Isabelle Aeberli

Evidence that the prevalence of childhood overweight is plateauing: data from nine countries

Until quite recently, there has been a widespread belief in the popular media and scientific literature that the prevalence of childhood obesity is rapidly increasing. However, high quality evidence has emerged from several countries suggesting that the rise in the prevalence has slowed appreciably, or even plateaued. This review brings together such data from nine countries (Australia, China, England, France, Netherlands, New Zealand, Sweden, Switzerland and USA), with data from 467,294 children aged 2-19 years. The mean unweighted rate of change in prevalence of overweight and obesity was +0.00 (0.49)% per year across all age ×sex groups and all countries between 1995 and 2008. For overweight alone, the figure was +0.01 (0.56)%, and for obesity alone -0.01 (0.24)%. Rates of change differed by sex, age, socioeconomic status and ethnicity. While the prevalence of overweight and obesity appears to be stabilizing at different levels in different countries, it remains high, and a significant public health issue. Possible reasons for the apparent flattening are hypothesised.

Low to moderate sugar-sweetened beverage consumption impairs glucose and lipid metabolism and promotes inflammation in healthy young men: a randomized controlled trial

BACKGROUND Sugar-sweetened beverages (SSBs) have unfavorable effects on glucose and lipid metabolism if consumed in high quantities by obese subjects, but the effect of lower doses in normal-weight subjects is less clear. OBJECTIVE The aim was to investigate the effects of SSBs consumed in small to moderate quantities for 3 wk on LDL particle distribution and on other parameters of glucose and lipid metabolism as well as on inflammatory markers in healthy young men. DESIGN Twenty-nine subjects were studied in a prospective, randomized, controlled crossover trial. Six 3-wk interventions were assigned in random order as follows: 600 mL SSBs containing 1)40 g fructose/d [medium fructose (MF)], 2) 80 g fructose/d [high fructose (HF)], 3) 40 g glucose/d [medium glucose (MG)], 4) 80 g glucose/d [high glucose (HG)], 5) 80 g sucrose/d [high sucrose (HS)], or 6) dietary advice to consume low amounts of fructose. Outcome parameters were measured at baseline and after each intervention. RESULTS LDL particle size was reduced after HF by -0.51 nm (95% CI: -0.19, -0.82 nm) and after HS by -0.43 nm (95% CI: -0.12, -0.74; P < 0.05 for both). Similarly, a more atherogenic LDL subclass distribution was seen when fructose-containing SSBs were consumed (MF, HF, and HS: P < 0.05). Fasting glucose and high-sensitivity C-reactive protein (hs-CRP) increased significantly after all interventions (by 4-9% and 60-109%, respectively; P < 0.05); leptin increased during interventions with SSBs containing glucose only (MG and HG: P < 0.05). CONCLUSION The present data show potentially harmful effects of low to moderate consumption of SSBs on markers of cardiovascular risk such as LDL particles, fasting glucose, and hs-CRP within just 3 wk in healthy young men, which is of particular significance for young consumers. This trial was registered at clinicaltrials.gov as NCT01021969.

Ten Repeat Collections for Urinary Iodine from Spot Samples or 24-Hour Samples Are Needed to Reliably Estimate Individual Iodine Status in Women

Although the median urinary iodine concentration (UIC) is a good indicator of iodine status in populations, there is no established biomarker for individual iodine status. If the UIC were to be used to assess individuals, it is unclear how many repeat urine collections would be needed and if the collections should be spot samples or 24-h samples. In a prospective, longitudinal, 15-mo study, healthy Swiss women (n = 22) aged 52-77 y collected repeated 24-h urine samples (total n = 341) and corresponding fasting, second-void, morning spot urine samples (n = 177). From the UIC in spot samples, 24-h urinary iodine excretion (UIE) was extrapolated based on the age- and sex-adjusted iodine:creatinine ratio. Measured UIE in 24-h samples, estimated 24-h UIE, and UIC in spot samples were (geometric mean ± SD) 103 ± 28 μg/24 h, 86 ± 33 μg/24 h, and 68 ± 28 μg/L, respectively, with no seasonal differences. Intra-individual variation (mean CV) was comparable for measured UIE (32%) and estimated UIE (33%). The CV tended to be higher for the spot UIC (38%) than for the estimated 24-h UIE (33%) (P = 0.12). In this population, 10 spot urine samples or 24-h urine samples were needed to assess individual iodine status with 20% precision. Spot samples would likely be preferable because of their ease of collection. However, the large number of repeated urine samples needed to estimate individual iodine status is a major limitation and emphasizes the need for further investigation of more practical biomarkers of individual iodine status.

Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification

Background:Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association between body mass index (BMI) and iron absorption, iron status and the response to iron fortification in populations from three transition countries (Thailand, Morocco and India).Methods:In Thai women (n=92), we examined the relationship between BMI and iron absorption from a reference meal containing ∼4 mg of isotopically labeled fortification iron. We analyzed data from baseline (n=1688) and intervention (n=727) studies in children in Morocco and India to look for associations between BMI Z-scores and baseline hemoglobin, serum ferritin and transferrin receptor, whole blood zinc protoporphyrin and body iron stores, and changes in these measures after provision of iron.Results:In the Thai women, 20% were iron deficient and 22% were overweight. Independent of iron status, a higher BMI Z-score was associated with decreased iron absorption (P=0.030). In the Indian and Moroccan children, 42% were iron deficient and 6.3% were overweight. A higher BMI Z-score predicted poorer iron status at baseline (P<0.001) and less improvement in iron status during the interventions (P<0.001).Conclusions:Adiposity in young women predicts lower iron absorption, and pediatric adiposity predicts iron deficiency and a reduced response to iron fortification. These data suggest the current surge in overweight in transition countries may impair efforts to control iron deficiency in these target groups. Interactions of the ‘double burden’ of malnutrition during the nutrition transition may have adverse consequences.

Increasing the iodine concentration in the Swiss iodized salt program markedly improved iodine status in pregnant women and children: a 5-y prospective national study

BACKGROUND Many industrialized countries struggle to maintain adequate iodine intake because of changes in dietary habits and the food supply. In Switzerland, because of declining iodine intakes in children and pregnant women, the iodine concentration in table salt was increased from 15 to 20 mg/kg. OBJECTIVE We evaluated Swiss iodine nutrition after the 1999 increase in the salt iodine concentration. DESIGN In 1999 and 2004, a 3-stage probability proportionate-to-size cluster sampling was done to obtain a representative national sample of primary schoolchildren and pregnant women. Urine and household salt were collected for iodine measurement. The frequency of elevated thyrotropin concentrations found in the newborn screening program was evaluated before and after the increase. RESULTS In 1999, median urinary iodine (UI) concentrations among children (n = 610) and pregnant women (n = 511) were 115 microg/L (range: 5-413 microg/L) and 138 microg/L (range: 5-1881 microg/L), respectively, which indicated marginal iodine status. In 2004, median UI concentrations among children (n = 386) and pregnant women (n = 279) were 141 microg/L (range: 0-516 microg/L) and 249 microg/L (range: 8-995 microg/L), respectively (P < 0.01). Newborn thyrotropin concentrations >5 mU/L decreased from 2.9% in 1992-1998 (n = 259 035) to 1.7% in 1999-2004 (n = 218 665) (P < 0.0001). CONCLUSIONS A 25% increase in iodine concentration in iodized table salt markedly improved iodine status in Switzerland, which showed the value of monitoring and adjusting iodine concentrations in national salt programs. The frequency of newborn thyrotropin concentrations >5 mU/L appears to be a sensitive indicator of iodine nutrition during pregnancy.

Moderate Amounts of Fructose Consumption Impair Insulin Sensitivity in Healthy Young Men A randomized controlled trial

OBJECTIVE Adverse effects of hypercaloric, high-fructose diets on insulin sensitivity and lipids in human subjects have been shown repeatedly. The implications of fructose in amounts close to usual daily consumption, however, have not been well studied. This study assessed the effect of moderate amounts of fructose and sucrose compared with glucose on glucose and lipid metabolism. RESEARCH DESIGN AND METHODS Nine healthy, normal-weight male volunteers (aged 21–25 years) were studied in this double-blind, randomized, cross-over trial. All subjects consumed four different sweetened beverages (600 mL/day) for 3 weeks each: medium fructose (MF) at 40 g/day, and high fructose (HF), high glucose (HG), and high sucrose (HS) each at 80 g/day. Euglycemic-hyperinsulinemic clamps with [6,6]-2H2 glucose labeling were used to measure endogenous glucose production. Lipid profile, glucose, and insulin were measured in fasting samples. RESULTS Hepatic suppression of glucose production during the clamp was significantly lower after HF (59.4 ± 11.0%) than HG (70.3 ± 10.5%, P < 0.05), whereas fasting glucose, insulin, and C-peptide did not differ between the interventions. Compared with HG, LDL cholesterol and total cholesterol were significantly higher after MF, HF, and HS, and free fatty acids were significantly increased after MF, but not after the two other interventions (P < 0.05). Subjects’ energy intake during the interventions did not differ significantly from baseline intake. CONCLUSIONS This study clearly shows that moderate amounts of fructose and sucrose significantly alter hepatic insulin sensitivity and lipid metabolism compared with similar amounts of glucose.

Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children

Background:Obesity increases the risk for iron deficiency, but the underlying mechanism is unclear. It is possible that overweight individuals may have lower dietary iron intake and/or bioavailability. Alternatively, obesity-related inflammation may increase hepcidin concentrations and reduce iron availability. Circulating hepcidin levels have not been compared in normal weight vs overweight individuals.Objective:The objective of this study was to compare iron status, dietary iron intake and bioavailability, as well as circulating levels of hepcidin, leptin and interleukin-6 (IL-6), in overweight vs normal weight children.Design:In 6–14-year-old normal and overweight children (n=121), we measured dietary iron intake, estimated iron bioavailability and determined body mass index s.d. scores (BMI-SDS). In all children (n=121), we measured fasting serum ferritin, soluble transferrin receptor (sTfR), C-reactive protein (CRP) and leptin; in a subsample, we measured IL-6 (n=68) and serum hepcidin (n=30).Results:There were no significant differences in dietary iron intake or bioavailability comparing normal and overweight children. The prevalence of iron-deficient erythropoiesis (an increased sTfR concentration) was significantly higher in the overweight than in the normal weight children (20 vs 6%, P=0.022, with sTfR concentrations of 4.40±0.77 and 3.94±0.88 mg l−1, respectively, P=0.010). Serum hepcidin levels were significantly higher in the overweight children (P=0.001). BMI-SDS significantly correlated with sTfR (P=0.009), serum hepcidin (P=0.005) and the three measures of subclinical inflammation, namely CRP (P<0.001), IL-6 (P<0.001) and leptin (P<0.001). In a multiple regression model, serum hepcidin was correlated with BMI-SDS (P=0.020) and body iron (P=0.029), but not with the inflammatory markers.Conclusion:Our findings indicate that there is reduced iron availability for erythropoiesis in overweight children and that this is unlikely due to low dietary iron supply but rather due to hepcidin-mediated reduced iron absorption and/or increased iron sequestration.

Sharply higher rates of iron deficiency in obese Mexican women and children are predicted by obesity-related inflammation rather than by differences in dietary iron intake

BACKGROUND Obese individuals may be at increased risk of iron deficiency (ID), but it is unclear whether this is due to poor dietary iron intakes or to adiposity-related inflammation. OBJECTIVE The aim of this study was to examine the relations between body mass index (BMI), dietary iron, and dietary factors affecting iron bioavailability, iron status, and inflammation [C-reactive protein (CRP)] in a transition country where obesity and ID are common. DESIGN Data from the 1999 Mexican Nutrition Survey, which included 1174 children (aged 5-12 y) and 621 nonpregnant women (aged 18-50 y), were analyzed. RESULTS The prevalence of obesity was 25.3% in women and 3.5% in children. The prevalence of ID was significantly (P < 0.05) higher in obese women and children compared with normal-weight subjects [odds ratios (95% CIs): 1.92 (1.23, 3.01) and 3.96 (1.34, 11.67) for women and children, respectively]. Despite similar dietary iron intakes in the 2 groups, serum iron concentrations were lower in obese women than in normal-weight women (62.6 ± 29.5 compared with 72.4 ± 34.6 μg/dL; P = 0.014), and total-iron-binding capacity was higher in obese children than in normal-weight children (399 ± 51 compared with 360 ± 48 μg/dL; P < 0.001). CRP concentrations in obese women and children were 4 times those of their normal-weight counterparts (P < 0.05). CRP but not iron intake was a strong negative predictor of iron status, independently of BMI (P < 0.05). CONCLUSIONS The risk of ID in obese Mexican women and children was 2-4 times that of normal-weight individuals at similar dietary iron intakes. This increased risk of ID may be due to the effects of obesity-related inflammation on dietary iron absorption. Thus, ID control efforts in Mexico may be hampered by increasing rates of adiposity in women and children.

The Swiss iodized salt program provides adequate iodine for school children and pregnant women, but weaning infants not receiving iodine-containing complementary foods as well as their mothers are iodine deficient.

BACKGROUND If children and pregnant women in the population are iodine sufficient, it is generally assumed infants are also sufficient. But weaning infants may be at risk of iodine deficiency because iodized salt contributes little dietary iodine during this period. To fill this gap, iodine fortification of infant formula milk (IFM) and complementary foods (CF) is likely important. OBJECTIVES The objective of the study was to first confirm that Swiss school children and pregnant women remain iodine sufficient and then to assess iodine status in infancy and the relative contribution of breast milk and IFM/CF to their iodine intakes. METHODS We measured urinary iodine concentrations (UIC) in national cross-sectional samples of: 1) pregnant women (n=648); 2) school children (n=916); 3) infants at three time points: at 3-4 d after birth and at 6 and 12 months (n=875); and 4) breast-feeding mothers (n=507). We measured breast milk iodine concentrations in the mothers, assessed iodine sources in infant diets, and analyzed iodine content of commercial IFM/CFs (n=22) and salt samples from the school childrens households (n=266). RESULTS Median (m) UICs in pregnant women (162 μg/liter) and school children (120 μg/liter) were sufficient, and 80% of the household salt was adequately iodized (≥15 ppm). However, mUICs in infants not receiving IFM/CF were not sufficient: 1) mUIC in breast-fed infants (82 μg/liter) was lower than in non-breast-fed infants (105 μg/liter) (P<0.001) and 2) mUIC in breast-fed weaning infants not receiving IFM/CF (70 μg/liter) was lower than infants receiving IFM (109 μg/liter) (P<0.01). mUIC was low in lactating mothers (67 μg/liter) and median breast milk iodine concentration was 49 μg/kg. CONCLUSIONS In countries in which iodized salt programs supply sufficient iodine to older children and pregnant women, weaning infants, particularly those not receiving iodine-containing IFM, may be at risk of inadequate iodine intakes.

Does Obesity Increase Risk for Iron Deficiency? A Review of the Literature and the Potential Mechanisms

Increasing obesity is a major global health concern while at the same time iron-deficiency anemia remains common worldwide. Although these two conditions represent opposite ends of the spectrum of over- and under-nutrition, they appear to be linked: overweight individuals are at higher risk of iron deficiency than normal-weight individuals. Potential explanations for this association include dilutional hypoferremia, poor dietary iron intake, increased iron requirements, and/or impaired iron absorption in obese individuals. Recent evidence suggests obesity-related inflammation may play a central role through its regulation of hepcidin. Hepcidin levels are higher in obese individuals and are linked to subclinical inflammation; this may reduce iron absorption and blunt the effects of iron fortification. Thus, low iron status in overweight individuals may result from a combination of nutritional (reduced absorption) and functional (increased sequestration) iron deficiency. In this review, we focus on subclinical inflammation in obesity, and its effect on hepcidin levels, as the most plausible explanation for the link between iron deficiency and obesity.