Caffeine ingestion and lower urinary tract symptoms in healthy volunteers

Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show?

Caffeine is a popular ergogenic aid that has a plethora of evidence highlighting its positive effects. A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. However, despite the vast amount of available data, it is intriguing that uncertainties persist regarding the effectiveness and safety of caffeine. These include but are not limited to: 1. Does caffeine dehydrate you at rest? 2. Does caffeine dehydrate you during exercise? 3. Does caffeine promote the loss of body fat? 4. Does habitual caffeine consumption influence the performance response to acute caffeine supplementation? 5. Does caffeine affect upper vs. lower body performance/strength differently? 6. Is there a relationship between caffeine and depression? 7. Can too much caffeine kill you? 8. Are there sex differences regarding caffeine's effects? 9. Does caffeine work for everyone? 10. Does caffeine cause heart problems? 11. Does caffeine promote the loss of bone mineral? 12. Should pregnant women avoid caffeine? 13. Is caffeine addictive? 14. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literature regarding caffeine supplementation.

The Effects of Caffeine on Voice: A Systematic Review

BACKGROUND

Caffeine is considered a dehydrating agent due to its diuretic effects and influences the body's fluid balance. The relationship between voice and hydration has been widely investigated and it is accepted that inadequate hydration has detrimental effects on phonation. Since dehydration negatively affects the vocal folds and caffeine is considered a dehydrating agent, it can be hypothesized that voice might be negatively affected by caffeine intake. This systematic review aims to summarize and appraise the available evidence regarding the effects of caffeine on voice.

METHODS

Randomized and non-randomized experimental studies of healthy participants were retrieved following an electronic searching of six databases in June 2020. No publication, language or date restrictions were applied. Data extraction of relevant data and risk of bias assessment was conducted independently by two reviewers.

RESULTS

Five non-randomized experimental studies were deemed eligible for inclusion. The format of the administered interventions in the included studies was either liquid (coffee) or solid (caffeine tablets). Reported outcome measures used to examine the effects of caffeine on phonation consisted of acoustic, aerodynamic and (auditory & self-) perceptual. No measures were adversely affected by caffeine consumption.

CONCLUSION

Clinicians commonly advise patients to refrain from caffeine, as caffeine intake increases diuresis with subsequent effects on fluid balance. Such imbalances can potentially induce dehydration which can be detrimental to phonation. This notion cannot be supported empirically, as the evidence is deemed unreliable and no firm conclusions can be elicited to guide clinical practice. The results of this review demonstrate the lack of research in the field and the necessity for future investigations in order to inform evidence-based practice through reliable and valid outcomes.

Nonalcoholic Beverages as Sources of Nutrients in the Average Polish Diet

The aim of the study was to analyze the sources of energy, carbohydrates, 10 minerals, and 9 vitamins from nonalcoholic beverages in the average Polish diet. For the analysis, we used data from the 2016 Household Budget Survey conducted on the representative sample of the Polish population (36,886 households, n = 99,230). According to the source of data, we included four subgroups in analyzed food category: fruit juices, vegetable juices and mixed, mineral and spring waters, and other nonalcoholic beverages. We used the cluster analysis to assess the impact of sociodemographic and economic characteristics of the households on the structure of supplying energy and nutrients from each subgroup of the nonalcoholic beverages. Our analyses have shown that nonalcoholic beverages are primarily important in providing several nutrients: vitamin C (15.9% of the total vitamin C supply), vitamin B6 (8.9% of vitamin B supply), folates (8.5% of folate supply), carbohydrates (6.8% of carbohydrate supply), calcium (5.9% of calcium supply), and magnesium (5.5% of magnesium supply). The analysis of the consumption structure of this category of food showed that the subgroup of other nonalcoholic beverages brings more than three-fourth of carbohydrates (77%), vitamin B6 and folates (76% each), and 43% of vitamin C supplied by nonalcoholic beverages. More than half (51%) of vitamin C provided by nonalcoholic beverages comes from fruit juices and the remaining 6% comes from other juices (vegetable and mixed). In the case of minerals, mineral and spring waters consumption is important as it accounts for 65% of the calcium supply and 55% of the magnesium in nonalcoholic beverages category. The share of individual subgroups of beverages in the supply of ingredients in the diet is significantly differentiated by four socioeconomic characteristics of households: family life phase, age, socioeconomic type of household, and number of people in the household. This is particularly evident in the case of other nonalcoholic beverages, that the share of this subgroup in the energy and carbohydrates supply in the households of young people, employees (both blue-collar and white-collar workers), and families with children increases to 10%. Our results show that in order to reduce the intake of free sugars and increase the intake of deficient minerals, which is crucial in preventing noncommunicable diseases (NCDs), it is necessary to encourage consumers to replace sugar-sweetened beverages (SSBs) with water and eat fruits instead of drinking juice.

Effect of coffee consumption on fetal renal artery blood flow and amniotic fluid volume in third trimester of pregnancy

Objective:

Coffee is frequently (one or two cups/day) consumed throughout pregnancy. Although there are a few studies evaluating caffeine effects on pregnancy; however, a diuretic effect of caffeine on fetal kidneys has not been reported. Therefore, after drinking coffee whether changing of amniotic fluid index (AFI) and fetal renal artery blood flow (FRABF, RI, Resistive index; PI, Pulsatility index) were evaluated in this study.

Methods:

This clinical study was performed with two groups. For the study group, 63 participants with isolated borderline oligohydramnios who agreed to drink one cup of instant coffee were included in this study while 63 participants with isolated borderline oligohydramnios who did not drink one cup of instant coffee formed the control group. AFI, RI and PI were evaluated both before and after coffee intake.

Results:

Maternal characteristics of all study population were homogenous. FRABF indices were similar in both before and after coffee consumption. AFI was increased significantly six hours after drinking coffee (p<0.001).

Conclusions:

The coffee consumption increased the amniotic fluid volume. However it does not seem to affect on FRABF. According to our study findings, coffee consumption may offer a new opportunity to improve amniotic fluid volume for pregnant women with oligohydramnios.

Coffee with High but Not Low Caffeine Content Augments Fluid and Electrolyte Excretion at Rest

BACKGROUND

Low levels of caffeine ingestion do not induce dehydration at rest, while it is not clear if larger doses do have an acute diuretic effect. The aim of the present investigation was to examine the acute effect of low and high levels of caffeine, via coffee, on fluid balance in habitual coffee drinkers (at least one per day) at rest.

METHODS

Ten healthy adults (eight males and two females; age: 27 ± 5 years, weight: 89.5 ± 14.8 kg, height: 1.75 ± 0.08 m, and body mass index: 29.1 ± 4.4 kg m^-2) ingested 200 mL of water (W), coffee with low caffeine (3 mg kg^-1, LCAF), or coffee with high caffeine (6 mg kg^-1, HCAF) on three respective separate occasions. All sessions were performed at 09:00 in the morning in a counterbalanced, crossover manner, at least 5 days apart. Subjects remained in the laboratory while urine samples were collected every 60 min for 3 h post ingestion.

RESULTS

Absolute caffeine consumption was 269 ± 45 and 537 ± 89 mg for the LCAF and HCAF, respectively. Coffee ingestion at the HCAF trial induced greater diuresis during the 3-h period (613 ± 101 mL, P < 0.05), when compared to W (356 ± 53 mL) and LCAF (316 ± 38 mL). In addition, cumulative urinary osmotic excretion was significantly greater in the HCAF (425 ± 92 mmol, P < 0.05), as compared to the W (249 ± 36 mmol) and LCAF (177 ± 16 mmol) trials.

CONCLUSION

The data indicate that caffeine intake of 6 mg kg^-1 in the form of coffee can induce an acute diuretic effect, while 3 mg kg^-1 do not disturb fluid balance in healthy casual coffee drinking adults at rest.

[Food, diet and dietetic in treatment of urinary tract dysfunctions. A review]

Overactive bladder symptoms (OAB) are frequent and can impact quality of life for these patients. Numerous and various treatments could be proposed in order to improve well-being and quality of life, but all these treatments have side effects and determine for many patients, important care constraints. We present here a review of food and diet in OAB.

MATERIAL AND METHODS

Literature review from PubMed Medline database and Google scholar to August 2016, without time restriction. Two hundred and ninety-six articles were screened, in English and in French, and finally, 10 were retained. HAS recommandation have been used for level of evidence.

RESULTS

On the 10 studies included, only two randomised controled trial were included. The first one showed decreases on urgency (by a half) (P=0.02) and on frequency (by a third) (P=0.035), secondary to reduction of caffeine consumption by a half after education [LE2]. The second randomized trial showed significant decreases on the first need to void in urodynamic study after caffeine consumption (170mL vs. 210mL) [LE2]. Feed like bread, chicken or nutrient like vitamin C or D were assessed in cohort or observational studies and appear as protective factors of OAB onset. Instead carbonated drinks may have a negative impact on symptoms, increasing urinary incontinence (OR 1.41 [95 % CI: 1.02-1.95]) [LE2], and there are contradictory results for alcohol consumption.

CONCLUSION

Diet seems to have an impact on overactive bladder syndrome and particularly caffeine consumption, which increases storage symptoms.

Association of coffee consumption and chronic kidney disease: A meta-analysis

BACKGROUND/OBJECTIVES

The risk of chronic kidney disease (CKD) in individuals who regularly drink coffee is controversial. The aim of this meta-analysis was to evaluate the association between coffee consumption and CKD.

METHODS

A literature search was performed using MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from inception until April 2016. We included studies that reported odd ratios or hazard ratios comparing the risk of CKD in individuals consuming significant amount of coffee vs. those who did not consume coffee. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method.

RESULTS

Four observational studies with 14 898 individuals were included in our analysis to assess the association between coffee consumption and CKD. Coffee consumption was defined as one cup of coffee per day or greater. The pooled RR of CKD in individuals consuming coffee was 0.71 (95% CI, 0.47-1.08). The subgroup analysis showed the pooled RRs of CKD of 1.10 (95% CI, 0.94-1.29) in males and 0.81 (95% CI, 0.58-1.13) in females, respectively.

CONCLUSIONS

Our study demonstrates no significant association between coffee consumption and CKD in males. However, future studies are required to assess a potential inverse association between coffee consumption and risk for developing CKD in females.

Lifestyle interventions for the treatment of urinary incontinence in adults

BACKGROUND

Low cost, non-invasive alterations in lifestyle are frequently recommended by healthcare professionals or those presenting with incontinence. However, such recommendations are rarely based on good evidence.

OBJECTIVES

The objective of the review was to determine the effectiveness of specific lifestyle interventions (i.e. weight loss; dietary changes; fluid intake; reduction in caffeinated, carbonated and alcoholic drinks; avoidance of constipation; stopping smoking; and physical activity) in the management of adult urinary incontinence.

SEARCH METHODS

We searched the Cochrane Incontinence Group Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and MEDLINE in process, and handsearching of journals and conference proceedings (searched 3 July 2013), and the reference lists of relevant articles. We incorporated the results of these searches fully in the review. We undertook an updated search of the Specialised Register, which now includes searches of ClinicalTrials.gov and WHO ICTRP, on 27 October 2014; potentially eligible studies from this search are currently awaiting classification.

SELECTION CRITERIA

Randomised and quasi-randomised studies of community-based lifestyle interventions compared with no treatment, other conservative therapies, or pharmacological interventions for the treatment of urinary incontinence in adults.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. We collected information on adverse effects from the trials. Data were combined in a meta-analysis when appropriate. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included 11 trials in the review, involving a total of 5974 participants.Four trials involving 4701 women compared weight loss programmes with a control intervention. Low quality evidence from one trial suggested that more women following weight loss programmes reported improvement in symptoms of incontinence at six months (163/214 (76%) versus 49/90 (54%), risk ratio (RR) 1.40, 95% confidence interval (CI) 1.14 to 1.71), and this effect was sustained at 18 months (N = 291, 75% versus 62%, RR not estimable, reported P value 0.02). No data were available for self-reported cure and quality of life. One of the weight loss trials involving 1296 women reported very low quality evidence for a reduction in weekly urinary incontinence a mean of 2.8 years after following a lifestyle weight loss intervention that had been compared with a pharmacological weight loss intervention.Three trials involving 181 women and 11 men compared change in fluid intake with no change. Limited, very low quality evidence suggested that symptom-specific quality of life scores improved when fluid intake was reduced, although some people reported headaches, constipation or thirst. A further three trials involving 160 women and nine men compared reduction in caffeinated drinks with no change, and one trial involving 42 women compared a soy-rich diet with soy-free diet. However, it was not possible to reach any conclusions about the effects of these changes, due to methodological limitations, that resulted in very low quality evidence.Adverse effects appeared relatively uncommon for all interventions studied.All included studies had a high or unclear risk of bias across all bias parameters, but most notably for allocation concealment. The main factors for our downgrading of the evidence were risk of bias, indirect evidence (less than 12 months of follow-up; and not all participants having confirmed urinary incontinence at baseline in some studies), and imprecise results with wide confidence intervals.Other interventions such as reduction in consumption of sweetened fizzy or diet drinks; reduction in alcohol consumption; avoiding constipation; smoking cessation; restricting strenuous physical forces; or reducing high levels of, or increasing low levels of, physical activity, could not be assessed in this review, as no evidence from randomized controlled trials or quasi-randomised trials was available.

AUTHORS' CONCLUSIONS

Evidence for the effect of weight loss on urinary incontinence is building and should be a research priority. Generally, there was insufficient evidence to inform practice reliably about whether lifestyle interventions are helpful in the treatment of urinary incontinence.

Accuracy of a combined heart rate and motion sensor for assessing energy expenditure in free-living adults during a double-blind crossover caffeine trial using doubly labeled water as the reference method

BACKGROUND/OBJECTIVES

A combined heart rate (HR) and motion sensor (Actiheart) has been proposed as an accurate method for assessing total energy expenditure (TEE) and physical activity energy expenditure (PAEE). However, the extent to which factors such as caffeine may affect the accuracy by which the estimated HR-related PAEE contribution will affect TEE and PAEE estimates is unknown. Therefore, we examined the validity of Actiheart in estimating TEE and PAEE in free-living adults under a caffeine trial compared with doubly labeled water (DLW) as reference criterion.

SUBJECTS/METHODS

Using a double-blind crossover trial (Clinicaltrials.gov ID: #NCT01477294) with two conditions (4-day each with a 3-day-washout period), randomly ordered as caffeine (5 mg/kg per day) and placebo (malt-dextrine) intake, TEE was measured by DLW in 17 physically active men (20-38 years) who were non-caffeine users. In each condition, resting energy expenditure (REE) was assessed by indirect calorimetry and PAEE was calculated as (TEE-(REE+0.1 TEE)). Simultaneously, PAEE and TEE were estimated by Actiheart using an individual calibration (ACC+HRstep).

RESULTS

Under caffeine, ACC+HRstep explained 76 and 64% of TEE and PAEE from DLW, respectively; corresponding results for the placebo condition were 82 and 66%. No mean bias was found between ACC+HRstep and DLW for TEE (caffeine:-468 kJ per day; placebo:-407 kJ per day), although PAEE was slightly underestimated (caffeine:-856 kJ per day; placebo:-1147 kJ per day). Similar limits of agreement were observed in both conditions ranging from -2066 to 3002 and from -3488 to 1776 kJ per day for TEE and PAEE, respectively.

CONCLUSIONS

Regardless of caffeine intake, the combined HR and motion sensor is valid for estimating free-living energy expenditure in a group of healthy men but is less accurate for an individual assessment.

Caffeine and diuresis during rest and exercise: A meta-analysis

OBJECTIVES

Although ergogenic, acute caffeine ingestion may increase urine volume, prompting concerns about fluid balance during exercise and sport events. This meta-analysis evaluated caffeine induced diuresis in adults during rest and exercise.

DESIGN

Meta-analysis.

METHODS

A search of three databases was completed on November 1, 2013. Only studies that involved healthy adults and provided sufficient information concerning the effect size (ES) of caffeine ingestion on urine volume were included. Sixteen studies met the inclusion criteria, providing a total of 28 ESs for the meta-analysis. Heterogeneity was assessed using a random-effects model.

RESULTS

The median caffeine dosage was 300 mg. The overall ES of 0.29 (95% confidence interval (CI) = 0.11-0.48, p = 0.001) corresponds to an increase in urine volume of 109 ± 195 mL or 16.0 ± 19.2% for caffeine ingestion vs. non-caffeine conditions. Subgroup meta-analysis confirmed exercise as a strong moderator: active ES = 0.10, 95% CI = -0.07 to 0.27, p = 0.248 vs. resting ES = 0.54, 95% CI = 0.22-0.85, p = 0.001 (Cochran's Q, p = 0.019). Females (ES = 0.75, 95% CI = 0.38-1.13, p < 0.001) were more susceptible to diuretic effects than males (ES = 0.13, 95% CI = -0.05 to 0.31, p = 0.158) (Cochran's Q, p = 0.003).

CONCLUSIONS

Caffeine exerted a minor diuretic effect which was negated by exercise. Concerns regarding unwanted fluid loss associated with caffeine consumption are unwarranted particularly when ingestion precedes exercise.

The effect of caffeine on postoperative urinary retention after joint replacement surgery

BACKGROUND

Review of data on complications following joint replacement surgery revealed that urinary retention is a potential cause of increased morbidity. Repeat catheterizations, urinary tract infections, and possible infection of the prosthetic joint can result in a prolonged hospital length of stay. This study examined the effect of warm caffeinated coffee on a patient's ability to spontaneously void after indwelling catheter removal and the correlation between bladder volume and the ability to void spontaneously.

METHODS

This was a randomized, controlled, pilot study of subjects who underwent unilateral total knee arthroplasty or total hip arthroplasty. The indwelling catheter was removed postoperative day 1. If unable to void within 3 hours, participants were randomized into a control group and an intervention group. At scheduled intervals, the control group consumed 8 oz of warm water and the intervention group consumed 8 oz of caffeinated coffee.

RESULTS

Thirty subjects were randomized; 14 were randomized to the water group and 16 to the caffeine group. Twenty-four subjects spontaneously voided after ingestion of fluid and six required straight catheterization. Of these six, five of the subjects had ingested water and one subject had ingested coffee. For those who spontaneously voided, there was not a significant difference between the caffeine group and the water group. There was a significant difference between caffeine ingestion and the volume of the void.

DISCUSSION

Findings from this study suggest that ingestion of caffeine after removal of an indwelling urinary catheter in the postoperative patient may increase the amount of voiding volumes initially, therefore avoiding the need for straight catheterization. To accurately assess this, extending the study into postoperative day 2 would allow us to evaluate whether lower voiding volumes lead to the need for catheterization.

No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population

It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance. The aim of this study was to directly compare the effects of coffee consumption against water ingestion across a range of validated hydration assessment techniques. In a counterbalanced cross-over design, 50 male coffee drinkers (habitually consuming 3–6 cups per day) participated in two trials, each lasting three consecutive days. In addition to controlled physical activity, food and fluid intake, participants consumed either 4×200 mL of coffee containing 4 mg/kg caffeine (C) or water (W). Total body water (TBW) was calculated pre- and post-trial via ingestion of Deuterium Oxide. Urinary and haematological hydration markers were recorded daily in addition to nude body mass measurement (BM). Plasma was analysed for caffeine to confirm compliance. There were no significant changes in TBW from beginning to end of either trial and no differences between trials (51.5±1.4 vs. 51.4±1.3 kg, for C and W, respectively). No differences were observed between trials across any haematological markers or in 24 h urine volume (2409±660 vs. 2428±669 mL, for C and W, respectively), USG, osmolality or creatinine. Mean urinary Na⁺ excretion was higher in C than W (p = 0.02). No significant differences in BM were found between conditions, although a small progressive daily fall was observed within both trials (0.4±0.5 kg; p<0.05). Our data show that there were no significant differences across a wide range of haematological and urinary markers of hydration status between trials. These data suggest that coffee, when consumed in moderation by caffeine habituated males provides similar hydrating qualities to water.

Caffeine intake, short bouts of physical activity, and energy expenditure: a double-blind randomized crossover trial

PA energy expenditure (PAEE) is the most variable component of Total Energy Expenditure (TEE) and largely due to the balance of sedentary time (SedT) and low intensity physical activity (LIPA). There has been an emergence for seeking an understanding of factors which determine variations in SedT, LIPA, and PAEE. Sedentary behavior and physical activity are relatively resistant to change by experimental dietary treatments and significant body weight changes. Although caffeine (Caf) is by far the most heavily used nutritional agent ingested to promote a sense of vigor/alertness, it is still unknown if Caf is effective in increasing PAEE and physical activity. The aim of the study was to test the hypothesis that 2 daily doses of Caf (as a capsule to blind the treatment and divided equally during breakfast and lunch) increase PAEE and TEE, and it would do so through increasing the frequent and brief bouts of physical activity (~1-5 min long) through the day as measured by accelerometry. In 21 low Caf users (<100 mg day(-1)), we used a double-blind crossover trial (ClinicalTrials.govID;NCT01477294) with two conditions (4-day each with a 3-day washout period) randomly ordered as 5 mg kg(-1) day(-1) of Caf and maltodextrin as placebo (Plc). Resting energy expenditure (REE) by indirect calorimetry, total energy expenditure (TEE) from doubly labeled water, PAEE calculated as TEE-(REE+0.1TEE), and accelerometry measurements of both LIPA and MVPA were not different between conditions. However, regardless of caffeine or placebo, there were several significant relationships between brief bouts of LIPA and MVPA with PAEE. In conclusion, this double-blind study found that low and moderate-vigorous activity as well as the total volume of PAEE in free-living conditions is resistant to dietary caffeine intake that was equivalent to 5 cups of espresso or 7 cups of tea.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01477294.

Total body water and its compartments are not affected by ingesting a moderate dose of caffeine in healthy young adult males

Acute and chronic caffeine intakes have no impact on hydration status (R.J. Maughan and J. Griffin, J. Hum. Nutr. Diet. 16(6): 411-420, 2003), although no research has been conducted to analyze the effects using dilution techniques on total-body water (TBW) and its compartments. Therefore, the aim of this study was to investigate the effects of a moderate dose of caffeine on TBW, extracellular water (ECW), and intracellular water (ICW) during a 4-day period in active males. Thirty men, nonsmokers and low caffeine users (<100 mg·day(-1)), aged 20-39 years, participated in this double-blind, randomized, crossover trial (ClinicalTrials.gov: No. NCT01477294). The study included 2 conditions (5 mg·kg(-1)·day(-1) of caffeine and placebo (malt-dextrin)) of 4 days each, with a 3-day washout period. TBW and ECW were assessed by deuterium oxide and sodium bromide dilution, respectively, whereas ICW was calculated as TBW minus ECW. Body composition was assessed by dual-energy X-ray absorptiometry. Physical activity (PA) was assessed by accelerometry and water intake was assessed by dietary records. Repeated-measures analysis of variance (ANOVA) was used to test main effects. No changes in TBW, ECW, or ICW and no interaction between the randomly assigned order of treatment and time were observed (p > 0.05). TBW, ECW, and ICW were unrelated to fat-free mass, water ingestion, and PA (p > 0.05). These findings indicate that a moderate caffeine dose, equivalent to approximately 5 espresso cups of coffee or 7 servings of tea, does not alter TBW and fluid distribution in healthy men, regardless of body composition, PA, or daily water ingestion.

Caffeine ingestion causes detrusor overactivity and afferent nerve excitation in mice

PURPOSE

We examined the effect of caffeine (Sigma®) on voiding patterns in mice and characterized potential changes in bladder function and sensory signaling.

MATERIALS AND METHODS

A total of 12 mice were fed high dose (150 mg/kg) caffeine daily for 2 weeks. Micturition frequency and volume were recorded at baseline and at the end point. The effects of chronic low dose (10 mg/kg) caffeine on voiding patterns were examined in 7 mice, which were subsequently studied using awake cystometry. In a separate study to characterize the effects of acute caffeine consumption on bladder function and sensory signaling cystometry was performed in 6 mice. Bladder extracellular multifiber afferent signaling was recorded at baseline and 1 hour after feeding low dose caffeine. In a separate group of mice baseline cystometrograms were done using normal saline, followed by a caffeine filling solution.

RESULTS

Compared to pretreatment conditions, daily oral high dose caffeine resulted in a significant increase in average micturition frequency and a decreased average volume per void. In animals fed low dose caffeine cystometry demonstrated a statistically significant increase in filling and threshold bladder pressure compared to caffeine naïve animals. Acute low dose caffeine ingestion resulted in a significant increase in filling pressure, an increased frequency of nonvoiding bladder contractions, a decrease in cystometric capacity and a 7.2-fold increase in the average firing rate of afferent nerves during filling. Caffeine administered intravesically had no effect on cystometric parameters.

CONCLUSIONS

Oral caffeine administration results in detrusor overactivity and increased bladder sensory signaling in the mouse.

Diet and its role in interstitial cystitis/bladder pain syndrome (IC/BPS) and comorbid conditions

What's known on the subject? and What does the study add? Nearly 90% of patients with interstitial cystitis/bladder pain syndrome (IC/BPS) report sensitivities to a wide variety of dietary comestibles. Current questionnaire-based literature suggests that citrus fruits, tomatoes, vitamin C, artificial sweeteners, coffee, tea, carbonated and alcoholic beverages, and spicy foods tend to exacerbate symptoms, while calcium glycerophosphate and sodium bicarbonate tend to improve symptoms. At present we recommend employing a controlled method to determine dietary sensitivities, such as an elimination diet, in order to identify sensitivities while at the same time maintain optimal nutritional intake. We review current literature with regard to diet's effect upon IC/BPS and common comorbidities (irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome, neuropathic pain, vulvodynia, and headache) with a focus upon questionnaire-based investigations. We discuss the pathologic mechanisms that may link diet and IC/BPS related-pain, concentrating upon specific comestibles such as acidic foods, foods high in potassium, caffeine, and alcohol. Up to 90% of patients with interstitial cystitis/bladder pain syndrome (IC/BPS) report sensitivities to a wide variety of comestibles.   Pathological mechanisms suggested to be responsible for the relationship between dietary intake and symptom exacerbation include peripheral and/or central neural upregulation, bladder epithelial dysfunction, and organ 'cross-talk', amongst others.   Current questionnaire-based data suggests that citrus fruits, tomatoes, vitamin C, artificial sweeteners, coffee, tea, carbonated and alcoholic beverages, and spicy foods tend to exacerbate symptoms, while calcium glycerophosphate and sodium bicarbonate tend to improve symptoms. Specific comestible sensitivities varied between patients and may have been influenced by comorbid conditions. This suggests that a controlled method to determine dietary sensitivities, such as an elimination diet, may play an important role in patient management.

Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial

There is a belief that caffeinated drinks, such as tea, may adversely affect hydration. This was investigated in a randomised controlled trial. Healthy resting males (n 21) were recruited from the general population. Following 24 h of abstention from caffeine, alcohol and vigorous physical activity, including a 10 h overnight fast, all men underwent four separate test days in a counter-balanced order with a 5 d washout in between. The test beverages, provided at regular intervals, were 4 × 240 ml black (i.e. regular) tea and 6 × 240 ml black tea, providing 168 or 252 mg of caffeine. The controls were identical amounts of boiled water. The tea was prepared in a standardised way from tea bags and included 20 ml of semi-skimmed milk. All food taken during the 12 h intervention period was controlled, and subjects remained at rest. No other beverages were offered. Blood was sampled at 0, 1, 2, 4, 8 and 12 h, and a 24 h urine sample was collected. Outcome variables were whole blood cell count, Na, K, bicarbonate, total protein, urea, creatinine and osmolality for blood; and total volume, colour, Na, K, creatinine and osmolality for urine. Although data for all twenty-one participants were included in the analysis (mean age 36 years and mean BMI 25·8 kg/m(2)), nineteen men completed all conditions. Statistical analysis, using a factorial ANOVA approach within PROC MIXED, revealed no significant differences between tea and water for any of the mean blood or urine measurements. It was concluded that black tea, in the amounts studied, offered similar hydrating properties to water.

Urinary frequency in community-dwelling women: what is normal?

OBJECTIVE

The objective of the study was to assess urinary frequency in community-dwelling women.

STUDY DESIGN

Voiding habits were assessed in 4061 women 25-84 years of age using survey responses from the Epidemiology of Prolapse and Incontinence Questionnaire. Bother related to daytime and nighttime frequency was assessed with 100-mm visual analog scales and compared using t tests and analysis of variance.

RESULTS

Median daytime frequency was every 3-4 hours. Urinary frequency every 2 hours or more occurred in 27% and was more bothersome than every 3-4 hours or less (51.7 +/- 30.1 mm vs 23.6 +/- 23.7 mm; P < .001). Nocturia was reported in 72%, whereas 33% had 2 or more voids per night. Bother increased with increasing nighttime frequency (27.3 +/- 26.3 for 1 time vs 57.3 +/- 28.5 for > or = 2 times; P < .001).

CONCLUSION

Bothersome urinary frequency is common and occurs when frequency is at least every 2 hours by day and more than once per night.

Effect of comestibles on symptoms of interstitial cystitis

PURPOSE

Anecdotal evidence suggests that patients with painful bladder syndrome/interstitial cystitis report symptom exacerbation after consuming particular foods, beverages and/or supplements. We determined the prevalence of the effect of comestibles on painful bladder syndrome/interstitial cystitis symptoms and identified particular comestible items more likely to affect such symptoms.

MATERIALS AND METHODS

A validated questionnaire designed to detect whether food, beverages and/or supplements have an effect on bladder symptoms was administered to 104 patients meeting National Institute for Diabetes and Digestive and Kidney Diseases criteria for interstitial cystitis. In addition to answering general questions about the effect of comestibles on painful bladder syndrome/interstitial cystitis symptoms, subjects were asked to indicate whether each of 175 individual items worsened, improved or had no effect on symptoms. Each response was numerically scored on a scale of -2 to 2 and mean values were generated for each comestible item.

RESULTS

Of the surveyed patients with painful bladder syndrome/interstitial cystitis 90.2% indicated that the consumption of certain foods or beverages caused symptom exacerbation. There was no correlation between allergies and the effect of comestibles on symptoms. Patients who reported that specific foods worsened symptoms tended to have higher O'Leary-Sant interstitial cystitis symptom index and problem index, and/or pelvic pain and urgency/frequency patient symptom scale scores. A total of 35 comestible items had a mean score of lower than -1.0, including caffeinated, carbonated and alcoholic beverages, certain fruits and juices, artificial sweeteners and spicy foods.

CONCLUSIONS

There is a large cohort of patients with painful bladder syndrome/interstitial cystitis in whom symptoms are exacerbated by the ingestion of specific comestibles. The most frequently reported and most bothersome comestibles were coffee, tea, soda, alcoholic beverages, citrus fruits and juices, artificial sweeteners and hot pepper.