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Effects of a 14-Day Hydration Intervention on Individuals with Habitually Low Fluid Intake.
Caldwell, AR, Rosa-Caldwell, ME, Keeter, C, Johnson, EC, Péronnet, F, Ganio, MS
Annals of nutrition & metabolism. 2020;:67-68
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Abstract
BACKGROUND Debate continues over whether or not individuals with low total water intake (TWI) are in a chronic fluid deficit (i.e., low total body water) [1]. When women with habitually low TWI (1.6 ± 0.5 L/day) increased their fluid intake (3.5 ± 0.1 L/day) for 4 days 24-h urine osmolality decreased, but there was no change in body weight, a proxy for total body water (TBW) [2]. In a small (n = 5) study of adult men, there were no observable changes in TBW, as measured by bioelectrical impedance, after increasing TWI for 4 weeks [3]. However, body weight increased and salivary osmolality decreased indicating that the study may have been underpowered to detect changes in TBW. Further, no studies to date have measured changes in blood volume (BV) when TWI is increased. OBJECTIVES Therefore, the purpose of this study was to identify individuals with habitually low fluid intake and determine if increasing TWI, for 14 days, resulted in changes in TBW or BV. METHODS In order to identify individuals with low TWI, 889 healthy adults were screened. Participants with a self-reported TWI less than 1.8 L/day (men) or 1.2 L/day (women), and a 24-h urine osmolality greater than 800 mOsm were included in the intervention phase of the study. For the intervention phase, 15 participants were assigned to the experimental group and 8 participants were assigned to the control group. The intervention period lasted for 14 days and consisted of 2 visits to our laboratory: one before the intervention (baseline) and 14 days into the intervention (14-day follow-up). At these visits, BV was measured using a CO-rebreathe procedure and deuterium oxide (D2O) was administered to measure TBW. Urine samples were collected immediately prior, and 3-8 h after the D2O dose to allow for equilibration. Prior to each visit, participants collected 24-h urine to measure 24-h hydration status. After the baseline visit, the experimental group increased their TWI to 3.7 L for males and 2.7 L for females in order to meet the current Institute of Medicine recommendations for TWI. RESULTS Twenty-four-hour urine osmolality decreased (-438.7 ± 362.1 mOsm; p < 0.001) and urine volume increased (1,526 ± 869 mL; p < 0.001) in the experimental group from baseline, while there were no differences in osmolality (-74.7 ± 572 mOsm; p = 0.45), or urine volume (-32 ± 1,376 mL; p = 0.89) in the control group. However, there were no changes in BV (Fig. 1a) or changes in TBW (Fig. 1b) in either group. CONCLUSIONS Increasing fluid intake in individuals with habitually low TWI increases 24-h urine volume and decreases urine osmolality but does not result in changes in TBW or BV. These findings are in agreement with previous work indicating that TWI interventions lasting 3 days [2] to 4 weeks [3] do not result in changes in TBW. Current evidence would suggest that the benefits of increasing TWI are not related changes in TBW.
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Peripheral Intrastromal Hydration Facilitates Safe, Deep Trephination in Corneas of Irregular Thickness.
Bovone, C, Myerscough, J, Friehmann, A, Elkadim, M, Parmeggiani, F, Busin, M
Cornea. 2020;(2):207-209
Abstract
PURPOSE To evaluate the feasibility of regularizing the peripheral corneal thickness before deep trephination in highly irregular corneas undergoing deep anterior lamellar keratoplasty (DALK) by means of intrastromal hydration with saline. METHODS This is an interventional case series including all eyes with irregular peripheral corneal thickness undergoing DALK for any indication between January 1, 2016, and January 1, 2017, at a single tertiary center in Forli, Italy. Before trephination, 1 mL of normal saline was injected intrastromally into each clock hour of peripheral thinning (determined using preoperative pachymetry) using a 30-gauge needle. A deep trephination of 400 to 450 μm was then performed, and DALK was completed as per our previously described technique. Primary outcome measures were perforation during trephination and intraoperative complications, with secondary outcomes of best corrected visual acuity and refraction. RESULTS Peripheral intrastromal hydration was performed in 61 eyes of 61 patients. Intrastromal hydration ensured a safe trephination without perforation into the anterior chamber (AC) in 59 of 61 eyes. In the 2 cases in which perforation occurred, the perforation site was sutured with a full-thickness suture and the surgery was completed successfully. No cases required conversion to penetrating keratoplasty. Intrastromal injection of 1 mL of normal saline resulted in an increase in corneal thickness of 31%. After surgery, double AC was observed in 3 cases (4.9%), with all cases being managed successfully by air injection into the AC. CONCLUSIONS Zonal peripheral intrastromal hydration is a feasible technique to enable safe, deep trephination even in corneas of highly irregular thickness.
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Reviewing the current methods of assessing hydration in athletes.
Barley, OR, Chapman, DW, Abbiss, CR
Journal of the International Society of Sports Nutrition. 2020;(1):52
Abstract
BACKGROUND Despite a substantial body of research, no clear best practice guidelines exist for the assessment of hydration in athletes. Body water is stored in and shifted between different sites throughout the body complicating hydration assessment. This review seeks to highlight the unique strengths and limitations of various hydration assessment methods described in the literature as well as providing best practice guidelines. MAIN BODY There is a plethora of methods that range in validity and reliability, including complicated and invasive methods (i.e. neutron activation analysis and stable isotope dilution), to moderately invasive blood, urine and salivary variables, progressing to non-invasive metrics such as tear osmolality, body mass, bioimpedance analysis, and sensation of thirst. Any single assessment of hydration status is problematic. Instead, the recommended approach is to use a combination, which have complementary strengths, which increase accuracy and validity. If methods such as salivary variables, urine colour, vital signs and sensation of thirst are utilised in isolation, great care must be taken due to their lack of sensitivity, reliability and/or accuracy. Detailed assessments such as neutron activation and stable isotope dilution analysis are highly accurate but expensive, with significant time delays due to data analysis providing little potential for immediate action. While alternative variables such as hormonal and electrolyte concentration, bioimpedance and tear osmolality require further research to determine their validity and reliability before inclusion into any test battery. CONCLUSION To improve best practice additional comprehensive research is required to further the scientific understanding of evaluating hydration status.
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Safety and Efficacy of Oral Intake of Ceramide-Containing Acetic Acid Bacteria for Improving the Stratum Corneum Hydration: A Randomized, Double-Blind, Placebo-Controlled Study over 12 Weeks.
Tsuchiya, Y, Ban, M, Kishi, M, Ono, T, Masaki, H
Journal of oleo science. 2020;(11):1497-1508
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Abstract
The barrier function of the skin protects it from external stresses to which it is constantly exposed, such as dryness, ultraviolet rays, and chemicals. Lipids, in particular a type of sphingolipid known as ceramides, play a central role in the barrier function of the skin by preventing dryness. The number of ceramides in the skin is known to decrease with age, which has led to the development of a large number of anti-aging cosmetic products that contain ceramides. Recently, it has become evident that oral intake of ceramides can also improve the quality of the skin. To elucidate the effects of oral ceramide intake on skin moisture content, we conducted a randomized, double-blinded, placebo-controlled parallel comparative study in which males and females between 20 and 60 years of age who were worried about dry skin ingested a food with acetic acid bacteria containing 0.8 mg of dihydroceramide or a placebo for 12 weeks. Concurrently, we investigated the safety of continuous ingestion of the ceramide-containing food over 12 weeks. Oral intake of ceramide over the 12 weeks significantly improved stratum corneum hydration, i.e. the moisture content of the skin, and did not result in harmful effects in any of the participants.
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Effect of Increased Daily Water Intake and Hydration on Health in Japanese Adults.
Nakamura, Y, Watanabe, H, Tanaka, A, Yasui, M, Nishihira, J, Murayama, N
Nutrients. 2020;(4)
Abstract
Increased hydration is recommended as healthy habit with several merits. However, supportive data are sparse. To assess the efficacy of increased daily water intake, we tested the effect of water supplementation on biomarkers in blood, urine, and saliva. Twenty-four healthy Japanese men and 31 healthy Japanese women with fasting blood glucose levels ranging from 90-125 mg/dL were included. An open-label, two-arm, randomized controlled trial was conducted for 12 weeks. Two additional 550 mL bottles of water on top of habitual fluid intake were consumed in the intervention group. The subjects drank one bottle of water (550 mL) within 2 h of waking, and one bottle (550 mL) 2 h before bedtime. Subjects increased mean fluid intake from 1.3 L/day to 2.0 L/day, without changes in total energy intake. Total body water rate increased with associated water supplementation. There were no significant changes in fasting blood glucose and arginine vasopressin levels, but systolic blood pressure was significantly decreased in the intervention group. Furthermore, water supplementation increased body temperature, reduced blood urea nitrogen concentration, and suppressed estimated glomerular filtration rate reduction. Additionally, existence of an intestinal microbiome correlated with decreased systolic blood pressure and increased body temperature. Habitual water supplementation after waking up and before bedtime in healthy subjects with slightly elevated fasting blood glucose levels is not effective in lowering these levels. However, it represents a safe and promising intervention with the potential for lowering blood pressure, increasing body temperature, diluting blood waste materials, and protecting kidney function. Thus, increasing daily water intake could provide several health benefits.
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Body hydration assessment using bioelectrical impedance vector analysis in neurologically impaired children.
Calcaterra, V, Cena, H, Manuelli, M, Sacchi, L, Girgenti, V, Larizza, C, Pelizzo, G
European journal of clinical nutrition. 2019;(12):1649-1652
Abstract
Dehydration is common and frequently under-diagnosed in chronic malnourished children, leading to life-threatening conditions. In this pilot study we applied bioimpedance vector analysis (BIVA) to determine hydration status in 52 neurologically impaired (NI) paediatric patients (14.08 ± 5.32). Clinical and biochemical data were used to define malnutrition and dehydration. Body composition analysis and hydration were also assessed by BIVA and we considered 143 normal-weight healthy subjects (15.0 ± 1.7), as controls for hydration status assessment. BIVA revealed a pathological hydration status in NI children, showing higher resistance (p < 0.001) and reactance values (p = 0.001) compared to controls. No differences in reactance and resistance were detected between well-nourished and under-nourished subjects. Four patients out of 52 showed mild signs of dehydration; no severe dehydration was detected. Laboratory data, suggestive for dehydration, were similar in well-nourished and under-nourished NI subjects. In conclusion, in our sample of NI paediatrics, dehydration according to clinical signs and laboratory data was under-diagnosed. BIVA showed specific bioelectrical characteristics that could be compatible with impaired hydration status. Further studies are necessary to confirm that BIVA may an applicable tool for defining dehydration status and guiding rehydration in NI children.
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Hydration Status and Cardiovascular Function.
Watso, JC, Farquhar, WB
Nutrients. 2019;(8)
Abstract
Hypohydration, defined as a state of low body water, increases thirst sensations, arginine vasopressin release, and elicits renin-angiotensin-aldosterone system activation to replenish intra- and extra-cellular fluid stores. Hypohydration impairs mental and physical performance, but new evidence suggests hypohydration may also have deleterious effects on cardiovascular health. This is alarming because cardiovascular disease is the leading cause of death in the United States. Observational studies have linked habitual low water intake with increased future risk for adverse cardiovascular events. While it is currently unclear how chronic reductions in water intake may predispose individuals to greater future risk for adverse cardiovascular events, there is evidence that acute hypohydration impairs vascular function and blood pressure (BP) regulation. Specifically, acute hypohydration may reduce endothelial function, increase sympathetic nervous system activity, and worsen orthostatic tolerance. Therefore, the purpose of this review is to present the currently available evidence linking acute hypohydration with altered vascular function and BP regulation.
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Effects of isomaltulose ingestion on postexercise hydration state and heat loss responses in young men.
Amano, T, Sugiyama, Y, Okumura, J, Fujii, N, Kenny, GP, Nishiyasu, T, Inoue, Y, Kondo, N, Sasagawa, K, Enoki, Y, et al
Experimental physiology. 2019;(10):1494-1504
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Abstract
NEW FINDINGS What is the central question of this study? What are the effects of isomaltulose, an ingredient in carbohydrate-electrolyte beverages to maintain glycaemia and attenuate the risk of dehydration during exercise heat stress, on postexercise rehydration and physiological heat loss responses? What is the main finding and its importance? Consumption of a 6.5% isomaltulose-electrolyte beverage following exercise heat stress restored hydration following a 2 h recovery as compared to a 2% solution or water only. While the 6.5% isomaltulose-electrolytes increased plasma volume and plasma osmolality, which are known to modulate postexercise heat loss, sweating and cutaneous vascular responses did not differ between conditions. Consequently, ingestion beverages containing 6.5% isomaltulose-electrolytes enhanced postexercise rehydration without affecting heat loss responses. ABSTRACT Isomaltulose is a disaccharide carbohydrate widely used during exercise to maintain glycaemia and hydration. We investigated the effects of ingesting a beverage containing isomaltulose and electrolytes on postexercise hydration state and physiological heat loss responses. In a randomized, single-blind cross-over design, 10 young healthy men were hypohydrated by performing up to three 30 min successive moderate-intensity (50% heart rate reserve) bouts of cycling, each separated by 10 min, while wearing a water-perfusion suit heated to 45°C. The protocol continued until a 2% reduction in body mass was achieved. Thereafter, participants performed a final 15 min moderate-intensity exercise bout followed by a 2 h recovery. Following cessation of exercise, participants ingested a beverage consisting of (i) water only (Water), (ii) 2% isomaltulose (CHO-2%), or (iii) 6.5% isomaltulose (CHO-6.5%) equal to the volume of 2% body mass loss within the first 30 min of the recovery. Changes in plasma volume (ΔPV) after fluid ingestion were greater for CHO-6.5% compared with CHO-2% (120 min postexercise) and Water (90 and 120 min) (all P ≤ 0.040). Plasma osmolality remained elevated with CHO-6.5% compared with consumption of the other beverages at 30 and 90 min postexercise (all P ≤ 0.050). Urine output tended to be reduced with CHO-6.5% compared to other fluid conditions (main effect, P = 0.069). Rectal and mean skin temperatures, chest sweat rate and cutaneous perfusion did not differ between conditions (all P > 0.05). In conclusion, compared with CHO-2% and Water, consuming a beverage consisting of CHO-6.5% and electrolytes during recovery under heat stress enhances PV recovery without modulating physiological heat loss responses.
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[Human Body Water Composition Measurement:Methods and Clinical Application].
Zhou, SG, Chen, W
Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae. 2018;(5):603-609
Abstract
Being the largest single component of the human body,water is essential for life. Disease can lead to salt and water imbalance, and it is particularly important to measure the content and distribution of water in body. The current body water measurement methods are still not mature,and it's even hard to measure extracellular and intracellular water. Isotope dilution method(ID),bioelectrical impedance analysis(BIA),skinfold thickness measurement,and resonant cavity perturbation(RCP)are the commonly used methods for measuring human body water composition. This paper analyzes the advantages and disadvantages of these methods and concludes that all these four methods can be used to measure total body water;more specifically,ID and BIA can measure extracellular water and intracellular water,whereas BIA is more suitable for clinical applications such as monitoring of fluid balance,guiding of fluid management,assessment of lymphedema and nutritional risk,and management of obesity. Body water measurement will play more important roles in diagnosis,prevention,treatment,and prognosis of diseases.
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Water Intake, Water Balance, and the Elusive Daily Water Requirement.
Armstrong, LE, Johnson, EC
Nutrients. 2018;(12)
Abstract
Water is essential for metabolism, substrate transport across membranes, cellular homeostasis, temperature regulation, and circulatory function. Although nutritional and physiological research teams and professional organizations have described the daily total water intakes (TWI, L/24h) and Adequate Intakes (AI) of children, women, and men, there is no widespread consensus regarding the human water requirements of different demographic groups. These requirements remain undefined because of the dynamic complexity inherent in the human water regulatory network, which involves the central nervous system and several organ systems, as well as large inter-individual differences. The present review analyzes published evidence that is relevant to these issues and presents a novel approach to assessing the daily water requirements of individuals in all sex and life-stage groups, as an alternative to AI values based on survey data. This empirical method focuses on the intensity of a specific neuroendocrine response (e.g., plasma arginine vasopressin (AVP) concentration) employed by the brain to regulate total body water volume and concentration. We consider this autonomically-controlled neuroendocrine response to be an inherent hydration biomarker and one means by which the brain maintains good health and optimal function. We also propose that this individualized method defines the elusive state of euhydration (i.e., water balance) and distinguishes it from hypohydration. Using plasma AVP concentration to analyze multiple published data sets that included both men and women, we determined that a mild neuroendocrine defense of body water commences when TWI is ˂1.8 L/24h, that 19⁻71% of adults in various countries consume less than this TWI each day, and consuming less than the 24-h water AI may influence the risk of dysfunctional metabolism and chronic diseases.