1) measure total mercury (THg) in blood and estimate dietary exposure in a population group with a wide range of seafood consumption, 2) assess the intake and blood concentration in relation to tolerable intake values, 3) characterise dietary sources, and 4) to investigate the relationship between dietary THg with THg in blood (BTHg), including factors that can explain the variance in BTHg concentrations. The participants (n=184) filled in an extensive food frequency questionnaire which was combined with a database on THg concentrations in Norwegian food, and donated blood and urine. Median consumption of seafood was 65 g/day (range 4 to 341 g/day). The calculated mean dietary THg exposure was 0.35 (median 0.30) μg/kg body weight/week. Seafood contributed on average 95% to the exposure. The JECFA Provisional Tolerable Weekly Intake (PTWI) of 1.6 μg MeHg/kg bw/week was not exceeded by any of the participants. BTHg ranged from 0.6 to 30 μg/L, with a mean of 5.3 (median 4.0 μg/L). There was a strong relationship between total seafood consumption and BTHg concentrations (r=0.58 95%CI: 0.48, 0.67) and between estimated THg dietary exposure and BTHg (r=0.46 95%CI: 0.35, 0.57). Fish consumption, sex, catching >50% of their seafood themselves, and living in coastal municipalities were significant factors in linear regression models with lnBTHg. Including urinary Hg in the regression model increased the explained variance from 54% to 65%. In a toxicokinetic model, the calculated dietary intake appeared to moderately underestimate the measured BTHg among the participants with the highest BTHg. Only two of the participants had BTHg slightly above a value equivalent to the JECFA PTWI, but none of them were women in fertile age.

Toxicogenomic profiles in relation to maternal immunotoxic exposure and immune functionality in newborns

A crucial period for the development of the immune system occurs in utero. This results in a high fetal vulnerability to immunotoxic exposure, and indeed, immunotoxic effects have been reported, demonstrating negative effects on immune-related health outcomes and immune functionality. Within the NewGeneris cohort BraMat, a subcohort of the Norwegian Mother and Child Cohort Study (MoBa), immunotoxicity was demonstrated for polychlorinated biphenyls and dioxins, showing associations between estimated maternal intake levels and reduced measles vaccination responses in the offspring at the age of 3. The present study aimed to investigate this link at the transcriptomic level within the same BraMat cohort. To this end, whole-genome gene expression in cord blood was investigated and found to be associated with maternal Food Frequency Questionnaires-derived exposure estimates and with vaccination responses in children at 3 years of age. Because the literature reports gender specificity in the innate, humoral, and cell-mediated responses to viral vaccines, separate analysis for males and females was conducted. Separate gene sets for male and female neonates were identified, comprising genes significantly correlating with both 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and polychlorinated biphenyls (PCB) exposure and with measles vaccination response. Noteworthy, genes correlating negatively with exposure in general show positive correlations with antibody levels and vice versa. For both sexes, these included immune-related genes, suggesting immunosuppressive effects of maternal exposure to TCDD and PCB at the transcriptomic level in neonates in relation to measles vaccination response 3 years later.

Humans seem to produce arsenobetaine and dimethylarsinate after a bolus dose of seafood

Seafood is the predominant food source of several organoarsenic compounds. Some seafood species, like crustaceans and seaweed, also contain inorganic arsenic (iAs), a well-known toxicant. It is unclear whether human biotransformation of ingested organoarsenicals from seafood result in formation of arsenicals of health concern. The present controlled dietary study examined the urinary excretion of arsenic compounds (total arsenic (tAs), iAs, AB (arsenobetaine), dimethylarsinate (DMA) and methylarsonate (MA)) following ingestion of a single test meal of seafood (cod, 780 μg tAs, farmed salmon, 290 μg tAs or blue mussel, 690 μg tAs or potato (control, 110 μg tAs)) in 38 volunteers. The amount of ingested tAs excreted via the urine within 0-72 h varied significantly among the groups: Cod, 74% (52-92%), salmon 56% (46-82%), blue mussel 49% (37-78%), control 45% (30-60%). The estimated total urinary excretion of AB was higher than the amount of ingested AB in the blue mussel group (112%) and also ingestion of cod seemed to result in more AB, indicating possible endogenous formation of AB from other organoarsenicals. Excretion of iAs was lower than ingested (13-22% of the ingested iAs was excreted in the different groups). Although the ingested amount of iAs+DMA+MA was low for all seafood groups (1.2-4.5% of tAs ingested), the urinary DMA excretion was high in the blue mussel and salmon groups, counting for 25% and 11% of the excreted tAs respectively. In conclusion our data indicate a possible formation of AB as a result of biotransformation of other organic arsenicals. The considerable amount of DMA excreted is probably not only due to methylation of ingested iAs, but due to biotransformation of organoarsenicals making it an inappropriate biomarker of iAs exposure in populations with a high seafood intake.

The relationship between life-style and cardio-metabolic risk indicators in children: the importance of screen time

AIMS

To examine differences between children with obesity and normal weight children (aged 7-13 years) in terms of physical activity, screen time, food intake and blood parameters indicative of cardio-metabolic risk. Further, to explore the relationship between physical activity, screen time and food intake with cardio-metabolic parameters.

METHODS

Forty-three children with obesity were compared with 43 normal weight peers. Physical activity was monitored by accelerometers and screen time and food intake by diaries. Blood parameters indicative of cardio-metabolic risk were analysed.

RESULTS

The group of children with obesity had significantly less vigorous activity (p = 0.013), more daily screen time (p = 0.004) and consumed more fat (p = 0.04) than the group of normal weight children. The former group also demonstrated higher values of triglycerides (p = 0.001), HbA1c (p = 0.009), C-peptide (p = 0.001), had a higher HOMA-R score (p = 0.001), and lower levels of HDL (p = 0.001). After controlling for weight category, regression analyses revealed that screen time was significantly and positively related to the HOMA-R score and C-peptide levels independent of physical activity and intake of fat and sugar.

CONCLUSIONS

The results indicate that screen time is an important behavioural factor related to obesity and cardio-metabolic risk indicators in children.

Mothers' negative affectivity during pregnancy and food choices for their infants

OBJECTIVE

The objective of this study was to analyze whether maternal negative affectivity assessed in pregnancy is related with subsequent infant food choices.

DESIGN

The study design was a cohort study.

SUBJECTS

The subjects were mothers (N=37 919) and their infants participating in the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health.

MEASUREMENTS

Maternal negative affectivity assessed prepartum (Hopkins Symptom Checklist 5 (SCL-5) at weeks 17 and 30 of pregnancy), introduction of solid foods by month 3 and feeding of sweet drinks by month 6 (by the reports of the mothers) were analyzed.

RESULTS

Mothers with higher negative affectivity were 64% more likely (95% confidence interval 1.5-1.8) to feed sweet drinks by month 6, and 79% more likely (95% confidence interval 1.6-2.0) to introduce solid foods by month 3. These odds decreased to 41 and 30%, respectively, after adjusting for mother's age, body mass index (BMI) and education.

CONCLUSION

The maternal trait of negative affectivity is an independent predictor of infant feeding practices that may be related with childhood weight gain, overweight and obesity.

Validation of self-reported recreational exercise in pregnant women in the Norwegian Mother and Child Cohort Study

We compared the self-reported frequency of recreational exercise and corresponding metabolic equivalent (MET)-minutes with physical activity measured with a position and motion sensor in pregnant women. One hundred and twelve women in the Norwegian Mother and Child Cohort Study (MoBa) completed questions about weekly participation in recreational exercise by week 17 of pregnancy and participated in the validation study around week 20. Data from a validated motion sensor (ActiReg) that measures physical activity and total energy expenditure (TEE) served as the "gold standard." Self-reported recreational exercise was compared with the following ActiReg-based measures: physical activity energy expenditure (PAEE), minutes of vigorous physical activity (VPA), physical activity level (PAL) and TEE. Pearson's correlations between self-reported weekly exercise and the objectively assessed variables were: rPAEE=0.26, rVPA=0.32, rPAL=0.30 (all P<0.01) and rTEE=0.17 (P=0.07). The partial correlation coefficients between the questionnaire responses and the ActiReg measurements were similar after adjusting for parity, body mass index, education, age, height and smoking, but rTEE increased (r=0.27, P<0.01). We observed significant positive associations between self-reported exercise activities and motion sensor measurements of physical activity, indicating that the questions used for exercise assessment in MoBa may be useful for ranking pregnant women according to the recreational exercise level.

Dioxin-like activity in plasma among Danish pregnant women: dietary predictors, birth weight and infant development

The aim of this study was to identify dietary predictors of plasma dioxin-like activity in women from the Danish National Birth Cohort. Associations between exposure and birth weight and infant development at 6 months were also explored. Diet was assessed in mid-pregnancy by a food-frequency questionnaire. One hundred nulliparous 25-35-year-old women of normal pre-pregnancy body-mass-index were chosen according to their intake of fatty fish, as fatty fish is a potential route of exposure. Intake of other foods of animal origin was also explored. Dioxin-like activity was measured in plasma using the Dioxin-Responsive Chemically Activated LUciferase eXpression (DR-CALUX) and quantified in toxic equivalents (CALUX-TEQs). Information on infant attainment of specific milestones was obtained by maternal report in a standardized interview. The sample mean was 46 pg CALUX-TEQ/g lipid. Plasma dioxin-like activity increased by 10.7 pg CALUX-TEQ/g lipid (95% CI: 1.8; 19.7) for the highest compared to the lowest tertile of total dietary fat intake but decreased by -9.8 pg CALUX-TEQ/g lipid (95% CI: -19.4; -0.2) for fatty fish intake. The inverse association for fatty fish was explained by lower intake of high-fat food groups such as red meat, fats and oils, which were also predictors of dioxin-like activity. Plasma dioxin-like activity was not associated with birth weight, but an inverse correlation was observed with total developmental score (Spearman r=-0.23, p=0.046). Our study indicates that dietary patterns associated with high fat intake may lead to increased plasma dioxin-like activity and in utero exposure might be related to early infant development.

Linking exposure to polychlorinated biphenyls with fatty fish consumption and reduced fetal growth among Danish pregnant women: a cause for concern?

In a selected group of women from the Danish National Birth Cohort, the authors investigated the association between intake of fatty fish and plasma concentrations of polychlorinated biphenyls (PCBs) on the one hand and the association between maternal PCB concentrations and fetal growth on the other. Of 70,183 women who filled in a food frequency questionnaire during 1996-2002, 100 nulliparous women aged 25-35 years with normal prepregnancy body mass index were selected according to their intake of fatty fish (low (0 meals/month, n = 34), medium (1-3 meals/month, n = 33), or high (> or = meals/month, n = 33)). Women with a high intake of fatty fish had 50% (95% confidence interval (CI): 31, 72) higher plasma PCB concentrations than women with low intake. Maternal plasma PCB concentrations were inversely associated with birth weight and placental weight. The adjusted mean difference between the 75th and 25th PCB percentiles was -155 g (95% CI: -291, -19) for birth weight and -81 g (95% CI: -135, -26) for placental weight. These results support previous findings from this cohort, where fatty fish intake was inversely associated with fetal growth. Dietary recommendations often encourage weekly consumption of fatty fish. These results suggest that potential exposure to PCBs should be carefully considered before recommending such intakes among women of childbearing age.

Is high consumption of fatty fish during pregnancy a risk factor for fetal growth retardation? A study of 44,824 Danish pregnant women

The authors examined the relation between fish consumption during pregnancy and fetal growth among 44,824 women from the Danish National Birth Cohort (1996-2002). They evaluated the associations between consumption of total fish, fatty fish, and lean fish in midpregnancy and birth weight, birth length, and head circumference among singleton full-term infants. Fish consumption was ascertained by food frequency questionnaire. The birth of infants classified below the 10th percentile for gestational age and gender was significantly increased among women who consumed more than 60 g of fish per day, as compared with women who consumed 5 g or less per day. Adjusted odds ratios were 1.24 (95% confidence interval (CI): 1.03, 1.49) for birth weight and 1.21 (95% CI: 1.01, 1.43) for head circumference. The adjusted odds ratio was borderline significant for birth length (odds ratio = 1.20, 95% CI: 1.00, 1.45). These increases in risk were followed by small decreases in average values for these growth measures. Furthermore, the inverse association for total fish consumption could be explained by consumption of fatty fish, while no association was found for lean fish. These results indicate that consumption of fatty fish, a known route of exposure to persistent organic pollutants, could be associated with reduced fetal growth.

Dietary intake of differently fed salmon: a preliminary study on contaminants

BACKGROUND

In a previous study, a group of coronary heart disease (CHD) patients exhibited positive cardioprotective effects of fatty acids derived from a diet of farmed Atlantic salmon fed fish oil (Seierstad et al. 2005). This follow-up study examines these patients for plasma exposure to selected organic and inorganic contaminants found in seafood that may detract from the benefits of eating oily fish.

METHODS

The study design was from Seierstad et al. (2005), where 58 patients were allocated into three groups consuming 700 g week(-1) of differently fed Atlantic salmon (Salmo salar) fillets for 6 weeks: 100% fish oil (FO), 100% rapeseed oil (RO), or 50% of each (FO/RO).

RESULTS

Different fillets showed graded levels (FO > FO/RO > RO) of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DLPCBs), indicator PCBs, polybrominated diphenyl ethers (PBDEs), and arsenic (As). Mercury (Hg) and lead (Pb) levels were similar across the three types of fillets. After 6 weeks of consumption, patient levels of PCDDs, DLPCBs, and PCBs in plasma decreased as the dietary intake of these contaminants increased. Plasma PBDEs only showed increases for the FO patients. Levels of inorganic contaminants in plasma showed only slight changes over the study period.

CONCLUSIONS

These results show a reduction in the use of marine oils in fish feed reduces organic contaminant levels in farmed salmon while still providing a good dietary source of marine fatty acids.

Near infrared spectroscopy-a potentially useful method for rapid determination of fat and protein content in homogenized diets

OBJECTIVE

To investigate the potential of near-infrared reflectance (NIR) spectroscopy as a rapid and non-destructive method to determine total fat and protein in mixed, homogenized and freeze-dried human diets.

DESIGN

29 students collected duplicate portions of their diet for four consecutive days. In addition, a detailed food diary was kept. The duplicate portions were analysed for total protein and fat content both by traditional chemical analysis (Kjeldahl and Folch methods) and through the recently developed NIR spectroscopy method. In addition, traditional computerized estimation of nutrient composition was performed.

RESULTS

Plotting of the NIR-predicted fat content against the chemically analysed fat content gave a correlation coefficient of 0. 99. Plotting of the NIR-predicted protein content against the Kjeldahl-analysed protein gave a correlation coefficient of 0.81.

CONCLUSION

NIR-spectroscopy seems to be able to determine fat content in mixed, homogenized diets to a high degree of accuracy. In surveys involving duplicate portion sampling this will save time and money. The prediction accuracy for protein was less convincing, but acceptable depending on the need for accurate individual data.

SPONSORSHIP

Norwegian Food Research Institute, Institute for Nutrition Research at the University of Oslo and the Research Society of the Norwegian Edible Fat Producers and the food company Mills DA. European Journal of Clinical Nutrition (2000) 54, 20-23

Supplementary selenium influences the response to fatty acid-induced oxidative stress in humans

The mutual influences of wheat selenium (Se) and n-3 polyunsaturated fatty acids (n-3 PUFA) on plasma Se and indicators of increased oxidative stress were investigated in a randomized, double-blind study with 31 women (23.5 +/- 3.4 yr). Groups 1 and 2 ingested 5.4 g n-3 PUFA daily (as ethyl esters), whereas groups 3 and 4 received placebo capsules. Groups 2 and 3 received 3 slices of high-Se bread daily, providing 115 micrograms Se, in addition to the 77 +/- 26 micrograms Se in the diet. Groups 1 and 4 received placebo slices. Blood samples were drawn at baseline and at 3 and 6 wk. Serum Se concentrations increased in both groups given Se-enriched bread, but significantly less in subjects given n-3 PUFA (group 2). There were no changes in the plasma ratio alpha-tocopherol:mg cholesterol or plasma ascorbic acid levels. In group 1, plasma-conjugated dienes and thiobarbituric acid-reactive substances (TBARS) rose by 130% (p < 0.005) and 126% (p < 0.005), respectively. Two-way ANOVA showed significant interaction effects of Se and n-3 PUFA on changes in conjugated dienes (p = 0.03) and TBARS (p = 0.015), Se treatment apparently modifying the peroxidative effects of n-3 PUFA. In subjects receiving n-3 PUFA, changes in conjugated dienes and TBARS were negatively correlated with changes in serum Se. In summary, n-3 PUFA modified the effect of Se supplementation, whereas Se seemed to modify the peroxidative effects of n-3 PUFA.

Oral intake of selenium has no effect on the serum concentrations of growth hormone, insulin-like growth factor-1, insulin-like growth factor-binding proteins 1 and 3 in healthy women

The administration of large doses of selenium (Se) to rats leads to reduced serum levels of somatotropin (growth hormone) and insulin-like growth factor-1 (IGF-1), followed by growth retardation. Similar experiments in humans have been contradictory. The effects of wheat Se and selenomethionine supplementation were investigated in healthy, Norwegian women. In study 1, the participants (n = 18) were given Se-rich bread with 100, 200 and 300 micrograms Se daily for 6 weeks. Initial serum Se concentration were 1.5 +/- 0.2 mumol/l (mean +/- SD). Serum Se increased in a dose-dependent manner in the three groups (p < 0.001). There was no effect on somatotropin and IGF-1 at any of the Se doses given. In study 2 (n = 24), the effects of 400 micrograms selenomethionine daily for 15 weeks were studied in a placebo controlled study. In the treatment group, serum Se concentrations increased by more than 100%. There was, however, no effect on serum somatotropin and IGF-1 concentrations, nor was there any effect on IGF-binding proteins 1 and 3. Our results indicate that at normal or slightly increased intakes, Se has no effect on the serum concentrations of these two hormones in healthy individuals.

Does dietary arsenic and mercury affect cutaneous bleeding time and blood lipids in humans?

Fish species may contain considerable amounts of trace elements, such as selenium (Se), arsenic (As), and mercury (Hg). The present study investigated the relationships between dietary intake of these elements and cutaneous bleeding time and blood lipids in 32 healthy volunteers. For 6 wk, one group (n = 11) consumed approx 250 g Se-rich fish daily, providing them with an average Se intake of 115 +/- 31 micrograms Se/d, Hg intake of 18 +/- 8 micrograms/d, and As intake of 806 +/- 405 micrograms/d, all values analyzed in 4-d duplicate food collections. To study the effect of Se alone, one group (n = 11) included Se-rich bread in their normal diet, giving them a Se intake (135 +/- 25 micrograms/d) that was comparable to the fish group. A control group (n = 10) ate their normal diet, providing 77 +/- 25 micrograms Se/d, 3.1 +/- 2.5 micrograms Hg/d, and 101 +/- 33 micrograms As/d. The dietary As load strongly correlated both with bleeding times and changes in bleeding times (r = 0.48, p < 0.01 and r = 0.54, p < 0.002, respectively). Dietary Hg showed a positive correlation with LDL-cholesterol (r = 0.55, p < 0.01), whereas dietary Hg in the fish group showed a strong negative relationship with HDL-cholesterol (r = -0.76, p < 0.01). Selenium seemed to have only a modest effect on bleeding time. Our results suggest that mercury and arsenic from fish may be factors contributing to or modifying some of the known effects of fish ingestion.

Bleeding times related to serum triglyceride levels in healthy young adults

A diet rich in fish tends to increase the bleeding time both in patients and healthy controls. Another effect of such a diet is a reduction in serum triglyceride levels in the individuals. It is not known whether these two effects are interrelated. In order to rule out effects of selenium in the fish diet, half of a control group consumed bread enriched with selenium while the other half had a normal diet. This combined control group (n = 21) was compared with healthy volunteers (n = 11) eating 250 g of fish daily for six weeks. Blood tests were performed at the start of the study, after three weeks and at the end. Changes in bleeding time were then related to changes in hemostatic variables and serum lipids. An inverse correlation (r = -0.41, p = 0.001) was present in the controls between serum triglyceride levels and bleeding times, but neither of the two variables changed in the course of the study. A negative correlation was observed in the fish eating group, and a change in the variables mentioned occurred in an orderly manner in the course of the study: a prolongation of the bleeding time from the start of the study to the end was only seen in individuals with low triglyceride levels, i.e. less than 1 mmol/L. Selenium in the diet, on the other hand, did not affect any of the observed variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet selenium as indicator of wheat selenium intake

The effect of an increased intake of wheat selenium (Se) on platelet Se, serum Se, whole-blood Se, and glutathione peroxidase (GSH-Px) levels was investigated in 14 healthy Norwegian females (age 21-53 years). The intake of 60 micrograms Se per day as wheat Se, for six weeks, significantly increased the platelet Se (mean +/- SEM) from 9.1 +/- 1.1 mumol/L to 11.4 +/- 0.9 mumol/L, the serum Se from 1.43 +/- 0.18 mumol/L to 1.63 +/- 0.25 mumol/L, and the whole blood Se from 1.77 +/- 0.18 mumol/L to 2.01 +/- 0.18 mumol/L. The increase in percent of initial Se values was twice as high for platelets as for serum and whole blood. The GSH-Px levels were not altered during the experiment. Platelet Se was not significantly correlated to the Se intake initially. At the end of the experimental period, the Se in platelets reflected the total Se intake, but not with a simple linear correlation. No significant correlation between the total Se intake and the Se concentration in whole blood or serum was found.

Supplementation with wheat selenium induces a dose-dependent response in serum and urine of a Se-replete population

In spite of a rather modest dietary intake of selenium (80 micrograms/10 MJ), Norwegian serum Se levels are among the highest in Europe. As part of an ongoing study of Se bioavailability, effects of different doses of wheat Se were investigated in eighteen healthy, Norwegian women. The participants were given Se-rich bread providing 100, 200 and 300 micrograms Se daily for 6 weeks. About 50% of the Se intake was excreted in the urine by week 6, compared with 67% before the intervention started. Serum Se increased by 20, 37 and 53 micrograms/l respectively, in the three group (P less than 0.001). The blood response and renal clearance results compare well with data obtained from less Se-replete populations, and support the hypothesis that selenomethionine from the diet is incorporated into a non-specific amino acid pool. Our study indicates that the intake of wheat Se is the main determinant of blood Se levels in Norway.

The form of selenium determines the response to supplementation in a selenium replete population

In an ongoing study of selenium bioavailability, effects of supplementation with organic and inorganic forms of selenium were investigated in healthy, Norwegian women, aged 23-50 years. In phase I of the study, 58 women received 200 micrograms selenium per day either as selenite or selenium-rich pea flour for 3 months. The selenium tablets were taken together with placebo or ascorbic acid in a double blind design. Initial blood and serum selenium concentrations were 153 +/- 15 micrograms/l and 117 +/- 12 micrograms/l, respectively. These are average values for Norwegians. Indications of increased blood levels were seen in all groups, but the rise reached significance only for the subgroup receiving selenite and ascorbic acid, 14 micrograms/l, P less than 0.05. On the other hand, selenium analysis of 72-h urine samples confirmed that at an average 50 per cent of the selenium supplements had been absorbed. In phase II of the study, 28 of the participants continued for another 5 weeks, still on 200 micrograms Se per day, but this time consuming commercially available preparations. Of four preparations that were tested, two consisted of yeast Se. Only one of these produced a significant rise in blood and serum selenium levels, 60 and 55 micrograms/l respectively. Blood glutathione peroxidase values were not affected by any supplementation. The study demonstrates that different forms of organic selenium elicit widely different responses when administered to a relatively selenium-replete population, and that the explanation for this must be sought at the metabolic level.

Iron status in a group of Norwegian menstruating women

Serum ferritin was determined in 170 healthy Norwegian women (18-48 years; median age 36 years) including 23 blood donors. In women with serum ferritin less than or equal to 20 micrograms/l haemoglobin, serum iron and total iron binding capacity were determined. Women using oral contraceptives were excluded. Information was collected on use of contraceptive techniques, habits of iron prophylaxis, and duration of menses. About 40 per cent of the participants used the intra-uterine device. Geometric mean serum ferritin was 26.9 micrograms/l with a prevalence of 21.8 per cent with exhausted iron stores (serum ferritin less than 17 micrograms/l) among the non-donors. In the group with low to empty iron stores (serum ferritin less than or equal to 20 micrograms/l) 13 per cent had anaemia (Hb less than 120 g/l). This may correspond to 4.1 per cent among all the non-donors. The blood donors had a geometric mean serum ferritin of 20.4 micrograms/l and 30 per cent with empty stores. Our study shows that in the group of non-donors there was a tendency to higher prevalence of low or empty iron stores among IUD-users and premenopausal women. In addition to these groups the blood donors are at risk of iron deficiency.

Bioavailability of daily low dose iron supplements in menstruating women with low iron stores

Women (n = 45; 18-48 years) with serum ferritin less than or equal to 20 micrograms/l and haemoglobin greater than 120 g/l participated in an iron supplement bioavailability study. They were randomized to one of three groups and given one of three different low-dose supplements (18-20 mg iron/d) for 6 months. One of the supplements contained haem iron and non-haem iron, the others contained non-haem iron only. Serum ferritin, haemoglobin, serum iron and total iron binding capacity (TIBC) were determined at start and after 1, 3 and 6 months. Dietary intakes were recorded during 4 and 3 consecutive days after 1 and 3 months, respectively, by the aid of household measures and a set of food models. The increase in mean serum ferritin was significant (P less than 0.01) for two of the supplements, the one containing haem iron giving the best result. All the supplements resulted in a significant (P less than 0.011) mean decrease in TIBC. No significant differences between the groups were found in daily intakes of food factors known to influence iron absorption. The improvement in iron status was therefore attributed to the supplements. None of the supplements caused iron intolerance. Thus low-dose iron supplements given to iron depleted non-anaemic women may be an alternative to high-dose therapy.

[Women and iron deficiency--a problem? Iron levels in a group of fertile Norwegian women and the bioavailability of 3 low-dose iron supplements in women with low iron stores]

Serum ferritin levels were determined in 170 healthy Norwegian women (18-48 y, median age 36 y) including 23 blood donors. Exhausted iron stores, defined by serum ferritin levels less than 17 micrograms/l, were found in 21.8% of the non-donors, and in 30.4% of the donors. Women with serum ferritin levels less than or equal to 20 micrograms/l participated in a bioavailability study. They were randomized to one of three groups and given one of three different low dose iron supplements (18-20 mg iron per day) for six months. One of the supplements contained heme iron and non-heme iron, the other two contained non-heme iron only. Mean serum ferritin increase was significant for two of the supplements, the one containing heme iron giving the best result. All the supplements resulted in a significant decrease in TIBC.