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1.
Effects of age on blood pressure and heart rate responses to whey protein in younger and older men.
Giezenaar, C, Oberoi, A, Jones, KL, Horowitz, M, Chapman, I, Soenen, S
Journal of the American Geriatrics Society. 2021;(5):1291-1299
Abstract
BACKGROUND Postprandial falls in blood pressure (BP) are more common in older compared to younger individuals. The effects of protein compared to carbohydrates and fat on postprandial BP, and the relation to gastric emptying rates, are poorly studied. OBJECTIVES To determine the effects of a whey protein compared to a control drink on systolic BP (SBP) and diastolic BP (DBP), and heart rate (HR) in healthy younger and older men, and to relate these effects to gastric emptying. DESIGN A pooled analyses of two randomized, double-blind, cross-over studies. SETTING Two acute clinical intervention studies with identical study design. PARTICIPANTS Nineteen older (age: 74 ± 1 years, body mass index: 26 ± 1 kg/m2 ) and 13 younger (23 ± 1 years, 24 ± 1 kg/m2 ) healthy men. INTERVENTION A 70 g/280 kcal whey-protein or control (water with diet cordial, ~2 kcal) drink (450 ml). MEASUREMENTS BP and HR were assessed with an automated device immediately before and at 3-min intervals after drink ingestion (0-180 min). Gastric emptying of the drinks was measured using 3D ultrasonography (0-180 min). RESULTS Older versus younger men exhibited a greater fall in SBP (-23 ± 2 vs -15 ± 2 mmHg, p = 0.001) after whey-protein versus control, as BP did not change after the two drinks in younger men (p > 0.05). The nadir in SBP occurred later in the older than younger men (114 ± 11 vs 62 ± 14 min; p < 0.001), with SBP still apparently declining 180 min after whey-protein ingestion in the older men. The magnitude of the rise in HR was greater (p < 0.05) in the younger than older men. CONCLUSION Following ingestion of 70 g whey protein, healthy older men exhibited a sustained fall in BP, despite an increase in HR, whereas in younger men there was no change in BP. BP may need to be monitored after high protein meals in older people at risk of postprandial hypotension.
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2.
The Influence of Heat Acclimation and Hypohydration on Post-Weight-Loss Exercise Performance.
Barley, OR, Chapman, DW, Mavropalias, G, Abbiss, CR
International journal of sports physiology and performance. 2020;(2):213-221
Abstract
PURPOSE To examine the influence of fluid intake on heat acclimation and the subsequent effects on exercise performance following acute hypohydration. METHODS Participants were randomly assigned to 1 of 2 groups, either able to consume water ad libitum (n = 10; age 23 [3] y, height 1.81 [0.09] m, body mass 87 [13] kg; HAW) or not allowed fluid (n = 10; age 26 [5] y, height 1.76 [0.05] m, body mass 79 [10] kg; HANW) throughout 12 × 1.5-h passive heat-acclimation sessions. Experimental trials were completed on 2 occasions before (2 baseline trials) and 1 following the heat-acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood samples were collected before, immediately, and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time points. RESULTS No meaningful differences in physiological or performance variables were observed between HANW and HAW at any time point. Using pooled data, mean sprint speed was significantly (P < .001) faster following heat acclimation (4.6 [0.7] s compared with 5.1 [0.8] s). Furthermore, heat acclimation appeared to improve mood following hypohydration. CONCLUSIONS Results suggest that passive heat-acclimation protocols may be effective at improving short-duration repeat-effort performance following acute hypohydration.
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3.
Impact of Nuun Electrolyte Tablets on Fluid Balance in Active Men and Women.
Pence, J, Bloomer, RJ
Nutrients. 2020;(10)
Abstract
BACKGROUND Maintaining adequate hydration is important for overall health and has major implications for athletes involved in physically demanding tasks. While water is viewed as an effective means to rehydrate, and is inexpensive and readily available, electrolyte beverages appear to be more beneficial, in particular for athletes who routinely lose electrolytes through sweating. Nuun tablets contain a mix of electrolytes and are quickly dissolved in water to create an electrolyte-rich beverage. We determined the impact of Nuun tablets on the fluid balance of healthy, exercise-trained men and women at rest. METHODS Eight men (25.9 ± 4.5 yrs) and 10 women (28.2 ± 9.4 yrs) ingested either water only or water with Nuun electrolyte tablets, at both a single and double strength concentration, in random order, on three separate occasions separated by approximately one week, in a fasted and euhydrated state. A total of 1 liter of fluid was ingested at each visit over a 30 minute period. Urine was collected from each subject at 0, 1, 2, 3, and 4 hours post-ingestion. Urine mass values were used to calculate fluid balance and the beverage hydration index (BHI; i.e., the volume of urine produced after drinking the Nuun beverages, relative to that of water only-control condition). Heart rate and blood pressure were measured throughout the four-hour period, while body weight was measured at the start and end of the experiment. RESULTS Neither heart rate nor blood pressure were impacted by beverage consumption. Nuun tablets resulted in a lower urine output compared to water, with fluid balances for both concentrations more favorable compared to water (p < 0.05), beginning at 2 h post-ingestion and continuing at the 3 h and 4 h times. Body weight loss was less with Nuun at the single dose (0.38 kg; p = 0.02) and double dose (0.43 kg; p = 0.08), compared to water (0.57 kg). The BHI was higher for Nuun (single dose in particular) compared to water at both 2 h (p = 0.05) and 4 h (p = 0.02). CONCLUSION The addition of Nuun electrolyte tablets to water improves the fluid balance and BHI in healthy men and women. Results were similar for both concentrations, suggesting that additional electrolytes are not necessary when in a rested state. Future studies should determine the impact of various concentrations of the Nuun beverage during physical exercise-in particular, exercise in the heat, when sweat loss may be highest.
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4.
Efficacy of Ingesting an Oral Rehydration Solution after Exercise on Fluid Balance and Endurance Performance.
Fan, PW, Burns, SF, Lee, JKW
Nutrients. 2020;(12)
Abstract
This study investigated the efficacy of ingesting an oral rehydration solution (DD) that has a high electrolyte concentration after exercise on fluid balance and cycling performance in comparison with a sports drink (SD) and water (WA). Nine healthy males aged 24 ± 2 years (mean ± SD), with peak oxygen uptake (VO2 peak) 55 ± 6 mL·kg-1·min-1 completed three experimental trials in a randomised manner ingesting WA, SD (carbohydrates: 62 g·L-1, sodium: 31 ± 3 mmol·L-1) or DD (carbohydrates: 33 g·L-1, sodium: 60 ± 3 mmol·L-1). On all trials, fluid was ingested during 75 min cycling at 65% VO2 peak (temperature: 30.4 ± 0.3 °C, relative humidity: 76 ± 1%, simulated wind speed: 8.0 ± 0.6 m·s-1) and during 2 h of recovery (temperature: 23.0 ± 1.0 °C, relative humidity: 67 ± 2%), with the total volume equivalent to 150% of sweat loss during the ride. A 45 min pre-load cycling time trial at a 65% VO2 peak followed by a 20 km time trial was conducted after a further 3 h of recovery. Fluid retention was higher with DD (30 ± 15%) than WA (-4 ± 19%; p < 0.001) and SD (10 ± 15%; p = 0.002). Mean ratings of palatability were similar among drinks (WA: 4.25 ± 2.60; SD: 5.61 ± 1.79; DD: 5.40 ± 1.58; p = 0.33). Although time trial performance was similar across all three trials (WA: 2365 ± 321 s; SD: 2252 ± 174 s; DD: 2268 ± 184 s; p = 0.65), the completion time was faster in eight participants with SD and seven participants with DD than with WA. Comparing SD with DD, completion time was reduced in five participants and increased in four participants. DD was more effective at restoring the fluid deficit during recovery from exercise than SD and WA without compromising the drink's palatability with increased sodium concentration. Most individuals demonstrated better endurance exercise time trial performance with DD and SD than with WA.
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5.
Water Consumption during a School Day and Children's Short-Term Cognitive Performance: The CogniDROP Randomized Intervention Trial.
Drozdowska, A, Falkenstein, M, Jendrusch, G, Platen, P, Luecke, T, Kersting, M, Jansen, K
Nutrients. 2020;(5)
Abstract
There is still little research examining the relationship between water consumption in school and specific cognitive performance. The aim of this cluster-randomized intervention CogniDROP trial was to investigate the short-term effects of drinking water during the morning on executive functions. The participants were from the 5th and 6th grade of a comprehensive school in Germany (14 classes, n = 250, 61.6% boys). The classes were randomly divided into an intervention group (an education on healthy drinking behavior and a promotion of water consumption) and a control group. A battery of computerized tasks (Switch Task, 2-Back Task, Corsi Block-Tapping Task and Flanker Task) was used to test executive functions. Urine color and thirst were evaluated to check the hydration level. Physical activity over the past 24 h was measured using GT3X ActiGraph. A non-linear relationship was observed between the amount of drinking water and executive performance. Consuming water up to 1000 mL (or up to 50% of Total Water Intake) had benefits during memory tasks. Urine color and number of steps on the study day correlated with water consumed. The results suggest that a water-friendly environment supports school-aged children in adequate water intake resulting in better cognitive performance, especially short-term memory.
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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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7.
Heart Rate Variability Behavior during Exercise and Short-Term Recovery Following Energy Drink Consumption in Men and Women.
Clark, NW, Herring, CH, Goldstein, ER, Stout, JR, Wells, AJ, Fukuda, DH
Nutrients. 2020;(8)
Abstract
This study examined the cardiac autonomic responses, as measured by heart rate variability (HRV), during cycling exercise and short-term rest after energy drink consumption. Seventeen participants (seven males and 10 females; age: 22.8 ± 3.5 years; BMI: 24.3 ± 3.3 kg/m2) completed this double-blind, placebo-controlled, counterbalanced crossover design study. Participants received an energy drink formula containing 140 mg of caffeine and a placebo in a randomized order before completing a 10-min steady-state warm up (WUP) and a graded exercise test to exhaustion (GXT) followed by a 15-min short-term rest (STR) period. Heartbeat intervals were recorded using a heart rate monitor. Data were divided into WUP, GXT, and STR phases, and HRV parameters were averaged within each phase. Additionally, root mean square of the standard deviation of R-R intervals (RMSSD) during GXT was analyzed to determine the HRV threshold. Separate two-way (sex (male vs. female) x drink (energy drink vs. placebo)) repeated measures ANOVA were utilized. Significant increases in high frequency (HF) and RMSSD were shown during WUP after energy drink consumption, while interactions between drink and sex were observed for HRV threshold parameters (initial RMSSD and rate of RMSSD decline). No significant differences were noted during STR. Energy drink consumption may influence cardiac autonomic responses during low-intensity exercise, and sex-based differences in response to graded exercise to exhaustion may exist.
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Açaí (Euterpe oleracea Mart.) and juçara (Euterpe edulis Mart.) juices improved HDL-c levels and antioxidant defense of healthy adults in a 4-week randomized cross-over study.
de Liz, S, Cardoso, AL, Copetti, CLK, Hinnig, PF, Vieira, FGK, da Silva, EL, Schulz, M, Fett, R, Micke, GA, Di Pietro, PF
Clinical nutrition (Edinburgh, Scotland). 2020;(12):3629-3636
Abstract
OBJECTIVE To evaluate the effects of moderate-term açaí and juçara juice intake on fasting glucose, lipid profile, and oxidative stress biomarkers in healthy subjects. METHODS A randomized cross-over study was performed with 30 healthy adults. The subjects were assigned to drink 200 mL/day of açaí or juçara juice for four weeks with a 4-week washout period. Before and after each nutritional intervention, blood samples were obtained to evaluate the outcomes: fasting glucose, total cholesterol, triglycerides, high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), small, dense LDL-c (sd-LDL-c), total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), uric acid, and activity of the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). RESULTS After four weeks, açaí and juçara juices increased the concentrations of HDL-c by 7.7% and 11.4%, respectively (P < 0.05). In addition, açaí juice intake promoted significant increases in TAC (66.7%), CAT (275.1%), GPx (15.3%), and a decrease in OSI (55.7%) compared to baseline (P < 0.05 for all). Juçara juice intake significantly increased CAT activity (~15.0%) in relation to baseline. No significant intergroup differences were observed for any outcomes (P > 0.05). CONCLUSION The results indicated a positive impact of regular consumption of açaí and juçara juices on the HDL-c levels, as well as on the antioxidant enzyme activities, which may contribute to cardiovascular health.
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Drinking water with consumption of a jelly filled doughnut has a time dependent effect on the postprandial blood glucose level in healthy young individuals.
Bipat, R, Toelsie, JR
Clinical nutrition ESPEN. 2018;:20-23
Abstract
An elevated postprandial glucose (PPG) level in plasma or blood is a risk factor for chronic disorders like obesity, diabetes mellitus type II and related cardiovascular conditions. Therefore, it is important to identify mechanisms that increase the value of postprandial glucose PPG levels. Hence in the present study we investigated the time dependent effect of drinking water during a meal on the level of PPG. Thirty-five volunteers were randomly assigned to five groups. Group A was given a jelly filled doughnut and group B, C, D and E had a similar doughnut in combination with a bottle of water along with the doughnut, thirty minutes before, thirty minutes after, and a second doughnut with water thirty minutes after the first one, respectively. Glucose was measured in capillary blood at intervals of 30 min up to 150 min (reg # FMeW 725B/17). PPG versus fasting glucose (Means ± SD, mmol/L) was for group A 5.4 ± 0.6 vs 4.6 ± 0.4, B 7.2 ± 0.7 vs 4.9 ± 0.4, C 5.5 ± 0.7 vs 4.4 ± 0.3, D 5.5 ± 0.6 vs 4.6 ± 0.3 and E 5.7 ± 0.5 vs 4.7 ± 0.2. The increase in group B was significantly higher than in all other groups (ANOVA, Dunnet's posttest). These results show that drinking water with consumption of a jelly-filled doughnut increases the postprandial blood glucose levels significantly compared to no drinking at all or thirty minutes before or after the consumption. It is therefore advisable that we should reconsider our eating and drinking habits to lower the PPG and consequently reduce the risks of abovementioned chronic disorders. Further assessment is necessary to evaluate this in more detail.
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Liberal fluid fasting: impact on gastric pH and residual volume in healthy children undergoing general anaesthesia for elective surgery.
Schmidt, AR, Buehler, KP, Both, C, Wiener, R, Klaghofer, R, Hersberger, M, Weiss, M, Schmitz, A
British journal of anaesthesia. 2018;(3):647-655
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Abstract
BACKGROUND The paediatric preoperative fasting time of 2 h for clear fluids, as suggested by guidelines, is often exceeded. Shorter preoperative fasting has been proposed to avoid potential outcomes such as dehydration, ketoacidosis, reduced arterial blood pressure, and patient discomfort. The aim of this study was to investigate whether liberal clear fluid intake until premedication significantly reduces actual fasting time and impacts gastric pH and residual volume. METHODS Children (1-16 yr old, ASA I or II) undergoing elective procedures with general anaesthesia requiring tracheal intubation were randomised for clear fluid intake until premedication with midazolam (liberal) or 2 h fluid fasting (standard). Actual fasting times were recorded. Gastric content was sampled after tracheal intubation with an orogastric tube to determine gastric pH and residual volume. Data are presented as median [interquartile range]. RESULTS We included 162 children aged 1.1-16 yr; gastric pH was determined in 138 patients. Patients' characteristics were similar in the two groups. The liberal fasting group had significantly shorter fasting times (48 [18.5-77.5] vs 234 [223.5-458.5] min; P<0.001). No significant difference was observed regarding gastric pH (1.6 [1.5-1.8] vs 1.6 [1.4-1.7]; P=0.237) or residual volume (0.38 [0.1-1.1] vs 0.43 [0.13-0.73] ml kg-1; P=0.535). Twelve patients (15%) in the liberal group (median fluid fasting 32 min) vs one patient (1%) had gastric residual volumes >2 ml kg-1 (P=0.001). CONCLUSION Fluid intake until premedication allows for significantly shorter fasting times. Elevated gastric residual volumes may occur more often in patients with fasting times of 30 min or shorter. CLINICAL TRIAL REGISTRATION NCT02603094.