(13)C mixed triglyceride breath testing using infrared spectrometry: comparison of two devices in early infancy.

BACKGROUND/OBJECTIVES: The (13)C mixed triglyceride (MTG) breath test has been proposed for the non-invasive assessment of fat digestion and absorption. To evaluate whether reference values for the adequacy of fat absorption, set in the non-dispersive infrared spectrometry (NDIRS) system software proposed for healthy children and adults using the (13)C MTG breath test, are also applicable to infants of <5 months of age. SUBJECTS/METHODS: (13)C MTG breath testing with the NDIRS technique was performed in 54 healthy infants <5 months of age (38 breast-fed, 16 formula-fed) and six infants diagnosed with cystic fibrosis (CF) using two NDIRS devices, IRIS and FANci2. RESULTS: The IRIS results were slightly higher compared with those assessed by the FANci2 device. The minimum cutoff value for pancreatic sufficiency (PS) is set as a cumulative percentage dose of (13)C recovered (cPDR) after 5 h of 13.0%. Pancreatic function status of six CF infants, three with PS and three with pancreatic insufficiency (PI), according to the 72 h-faecal fat balance test could be correctly determined with the (13)C MTG breath test using two NDIRS techniques. However, if these reference values had been used to determine pancreatic function status in healthy infants, 26 out of 54 infants would have been misclassified as pancreatic insufficient. CONCLUSIONS: Although the (13)C MTG breath test with the MS technique has the potential to be a suitable assessment of fat absorption in infants, the technique of NDIRS appears too insensitive in an infant population group.

Examination of iodine status in the German population: an example for methodological pitfalls of the current approach of iodine status assessment.

PURPOSE: Preliminary iodine concentration (UIC) measurements in spot urines of the representative German adult study DEGS indicated a severe worsening of iodine status compared to previous results in German children (KiGGS study). Therefore, we aimed to evaluate adult iodine status in detail and to investigate the impact of hydration status on UIC. METHODS: UIC and creatinine concentrations were measured in 6978 spot urines from the German nationwide DEGS study (2008-2011). Twenty-four-hour iodine excretions (24-h UIE) were estimated by relating iodine/creatinine ratios to age- and sex-specific 24-h creatinine reference values. Urine osmolality was measured in two subsamples of spot urines (n = 100 each) to determine the impact of hydration status on UIC. RESULTS: In DEGS, median UIC was 69 µg/L in men and 54 µg/L in women, lying clearly below the WHO cutoff for iodine sufficiency (100 µg/L). Estimated median 24-h UIE was 113 µg/day, accompanied by 32 % of DEGS adults, lying below the estimated average requirement (EAR) for iodine. Comparative analysis with the KiGGS data (>14,000 spot urines of children; median UIC 117 µg/L) revealed a comparable percentage

Urinary 24-h creatinine excretion in adults and its use as a simple tool for the estimation of daily urinary analyte excretion from analyte/creatinine ratios in populations.

BACKGROUND/OBJECTIVES: The assessment of urinary excretion of specific nutrients (e.g. iodine, sodium) is frequently used to monitor a population's nutrient status. However, when only spot urines are available, always a risk of hydration-status-dependent dilution effects and related misinterpretations exists. The aim of the present study was to establish mean values of 24-h creatinine excretion widely applicable for an appropriate estimation of 24-h excretion rates of analytes from spot urines in adults. SUBJECTS/METHODS: Twenty-four-hour creatinine excretion from the formerly representative cross-sectional German VERA Study (n=1463, 20-79 years old) was analysed. Linear regression analysis was performed to identify the most important influencing factors of creatinine excretion. In a subsample of the German DONALD Study (n=176, 20-29 years old), the applicability of the 24-h creatinine excretion values of VERA for the estimation of 24-h sodium and iodine excretion from urinary concentration measurements was tested. RESULTS: In the VERA Study, mean 24-h creatinine excretion was 15.4 mmol per day in men and 11.1 mmol per day in women, significantly dependent on sex, age, body weight and body mass index. Based on the established 24-h creatinine excretion values, mean 24-h iodine and sodium excretions could be estimated from respective analyte/creatinine concentrations, with average deviations <10% compared with the actual 24-h means. CONCLUSIONS: The present mean values of 24-h creatinine excretion are suggested as a useful tool to derive realistic hydration-status-independent average 24-h excretion rates from urinary analyte/creatinine ratios. We propose to apply these creatinine reference means routinely in biomarker-based studies aiming at characterizing the nutrient or metabolite status of adult populations by simply measuring metabolite/creatinine ratios in spot urines.

Current daily salt intake in Germany: biomarker-based analysis of the representative DEGS study.

PURPOSE: A high dietary salt intake is a serious risk factor for the development of hypertension. Daily salt intake in most of the European countries substantially exceeds the current recommendations of salt intake. For Germany, so far, no valid biomarker-based data on current daily salt intake are available. METHODS: Data basis for this biomarker-based estimation of salt intake in the German population was the representative DEGS Study (German Health Interview and Examination Survey for Adults) conducted 2008-2011 in 18-79 old adults living in Germany. Daily salt intake was estimated from 6,962 sodium and creatinine measurements in spot urine samples. RESULTS: Median estimated daily salt intake of the 18-79 olds was 10.0 g in men and 8.4 g in women. More than 75% of men and about 70% of women exceeded the current recommendation of a maximum salt intake of 6 g/day. Fifty percentage of men and more than 35% of the women had a daily salt intake >10 g. CONCLUSION: Daily salt intake of the German population considerably exceeds the current recommendation to eat no more than 6 g salt per day. A general reduction of salt content in processed foods-which are currently the main source of salt intake-offers a promising and cost-effective potential for the improvement of all salt intake-dependent health outcomes in the population.

Established dietary estimates of net acid production do not predict measured net acid excretion in patients with Type 2 diabetes on Paleolithic-Hunter-Gatherer-type diets.

BACKGROUND/OBJECTIVES: Formulas developed to estimate diet-dependent net acid excretion (NAE) generally agree with measured values for typical Western diets. Whether they can also appropriately predict NAE for 'Paleolithic-type' (Paleo) diets-which contain very high amounts of fruits and vegetables (F&V) and concurrent high amounts of protein is unknown. Here, we compare measured NAEs with established NAE estimates in subjects with Type 2 diabetes (T2D). SUBJECTS/METHODS: Thirteen subjects with well-controlled T2D were randomized to either a Paleo or American Diabetes Association (ADA) diet for 14 days. Twenty-four hour urine collections were performed at baseline and end of the diet period, and analyzed for titratable acid, bicarbonate and ammonium to calculate measured NAE. Three formulas for estimating NAE from dietary intake were used; two (NAE_diet R or L) that include dietary mineral intake and sulfate- and organic acid (OA) production, and one that is empirically derived (NAE_diet F) only considering potassium and protein intake. RESULTS: Measured NAE on the Paleo diet was significantly lower than on the ADA-diet (+31±22 vs 112±52 mEq/day, P=0.002). Although all formula estimates showed similar and reasonable correlations (r=0.52-0.76) with measured NAE, each one underestimated measured values. The formula with the best correlation did not contain an estimate of dietary OA production. CONCLUSIONS: Paleo-diets are lower in NAE than typical Western diets. However, commonly used formulas clearly underestimate NAE, especially for diets with very high F&V (as the Paleo diet), and in subjects with T2D. This may be due to an inappropriate estimation of proton loads stemming from OAs, underlining the necessity for improved measures of OA-related proton sources.

Prospective association of protein intake during puberty with body composition in young adulthood.

OBJECTIVE: To examine the association of habitual animal and plant protein intake during the potentially critical period of puberty with body composition in young adulthood. DESIGN AND METHODS: Multivariable regression analyses were performed on data from 140 female and 122 male participants of the DONALD Study with ≥2 3-day weighed dietary records during puberty (girls 9-14 years; boys 10-15 years) and anthropometric measurements in young adulthood (18-25 years). Fat-free mass index (FFMI) and fat mass index (FMI) were estimated from four skinfolds. RESULTS: In women, a higher pubertal animal protein consumption was independently related to higher levels of FFMI (ptrend = 0.001), but not to FMI (ptrend = 0.5). Adjusted means of FFMI in energy-adjusted tertiles of animal protein intake were 15.3 (95% confidence interval: 15.0, 15.5), 15.4 (15.1, 15.7), 16.2 (15.9, 16.6) kg/m(2) . In men, a higher animal protein intake was related to a higher FFMI (ptrend = 0.04) and a lower FMI (ptrend = 0.001) only after adjusting FFMI for current FMI levels and vice versa. Plant protein was not associated with body composition among either sex. CONCLUSIONS: Our results show that a higher pubertal animal protein consumption may yield a higher fat-free mass in young adulthood.

[The DONALD cohort. An updated overview on 25 years of research based on the Dortmund Nutritional and Anthropometric Longitudinally Designed study]. / Die DONALD Kohorte. Ein aktueller Überblick zu 25 Jahren Forschung im Rahmen der Dortmund Nutritional and Anthropometric Longitudinally Designed Study.

The DONALD study has been conducted in Dortmund, Germany since 1985 to examine the complex relations between nutritional intake, metabolism and growth from infancy to adulthood. Every year, approximately 40 infants are newly recruited into the open cohort study. Examinations conducted at ages 3, 6, 9, 12, 18, 24 months and then annually until young adulthood, comprise anthropometry, a 3 day weighed dietary record, a 24 h urine sample (from age 3-4 years onwards), medical examinations and parental interviews. Since 2005, participants are invited for follow-up visits during adulthood (including fasting blood samples). Approximately 1,400 children have been recruited into the study up to 2010. Recent findings revealed e.g. (i) the relevance of early life factors for subsequent development of body composition and puberty timing, (ii) the relation between pubertal hormonal status and puberty onset, (iii) age and time trends in iodine status and modern dietary habits and (iv) potential furan and benzol exposition by commercial weaning foods. Future analyses will provide insight into the extent to which health in young adulthood is receptive to diet, anthropometric pattern and hormonal status in distinct potentially critical periods during childhood.

Urinary fructose: a potential biomarker for dietary fructose intake in children.

BACKGROUND/OBJECTIVES: Recently, urinary fructose and sucrose excretion in 24-h urine have been established experimentally as new biomarkers for dietary sugar intake in adults. Our objective was to investigate 1) whether the fructose biomarker is also applicable in free-living children and 2) for what kind of sugar it is standing for. SUBJECTS/METHODS: Intakes of added and total sugar (including additional sugar from fruit and fruit juices) were assessed by 3-day weighed dietary records in 114 healthy prepubertal children; corresponding 24-h urinary fructose excretion was measured photometrically. The associations between dietary sugar intakes and urinary fructose excretion were examined using linear regression models. To determine whether one of the two sugar variables may be better associated with the urinary biomarker, the statistical Pitman's test was used. RESULTS: Added and total sugar correlated significantly with urinary fructose, but the linear regression indicated a weak association between intake of added sugar and urinary log-fructose excretion (ß=0.0026, R(2)=0.055, P=0.01). The association between total sugar intake and log-urinary fructose (ß=0.0040, R(2)=0.181, P<0.001) showed a significantly better fit (P<0.05). CONCLUSIONS: Urinary fructose excretion seems to be rather applicable for the estimation of total sugar intake than for the estimation of added dietary sugar intake in children. However, as excreted fructose stems almost exclusively from the diet (both from food-intrinsic and added intakes), it can be assumed that urinary fructose represents a potential biomarker for total dietary fructose intake, irrespective of its source.

[Iodine deficiency in infancy - a risk for cognitive development]. / Jodmangel im Säuglingsalter - ein Risiko für die kognitive Entwicklung.

Severe iodine deficiency during pregnancy seriously influences fetal brain development and in the worst case induces cretinism. Recent studies have shown that even a mild iodine deficiency during pregnancy and during the first years of life adversely affects brain development. The World Health Organisation (WHO) considers iodine deficiency as the most common preventable cause of early childhood mental deficiency. In this context, the insufficient production of the four iodine atoms containing thyroxine seems to play a causal role, i. e., due to the iodine substrate deficiency the neuronally particularly relevant free-thyroxine level falls. Due to the very limited iodine storage capacity, the infantile thyroid is eminently dependent on an adequate and steady iodine supply. In the first month of life, when milk is the only energy- and nutrient provider, infants fed a commercial formula regularly have a sufficient iodine supply. However, breastfed infants, who depend on maternal iodine status, frequently show an inadequate iodine intake. Furthermore, iodine intake is critical when complementary food (CF) is introduced. Especially homemade CF is poor in iodine, but also commercial CFs are only partly fortified. A simultaneous inadequate iodine supply of the breastfeeding mother and the preferential use of mostly iodine-poor organic milk cannot ensure an adequate iodine supply of the infant. In terms of an improvement of nutrient supply, especially concerning an unhindered brain development, the corresponding German reference value for iodine intake of infants until age 4 month should be raised from currently 40 microg/d to at least 60 microg/d (WHO-reference: 90 microg/d).

Iodine intake in the youngest: impact of commercial complementary food.

Iodine is a nutrient contributing to the development of the central nervous system. To assure a sufficient iodine intake, iodine fortification of complementary food (CF) is recommended. We describe the current fortification practice of commercial CF and formula in Germany as an example for other European countries, based on a market survey conducted in autumn 2008. In addition, we estimated the iodine intake of an 8-month-old infant, fed one portion of milk and three complementary meals per day. All formulae were fortified with iodine, and half of CF products. Iodine concentration varied depending on product groups. A partially breast-fed infant getting homemade CF reached less than 50% of the recommended iodine intake. Using infant formula and commercial CF, the recommended intake was exceeded by 39 or 100%, depending on which products were chosen. A well-balanced fortification of commercial CF, including pure infant cereals, would be required to ensure an adequate iodine supply.

Muscularity and adiposity in addition to net acid excretion as predictors of 24-h urinary pH in young adults and elderly.

OBJECTIVE: In patients with nephrolithiasis, an inverse relationship between 24-h urinary pH (24h-UpH) and body weight has been reported. Whether body composition indices and 24h-UpH are similarly associated in healthy subjects needs investigation. DESIGN: Cross-sectional, retrospective analysis. SETTING: Dortmund, Germany and Gothenburg, Sweden. SUBJECTS: Healthy young adults (18-23 years; n=117) and elderly (55-75 years; n=85) having a mean body mass index (BMI) of 22.80+/-3.4 and 25.3+/-3.9 kg/m2, respectively. METHODS: Anthropometric data, 24h-UpH, and 24-h urinary excretion rates of net acid (NAE), creatinine, and urea were determined. After adjusting for urea (reflecting protein intake), renal creatinine output was used as a biochemical marker for muscularity. The BMI served as a marker of adiposity. RESULTS: NAE, body weight, and BMI were significantly (P<0.05) higher, and height and creatinine significantly lower in the elderly, whereas body-surface area (BSA) was not different. Step-wise multiple regression analysis using BSA-corrected urinary variables revealed NAE as the primary predictor of 24h-UpH (with R2 values of 0.64 and 0.68 in young adults and elderly, respectively, P<0.0001), followed by urea (P<0.0001), creatinine (P<0.05), and BMI (P<0.05 for the young adults and P=0.12 for the elderly). These associations were negative for NAE and BMI, and positive for urea and creatinine. CONCLUSIONS: Muscularity (i.e. creatinine adjusted for urea) and particularly in the group of young adults, adiposity (i.e. BMI) proved to be modest, but significant predictors of 24h-UpH. Future research should focus on more obese subjects in whom insulin resistance and particular kidney functions should also be examined to further substantiate the role of obesity in low-urine pH-associated conditions, for example, nephrolithiasis.

The bone mass concept: problems in short stature.

Bone densitometry is currently one of the mainstays in the evaluation of systemic bone diseases in adults and is also increasingly used to assess primary or secondary bone disorders in children and adolescents. The purpose of carrying out densitometric studies in such circumstances is to measure the densitometric indicators of bone stability. Following procedures which were established for diagnosing adult osteoporosis, a decrease in densitometric surrogates of bone stability is usually interpreted as indicating increased fracture risk. The most basic densitometric parameter is bone mineral content (BMC), which can be measured with most densitometric techniques. BMC is either defined as the mass of mineral contained in an entire bone or as the mass of mineral per unit bone length. While mineral mass can be expected to be a good surrogate for bone stability, BMC is obviously a size-dependent parameter, since small bones weigh less than big bones. This is a drawback in paediatric use, since many children and adolescents who are examined by densitometry suffer from chronic disorders and are small-for-age. Short children will have a lower BMC than their healthy age-matched peers, even if their (smaller) bones are otherwise completely normal.

Long-Term stability of 6-hydroxymelatonin sulfate in 24-h urine samples stored at -20 degrees C.

The purpose of the present feasibility study was to determine whether the concentration of 6-hydroxymelatonin sulfate (6-OHMS) remains stable in urine samples stored over at least 15 yr. To test this, 117 twenty-four-hour urine samples were analyzed, which were obtained from healthy children ages 8 to 9 yr within the periods of 1985-1987,1991-1993, and 1997-1999. 6-OHMS concentrations were determined by enzyme-linked immunosorbent assay. The statistical analyses clearly indicate that the concentration of 6-OHMS remains stable for at least 15 yr if the urine is stored at -20 degrees C.

The midgrowth spurt in healthy children is not caused by adrenarche.

A small transient increase in growth, the midgrowth spurt, has been observed in several growth studies in healthy children around the age of 7 yr. During this time adrenarche (the physiological increase in adrenal androgen secretion) also occurs. Although it is now well established that estrogen, not androgen, has a critical role in the male (and female) pubertal growth spurt, a direct effect of androgens on growth cannot be excluded. In accordance with published observations that growth is frequently accelerated in infants and young children with late-diagnosed 21-hydroxylase deficiency (before adequate androgen suppression), it has been speculated that the adrenarchal increase in adrenal androgen secretion in healthy children could be responsible for the midgrowth spurt. To test this hypothesis we studied long-term serial changes in urinary 24-h excretion rates of dehydroepiandrosterone sulfate and total 17-ketosteroid sulfates in a group of healthy children (n = 12) in which yearly auxological measurements allowed the identification of a midgrowth spurt. Annual measurements of standing height were performed over periods of 6-9 yr before the onset of puberty. All children collected five to seven serial 24-h urine samples (1-yr intervals) each at the time of anthropometric examination. The peak of the midgrowth spurt was found to occur at a mean age of 6.8 +/- 1.0 yr. The average height of the midgrowth peak, i.e. average maximum gain in height velocity, was 0.9 cm/yr. In a peak-centered examination of individual 24-h excretion rates of dehydroepiandrosterone sulfate and 17-ketosteroid sulfates, primarily weak 1-yr changes in adrenal androgens were observed until the peak was attained. Only after the peak did increments in urinary adrenal androgen output become more pronounced. ANOVA performed on the peak-centered dehydroepiandrosterone sulfate and 17-ketosteroid sulfate excretion rates revealed a highly significant overall increase in adrenal androgen secretion from 2 yr before to 2 yr after the midgrowth spurt. After multiple testing, however, significant increments, when compared with the respective preceding androgen excretion levels, were for the first time seen 1 yr after the midgrowth spurt (dehydroepiandrosterone sulfate) or 2 yr later (17-ketosteroid sulfates). In conclusion, our longitudinal analysis of prepubertal growth and urinary adrenal androgen excretion in healthy children disproves the speculation that the midgrowth spurt is primarily caused by the adrenarchal increase in adrenal androgen secretion. However, the present results do not rule out a growth-accelerating effect of clearly higher androgen levels, as in premature adrenarche.

Measurements of urinary leptin and capillary leptin: alternative tools for the assessment of the leptin status?

OBJECTIVES: The aim of this study was to check whether leptin is reliably measurable in urine samples of children, adolescents, and adults and to examine whether capillary leptin measurements can be utilized as an alternative tool to assess the leptin status. METHODS: Two studies were performed. In both studies, leptin was quantified by an ultrasensitive and highly specific enzyme immunoassay (ELISA; R & D Systems). Anthropometric measures were taken from all study subjects, and body fat was calculated using skinfold thickness measurements. In study 1, leptin was analyzed in 24-hour urine samples of 155 healthy children and adolescents and 26 healthy adults after a methodological modification of the assay necessary for urine analysis. In study 2, venous and capillary blood samples were collected in 26 healthy adults within 10 min on the same day. RESULTS: After adapting the assay system to urine matrix, the detection range was 20-160 pg/ml. Only in 2 of 181 urine samples reproducibly measurable urinary leptin concentrations in the lowest detection range were found. In study 2, a close correlation was found between log capillary and log venous leptin concentrations (r = 0.98, p < 0.001) and between log capillary as well as log venous leptin levels and percent body fat (r = 0.86, p < 0.001). CONCLUSIONS: Our results based on one of the most specific and sensitive ELISAs currently available show that leptin is generally undetectable in the urine from healthy children, adolescents and adults. Thus, urinary leptin excretion cannot be used as a noninvasive marker of the leptin status. Our findings in healthy adults show that the merely moderately invasive determination of capillary leptin allows a reliable assessment of the individual leptin status and may be used instead of venous leptin as a biochemical indicator of body fatness.

Influence of nutrition on acid-base balance--metabolic aspects.

BACKGROUND: Nutrition has long been known to strongly influence acid-base balance. Recently, we have shown that it is possible to appropriately estimate the renal net acid excretion (NAE) of healthy subjects from the composition of their diets. AIM OF THE STUDY: 1) To briefly present a physiologically based calculation model that allows a reasonable estimation of the analytically determined urinary NAE, 2) to summarize the underlying metabolic mechanisms and 3) to study the specific effect of protein on ammoniagenesis which may counteract, to a small degree, the primary acid load-increasing potential of protein. METHODS: The calculation model and the algorithm for predicting the dietary acid load are summarized, major metabolic (and intestinal) pathways of acid and base equivalents are explained, and urinary excretion rates of ammonium and NAE were specifically examined with special regard to the respective protein intake levels. For the latter examinations, data from diet experiments in adults and epidemiological data from children (protein intake; NAE, pH, and ammonium excretion in 24-h urine samples) were analyzed. RESULTS: The paper shows that the diet-induced generation of acidity and alkalinity is not only determined by the metabolism (oxidation) of sulfur-containing amino acids and organic acid anions of alkali salts, respectively. The intestine is also directly involved in the generation of food-derived acid or alkali loads which is due to the considerably different intestinal absorption rates of relevant food components, i. e., protein and minerals. Further analyses of the interrelation between diet and acid-base status revealed that increasing protein intake (despite its potential to increase NAE) also significantly improves the capacity for renal net acid excretion by stimulating urinary ammonium excretion. CONCLUSION: An adequate concept to estimate renal NAE and potential renal acid loads from dietary intakes must consider the specific bioavailability of the individual nutrients. Furthermore, an increased protein intake does not necessarily result in an accordingly increased use of endogenous acid excretion capacity for two reasons: 1) additional alkali loads in an appropriately composed diet can compensate for the protein-related raised acid production and 2) protein itself moderately improves the renal capacity to excrete net acid by increasing the endogenous supply of ammonia which is the major urinary hydrogen ion acceptor.

Adrenarche and nutritional status.

The prepubertal fat spurt seen in mid-childhood coincides with the beginning of adrenarche and is associated with rising serum levels of insulin and insulin-like growth factor-I. As the adrenal cortex expresses receptors for these anabolic peptides, implying that the nutritional status is communicated to the adrenal gland, we hypothesized that nutritional status may be causally involved in the regulation of adrenal androgen secretion. To test this hypothesis, anthropometric indices of the nutritional status and 24-h urinary excretion rates of dehydroepiandrosterone sulfate (DHEAS) were studied longitudinally (during observation periods of at least 4 years) in healthy normal-weight prepubertal and pubertal children. Increases in urinary DHEAS excretion proved to be significantly elevated during periods of individual highest rises in body mass index. These findings provide the first in vivo evidence that a change in nutritional status is an important physiological regulator of adrenarche.