Research Studies & Publications
Health
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Influence of progressive fluid restriction on mood and physiological markers of dehydration in women
Pross, N., et al., British Journal of Nutrition - 2013, 109, 313-321.
The present study evaluated, using a well-controlled dehydration protocol, the effects of 24 h fluid deprivation (FD) on selected mood and physiological parameters. In the present cross-over study, twenty healthy women (age 25 (SE 0·78) years) participated in two randomised sessions: FD-induced dehydration v. a fully hydrated control condition. In the FD period, the last water intake was between 18.00 and 19.00 hours and no beverages were allowed until 18.00 hours on the next day (23–24 h). Water intake was only permitted at fixed periods during the control condition. Physiological parameters in the urine, blood and saliva (osmolality) as well as mood and sensations (headache and thirst) were compared across the experimental conditions. Safety was monitored throughout the study. The FD protocol was effective as indicated by a significant reduction in urine output. No clinical abnormalities of biological parameters or vital signs were observed, although heart rate was increased by FD. Increased urine specific gravity, darker urine colour and increased thirst were early markers of dehydration. Interestingly, dehydration also induced a significant increase in saliva osmolality at the end of the 24 h FD period but plasma osmolality remained unchanged. The significant effects of FD on mood included decreased alertness and increased sleepiness, fatigue and confusion. The most consistent effects of mild dehydration on mood are on sleep/wake parameters. Urine specific gravity appears to be the best physiological measure of hydration status in subjects with a normal level of activity; saliva osmolality is another reliable and noninvasive method for assessing hydration status.
Blood pressure hyperreactivity: an early cardiovascular risk in normotensive men exposed to low-to-moderate inorganic arsenic in drinking water
Kunrath, J., et al., Journal of Hypertension - February 2013
Background: Essential hypertension is associated with chronic exposure to high levels of inorganic arsenic in drinking water. However, early signs of risk for developing hypertension remain unclear in people exposed to chronic low-to-moderate inorganic arsenic. OBJECTIVE: We evaluated cardiovascular stress reactivity and recovery in healthy, normotensive, middle-aged men living in an arsenic-endemic region of Romania. METHODS: Unexposed (n = 16) and exposed (n = 19) participants were sampled from communities based on WHO limits for inorganic arsenic in drinking water (<10 μg/l). Water sources and urine samples were collected and analyzed for inorganic arsenic and its metabolites. Functional evaluation of blood pressure included clinical, anticipatory, cold pressor test, and recovery measurements. Blood pressure hyperreactivity was defined as a combined stress-induced change in SBP (>20 mmHg) and DBP (>15 mmHg). RESULTS: Drinking water inorganic arsenic averaged 40.2 ± 30.4 and 1.0 ± 0.2 μg/l for the exposed and unexposed groups, respectively (P < 0.001). Compared to the unexposed group, the exposed group expressed a greater probability of blood pressure hyperreactivity to both anticipatory stress (47.4 vs. 12.5%; P = 0.035) and cold stress (73.7 vs. 37.5%; P = 0.044). Moreover, the exposed group exhibited attenuated blood pressure recovery from stress and a greater probability of persistent hypertensive responses (47.4 vs. 12.5%; P = 0.035). CONCLUSIONS: Inorganic arsenic exposure increased stress-induced blood pressure hyperreactivity and poor blood pressure recovery, including persistent hypertensive responses in otherwise healthy, clinically normotensive men. Drinking water containing even low-to-moderate inorganic arsenic may act as a sympathetic nervous system trigger for hypertension risk.
Water consumption, not expectancies about water consumption, affects cognitive performance in adults
Edmonds, C.J., et al., Appetite - January 2013
Research has shown that water supplementation positively affects cognitive performance in children and adults. The present study considered whether this could be a result of expectancies that individuals have about the effects of water on cognition. Forty-seven participants were recruited and told the study was examining the effects of repeated testing on cognitive performance. They were assigned either to a condition in which positive expectancies about the effects of drinking water were induced, or a control condition in which no expectancies were induced. Within these groups, approximately half were given a drink of water, while the remainder were not. Performance on a thirst scale, letter cancellation, digit span forwards and backwards and a simple reaction time task was assessed at baseline (before the drink) and 20 min and 40 min after water consumption. Effects of water, but not expectancy, were found on subjective thirst ratings and letter cancellation task performance, but not on digit span or reaction time. This suggests that water consumption effects on letter cancellation are due to the physiological effects of water, rather than expectancies about the effects of drinking water.
Observations of drinking water access in school food service areas before implementation of federal and state school water policy, California, 2011
Al Patel, et al., Preventing Chronic Disease - September 2012
Recent legislation requires schools to provide free drinking water in food service areas (FSAs). Our objective was to describe access to water at baseline and student water intake in school FSAs and to examine barriers to and strategies for implementation of drinking water requirements. METHODS: We randomly sampled 24 California Bay Area public schools. We interviewed 1 administrator per school to assess knowledge of water legislation and barriers to and ideas for policy implementation. We observed water access and students' intake of free water in school FSAs. Wellness policies were examined for language about water in FSAs. RESULTS: Fourteen of 24 schools offered free water in FSAs; 10 offered water via fountains, and 4 provided water through a nonfountain source. Four percent of students drank free water at lunch; intake at elementary schools (11%) was higher than at middle or junior high schools (6%) and high schools (1%). In secondary schools when water was provided by a nonfountain source, the percentage of students who drank free water doubled. Barriers to implementation of water requirements included lack of knowledge of legislation, cost, and other pressing academic concerns. No wellness policies included language about water in FSAs. CONCLUSION: Approximately half of schools offered free water in FSAs before implementation of drinking water requirements, and most met requirements through a fountain. Only 1 in 25 students drank free water in FSAs. Although schools can meet regulations through installation of fountains, more appealing water delivery systems may be necessary to increase students' water intake at mealtimes.
Sugar-Sweetened Beverages and Genetic Risk of Obesity
Qibin Qi, Ph.D., et al., The New England Journal of Medicine - September 21, 2012
Temporal increases in the consumption of sugar-sweetened beverages have paralleled the rise in obesity prevalence, but whether the intake of such beverages interacts with the genetic predisposition to adiposity is unknown. We analyzed the interaction between genetic predisposition and the intake of sugar-sweetened beverages in relation to body-mass index (BMI; the weight in kilograms divided by the square of the height in meters) and obesity risk in 6934 women from the Nurses' Health Study (NHS) and in 4423 men from the Health Professionals Follow-up Study (HPFS) and also in a replication cohort of 21,740 women from the Women's Genome Health Study (WGHS). The genetic-predisposition score was calculated on the basis of 32 BMI-associated loci. The intake of sugar-sweetened beverages was examined prospectively in relation to BMI. In the NHS and HPFS cohorts, the genetic association with BMI was stronger among participants with higher intake of sugar-sweetened beverages than among those with lower intake. In the combined cohorts, the increases in BMI per increment of 10 risk alleles were 1.00 for an intake of less than one serving per month, 1.12 for one to four servings per month, 1.38 for two to six servings per week, and 1.78 for one or more servings per day (P<0.001 for interaction). For the same categories of intake, the relative risks of incident obesity per increment of 10 risk alleles were 1.19 (95% confidence interval [CI], 0.90 to 1.59), 1.67 (95% CI, 1.28 to 2.16), 1.58 (95% CI, 1.01 to 2.47), and 5.06 (95% CI, 1.66 to 15.5) (P=0.02 for interaction). In the WGHS cohort, the increases in BMI per increment of 10 risk alleles were 1.39, 1.64, 1.90, and 2.53 across the four categories of intake (P=0.001 for interaction); the relative risks for incident obesity were 1.40 (95% CI, 1.19 to 1.64), 1.50 (95% CI, 1.16 to 1.93), 1.54 (95% CI, 1.21 to 1.94), and 3.16 (95% CI, 2.03 to 4.92), respectively (P=0.007 for interaction).
Arcobacter in Lake Erie Beach Waters: an Emerging Gastrointestinal Pathogen Linked with Human-Associated Fecal Contamination
Cheonghoon Lee, et al., Applied and Environmental Microbiology - September 2012
The genus Arcobacter has been associated with human illness and fecal contamination by humans and animals. To better characterize the health risk posed by this emerging waterborne pathogen, we investigated the occurrence of Arcobacter spp. in Lake Erie beach waters. During the summer of 2010, water samples were collected 35 times from the Euclid, Villa Angela, and Headlands (East and West) beaches, located along Ohio's Lake Erie coast. After sample concentration, Arcobacter was quantified by real-time PCR targeting the Arcobacter 23S rRNA gene. Other fecal genetic markers (Bacteroides 16S rRNA gene [HuBac], Escherichia coli uidA gene, Enterococcus 23S rRNA gene, and tetracycline resistance genes) were also assessed. Arcobacter was detected frequently at all beaches, and both the occurrence and densities of Arcobacter spp. were higher at the Euclid and Villa Angela beaches (with higher levels of fecal contamination) than at the East and West Headlands beaches. The Arcobacter density in Lake Erie beach water was significantly correlated with the human-specific fecal marker HuBac according to Spearman's correlation analysis (r = 0.592; P < 0.001). Phylogenetic analysis demonstrated that most of the identified Arcobacter sequences were closely related to Arcobacter cryaerophilus, which is known to cause gastrointestinal diseases in humans. Since human-pathogenic Arcobacter spp. are linked to human-associated fecal sources, it is important to identify and manage the human-associated contamination sources for the prevention of Arcobacter-associated public health risks at Lake Erie beaches.
Hydration biomarkers and dietary fluid consumption of women.
Armstrong, L., et. al. Journal of the Academy of Nutrition and Dietetics - July 2012
Normative values and confidence intervals for the hydration indices of women do not exist. Also, few publications have precisely described the fluid types and volumes that women consume. This investigation computed seven numerical reference categories for widely used hydration biomarkers (eg, serum and urine osmolality) and the dietary fluid preferences of self-reported healthy, active women. Participants (n=32; age 20±1 years; body mass 59.6±8.5 kg; body mass index [calculated as kg/m(2)] 21.1±2.4) were counseled in the methods to record daily food and fluid intake on 2 consecutive days. To reduce day-to-day body water fluctuations, participants were tested only during the placebo phase of the oral contraceptive pill pack. Euhydration was represented by the following ranges: serum osmolality=293 to 294 mOsm/kg; mean 24-hour total fluid intake=2,109 to 2,506 mL/24 hours; mean 24-hour total beverage intake=1,300 to 1,831 mL/24 hours; urine volume=951 to 1,239 mL/24 hours; urine specific gravity=1.016 to 1.020; urine osmolality=549 to 705 mOsm/kg; and urine color=5. However, only 3% of women experienced a urine specific gravity <1.005, and only 6% exhibited a urine color of 1 or 2. Water (representing 45.3% and 47.9% of 24-hour total fluid intake), tea, milk, coffee, and fruit juice were consumed in largest volumes. In conclusion, these data provide objective normative values for hyperhydration, euhydration, and dehydration that can be used by registered dietitians and clinicians to counsel women about their hydration status
Lead (Pb) in Tap Water and in Blood: Implications for Lead Exposure in the United States
Triantafyllidou, S., Edwards, M., Critical Reviews in Environmental Science and Technology - July 2012
Lead is widely recognized as one of the most pervasive environmental health threats in the United States, and there is increased concern over adverse health impacts at levels of exposure once considered safe. Lead contamination of tap water was once a major cause of lead exposure in the United States and, as other sources have been addressed, the relative contribution of lead in water to lead in blood is expected to become increasingly important. Moreover, prior research suggests that lead in water may be more important as a source than is presently believed. The authors describe sources of lead in tap water, chemical forms of the lead, and relevant U.S. regulations/guidelines, while considering their implications for human exposure. Research that examined associations between water lead levels and blood lead levels is critically reviewed, and some of the challenges in making such associations, even if lead in water is the dominant source of lead in blood, are highlighted. Better protecting populations at risk from this and from other lead sources is necessary, if the United States is to achieve its goal of eliminating elevated blood lead levels in children by 2020.
French children start their school day with a hydration deficit
Bonnet, F., et al., Annals of Nutrition & Metabolism - June 1, 2012
Background and Aims: Fluid requirements of children vary as a function of gender and age. To our knowledge, there is very little literature on the hydration status of French chil- dren. We assessed the morning hydration status in a large sample of 529 French schoolchildren aged 9–11 years. Methods: Recruited children completed a questionnaire on fluid and food intake at breakfast and collected a urine sample the very same day after breakfast. Breakfast food and fluid nutritional composition was analyzed and urine osmolality was measured using a cryoscopic osmometer. Results: More than a third of the children had a urine osmolality between 801 and 1,000 mosm/kg while 22.7% had a urine osmolality over 1,000 mosm/kg. This was more frequent in boys than in girls (p ! 0.001). A majority of children (73.5%) drank less than 400 ml at breakfast. Total water intake at breakfast was significantly and inversely correlated with high osmolality values. Conclusions: Almost two thirds of the children in this large cohort had evidence of a hydration deficit when they went to school in the morning, despite breakfast intake. Children’s fluid intake at breakfast does not suffice to maintain an adequate hydration status for the whole morning.
Mild Dehydration Affects Mood in Healthy Young Women
Lawrence Armstrong, et al., The Journal of Nutrition - February 2012
Limited information is available regarding the effects of mild dehydration on cognitive function. Therefore, mild dehydration was produced by intermittent moderate exercise without hyperthermia and its effects on cognitive function of women were investigated. Twenty-five females (age 23.0 ± 0.6 y) participated in three 8-h, placebo-controlled experiments involving a different hydration state each day: exercise-induced dehydration with no diuretic (DN), exercise-induced dehydration plus diuretic (DD; furosemide, 40 mg), and euhydration (EU). Cognitive performance, mood, and symptoms of dehydration were assessed during each experiment, 3 times at rest and during each of 3 exercise sessions. The DN and DD trials in which a volunteer attained a ≥1% level of dehydration were pooled and compared to that volunteer’s equivalent EU trials. Mean dehydration achieved during these DN and DD trials was −1.36 ± 0.16% of body mass. Significant adverse effects of dehydration were present at rest and during exercise for vigor-activity, fatigue-inertia, and total mood disturbance scores of the Profile of Mood States and for task difficulty, concentration, and headache as assessed by questionnaire. Most aspects of cognitive performance were not affected by dehydration. Serum osmolality, a marker of hydration, was greater in the mean of the dehydrated trials in which a ≥1% level of dehydration was achieved (P = 0.006) compared to EU. In conclusion, degraded mood, increased perception of task difficulty, lower concentration, and headache symptoms resulted from 1.36% dehydration in females. Increased emphasis on optimal hydration is warranted, especially during and after moderate exercise.
Health Risks of Limited-Contact Water Recreation
Samuel Dorevitch, et al., Environmental Health Perspectives - February 2012
Wastewater-impacted waters that do not support swimming are often used for boating, canoeing, fishing, kayaking, and rowing. Little is known about the health risks of these limited-contact water recreation activities. We evaluated the incidence of illness, severity of illness, associations between water exposure and illness, and risk of illness attributable to limited-contact water recreation on waters dominated by wastewater effluent and on waters approved for general use recreation (such as swimming). The Chicago Health, Environmental Exposure, and Recreation Study was a prospective cohort study that evaluated five health outcomes among three groups of people: those who engaged in limited-contact water recreation on effluent-dominated waters, those who engaged in limited-contact recreation on general-use waters, and those who engaged in non–water recreation. Data analysis included survival analysis, logistic regression, and estimates of risk for counterfactual exposure scenarios using G-computation. Results: Telephone follow-up data were available for 11,297 participants. With non–water recreation as the reference group, we found that limited-contact water recreation was associated with the development of acute gastrointestinal illness in the first 3 days after water recreation at both effluent-dominated waters [adjusted odds ratio (AOR) 1.46; 95% confidence interval (CI): 1.08, 1.96] and general-use waters (1.50; 95% CI: 1.09, 2.07). For every 1,000 recreators, 13.7 (95% CI: 3.1, 24.9) and 15.1 (95% CI: 2.6, 25.7) cases of gastrointestinal illness were attributable to limited-contact recreation at effluent-dominated waters and general-use waters, respectively. Eye symptoms were associated with use of effluent-dominated waters only (AOR 1.50; 95% CI: 1.10, 2.06). Among water recreators, our results indicate that illness was associated with the amount of water exposure. Conclusions: Limited-contact recreation, both on effluent-dominated waters and on waters designated for general use, was associated with an elevated risk of gastrointestinal illness.
Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial
Deborah F Tate, et al., The American Journal of Clinical Nutrition - February 2012
Replacement of caloric beverages with noncaloric beverages may be a simple strategy for promoting modest weight reduction; however, the effectiveness of this strategy is not known. We compared the replacement of caloric beverages with water or diet beverages (DBs) as a method of weight loss over 6 mo in adults and attention controls (ACs). Results: In an intent-to-treat analysis, a significant reduction in weight and waist circumference and an improvement in systolic blood pressure were observed from 0 to 6 mo. Mean (±SEM) weight losses at 6 mo were −2.5 ± 0.45% in the DB group, −2.03 ± 0.40% in the Water group, and −1.76 ± 0.35% in the AC group; there were no significant differences between groups. The chance of achieving a 5% weight loss at 6 mo was greater in the DB group than in the AC group (OR: 2.29; 95% CI: 1.05, 5.01; P = 0.04). A significant reduction in fasting glucose at 6 mo (P = 0.019) and improved hydration at 3 (P = 0.0017) and 6 (P = 0.049) mo was observed in the Water group relative to the AC group. In a combined analysis, participants assigned to beverage replacement were 2 times as likely to have achieved a 5% weight loss (OR: 2.07; 95% CI: 1.02, 4.22; P = 0.04) than were the AC participants. Conclusions: Replacement of caloric beverages with noncaloric beverages as a weight-loss strategy resulted in average weight losses of 2% to 2.5%. This strategy could have public health significance and is a simple, straightforward message. This trial was registered at clinicaltrials.gov as NCT01017783
Atrazine Exposure in Public Drinking Water and Preterm Birth
Rinsky, Jessica L., et al., Public Health Reports - January/February 2012
Approximately 13% of all births occur prior to 37 weeks gestation in the U.S. Some established risk factors exist for preterm birth, but the etiology remains largely unknown. Recent studies have suggested an association with environmental exposures. We examined the relationship between preterm birth and exposure to a commonly used herbicide, atrazine, in drinking water. RESULTS: An increase in the odds of preterm birth was found for women residing in the counties included in the highest atrazine exposure group compared with women residing in counties in the lowest exposure group, while controlling for covariates. Analyses using the three exposure assessment approaches produced odds ratios ranging from 1.20 (95% confidence interval [CI] 1.14, 1.27) to 1.26 (95% CI 1.19, 1.32), for the highest compared with the lowest exposure group.
What is the cell hydration status of healthy children in the USA? Preliminary data on urine osmolality and water intake
Stookey JD, Brass B, Holliday A, Arieff A, Public Health Nutrition - January 27, 2012
Hyperosmotic stress on cells limits many aspects of cell function, metabolism and health. International data suggest that schoolchildren may be at risk of hyperosmotic stress on cells because of suboptimal water intake. The present study explored the cell hydration status of two samples of children in the USA. RESULTS: Elevated urine osmolality (>800 mmol/kg) was observed in 63 % and 66 % of participants in LA and NYC, respectively. In multivariable-adjusted logistic regression models, elevated urine osmolality was associated with not reporting intake of drinking water in the morning (LA: OR = 2·1, 95 % CI 1·2, 3·5; NYC: OR = 1·8, 95 % CI 1·0, 3·5). Although over 90 % of both samples had breakfast before giving the urine sample, 75 % did not drink water. CONCLUSIONS: Research is warranted to confirm these results and pursue their potential health implications.
The effects of water shortages on health and human development
Faissal Tarrass and Meryem Benjelloun, Perspectives in Public Health - April 2011
Shortages of water could become a major obstacle to public health and development. Currently, the United Nations Children’s Fund (UNICEF) and the World Health Organization (WHO) estimate that 1.1 billion people lack access to a water supply and 2.6 billion people lack adequate sanitation. The global health burden associated with these conditions is staggering, with an estimated 1.6 million deaths every year from diseases associated with lack of access to safe drinking water, inadequate sanitation and poor hygiene. In this paper we review the impact of water shortages on health and human development.
Bromate reduction in simulated gastric juice
Joseph A. Cotruvo, Jason D. Keith, Richard J. Bull, Gilbert E. Pacey, and Gilbert Gordon, e-Journal AWWA - November 2010
This article advocates for a revised risk assessment for bromate to reflect presystemic chemistry not usually considered when low-dose risks are calculated from high-dose toxicology data. Because of high acidity and the presence of reducing agents, presystemic decomposition of bromate can begin in the stomach, which should contribute to lower-than-expected doses to target organs. In this research, bromate decomposition kinetics with simulated stomach/gastric juice were studied to determine the risk of environmentally relevant exposure to bromate.
Association between children’s blood lead levels, lead service lines, and water disinfection, Washington, DC, 1998–2006
Mary Jean Brown, Jaime Raymond, David Homa, Chinaro Kennedy, Thomas Sinks, Environmental Research - October 2010
Objective: Evaluate the effect of changes in the water disinfection process, and presence of lead service lines (LSLs), on children’s blood lead levels (BLLs) in Washington, DC. Methods: Three cross-sectional analyses examined the relationship of LSL and changes in water disinfectant with BLLs in children o6 years of age. The study population was derived from the DC Childhood Lead Poisoning Prevention Program blood lead surveillance system of children who were tested and whose blood lead test results were reported to the DC Health Department. The Washington, DC Water and Sewer Authority (WASA) provided information on LSLs. The final study population consisted of 63,854 children with validated addresses. Results: Controlling for age of housing, LSL was an independent risk factor for BLLs Z10 mg/dL, and Z5 mg/dL even during time periods whenwater levelsmet theUS Environmental Protection Agency (EPA) action level of 15 parts per billion (ppb). When chloramine alone was used to disinfect water, the risk for BLL in the highest quartile among children in homes with LSL was greater than when either chlorine or chloramine with orthophosphate was used. For children tested after LSLs in their houses were replaced, those with partially replaced LSL were 43 times as likely to have BLLs Z10 mg/dL versus children who never had LSLs. Conclusions: LSLs were a risk factor for elevated BLLs even when WASA met the EPA water action level. Changes in water disinfection can enhance the effect of LSLs and increase lead exposure. Partially replacing LSLs may not decrease the risk of elevated BLLs associated with LSL exposure.
Drinking Water and Risk of Stroke
Gustavo Saposnik, MD, MSc, FAHA, Stroke - October 2010
In the present issue of Stroke, the authors investigate the association between low-level arsenic exposure in drinking water and the ischemic stroke admissions in Michigan.11 They found that even low exposure to arsenic is associated with an increased incident risk of stroke (relative risk, 1.03; 95% CI, 1.01 to 1.05 per µg/L increase in arsenic concentration). The authors also compared whether that exposure was associated with other nonvascular conditions (hernia, duodenal ulcer) not expected to increase their risk. Comparing zip codes in Genesee County at the 90th percentile of arsenic levels (21.6 µg/L) with those at the 10th percentile (0.30 µg/L), there was a 91% increase in risk of stroke admission (relative risk, 1.91; 95% CI, 1.27 to 2.88). The results were consistent in showing an increased risk for stroke, but not for other control medical conditions (hernia and duodenal ulcer). Moreover, they found a graded effect: a higher incident risk among those individuals exposed to higher water concentrations of arsenic (Figure 2).
Scientific Opinion on Dietary Reference Values for water
European Food Safety Authority (EFSA), Parma, Italy, EFSA Journal - March 2010
This Opinion of the EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA) deals with the setting of dietary reference values for water for specific age groups. Adequate Intakes (AI) have been defined derived from a combination of observed intakes in population groups with desirable osmolarity values of urine and desirable water volumes per energy unit consumed. The reference values for total water intake include water from drinking water, beverages of all kind, and from food moisture and only apply to conditions of moderate environmental temperature and moderate physical activity levels (PAL 1.6).
Water as an essential nutrient: the physiological basis of hydration
E Jéquier and F Constant, EJCN - European Journal of Clinical Nutrition, September 2009
How much water we really need depends on water functions and the mechanisms of daily water balance regulation. The aim of this review is to describe the physiology of water balance and consequently to highlight the new recommendations with regard to water requirements.
Reduction in consumption of sugar-sweetened beverages is associated with weight loss: the PREMIER trial
Liwei Chen, Lawrence J Appel, Catherine Loria, Pao-Hwa Lin, Catherine M Champagne, Patricia J Elmer, Jamy D Ard, Diane Mitchell, Bryan C Batch, Laura P Svetkey, and Benjamin Caballero, The American Journal of Clinical Nutrition , May 2009
Consumption of liquid calories from beverages has increased in parallel with the obesity epidemic in the US population, but their causal relation remains unclear. The objective of this study was to examine how changes in beverage consumption affect weight change among adults. Results: Baseline mean intake of liquid calories was 356 kcal/d (19% of total energy intake). After potential confounders and intervention assignment were controlled for, a reduction in liquid calorie intake of 100 kcal/d was associated with a weight loss of 0.25 kg (95% CI: 0.11, 0.39; P < 0.001) at 6 mo and of 0.24 kg (95% CI: 0.06, 0.41; P = 0.008) at 18 mo. A reduction in liquid calorie intake had a stronger effect than did a reduction in solid calorie intake on weight loss. Of the individual beverages, only intake of sugar-sweetened beverages (SSBs) was significantly associated with weight change. A reduction in SSB intake of 1 serving/d was associated with a weight loss of 0.49 kg (95% CI: 0.11, 0.82; P = 0.006) at 6 mo and of 0.65 kg (95% CI: 0.22, 1.09; P = 0.003) at 18 mo. Conclusions: These data support recommendations to limit liquid calorie intake among adults and to reduce SSB consumption as a means to accomplish weight loss or avoid excess weight gain. This trial was registered at clinicaltrials.gov as NCT00000616
Promotion and Provision of Drinking Water in Schools for Overweight Prevention: Randomized, Controlled Cluster Trial
Rebecca Muckelbauer, MSc, Lars Libuda, MSc, Kerstin Clausen, PhD, André Michael Toschke, MD, MSc, MPH, Thomas Reinehr, MD, and Mathilde Kersting, PhD, Pediatrics-- Official Journal of the American Academy of Pediatrics, April 2009
Our environmental and educational, school-based intervention proved to be effective in the prevention of overweight among children in elementary school, even in a population from socially deprived areas.
Just Add Water
Dan Negoianu, Stanley Goldfarb, Journal of the American Society of Nephrology, June 2008
To summarize the conclusions of other, more exhaustive reviews: There is no clear evidence of benefit from drinking increased amounts of water. Although we wish we could demolish all of the urban myths found on the Internet regarding the benefits of supplemental water ingestion, we concede there is also no clear evidence of lack of benefit. In fact, there is simply a lack of evidence in general. Given the central role of water not only in our bodies but also in our profession, it seems a deficit worthy of repletion.
Pediatric Emergency Department Visits for Diarrheal Illness Increased After Release of Undertreated Sewage
Ryan L. Redman, MDa, Cheryl A. Nenn, MSb, Daniel Eastwood, MSa and Marc H. Gorelick, MD, MSCEa, Pediatrics, December 2007
Emergency department visits for diarrheal illness increased significantly after 2 events of release of partially treated sewage into area waterways. These data suggest a potentially harmful effect of such practices.
An Investigation of Bottled Water Use and Caries in the Mixed Dentition
Barbara Broffitt, MS; Steven M. Levy, DDS, MPH; John J. Warren, DDS, MS; Joseph E. Cavanaugh, PhD American Association of Public Health Dentistry - Summer 2007
Bottled water consumption in the United States has greatly increased in the past decade. Because the majority of commercial bottled water is low in fluoride, there is the potential for an increase in dental caries. In these secondary data analyses, associations between bottled water use and dental caries were explored. Methods: Subjects (n = 413) are in the Iowa Fluoride Study, which included dental examinations of the primary (approximately aged 5) and early erupting permanent (approximately aged 9) dentitions by trained dentist examiners. Permanent tooth caries and primary second molar increments were related to bottled water use using logistic and negative binomial regression models. All models were adjusted for age and the frequency of toothbrushing. Results: Bottled water use in this cohort was fairly limited (~10 percent). While bottled water users had significantly lower fluoride intakes, especially fluoride from water, there were no significant differences found in either permanent tooth caries (P = 0.20 and 0.91 for prevalence and D2+FS, respectively) or primary second molar caries (P = 0.94 and 0.74 for incidence and d2+fs increment, respectively). Results for smooth surfaces differed somewhat from those for pit and fissure surfaces, but neither showed significant differences related to bottled water use. Conclusion: While bottled water users had significantly lower fluoride intakes, this study found no conclusive evidence of an association with increased caries. Further study is warranted, preferably using studies designed specifically to address this research question.
Soft Drink Consumption and Risk of Developing Cardiometabolic Risk Factors and the Metabolic Syndrome in Middle-Aged Adults in the Community
Ravi Dhingra, MD; Lisa Sullivan, PhD; Paul F. Jacques, PhD; Thomas J. Wang, MD; Caroline S. Fox, MD; James B. Meigs, MD, MPH; Ralph B. D'Agostino, PhD; J. Michael Gaziano, MD, MPH; Ramachandran S. Vasan, MD, Circulation, July 2007
Consumption of soft drinks has been linked to obesity in children and adolescents, but it is unclear whether it increases metabolic risk in middle-aged individuals. Methods and Results - We related the incidence of metabolic syndrome and its components to soft drink consumption in participants in the Framingham Heart Study (6039 person-observations, 3470 in women; mean age 52.9 years) who were free of baseline metabolic syndrome. Metabolic syndrome was defined as the presence of 3 of the following: waist circumference 35 inches (women) or 40 inches (men); fasting blood glucose 100 mg/dL; serum triglycerides 150 mg/dL; blood pressure 135/85 mm Hg; and high-density lipoprotein cholesterol <40 mg/dL (men) or <50 mg/dL (women). Multivariable models included adjustments for age, sex, physical activity, smoking, dietary intake of saturated fat, trans fat, fiber, magnesium, total calories, and glycemic index. Cross-sectionally, individuals consuming 1 soft drink per day had a higher prevalence of metabolic syndrome (odds ratio [OR], 1.48; 95% CI, 1.30 to 1.69) than those consuming <1 drink per day. On follow-up (mean of 4 years), new-onset metabolic syndrome developed in 765 (18.7%) of 4095 participants consuming <1 drink per day and in 474 (22.6%) of 2059 persons consuming 1 soft drink per day. Consumption of 1 soft drink per day was associated with increased odds of developing metabolic syndrome (OR, 1.44; 95% CI, 1.20 to 1.74), obesity (OR, 1.31; 95% CI, 1.02 to 1.68), increased waist circumference (OR, 1.30; 95% CI, 1.09 to 1.56), impaired fasting glucose (OR, 1.25; 95% CI, 1.05 to 1.48), higher blood pressure (OR, 1.18; 95% CI, 0.96 to 1.44), hypertriglyceridemia (OR, 1.25; 95% CI, 1.04 to 1.51), and low high-density lipoprotein cholesterol (OR, 1.32; 95% CI 1.06 to 1.64). Conclusions - In middle-aged adults, soft drink consumption is associated with a higher prevalence and incidence of multiple metabolic risk factors.
Bladder Cancer and Exposure to Water Disinfection By-Products through Ingestion, Bathing, Showering, and Swimming in Pools
Cristina M. Villanueva, Kenneth P. Cantor, Joan O. Grimalt, Nuria Malats, Debra Silverman, Adonina Tardon, Reina Garcia-Closas, Consol Serra, Alfredo Carrato, Gemma Castaño-Vinyals, Ricard Marcos, Nathaniel Rothman, Francisco X. Real, Mustafa Dosemeci and Manolis Kogevinas, American Journal of Epidemiology, Vol. 165, No. 2, 148-156, January 2007
Bladder cancer has been associated with exposure to chlorination by-products in drinking water, and experimental evidence suggests that exposure also occurs through inhalation and dermal absorption. The authors examined whether bladder cancer risk was associated with exposure to trihalomethanes (THMs) through ingestion of water and through inhalation and dermal absorption during showering, bathing, and swimming in pools.
Assessing Hydration Status: The Elusive Gold Standard
Lawrence E. Armstrong, Journal of the American College of Nutrition, Vol. 26, No. 5, 575S-584S, 2007
Acknowledging that total body water (TBW) turnover is complex, and that no measurement is valid for all situations, this review evaluates 13 hydration assessment techniques. Although validated laboratory methods exist for TBW and extracellular volume, no evidence incontrovertibly demonstrates that any concentration measurement, including plasma osmolality (Posm), accurately represents TBW gain and loss during daily activities. Further, one blood or urine sample cannot validly represent fluctuating TBW and fluid compartments. Future research should (a) evaluate novel techniques that assess hydration in real time and are precise, accurate, reliable, non-invasive, portable, inexpensive, safe, and simple; and (b) clarify the relationship between Posm and TBW oscillations in various scenarios.
Dehydration and Cognitive Performance
Ann C. Grandjean, Nicole R. Grandjean, Journal of the American College of Nutrition, Vol. 26, No. 5, 549S-554S, 2007
Human neuropsychology investigates brain-behavior relationships, using objective tools (neurological tests) to tie the biological and behavior aspects together. The use of neuropsychological assessment tools in assessing potential effects of dehydration is a natural progression of the scientific pursuit to understand the physical and mental ramifications of dehydration. It has long been known that dehydration negatively affects physical performance. Examining the effects of hydration status on cognitive function is a relatively new area of research, resulting in part from our increased understanding of hydration's impact on physical performance and advances in the discipline of cognitive neuropsychology. The available research in this area, albeit sparse, indicates that decrements in physical, visuomotor, psychomotor, and cognitive performance can occur when 2% or more of body weight is lost due to water restriction, heat, and/or physical exertion. Additional research is needed, especially studies designed to reduce, if not remove, the limitations of studies conducted to date.
Exercise, Heat, Hydration and the Brain
R.J. Maughan, S.M. Shirreffs, P. Watson, Journal of the American College of Nutrition, Vol. 26, No. 5, 604S-612S, 2007
The performance of both physical and mental tasks can be adversely affected by heat and by dehydration. There are well-recognized effects of heat and hydration status on the cardiovascular and thermoregulatory systems that can account for the decreased performance and increased sensation of effort that are experienced in the heat. Provision of fluids of appropriate composition in appropriate amounts can prevent dehydration and can greatly reduce the adverse effects of heat stress. There is growing evidence that the effects of high ambient temperature and dehydration on exercise performance may be mediated by effects on the central nervous system. This seems to involve serotonergic and dopaminergic functions. Recent evidence suggests that the integrity of the blood brain barrier may be compromised by combined heat stress and dehydration, and this may play a role in limiting performance in the heat.
How Primary Care Providers Might Review Evidence on Hydration
Kathryn M. Kolasa, Carolyn J. Lackey, David G. Weismiller, Journal of the American College of Nutrition, Vol. 26, No. 5, 570S-574S, 2007
Primary care providers (PCPs) are increasing their use of evidence-based medicine (EBM) in the care they give patients. They evaluate the available evidence to determine if it applies to their patients and seek to complement their clinical experience with EBM to improve patient outcomes. In evidence-based practices, patient oriented data are valued more highly than disease oriented evidence. More than 8 million biomedical articles are published annually, but only an estimated 2% of those are relevant to improved patient outcomes (POEMs - patient oriented evidence that matters). This paper describes some of the tools used by PCPs to search for evidence and the decision-making process used to determine if they will change their practice. Understanding how PCPs evaluate research findings and other evidence can help hydration researchers frame their research questions and study reports.
Hydration and Cognition: A Critical Review and Recommendations for Future Research
Harris R. Lieberman, Journal of the American College of Nutrition, Vol. 26, No. 5, 555S-561S, 2007
The limited literature on the effects of dehydration on human cognitive function is contradictory and inconsistent. Although it has been suggested that decrements in cognitive performance are present in the range of a 2 to 3% reduction in body weight, several dose-response studies indicate dehydration levels of 1% may adversely affect cognitive performance. When a 2% or more reduction in body weight is induced by heat and exercise exposure, decrements in visual-motor tracking, short-term memory and attention are reported, but not all studies find behavioral effects in this range. Future research should be conducted using dose-response designs and state-of-the-art behavioral methods to determine the lowest levels of dehydration that produce substantive effects on cognitive performance and mood. Confounding factors, such as caffeine intake and the methods used to produce dehydration, need to be considered in the design and conduct of such studies. Inclusion of a positive control condition, such as alcohol intake, a hypnotic drug, or other treatments known to produce adverse changes in cognitive performance should be included in such studies. To the extent possible, efforts to blind both volunteers and investigators should be an important consideration in study design.
Hydration and Disease
Friedrich Manz, Journal of the American College of Nutrition, Vol. 26, No. 5, 535S-541S, 2007
Many diseases have multifactorial origins. There is increasing evidence that mild dehydration plays a role in the development of various morbidities. In this review, effects of hydration status on acute and chronic diseases are depicted (excluding the acute effects of mild dehydration on exercise performance, wellness, cognitive function, and mental performance) and categorized according to four categories of evidence (I-IV). Avoidance of a high fluid intake as a precautionary measure may be indicated in patients with cardiovascular disorders, pronounced chronic renal failure (III), hypoalbuminemia, endocrinopathies, or in tumor patients with cisplatin therapy (IIb) and menace of water intoxication. Acute systemic mild hypohydration or dehydration may be a pathogenic factor in oligohydramnios (IIa), prolonged labor (IIa), cystic fibrosis (III), hypertonic dehydration (III), and renal toxicity of xenobiotica (Ib). Maintaining good hydration status has been shown to positively affect urolithiasis (Ib) and may be beneficial
in treating urinary tract infection (IIb), constipation (III), hypertension (III), venous thromboembolism (III), fatal coronary heart disease (III), stroke (III), dental disease (IV), hyperosmolar hyperglycemic diabetic ketoacidosis (IIb), gallstone disease (III), mitral valve prolapse (IIb), and glaucoma (III). Local mild hypohydration or dehydration may play a critical role in the pathogenesis of several bronchopulmonary disorders like exercise asthma (IIb) or cystic fibrosis (Ib). In bladder and colon cancers, the evidence on hydration status' effects is inconsistent.
Hydration and Physical Performance
Bob Murray, Journal of the American College of Nutrition, Vol. 26, No. 5, 542S-548S, 2007
There is a rich scientific literature regarding hydration status and physical function that began in the late 1800s, although the relationship was likely apparent centuries before that. A decrease in body water from normal levels (often referred to as dehydration or hypohydration) provokes changes in cardiovascular, thermoregulatory, metabolic, and central nervous function that become increasingly greater as dehydration worsens. Similarly, performance impairment often reported with modest dehydration (e.g., -2% body mass) is also exacerbated by greater fluid loss. Dehydration during physical activity in the heat provokes greater performance decrements than similar activity in cooler conditions, a difference thought to be due, at least in part, to greater cardiovascular and thermoregulatory strain associated with heat exposure. There is little doubt that performance during prolonged, continuous exercise in the heat is impaired by levels of dehydration >= -2% body mass, and there is some evidence that lower levels of dehydration can also impair performance even during relatively short-duration, intermittent exercise. Although additional research is needed to more fully understand low-level dehydration's effects on physical performance, one can generalize that when performance is at stake, it is better to be well-hydrated than dehydrated. This generalization holds true in the occupational, military, and sports settings.
Key teaching points:
- Dehydration during physical activity is commonplace because voluntary fluid intake is often less than fluid loss through sweating.
- Dehydration results in unavoidable, negative effects on physiological function and exercise performance. The magnitude of the effects of dehydration is exacerbated by increases in heat stress, exercise duration, and exercise intensity.
- Adequate drinking during exercise helps attenuate the reductions in blood volume, cardiac output, muscle blood flow, skin blood flow, the rise in core temperature, and the impairment in exercise performance that accompany dehydration.
Hydration at the Work Site
Robert W. Kenefick, Michael N. Sawka, Journal of the American College of Nutrition, Vol. 26, No. 5, 597S-603S, 2007
When performing physical work, sweat output often exceeds water intake, producing a body water deficit or dehydration. Specific to the work place, dehydration can adversely affect worker productivity, safety, and morale. Legislative bodies in North America such as the Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) recommend replacing fluids frequently when exposed to heat stress, such as one cup (250 ml) every 20 minutes when working in warm environments. However, the majority of legislative guidelines provide vague guidance and none take into account the effects of work intensity, specific environments, or protective clothing. Improved occupational guidelines for fluid and electrolyte replacement during hot weather occupational activities should be developed to include recommendations for fluid consumption before, during, and after work.
Hydration in Children
Friedrich Manz, Journal of the American College of Nutrition, Vol. 26, No. 5, 562S-569S, 2007
Water supply is a basic public problem. In modern science, three periods with different approaches to define recommended water intake in adults can be distinguished. Pediatricians agree that hydration in children may be optimal only in breastfed infants. More data are required on the health effects of different hydration states and varying water intakes in particular age and gender groups to define optimal ranges of water intake. The fetus grows in an exceptionally well-hydrated environment. Water metabolism shows several peculiarities in preterm and term infants. Infant diarrhea remains a major topic of basic and clinical research. Water intoxication in infants, toddlers, and children is rare and can only be found in exceptional circumstances. Hydration status characterized by hyponatremia may play a role in the pathogenesis of febrile convulsions in toddlers. There is increasing indirect evidence that spontaneous drinking behavior of a population may be fixed and anchored in the age range of toddlers.
Sex differences in hydration status are common, but not obligatory. What causes theses differences? What is behind the various circadian rhythms of urine osmolality in children? At what age and in what quantities can alcohol and caffeine consumption be tolerated? How can individual susceptibility be defined? Reflecting on the modern epidemic of obesity in children and adolescents, a public consensus concerning use and misuse of sweetened drinks seems mandatory. Dietary reference intakes of water refer to 24-hour intake. In nutritional counseling, food and meal-based dietary advice is primarily given. Young parents are confronted with a flood of advice of varying quality. Recommendations on fluid consumption should be collated and revised.
Hydration Needs throughout the Lifespan
Sheila M. Campbell, Journal of the American College of Nutrition, Vol. 26, No. 5, 585S-587S, 2007
In 2004, the Institute of Medicine (IOM) issued a report presenting reference intake information about water, sodium, potassium, and other electrolytes for Americans and Canadians [1]. The report established, for the first time, adequate intakes (AI) for total water (from drinking water, beverages, and food) for healthy people. An AI is the recommended average daily intake level based on observed or experimentally-determined approximations or estimates of nutrient intake by a group or groups of apparently health people that are assumed to be adequate. The AI for water is based on US survey data. The recommendations about water intake are for healthy populations - they do not apply to at-risk groups.
Limitations of Data on Fluid Intake
Victor L. Fulgoni, III, Journal of the American College of Nutrition, Vol. 26, No. 5, 588S-591S, 2007
The Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, provided extensive tables of data on total water intake, water intake from beverages and water intake from foods; however, very little information was provided about the specific details of these analyses. Reported total water intake varied with gender and somewhat with age and suggested that further sources of variation in total water intake were due to differences in body size, physical activity, and climatic exposure. Objective and Methods: In an attempt to better understand the variation in reported water intake, we examined water intake from foods and beverages and plain water intake in the National Health and Nutrition Examination Surveys (NHANES), 1999-2002. Results: Non-Hispanic black children (4 to 18 years) had less water from food and beverages (~ 0.15 L/day) than non-Hispanic whites and Hispanics. Non-Hispanic black children had less (~ 0.15 L/day) plain water than other ethnicities. Adult non-Hispanic whites had more water intake from food and beverages (~ 0.4 L/day) and non-Hispanic blacks had less (~ 0.2 L/day) than Hispanics and Other ethnic group. Non-Hispanic black adults had less (~ 0.2 L/day) plain water than non-Hispanic whites and the Other ethnic group but had similar plain water consumption as Hispanics. Conclusion: These data indicate further investigation into the sources of variation of water intake should include consideration of ethnic differences.
Mechanisms and Significance of Cell Volume Regulation
Florian Lang, Journal of the American College of Nutrition, Vol. 26, No. 5, 613S-623S, 2007
Survival of human and animal cells requires avoidance of excessive alterations of cell volume. The osmolarity amassed by cellular accumulation of organic substances must be compensated by lowering cytosolic ion concentrations. The Na+/K+ ATPase extrudes Na+ in exchange for K+, which can permeate the cell membrane through K+ channels. K+ exit generates a cell-negative potential difference across the cell membrane, driving the exit of anions such as Cl-. The low cytosolic Cl- concentrations counterbalance the excess cellular osmolarity by organic substances. Cell volume regulation following cell swelling involves releasing ions through activation of K+ channels and/or anion channels, KCl-cotransport, or parallel activation of K+/H+ exchange and Cl-/HCO3- exchange. Cell volume regulation following cell shrinkage involves accumulation of ions through activation of Na+, K+, 2Cl- cotransport, Na+/H+ exchange in parallel to Cl-/HCO3- exchange, or Na+ channels. The Na+ taken up is extruded by the Na+/K+ ATPase in exchange for K+. Shrunken cells further accumulate organic osmolytes such as sorbitol and glycerophosphorylcholine, and monomeric amino acids by altered metabolism and myoinositol (inositol), betaine, taurine, and amino acids by Na+ coupled transport. They
release osmolytes during cell swelling. Challenges of cell volume homeostasis include transport, hormones, transmitters, and drugs. Moreover, alterations of cell volume participate in the machinery regulating cell proliferation and apoptotic cell death. Deranged cell volume regulation significantly contributes to the pathophysiology
of several disorders such as liver insufficiency, diabetic ketoacidosis, hypercatabolism, fibrosing disease, sickle cell anemia, and infection.
Role of Whole Foods in Promoting Hydration after Exercise in Humans
Rick L. Sharp, Journal of the American College of Nutrition, Vol. 26, No. 5, 592S-596S, 2007
Various reports indicate that humans receive 20-25% of their daily water intake from food. Fruits, vegetables and other high-moisture foods, therefore, make an important contribution to total fluid intake. In addition, co-ingestion of other nutrients and ingredients can impact drinking behavior, absorption, distribution and retention of water, all of which contribute to the person's hydration state. Therefore, a food's hydration value derives from the interaction between its water content and the presence of these co-nutrients and ingredients. Research is reviewed in this paper showing increased voluntary fluid intake of young boys during exercise when the beverage is flavored and contains sodium chloride and carbohydrate. Additional research on rehydration after exercise and heat exposure showed improved recovery of plasma volume and fluid status when food was ingested before consuming water in the two hours after exercise. Collectively, these findings point to an interaction between fluid intake and co-ingested nutrients in regulating human hydration during and after exercise.
An approach for developing a national estimate of waterborne disease due to drinking water and a national estimate model application
Michael Messner, Susan Shaw, Stig Regli, Ken Rotert, Valerie Blank and Jeff Soller, Journal of Water and Health, Vol 04 No Suppl 2 pp 201–240, 2006
In this paper, the US Environmental Pro