Challenges in the assessment of total fluid intake in children and adolescents: a discussion paper

Temporal trends of per- and polyfluoroalkyl substances concentrations: Insights from Australian human biomonitoring 2002-2021 and the U.S. NHANES programs 2003-2018

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA) are persistent contaminants detected in human blood worldwide, raising significant health concerns. In response, countries such as the United States and Australia have implemented regulatory measures to limit their use. This study analysed temporal trends in serum concentrations of these four PFAS and how these trends align with regulatory measures, using data from NHANES (2003-2004 to 2017-2018) and the Australian Human Biomonitoring Program (2002-2003 to 2020-2021). Multiple regression analyses adjusted for age and gender were performed to estimate mean concentration changes over time, and differences within each dataset were assessed. Results indicated significant reductions (p < 0.001) in PFOS, PFOA, and PFHxS concentrations post-2002-2003, while PFNA concentrations increased until 2009-2010 before declining in both Australia and the U.S. Age-related trends in the U.S. during the last monitoring period showed higher PFAS concentrations in the oldest age groups, while in Australia, this trend was evident for PFOS and PFHxS. In Australia, the age group of 0-5 years had PFOA and PFNA concentrations similar to those of adults over 46 years, indicating ongoing exposure. Gender differences were consistent in both programs, with females aged 6-15, 31-45, and 46-60 years exhibiting lower serum concentrations, particularly in the 31-45 years age group. These findings support Australian and U.S. efforts to reduce PFAS exposure through regulatory actions, highlight the need to address ongoing exposure in young children, and consider gender-specific factors affecting PFAS concentrations.

Assessment of Water Intake among Chinese Toddlers: The Report of a Survey

Toddlerhood (aged 13~36 months) is a period of dietary transition, with water intake being significantly influenced by parental feeding patterns, cultural traditions, and the availability of beverages and food. Nevertheless, given the lack of applicable data, it is challenging to guide and evaluate the water intake of toddlers in China. In this study, our objectives were to assess the daily total water intake (TWI), evaluate the consumption patterns of various beverages and food sources contributing to the TWI, determine the conformity of participants to the adequate intake (AI) recommendation of water released by the Chinese Nutrition Society, and analyze the various contributors to the daily total energy intake (TEI). The data for the assessment of water and dietary intake were obtained from the cross-sectional dietary intake survey of infants and young children (DSIYC, 2018-2019). A total of 1360 eligible toddlers were recruited in the analysis. The differences in related variables between two age groups were compared by Mann-Whitney U test and Chi-Square test. The potential correlation between water and energy intake was examined utilizing age-adjusted partial correlation. Toddlers consumed a median daily TWI of 1079 mL, with 670 mL (62.3%, r = 0.752) derived from beverages and 393 mL (37.7%, r = 0.716) from foods. Plain water was the primary beverage source, contributing 300 mL (52.2%, r = 0.823), followed by milk and milk derivatives (MMDs) at 291 mL (45.6%, r = 0.595). Notably, only 28.4% of toddlers managed to reach the recommended AI value. Among these, toddlers obtain more water from beverages than from foods. The median daily TEI of toddlers was 762 kcal, including 272 kcal from beverages (36.4%, r = 0.534) and 492 kcal from foods (63.6%, r = 0.894). Among these, the median daily energy intake from MMDs was 260 kcal, making up 94.6% of the energy intake from beverages (r = 0.959). As the pioneer survey on TWI of toddlers in China based on nationally representative data, attention to the quality and quantity of water intake and actions to better guide parents by both individuals and authorities are eagerly anticipated. Additionally, the revision of the reference value of TWI for Chinese toddlers is urgently required.

An Analysis of Fluid Intake Assessment Approaches for Fluid Intake Monitoring System

Monitoring fluid intake is essential to help people manage their individual fluid intake behaviors and achieve adequate hydration. Previous studies of fluid intake assessment approaches based on inertial sensors can be categorized into wrist-worn-based and smart-container-based approaches. This study aims to analyze wrist-worn-based and smart-container-based fluid intake assessment approaches using inertial sensors. The comparison of these two approaches should be analyzed according to gesture recognition and volume estimation. In addition, the influence of the fill level and sip size information on the performance is explored in this study. The accuracy of gesture recognition with postprocessing is 92.89% and 91.8% for the wrist-worn-based approach and smart-container-based approach, respectively. For volume estimation, sip-size-dependent models can achieve better performance than general SVR models for both wrist-worn-based and smart-container-based approaches. The improvement of MAPE, MAD, and RMSE can reach over 50% except MAPE for small sip sizes. The results demonstrate that the sip size information and recognition performance are important for fluid intake assessment approaches.

Children's water intake and hydration: a public health issue

Optimal hydration is required for all physiologic functions and cognition. Children, especially younger ones, are particularly susceptible to dehydration, given their physiological specificities, in particular, their renal immaturity and relatively large skin surface in early life, but also their dependence on adults and their greater propensity to develop digestive diseases leading to fluid losses. Mild dehydration consequences are dominated by their impact on cognitive functions, whereas more severe dehydration may endanger the health outcome. Studies on this subject in children are scarce; in particular, the long-term consequence on renal function remains questionable. This review considers how children's water intake including fluid intake and water content of food, are worrying. The findings show that, worldwide, most children do not meet adequate water intake recommendations. The main problems likely to explain insufficient water intake are access to safe water, availability of drinking water at school, and healthy-hydration education, which are all points that need to be improved within health policy.

Total water intake and its contributors in infants and young children

Hydration is a particular concern for infants and young children due to their greater risk of dehydration. However, studies on their water intakes are scarce. The current survey aimed to analyse total water intake (TWI) in non-breastfed children aged 0·5-35 months compared with the adequate intake (AI) for the same age group set by the European Food Safety Authority and to examine the different contributors to TWI as well as beverage consumption patterns. Nationally representative data from the Nutri-Bébé cross-sectional survey were used to assess food, beverage and plain water consumption by age group over three non-consecutive days. With age, median TWI in 1035 children increased from 732 to 1010 ml/d, without differences between sexes, but with a great inter-individual variation, and the percentage of children who did not meet the AI increased from 10 to 88 %. Median weight-related TWI decreased from 136·6 to 69·0 ml/kg per d. Among infants, 90 % had a ratio of water:energy below the AI, similarly for about 75 % of toddlers. Milk and milk products were the main contributors to TWI, while the part of plain water increased gradually to be 25 % in the older toddlers, half of which was tap water. The beverage consumption pattern varied in types and timing, with little consumption of juices and sweetened beverages. Vegetables and fruits accounted for 20 % of TWI after the age of 6 months. These initial results, showing strong discrepancies between actual and recommended water intakes in young children, should help identify ways to increase children's water consumption.

Variations in human body water isotope composition across the United States

Accurate human provenancing using stable isotopes depends directly on solid understandings of the geographic and individual factors affecting isotope variability and incorporation into human tissues. Transfer of isotopic, and therefore spatial, information between environmental water and biological tissues is mediated by the isotopic composition of body water. Thus, there is a need to study body water isotope ratios at a population level and over a large isotopic and geographic range. We evaluated oxygen (δ¹⁸O_bw) and hydrogen (δ²H_bw) isotope values of body water from 72 volunteers in 10 different cities across the US, and over a 5-10-day period. We analyzed covariates (e.g., water intake, physical activity, biometrics, gender) that might explain individual stable isotope ratio variations and tested a predictive model that incorporates the δ-values of drinking water, food, and O₂ as well as individual variables to predict the δ-values of body water. The individual variability in body water isotope values overtime (mean 0.3‰ for δ¹⁸O_bw and 2.3‰ for δ²H_bw) was lower than the intra-city variability (mean 0.9‰ for δ¹⁸O_bw and 6.9‰ for δ²H_bw). Body water isotope values differed among cities (ANOVA: δ¹⁸O_bwF = 97.2, p < 0.001; δ²H_bwF = 176.2, p < 0.001). However, significant overlap among some cities with different drinking water was discovered. We detected significant covariation of measured drinking water and human body water isotope values (both isotope systems R² ≥ 0.89, p < 0.001) and small but significant effects of the average daily exercise and amount of fluid intake. The differences between measured and model-predicted body water values (mean 0.12 ± 1.2‰ for Δδ¹⁸O and -1.2 ± 8.2‰ for Δδ²H) were statistically indistinguishable from zero (Δδ¹⁸O t = -0.751, p = 0.45; Δδ²H t = 1.133, p = 0.26). Here we show that community level variation exists in the δ¹⁸O_bw and δ²H_bw values and the primary drivers are the regional differences in drinking water isotopes. Consistency of the body water isotope composition over the study period suggests that tissues would incorporate a stable isotope signal over time. The amount of drinking water and physical activity influence body water values, while the variation in the isotopic values of food may contribute to regional level variability, but that still remains to be assessed further. The human body water model provides accurate estimates for measured values, capturing and reproducing the main features of the body water isotope variation across space.

Evaluation of the 'H2NOE Water Schools' programme to promote water consumption in elementary school children - a non-randomised controlled cluster trial

Objective:

This study evaluated a simple environmental intervention called ‘Water Schools’ in Lower Austria providing free refillable water bottles and educational material.

Design:

Non-randomised controlled cluster trial with three measurements: at baseline (T0), after the intervention at 9 months (T1) and after 1-year follow-up (T2).

Setting:

Half-day elementary schools in Lower Austria (Austria).

Participants:

Third-grade pupils from twenty-two schools in the intervention group (IG) and thirty-two schools in the control group (CG) participated in the study. Data were analysed for 569 to 598 pupils in the IG and for 545 to 613 in the CG, depending on the time of measurement.

Results:

The consumption of tap water increased in the IG from baseline to T1 and then decreased again at T2, but this was similar in the CG (no statistically significant difference in the time trend between the IG and CG). Similar results were seen for tap water consumption in the mornings. The proportion of children who only drank tap water on school mornings increased significantly from baseline to T1 in the IG compared to the CG (P = 0·020). No difference in the changes over time occurred between the groups for the proportion of pupils drinking approximately one bottle of tap water during school mornings.

Conclusions:

Not only the children in the IG but also those in the CG drank more tap water after 1 school year than at the beginning. The measurement of drinking habits in the CG may have been intervention enough to bring about changes or to initiate projects.

Evaluation of daily hydration in pediatric outpatients over 3 years old

The topic of hydration of children over 3 years of age is often neglected in general pediatric consultations, even though proper hydration is essential for optimal physical and intellectual functions.

OBJECTIVE

To evaluate the daily water and beverage consumption of 3- to 8-year-old patients in a private pediatric practice through a retrospective observational study.

METHOD

This single-centre study was conducted in a French private practice with five pediatricians and included 200 healthy children, aged 3-8 years.

RESULTS

Recommended intake of beverages was reached in 62% of 54 children in the 3- to 4-year-old group and 43% of the 146 children in the 4- to 8-year-old group. Recommended beverages intake of±20% was found in 55% of the 3- to 4-year-old group and 45% of the 4- to 8-year-old group. The potential risk factors of inadequate hydration could not be demonstrated in this study. Water alone was the predominant intake in 63% of the 200 children; milk accounted for 19%, and sweetened drinks for 17%.

CONCLUSIONS

These results show a persistent gap between recommended and observed total beverage intake. Although our results are more robust than previous French and international published data, they remain insufficient. In the future, a systematic approach to hydration with parents and children is needed including personalised advice, while maintaining other public health interventions in schools and canteens.

Fluid Intake Restriction Concomitant to Sweetened Beverages Hydration Induce Kidney Damage

Currently, there is the paradox of low water intake but increased intake of sugar-sweetened beverages (SB) in several populations; those habits are associated with an increased prevalence of metabolic derangements and greater chronic disease mortality. Persistent heat dehydration and increased SB intake stimulate the continued release of vasopressin and overactivation of the polyol-fructokinase pathway, synergizing each other, an effect partially mediated by oxidative stress. The objective of the present study was to evaluate whether water restriction concurrent with SB hydration can cause renal damage by stimulating similar pathways as heat dehydration. Three groups of male Wistar rats (n = 6) were fluid restricted; from 10 am to 12 pm animals could rehydrate with tap water (W), or sweetened beverages, one prepared with 11% of a fructose-glucose combination (SB), or with the noncaloric edulcorant stevia (ST). A normal control group of healthy rats was also studied. The animals were followed for 4 weeks. Markers of dehydration and renal damage were evaluated at the end of the study. Fluid restriction and water hydration mildly increased urine osmolality and induced a 15% fall in CrCl while increased the markers of tubular damage by NAG and KIM-1. Such changes were in association with a mild overexpression of V1a and V2 renal receptors, polyol fructokinase pathway overactivation, and increased renal oxidative stress with reduced expression of antioxidant enzymes. Hydration with SB significantly amplified those alterations, while in stevia hydrated rats, the changes were similar to the ones observed in water hydrated rats. These data suggest that current habits of hydration could be a risk factor in developing kidney damage.

Interventions to increase the consumption of water among children: A systematic review and meta-analysis

The aim of this study was to conduct a systematic review and meta-analysis on the effectiveness of interventions to increase children's water consumption. A systematic literature search was conducted in seven electronic databases. Studies published in English before 18 February 2019 that evaluated any type of intervention that measured change in water consumption among children aged 2 to 12 years by applying any type of design were included. Of the 47 interventions included in the systematic review, 24 reported a statistically significant increase in water consumption. Twenty-four interventions (17 randomized controlled trials and seven studies with other controlled designs) were included in the meta-analysis. On average, children in intervention groups consumed 29 mL/d (confidence interval [CI] = 13-46 mL/d) more water than did children in control groups. This effect was larger in eight interventions focused specifically on diet (MD = 73 mL/d, CI = 20-126 mL/d) than in 16 interventions focused also on other lifestyle factors (MD = 15 mL/d, CI = 1-29 mL/d). Significant subgroup differences were also found by study setting and socioecological level targeted but not by children's age group, intervention strategy, or study design. In conclusion, there is evidence that, on average, lifestyle interventions can lead to small increases in children's daily water consumption. More research is needed to further understand the specific intervention elements that have the greatest effect.

Reproducibility of A Non-Quantitative Food Frequency Questionnaire (62-Item FFQ-6) and PCA-Driven Dietary Pattern Identification in 13-21-Year-Old Females

The aim of this study was to evaluate the test-retest reproducibility of a non-quantitative food frequency questionnaire (acronym: 62-item FFQ-6) and the possibility of identifying dietary patterns (DPs) in 13-21-year-old females. The study involved 97 females within three age groups: 13-15, 16-18, and 19-21 years, including 31, 38, and 28 subjects, respectively. The questionnaire was completed twice with a two-week interval (test and retest). For the total sample, using a principal component analysis (PCA), two similar PCA-driven DPs (DP1 and DP2) were identified separately from test data and retest data, considering two sets of input variables. 60-item-DP1 and 60-item-DP2 were identified after excluding two items-vegetables and fruits in general-due to including single items of various kinds of vegetables and fruits. After an aggregation of some items of the questionnaire, 25-item-DP1 and 25-item-DP2 were identified. The kappa statistic (test vs. retest) in the total sample averaged at 0.52 (0.32-0.72 for food items), while within age groups, it averaged at 0.41, 0.53, and 0.65, respectively. The percentage of subjects classified into the same food frequency category (test vs. retest) in the total sample averaged at 68% (51%-89% for food items), while within age groups, it averaged at 60%, 68%, and 77%, respectively. The Spearman correlations between dietary pattern scores (test vs. retest) in the total sample were: 0.84 (within age groups 0.83, 0.81, and 0.78, respectively) for 60-item-DP1, 0.68 (within age groups 0.24, 0.79, and 0.76, respectively) for 60-item-DP2, 0.76 (within age groups 0.56, 0.82, and 0.89, respectively) for 25-item-DP1, and 0.48 (within age groups 0.40, 0.57, and 0.53, respectively) for 25-item-DP2 (p < 0.05 for all). In conclusion, the test-retest reproducibility of the 62-item FFQ-6 was good or very good for most food items, with a tendency to be higher in older age groups of females under study. Due to the acceptable-to-good reproducibility of dietary pattern identification, the use of a 62-item FFQ-6 to describe the overall diet of young Polish females can be recommended.

Water and Beverage Consumption among a Nationally Representative Sample of Children and Adolescents in the United Arab Emirates

There are limited studies examining water consumption among individuals in hot climates. We assessed the daily total water intake from plain water, other beverages, and food in a nationally representative sample of children and adolescents aged 6-18 years in the United Arab Emirates. Total water intake was compared against the recommendations of the Institute of Medicine and the European Food Safety Authority. Sociodemographic information, 24 h dietary recall, physical activity levels, and anthropometric data were collected from 527 participants. The mean ± SE of total water intake was 1778.4 ± 33.8 mL/day. Plain drinking water was the largest contributor to total water intake (51.6%), followed by food (27.3%). Sugar-sweetened beverages constituted 13.9% of water intake. The proportion of participants who met the Institute of Medicine recommendations ranged from 15% (males aged 14-18) to 25% (children aged 6-8). The proportion of participants who met the European Food Safety Authority recommendations ranged from 31% (females aged 14-18) to 36% (males aged 14-18). The water-to-energy ratio was 1.0-1.15 L/1000 kcal, meeting recommendations. The majority of participants failed to meet water intake recommendations, highlighting the need for targeted interventions to promote increased water consumption among children and adolescents.

Adaptation and Validation of the Hydration Status Questionnaire in a Spanish Adolescent-Young Population: A Cross Sectional Study

The achievement of adequate hydration status is essential for mental and physical performance and for health in general, especially in children and adolescents. Nevertheless, little is known about hydration status of this population, mainly due to the limited availability of research tools; thus, the objective of the current study was to adapt and validate our hydration status questionnaire in a Spanish adolescent-young population. The questionnaire was validated against important hydration markers: urine colour, urine specific gravity, haemoglobin, haematocrit and total body water and involved 128 subjects aged between 12⁻17 years. Water intake was also estimated through a three-day dietary record and physical activity was assessed through accelerometers. Participants completed the questionnaire twice. Water balance and water intake were correlated with urine specific gravity and with total body water content. Water intake obtained by the questionnaire was correlated with results from the three-day dietary record. The intraclass correlation coefficient indicated moderate concordance between both recordings and the Cronbach's alpha revealed high consistency. The Bland and Altman method indicated that the limits of agreement were acceptable to reveal the reliability of the estimated measures. In conclusion, this is the first time that a questionnaire is valid and reliable to estimate hydration status of adolescent-young populations.

Narrative Review of Hydration and Selected Health Outcomes in the General Population

Although adequate hydration is essential for health, little attention has been paid to the effects of hydration among the generally healthy population. This narrative review presents the state of the science on the role of hydration in health in the general population, specifically in skin health, neurological function (i.e., cognition, mood, and headache), gastrointestinal and renal functions, and body weight and composition. There is a growing body of evidence that supports the importance of adequate hydration in maintaining proper health, especially with regard to cognition, kidney stone risk, and weight management. However, the evidence is largely associative and lacks consistency, and the number of randomized trials is limited. Additionally, there are major gaps in knowledge related to health outcomes due to small variations in hydration status, the influence of sex and sex hormones, and age, especially in older adults and children.

Ferroportin-Hepcidin Axis in Prepubertal Obese Children with Sufficient Daily Iron Intake

Iron metabolism may be disrupted in obesity, therefore, the present study assessed the iron status, especially ferroportin and hepcidin concentrations, as well as associations between the ferroportin-hepcidin axis and other iron markers in prepubertal obese children. The following were determined: serum ferroportin, hepcidin, ferritin, soluble transferrin receptor (sTfR), iron concentrations and values of hematological parameters as well as the daily dietary intake in 40 obese and 40 normal-weight children. The ferroportin/hepcidin and ferritin/hepcidin ratios were almost two-fold lower in obese children (p = 0.001; p = 0.026, respectively). Similar iron concentrations (13.2 vs. 15.2 µmol/L, p = 0.324), the sTfR/ferritin index (0.033 vs. 0.041, p = 0.384) and values of hematological parameters were found in obese and control groups, respectively. Iron daily intake in the obese children examined was consistent with recommendations. In this group, the ferroportin/hepcidin ratio positively correlated with energy intake (p = 0.012), dietary iron (p = 0.003) and vitamin B₁₂ (p = 0.024). In the multivariate regression model an association between the ferroportin/hepcidin ratio and the sTfR/ferritin index in obese children (β = 0.399, p = 0.017) was found. These associations did not exist in the controls. The results obtained suggest that in obese children with sufficient iron intake, the altered ferroportin-hepcidin axis may occur without signs of iron deficiency or iron deficiency anemia. The role of other micronutrients, besides dietary iron, may also be considered in the iron status of these children.