Elevated copeptin, a surrogate marker of vasopressin, is linked to low water intake and increased diabetes risk. Water supplementation in habitual low-drinkers with high copeptin significantly lowers ...both fasting plasma (fp) copeptin and glucose. This study aims at investigating possible underlying mechanisms. Thirty-one healthy adults with high copeptin (> 10.7 pmol·L
(men), > 6.1 pmol
(women)) and 24-h urine volume of < 1.5L and osmolality of > 600 mOsm·kg
were included. The intervention consisted of addition of 1.5 L water daily for 6 weeks. Fp-adrenocorticotropic hormone (ACTH), fp-cortisol, 24-h urine cortisol, fasting and 2 h (post oral glucose) insulin and glucagon were not significantly affected by the water intervention. However, decreased (Δ baseline-6 weeks) fp-copeptin was significantly associated with Δfp-ACTH (r = 0.76, p < 0.001) and Δfp-glucagon (r = 0.39, p = 0.03), respectively. When dividing our participants according to baseline copeptin, median fp-ACTH was reduced from 13.0 (interquartile range 9.2-34.5) to 7.7 (5.3-9.9) pmol L
, p = 0.007 in the top tertile of copeptin, while no reduction was observed in the other tertiles. The glucose lowering effect from water may partly be attributable to decreased activity in the hypothalamic-pituitary-adrenal axis.ClinicalTrials.gov: NCT03574688.
Growing evidence suggests that sustained concentrated urine contributes to chronic metabolic and kidney diseases. Recent results indicate that a daily urinary concentration of 500 mOsm/kg reflects ...optimal hydration. This study aims at providing personalized advice for daily water intake considering personal intrinsic (age, sex, height, weight) and extrinsic (food and fluid intakes) characteristics to achieve a target urine osmolality (U
) of 500 mOsm/kg using machine learning and optimization algorithms. Data from clinical trials on hydration (four randomized and three non-randomized trials) were analyzed. Several machine learning methods were tested to predict U
. The predictive performance of the developed algorithm was evaluated against current dietary guidelines. Features linked to urine production and fluid consumption were listed among the most important features with relative importance values ranging from 0.10 to 0.95. XGBoost appeared the most performing approach (Mean Absolute Error (MAE) = 124.99) to predict U
. The developed algorithm exhibited the highest overall correct classification rate (85.5%) versus that of dietary guidelines (77.8%). This machine learning application provides personalized advice for daily water intake to achieve optimal hydration and may be considered as a primary prevention tool to counteract the increased incidence of chronic metabolic and kidney diseases.
Purpose
An increasing body of evidence suggests that excreting a generous volume of diluted urine is associated with short- and long-term beneficial health effects, especially for kidney and ...metabolic function. However, water intake and hydration remain under-investigated and optimal hydration is poorly and inconsistently defined. This review tests the hypothesis that optimal chronic water intake positively impacts various aspects of health and proposes an evidence-based definition of optimal hydration.
Methods
Search strategy included PubMed and Google Scholar using relevant keywords for each health outcome, complemented by manual search of article reference lists and the expertise of relevant practitioners for each area studied.
Results
The available literature suggest the effects of increased water intake on health may be direct, due to increased urine flow or urine dilution, or indirect, mediated by a reduction in osmotically -stimulated vasopressin (AVP). Urine flow affects the formation of kidney stones and recurrence of urinary tract infection, while increased circulating AVP is implicated in metabolic disease, chronic kidney disease, and autosomal dominant polycystic kidney disease.
Conclusion
In order to ensure optimal hydration, it is proposed that optimal total water intake should approach 2.5 to 3.5 L day
−1
to allow for the daily excretion of 2 to 3 L of dilute (< 500 mOsm kg
−1
) urine. Simple urinary markers of hydration such as urine color or void frequency may be used to monitor and adjust intake.
Purpose
Growing evidence suggests hydration plays a role in metabolic dysfunction, however data in humans are scarce. This study examined the cross-sectional association between hydration and ...metabolic dysfunction in a representative sample of the US population.
Methods
Data from 3961 adult NHANES (National Health and Nutrition Examination Survey) participants (49.8% female; age 46.3 ± 0.5 years) were grouped by quartile of urine specific gravity (
U
SG
, 2007–2008 cohort) or urine osmolality (
U
Osm
, 2009–2010 cohort) as measures of hydration. Metabolic dysfunction was assessed by glycemic and insulinemic endpoints and by components of the metabolic syndrome. Multivariate-adjusted linear and logistic regression models were used.
Results
Increasing quartiles of
U
SG
but not
U
Osm
was associated with higher fasting plasma glucose (FPG), glycated hemoglobin (all
P
< 0.01), HOMA-IR and elevated insulin (all
P
< 0.05). Compared with the lowest quartile, those with the highest
U
SG
but not
U
Osm
had greater risk of metabolic syndrome (Q4 vs. Q1, OR (99% CI): 1.6 (1.0, 2.7),
P
= 0.01) and diabetes (Q4 vs. Q1, OR: 1.8 (1.0, 3.4),
P
< 0.05). Additionally, those with
U
SG
> 1.013 or
U
Osm
> 500 mOsm/kg, common cut-off values for optimal hydration based on retrospective analyses of existing data, had less favorable metabolic markers. In a subset of participants free from diabetes mellitus, impaired kidney function, hypertension and diuretic medication,
U
SG
remained positively associated with FPG (
P
< 0.01) and elevated FPG (
P
< 0.05).
Conclusion
These analyses provide population-based evidence that
U
SG
as a proxy for hydration is associated with glucose homeostasis in NHANES 2007–2008. The same association was not significant when
U
Osm
was used as a proxy for hydration in the 2009–2010 wave.
Clinical trial registry
Not applicable, as this was a reanalysis of existing NHANES data.
Introduction: The gut microbiome exerts a fundamental role in host physiology. Extrinsic factors such as lifestyle and diet are widely recognized as the main drivers of gut microbiota composition ...<xref ref-type="bibr" rid="ref1">1 , <xref ref-type="bibr" rid="ref2">2 . While drinking water is among the food items consumed in the largest amount, little is known about its potential impact on gut microbiota structures <xref ref-type="bibr" rid="ref3">3 -<xref ref-type="bibr" rid="ref5">5 . Objective: We explored the associations between plain drinking water source and gut microbiota compositions in a large microbiota-based cohort. Methods: Participants in the American Gut Project database provided fecal samples and completed health, lifestyle, and food records which included plain drinking water source (bottled, tap, filtered, or well water). Associations between drinking water source and gut microbiota were evaluated using models adjusted for anthropometric, diet, and lifestyle factors in 3,413 individuals <xref ref-type="bibr" rid="ref6">6 . Index of intra-individual fecal microbial diversity, inter-individual differences in composition, and taxa abundance were estimated by 16S rRNA sequencing. Results: The type of drinking water was associated with fecal microbiota composition. Drinking water source ranked among the key contributing factor explaining the gut microbiota variation both in alpha and beta diversity analyses, with effect sizes comparable to that of alcohol or diet type <xref ref-type="bibr" rid="ref6">6 (Fig. <xref ref-type="fig" rid="f01">1 ). Subjects drinking different sources of water had differences in gut microbiota signatures, as revealed by beta diversity analyses (p < 0.05; Bray-Curtis dissimilarity, Weighted UniFrac distance) <xref ref-type="bibr" rid="ref6">6 . Subjects drinking mostly well water also had higher fecal alpha diversity than the other groups (p < 0.05; Faith’s PD, Observed OTUs) <xref ref-type="bibr" rid="ref6">6 . Taxonomic differences were found in well water drinkers, with clinically important taxa, such as Bacteroides, Odoribacter, and Streptococcus being depleted and Dorea being increased as compared to the other groups 6. Conclusions: Our results reveal that drinking water may be an important factor in shaping the gut microbiome. Future research investigating the gut microbiota in relation to environmental factors may benefit from integrating drinking water source as a covariate in the analyses.
The microbiome of the digestive tract exerts fundamental roles in host physiology. Extrinsic factors including lifestyle and diet are widely recognized as key drivers of gut and oral microbiome ...compositions. Although drinking water is among the food items consumed in the largest amount, little is known about its potential impact on the microbiome.
We explored the associations of plain drinking water source and intake with gut and oral microbiota compositions in a population-based cohort.
Microbiota, health, lifestyle, and food intake data were extracted from the American Gut Project public database. Associations of drinking water source (bottled, tap, filtered, or well water) and intake with global microbiota composition were evaluated using linear and logistic models adjusted for anthropometric, diet, and lifestyle factors in 3413 and 3794 individuals, respectively (fecal samples; 56% female, median IQR age: 48 36–59 y; median IQR BMI: 23.3 20.9–26.3 kg/m2), and in 283 and 309 individuals, respectively (oral samples).
Drinking water source ranked among the key contributing factors explaining the gut microbiota variation, accounting for 13% Faith's phylogenetic diversity (Faith's PD) and 47% (Bray–Curtis dissimilarity) of the age effect size. Drinking water source was associated with differences in gut microbiota signatures, as revealed by β diversity analyses (P < 0.05; Bray–Curtis dissimilarity, weighted UniFrac distance). Subjects drinking mostly well water had higher fecal α diversity (P < 0.05; Faith's PD, observed amplicon sequence variants), higher Dorea, and lower Bacteroides, Odoribacter, and Streptococcus than the other groups. Low water drinkers also exhibited gut microbiota differences compared with high water drinkers (P < 0.05; Bray–Curtis dissimilarity, unweighted UniFrac distance) and a higher abundance of Campylobacter. No associations were found between oral microbiota composition and drinking water consumption.
Our results indicate that drinking water may be an important factor in shaping the human gut microbiome and that integrating drinking water source and intake as covariates in future microbiome analyses is warranted.
The idea that water intake or hydration may play an intrinsic, independent role in modulating metabolic disease risk is relatively recent. Here, we outline the journey from early experimental works ...to more recent evidence linking water and hydration to metabolic health. It has been known for decades that individuals with existing metabolic dysfunction experience challenges to body water balance and have elevated arginine vasopressin (AVP), a key hormone regulating body fluid homeostasis. Later, intervention studies demonstrated that altering fluid balance in these individuals could worsen their condition, suggesting that hydration played a role in modulating glycemic control. More recently, observational and interventional studies in healthy individuals have implicated the hydration-vasopressin axis in the pathophysiology of metabolic diseases. Individuals with higher AVP (or its surrogate, copeptin) are at higher risk for developing type 2 diabetes and components of the metabolic syndrome, an association that remains even when controlling for known risk factors. Supporting preclinical work also suggests a causal role for AVP in metabolic dysfunction. It is known that individuals who habitually drink less fluids tend to have higher circulating AVP, which may be lowered by increasing water intake. In the short term, water supplementation in habitual low drinkers with high copeptin may reduce fasting glucose or glucagon, generating a proof of concept for the role of water supplementation in reducing incident metabolic disease. A large randomized trial is ongoing to determine whether water supplementation for 1 year in subjects with low water intake can meaningfully reduce fasting glucose, risk of new-onset diabetes, and other cardiometabolic risk factors.
Abstract
Objective
Because elevated copeptin, a marker of vasopressin, is linked to low water intake and high diabetes risk, we tested the effect of water supplementation on copeptin and fasting ...glucose.
Design, Setting, and Participants
Thirty-one healthy adults with high copeptin (>10.7 pmol · L−1 in men and >6.1 pmol·L−1 in women) identified in a population-based survey from 2013 to 2015 and with a current 24-hour urine osmolality of >600 mOsm · kg−1 were included.
Intervention
Addition of 1.5 L water daily on top of habitual fluid intake for 6 weeks.
Main outcome measure
Pre- and postintervention fasting plasma copeptin concentrations.
Results
Reported mean water intake increased from 0.43 to 1.35 L · d−1 (P < 0.001), with no other observed changes in diet. Median (interquartile range) urine osmolality was reduced from 879 (705, 996) to 384 (319, 502) mOsm · kg−1 (P < 0.001); urine volume increased from 1.06 (0.90, 1.20) to 2.27 (1.52, 2.67) L · d−1 (P < 0.001); and baseline copeptin decreased from 12.9 (7.4, 21.9) pmol · L−1 to 7.8 (4.6;11.3) pmol · L−1 (P < 0.001). Water supplementation reduced fasting plasma glucose from a mean (SD) of 5.94 (0.44) to 5.74 (0.51) (P = 0.04). The water-associated reduction of both fasting copeptin and glucose concentration in plasma was most pronounced in participants in the top tertile of baseline copeptin.
Conclusions
Water supplementation in persons with habitually low water consumption and high copeptin levels is effective in lowering copeptin. It appears a safe and promising intervention with the potential of lowering fasting plasma glucose and thus reducing diabetes risk. Further investigations are warranted to support these findings.
In individuals with high plasma concentration of the vasopressin marker copeptin, increased water intake of 1.5 L daily during 6 weeks significantly reduced copeptin and fasting glucose.
Epidemiological studies in humans show increased concentrations of copeptin, a surrogate marker of arginine vasopressin (AVP), to be associated with increased risk for type 2 diabetes.
To examine the ...acute and independent effect of osmotically stimulated AVP, measured via the surrogate marker copeptin, on glucose regulation in healthy adults.
Sixty subjects (30 females) participated in this crossover design study. On 2 trial days, separated by ≥7 d (males) or 1 menstrual cycle (females), subjects were infused for 120 min with either 0.9% NaCl isotonic (ISO) or 3.0% NaCl hypertonic (HYPER). Postinfusion, a 240-min oral-glucose-tolerance test (OGTT; 75 g) was administered.
During HYPER, plasma osmolality and copeptin increased (P < 0.05) and remained elevated during the entire 6-h protocol, whereas renin-angiotensin-aldosterone system hormones were within the lower normal physiological range at the beginning of the protocol and declined following infusion. Fasting plasma glucose did not differ between trials (P > 0.05) at baseline and during the 120 min of infusion. During the OGTT the incremental AUC for glucose from postinfusion baseline (positive integer) was greater during HYPER (401.5 ± 190.5 mmol/L·min) compared with the ISO trial (354.0 ± 205.8 mmol/L·min; P < 0.05). The positive integer of the AUC for insulin during OGTT did not differ between trials (HYPER 55,850 ± 36,488 pmol/L·min compared with ISO 57,205 ± 31,119 pmol/L·min). Baseline values of serum glucagon were not different between the 2 trials; however, the AUC of glucagon during the OGTT was also significantly greater in HYPER (19,303 ± 3939 ng/L·min) compared with the ISO trial (18,600 ± 3755 ng/L·min; P < 0.05).
The present data indicate that acute osmotic stimulation of copeptin induced greater hyperglycemic responses during the oral glucose challenge, possibly due to greater glucagon concentrations.
This study was registered at clinicaltrials.gov as NCT02761434.
Objective: Because elevated copeptin, a marker of vasopressin, is linked to low water intake and high diabetes risk, we tested the effect of water supplementation on copeptin and fasting glucose. ...Design, Setting, and Participants: Thirty-one healthy adults with high copeptin (> 10.7 pmol x L.sup.-1 in men and > 6.1 pmolxL.sup.-1 in women) identified in a population-based survey from 2013 to 2015 and with a current 24-hour urine osmolality of >600 mOsm x kg.sup.1 were included. Intervention: Addition of 1.5 L water daily on top of habitual fluid intake for 6 weeks. Main outcome measure: Pre- and postintervention fasting plasma copeptin concentrations. Results: Reported mean water intake increased from 0.43 to 1.35 L x d.sup.-1 (P < 0.001), with no other observed changes in diet. Median (interquartile range) urine osmolality was reduced from 879 (705, 996) to 384 (319, 502) mOsm x kg.sup.-1 (P < 0.001); urine volume increased from 1.06(0.90, 1.20) to 2.27 (1.52, 2.67) L x d.sup.-1 (P < 0.001); and baseline copeptin decreased from 12.9 (7.4, 21.9) pmol x L.sup.-1 to 7.8 (4.6;11.3) pmol x L.sup.-1 (P < 0.001). Water supplementation reduced fasting plasma glucose from a mean (SD) of 5.94 (0.44) to 5.74 (0.51) (P = 0.04). The water-associated reduction of both fasting copeptin and glucose concentration in plasma was most pronounced in participants in the top tertile of baseline copeptin. Conclusions: Water supplementation in persons with habitually low water consumption and high copeptin levels is effective in lowering copeptin. It appears a safe and promising intervention with the potential of lowering fasting plasma glucose and thus reducing diabetes risk. Further investigations are warranted to support these findings. (J Clin Endocrinol Metab 104: 1917-1925, 2019)
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