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Influence of acute consumption of caffeine vs. placebo over Bia-derived measurements of body composition: a randomized, double-blind, crossover design.
Williamson, CM, Nickerson, BS, Bechke, EE, McLester, CN, Kliszczewicz, BM
Journal of the International Society of Sports Nutrition. 2018;15:7
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Bioelectrical analysis (BIA) is a commonly used method to assess body fat percentage and water values, by running a small electrical current through the body. Prior to testing using BIA, it is necessary to avoid exercise, fasting and caffeine consumption for accurate results. Caffeine’s role as a diuretic is well understood, however, its impact on measures of body water values when consumed prior to BIA testing has not been examined. The main aim of this study was to determine if the consumption of caffeine prior to BIA testing influences the cellular fluid balance and body fat percentage. Participants in the trial were measured on three separate occasions. The first visit worked as a control whilst the second and third visit were conducted using a double blind randomised crossover method. The total number of participants included in the trial were 20 physically active males who were habitual coffee drinkers. Participants were given either 200mg of caffeine or 200mg dextrose (control). The BIA measurements were taken at seven different time points after the preliminary measurements, separated by 15-min. The authors concluded that caffeine consumption in habitual users just prior to testing produced no significant changes in the BIA measurements. Therefore, the pre-testing guidelines for caffeine consumption may not be necessary in habitual caffeine consumers.
Abstract
BACKGROUND Bioelectrical impedance analysis (BIA) is often used to estimate total body water (TBW), intracellular body water (ICW), extracellular body water (ECW), and body fat percentage (BF%). A common restriction for BIA analysis is abstinence from caffeine 12-h prior to testing. However, research has yet to determine whether the consumption of caffeine influences BIA testing results. The purpose of this study was to determine if the consumption of caffeine influences BIA-derived BF% and body water values in habitual caffeine users. METHODS Twenty apparently healthy males (26.6 ± 4.1 years) identified as habitual caffeine consumers (≥ one 95 mg serving per day ≥ four days per week) participated in this study. Participants came to the lab on three occasions, the first visit serving as the control (CON) with no supplementation. The remaining two visits were performed in a randomized double-blind, cross-over fashion. Participants consumed 200 mg of dextrose (PLA) or caffeine (CAF) in capsule form. During each visit, seven multi-frequency BIA measurements were conducted before (PRE) and after (15-min, 30-min, 45-min, 60-min, 75-min, 90-min) consumption. RESULTS Repeated measures ANOVA revealed BF% for CAF was lower than the CON and PLA conditions at PRE and 15-min (p < 0.001, p = 0.004), but not statistically significant for the remaining time points (i.e., 30-, 45-, 60-, 75-, and 90-min). However, the effect size (ES) of the BF% differences were trivial. The CON, PLA, and CAF conditions had higher PRE ICW values than their associated post time points (i.e., 15-, 30-, 45-, 60-, 75-, and 90-min). Similar to BF%, ES of the mean differences for ICW were trivial. No other differences were observed. CONCLUSION Caffeine consumption in habitual users produced trivial changes in TBW, ECW, ICW, or BF%. Therefore, the pre-testing guidelines for caffeine consumption may not be necessary in habitual caffeine consumers.
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A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.
Proctor, DM, Fukuyama, JA, Loomer, PM, Armitage, GC, Lee, SA, Davis, NM, Ryder, MI, Holmes, SP, Relman, DA
Nature communications. 2018;9(1):681
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Identifying spatial patterns in the human microbiota is necessary to provide insight into mechanisms that either maintain or disrupt its healthy state. The aim of this study was to identify the type and extent of oral spatial patterns formed by bacterial communities, as well as observe the impact of low salivary flow on the spatial patterns. Dental exams were performed on 31 participants to evaluate the oral health status and follow-up was dependent on group allocation. This study found bacterial communities were distinguishable depending on types of teeth and tissue. Further, bacteria on soft and hard tissues varied across the front and back of the oral cavity in a gradient-manner, implying that salivary flow plays a role in establishing the bacterial community gradient in the oral cavity. Based on these results, the authors recommend spatial patterns and processes be explored in other body parts to better understand health and disease.
Abstract
Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.
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Emollient use alters skin barrier and microbes in infants at risk for developing atopic dermatitis.
Glatz, M, Jo, JH, Kennedy, EA, Polley, EC, Segre, JA, Simpson, EL, Kong, HH
PloS one. 2018;13(2):e0192443
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Atopic dermatitis (AD) is a type of eczema common in babies and young children. Poor function of the skin barrier is thought to lead to changes in the composition of bacteria found on the skin. This small study investigated the effects of daily use of an emollient, Cetaphil Moisturising Cream, on the barrier function and bacterial communities on the skin of infants at risk of developing AD. After 6 months, the emollient group had a lower skin pH than the control group. The group using the emollient had more diverse skin bacterial communities than the control group. The proportion of Streptococcus salivarius was higher in the emollient versus control groups. The authors concluded that lower skin pH and increased skin bacterial diversity after long-term emollient use may reduce inflammation and lower the risk of infants developing AD.
Abstract
BACKGROUND Emollients are a mainstay of treatment in atopic dermatitis (AD), a disease distinguished by skin bacterial dysbiosis. However, changes in skin microbiota when emollients are used as a potential AD preventative measure in infants remain incompletely characterized. RESULTS We compared skin barrier parameters, AD development, and bacterial 16S ribosomal RNA gene sequences of cheek, dorsal and volar forearm samples from 6-month-old infants with a family history of atopy randomized to receive emollients (n = 11) or no emollients (controls, n = 12). The emollient group had a lower skin pH than the control group. The number of bacterial taxa in the emollient group was higher than in the control group at all sites. The Streptococcus salivarius proportion was higher in the emollient versus control groups at all sites. S. salivarius proportion appeared higher in infants without AD compared to infants with AD. A decrease in S. salivarius abundance was further identified in a separate larger population of older children demonstrating an inverse correlation between AD severity at sampling sites and S. salivarius proportions. CONCLUSIONS The decreased skin pH and the increased proportion of S. salivarius after long-term emollient use in infants at risk for developing AD may contribute to the preventative effects of emollients in high-risk infants.
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Effects of Three Commercially Available Sports Drinks on Substrate Metabolism and Subsequent Endurance Performance in a Postprandial State.
Qin, L, Wang, QR, Fang, ZL, Wang, T, Yu, AQ, Zhou, YJ, Zheng, Y, Yi, MQ
Nutrients. 2017;9(4)
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The depletion of stored glucose and the reduction of the availability of carbohydrates can contribute to fatigue during moderate-to-high intensity exercise. Studies have shown that carbohydrate consumption can reduce the depletion of stored energy and that the combination of protein and carbohydrate supplementation resulted in greater replenishment during intense exercise. Nowadays, most commercial sports beverages contain both carbohydrates and proteins. The present study looked at the postprandial effects of commercially available beverages on carbohydrate and fat metabolism and exercise performance. Ten healthy male participants with a history of running or cycling exercise participated in two studies in a double-blinded, counterbalanced manner. Commercially available beverages with low carbohydrate, high carbohydrate, and a combination of proteins and carbohydrates were tested, and it was found that a beverage containing both proteins and carbohydrates maintained insulin levels and provided greater energy during endurance exercise. It is important to conduct future studies on athletes with higher fitness levels to evaluate the benefits of commercially available beverages. Based on the findings of this study, healthcare professionals can learn more about the benefits of commercially available beverages that combine carbohydrates and proteins and have a low carbohydrate content.
Abstract
Purpose: To examine the effects of commercially available sports beverages with various components on substrate metabolism and subsequent performance. Methods: Two studies were conducted in a double-blinded, counterbalanced manner. Study I was designed to determine the glycemic index, while study II determined the utilization of substrates and subsequent exercise performance. Ten healthy male participants (age 21.70 ± 2.41 years, height 176.60 ± 5.23 cm, weight 66.58 ± 5.38 kg, V̇O2max 48.1 ± 8.4 mL/kg/min) participated in both study I and study II. Three types of commercially available sports beverage powders were used. The powders consisted primarily of oligosaccharides (low molecular weight carbohydrates, L-CHO), hydrolyzed starch (high molecular weight CHO, H-CHO), and whey protein powder with carbohydrate (CHO-PRO). They were dissolved in purified water with identical CHO concentration of 8% (w/v). In study I, each participant underwent two oral glucose tolerance tests (OGTT) and one glycemic response test for each sports drink. In study II, participants cycled for 60 min at 70% V̇O2max, one hour after consuming a standardized breakfast. One of four prescribed beverages (L-CHO, H-CHO, CHO-PRO, and Placebo control, PLA) was served at 0, 15, 30, 45 min during the exercise. Six hours after the first exercise session, participants came back for a "time to exhaustion test" (TTE). Blood samples were drawn at 0, 30, and 60 min in the first exercise session, while arterial blood gas analysis was conducted at 0, 30, and 60 min in both sessions. Subjective feelings (rating of perceived exertion and abdominal discomfort) were also evaluated every 30 min during exercise. Results: Compared to the reference standardized glucose solution, the glycemic index of the L-CHO beverage was 117.70 ± 14.25, while H-CHO was 105.50 ± 12.82, and CHO-PRO was 67.23 ± 5.88. During the exercise test, the insulin level at 30 and 60 min was significantly lower than baseline following the treatment of L-CHO, H-CHO, and PLA (p < 0.05). The CHO oxidation rate at 60 min in the first exercise session was significantly higher than that at 60 min in the second exercise session following the L-CHO treatment (p < 0.05). Time to exhaustion was not significantly different (p > 0.05). Conclusion: The CHO sports beverage with additional PRO maintains insulin production during endurance cycling at 70% V̇O2max in the postprandial state. L-CHO sports beverage suppresses fat utilization during the subsequent exercise performance test. The subsequent exercise performance (as evaluated by TTE) was not influenced by the type of CHO or the addition of PRO in the commercially available sports beverages used in the present study.