Daily Caffeine Consumption Research Articles

Tobacco smoking among people living with a psychotic illness: The second Australian survey of psychosis

The aims of this study were to (a) describe patterns of tobacco smoking among Australians living with a psychotic illness and (b) explore the association between smoking and measures of psychopathology, psychiatric history, psychosocial functioning, physical health, substance use and demographic characteristics. Data were from 1812 participants in the 2010 Australian Survey of High Impact Psychosis. Participants were aged 18-64 years and resided in seven mental health catchment sites across five states of Australia. Bivariate statistics were used to compare smokers with non-smokers on the measures of interest, and to compare ICD-10 diagnostic categories on measures of smoking prevalence, nicotine addiction and quitting history. Multivariate logistic regression was used to test whether (a) demographics and psychiatric history were associated with having ever smoked and (b) whether symptoms and psychosocial functioning were independently associated with current smoking, after controlling for demographics, psychiatric history and substance use. The prevalence of current tobacco smoking was 66.6% (72% of men and 59% of women); lifetime prevalence was 81%. In univariate analyses, individuals with a diagnosis of schizophrenia or schizoaffective disorder were most likely to be smoking tobacco (70%) and were more nicotine dependent. Smokers reported worse perceived physical health, lower body mass index and waist circumference, and more lifetime medical conditions. A younger age of illness onset, male gender and low education were associated with having ever smoked. Associations with current smoking included low education, male gender, no formal employment, worse negative symptoms, higher daily caffeine consumption, and alcohol dependence and substance abuse/dependence. The prevalence of tobacco smoking is high amongst people with a psychotic disorder, and is associated with adverse mental health symptoms as well as high rates of other substance use, poorer subjective physical health, and a higher risk of the many known health consequences of smoking.

Daily caffeine consumption is associated with fibromyalgia pain

Daily caffeine consumption is associated with fibromyalgia pain

Supraventricular tachycardia induced by chocolate: is chocolate too sweet for the heart?

Conflicting studies have been published concerning the association between chocolate and cardiovascular diseases. Fewer articles have described the potential arrhythmogenic risk related to chocolate intake. We present a case of paroxysmal supraventricular tachycardia in a woman after consumption of large quantity of chocolate. A 53-year-old woman with no significant medical history presented to us with complaints of palpitations and shortness of breath after consuming large amounts of chocolate. Electrocardiogram showed supraventricular tachycardia at 165 beats per minute, which was restored to sinus rhythm after adenosine bolus injection. Electrophysiology studies showed atrioventricular nodal reentry tachycardia, which was treated with radiofrequency ablation. Chocolate contains caffeine and theobromine, which are methylxanthines and are competitive antagonists of adenosine and can have arrhythmogenic potential. Our case very well describes an episode of tachycardia precipitated by large amount of chocolate consumption in a patient with underlying substrate. There are occasional case reports describing association between chocolate, caffeine, and arrhythmias. A large Danish study, however, did not find any association between amount of daily caffeine consumption and risk of arrhythmia.

Adolescent Caffeine Consumption, Daytime Sleepiness, and Anger

Introduction: Caffeine use has been increasing among adolescents and young adults but much remains to be known about the consequences and context of their use. Methods: With self-reported anger as the key outcome variable, 7348 Icelandic adolescents were surveyed for caffeine consumption, cigarette smoking, alcohol use, daytime sleepiness, and potential confounders. Structural equation modeling was used to examine direct and indirect effects of seven latent constructs: parental education, parental support, peer support, caffeine consumption, licit substance use (nicotine and alcohol), sleepiness, and anger; and two direct effects were measured using variables for family structure and family financial status. Results: Daily caffeine consumption was reported by 76.3% of participants, and of the four caffeine beverages surveyed, cola drinks were most often consumed, followed by energy drinks, tea, and coffee. Boys reported more caffeine use on average than girls, with the difference being particularly marked...

Association of caffeine intake and histological features of chronic hepatitis C

The severity of chronic hepatitis C (CHC) is modulated by host and environmental factors. Several reports suggest that caffeine intake exerts hepatoprotective effects in patients with chronic liver disease. The aim of this study was to evaluate the impact of caffeine consumption on activity grade and fibrosis stage in patients with CHC. A total of 238 treatment-naïve patients with histologically-proven CHC were included in the study. Demographic, epidemiological, environmental, virological, and metabolic data were collected, including daily consumption of alcohol, cannabis, tobacco, and caffeine during the six months preceding liver biopsy. Daily caffeine consumption was estimated as the sum of mean intakes of caffeinated coffee, tea, and caffeine-containing sodas. Histological activity grade and fibrosis stage were scored according to Metavir. Patients (154 men, 84 women, mean age: 45±11 years) were categorized according to caffeine consumption quartiles: group 1 (<225 mg/day, n=59), group 2 (225-407 mg/day, n=57), group 3 (408-678 mg/day, n=62), and group 4 (>678 mg/day, n=60). There was a significant inverse relationship between activity grade and daily caffeine consumption: activity grade>A2 was present in 78%, 61%, 52%, and 48% of patients in group 1, 2, 3, and 4, respectively (p<0.001). By multivariate analysis, daily caffeine consumption greater than 408 mg/day was associated with a lesser risk of activity grade>A2 (OR=0.32 (0.12-0.85). Caffeine intake showed no relation with fibrosis stage. Caffeine consumption greater than 408 mg/day (3 cups or more) is associated with reduced histological activity in patients with CHC. These findings support potential hepatoprotective properties of caffeine in chronic liver diseases.

Counseling patients regarding reducing caffeine consumption before in vitro fertilization (IVF) is associated with a decreased number of immature oocytes

OBJECTIVE: The mechanism of caffeine's effect on fertility is unknown. IVF patients who consume caffeine have lower live birth rates. Caffeine is a phosphodiesterase inhibitor. The phosphodiesterase inhibitor ORG 9935 inhibited oocyte maturation in rhesus macaques stimulated with gonadotropins. We hypothesize that reducing caffeine intake before IVF would decrease the number of immature oocytes retrieved.DESIGN: Retrospective Chart Review.MATERIALS AND METHODS: In 2007 our infertility center incorporated caffeine cessation counseling into the IVF program. IRB approval was obtained to review non-donor fresh IVF cycles from 2006 and 2008, the years prior and after this recommendation. Cycles that utilized conventional fertilization were excluded as oocyte maturation was not determined. Daily caffeine consumption was documented at the patient's first clinic visit. The primary outcome was the number of immature oocytes defined as the combined number of metaphase I (MI) and germinal vesicle (GV) oocytes. Groups were compared using t-tests with p-values less than 5% considered significant.RESULTS: Baseline characteristics between the two years were similar. In 2006, 22 cycles (38.0%) patients reported less than 100mg caffeine consumption (mean 10mg) and 36 cycles (62.0%) patients reported 100mg or more (mean 161mg). In 2008, 41 cycles (41.4%) patients reported less than 100mg caffeine (mean 11mg) and 58 cycles (58.6%) patients reported 100mg or more (mean 187mg) prior to caffeine cessation counseling. The number of oocytes retrieved in the low and high caffeine groups did not differ significantly in either 2006 (P=0.47) or 2008 (P=0.74). In 2006, the <100mg caffeine group had a significantly lower number of immature oocytes as compared to the ≥100mg caffeine group (P=0.03), while in 2008 after the caffeine recommendation there was no difference in the number of immature oocytes between the groups (P=0.49).CONCLUSION: Caffeine cessation counseling before IVF may be beneficial in decreasing high percentage of immature oocytes. OBJECTIVE: The mechanism of caffeine's effect on fertility is unknown. IVF patients who consume caffeine have lower live birth rates. Caffeine is a phosphodiesterase inhibitor. The phosphodiesterase inhibitor ORG 9935 inhibited oocyte maturation in rhesus macaques stimulated with gonadotropins. We hypothesize that reducing caffeine intake before IVF would decrease the number of immature oocytes retrieved. DESIGN: Retrospective Chart Review. MATERIALS AND METHODS: In 2007 our infertility center incorporated caffeine cessation counseling into the IVF program. IRB approval was obtained to review non-donor fresh IVF cycles from 2006 and 2008, the years prior and after this recommendation. Cycles that utilized conventional fertilization were excluded as oocyte maturation was not determined. Daily caffeine consumption was documented at the patient's first clinic visit. The primary outcome was the number of immature oocytes defined as the combined number of metaphase I (MI) and germinal vesicle (GV) oocytes. Groups were compared using t-tests with p-values less than 5% considered significant. RESULTS: Baseline characteristics between the two years were similar. In 2006, 22 cycles (38.0%) patients reported less than 100mg caffeine consumption (mean 10mg) and 36 cycles (62.0%) patients reported 100mg or more (mean 161mg). In 2008, 41 cycles (41.4%) patients reported less than 100mg caffeine (mean 11mg) and 58 cycles (58.6%) patients reported 100mg or more (mean 187mg) prior to caffeine cessation counseling. The number of oocytes retrieved in the low and high caffeine groups did not differ significantly in either 2006 (P=0.47) or 2008 (P=0.74). In 2006, the <100mg caffeine group had a significantly lower number of immature oocytes as compared to the ≥100mg caffeine group (P=0.03), while in 2008 after the caffeine recommendation there was no difference in the number of immature oocytes between the groups (P=0.49). CONCLUSION: Caffeine cessation counseling before IVF may be beneficial in decreasing high percentage of immature oocytes.

Caffeine, a drug for all seasons

Increased caffeine consumption is associated with reduced hepatic fibrosis. Apurva A. Modi, Jordan J. Feld, Yoon Park,David E. Kleiner, James E. Everhart, T. Jake Liang, Jay H. Hoofnagle. Hepatology, 2010 Jan;51(1):201-9.

The relationship between daily caffeine consumption and withdrawal symptoms: a questionnaire-based study

To estimate daily caffeine intake among a group of university students at the Kocaeli Vocational School of Health Services in Turkey, and to determine the relationship between daily caffeine consumption and withdrawal symptoms. Materials and methods: This survey study was conducted using a questionnaire that was administered to 156 university students (129 females, 27 males) at the Kocaeli Vocational School of Health Services in Kocaeli, Turkey. The quantity of caffeine-containing products consumed was recorded on a daily basis, depending on the dietary habits of the consumer. The t test for differences between 2 proportions (using the normal approximation) was used for comparison of the frequency of complaints that began within 12-24 h of the cessation of caffeine consumption in relation to the quantities of daily caffeine consumption at P < 0.05. Results: Daily caffeine intake was estimated to range from 0 to 500 mg day_{-1} A significant increase in headache, fatigue, irritability, and sleepiness/drowsiness (P < 0.05) was reported by student's whose daily caffeine consumption was > 200 mg than by those whose daily caffeine consumption was < 200 mg. Conclusion: The data obtained show that Turkish university students consume similar amounts of caffeine as American, Canadian, Swedish, and British university students. The survey results show that there was a relationship between daily caffeine consumption and withdrawal symptoms (headache, fatigue, irritability, and sleepiness/drowsiness).

Glucose homeostasis remains altered by acute caffeine ingestion following 2 weeks of daily caffeine consumption in previously non-caffeine-consuming males

Acute caffeine ingestion increases serum NEFA and plasma adrenaline and decreases insulin sensitivity. Although frequently suggested, it is not known if a tolerance to these alterations in glucose homeostasis is developed in habitual caffeine consumers. Our objective was to determine whether acute caffeine ingestion continued to alter insulin, glucose, NEFA and adrenaline during an oral glucose tolerance test (OGTT) following 14 d of caffeine consumption. Twelve caffeine-naive young males underwent four OGTTs over a 4-week period. Subjects ingested a gelatin-filled placebo (PLA) capsule on the first trial day and 5 mg caffeine/kg body weight on the remaining three trial days (day 0, day 7, day 14) before a 2 h OGTT. Following day 0 and day 7, subjects were given six dosages of 5 mg caffeine/kg to consume per d between trials. Serum insulin and blood glucose area under the curve (AUC) were significantly elevated (P < 0.05) v. PLA on day 0 (36 and 103 %, respectively) and were not different from PLA on day 7. On day 14, insulin AUC was 29 % greater than PLA (P < 0.05), and glucose was greater (P < 0.05) during the first hour, although the 50 % elevation in glucose AUC was not different from PLA. Before the OGTT, caffeine resulted in greater (P < 0.05) serum NEFA and plasma adrenaline concentrations in all three caffeine trials, but both NEFA and adrenaline concentrations were decreased (P < 0.05) on day 14 v. day 0. Although 14 d of caffeine consumption by previously caffeine-naive subjects reduced its impact on glucose homeostasis, carbohydrate metabolism remained disrupted.

Survey of Literature

Effects of daily caffeine consumption on open-field behaviours, serum corticosterone and brain antioxidant levels were investigated after six hours of total sleep-deprivation in prepubertal mice. We tested the hypothesis that daily caffeine consumption may significantly alter behaviour, stress and antioxidative response of prepubertal mice to an acute episode of total sleep-deprivation.Prepubertal Swiss mice of both sexes were assigned to two main groups of 120 each (subdivided into 6 groups of 10 each, based on sex), and administered vehicle or graded oral doses of caffeine (10, 20, 40, 80 and 120 mg/kg/day) for 14 days. On day 14, a main group was subjected to 6 h of total sleep-deprivation by ‘gentle-handling’. Open-field behaviours were then assessed in both groups, after which animals were euthanized, and levels of corticosterone, superoxide dismutase and glutathione peroxidase assayed.Horizontal locomotion, rearing and grooming increased significantly, compared to control, with sleep-deprived (SD) mice showing stronger caffeine-driven responses at higher doses; and SD female mice showing sustained response to caffeine, compared to respective males. Plasma corticosterone increased with increasing doses of caffeine in both non sleep-deprived (NSD) and SD mice; although SD mice had higher corticosterone levels. Sleep-deprivation and/or higher doses of caffeine were associated with derangements in brain antioxidant levels.Repeated caffeine consumption and/or acute sleep-deprivation led to significant changes in pattern of open-field behaviour and stress/antioxidant response in mice. Responses seen in the study are probably due to modulatory effects of caffeine on the total body response to stressful stimuli.

The effects of male age on sperm DNA damage in healthy non-smokers

The trend for men to have children at older age raises concerns that advancing age may increase the production of genetically defective sperm, increasing the risks of transmitting germ-line mutations. We investigated the associations between male age and sperm DNA damage and the influence of several lifestyle factors in a healthy non-clinical group of 80 non-smokers (mean age: 46.4 years, range: 22-80 years) with no known fertility problems using the sperm Comet analyses. The average percentage of DNA that migrated out of the sperm nucleus under alkaline electrophoresis increased with age (0.18% per year, P = 0.006), but there was no age association for damage measured under neutral conditions (P = 0.7). Men who consumed >3 cups coffee per day had approximately 20% higher percentage tail DNA under neutral but not alkaline conditions compared with men who consumed no caffeine (P = 0.005). Our findings indicate that (i) older men have increased sperm DNA damage associated with alkali-labile sites or single-strand DNA breaks and (ii) independent of age, men with substantial daily caffeine consumption have increased sperm DNA damage associated with double-strand DNA breaks. DNA damage in sperm can be converted to chromosomal aberrations and gene mutations after fertilization, increasing the risks of developmental defects and genetic diseases among offspring.

Correlates of daily caffeine consumption

A study of 376 young British adults showed that estimated daily caffeine consumption increased with age, and was associated with smoking and greater alcohol consumption. Non-consumers of caffeine avoided tea and coffee (even the de-caffeinated form). Level of caffeine consumption was not associated with impulsivity, sociability, extraversion or trait anxiety.

Long-term use of oral contraceptives increases the risk of miscarriage

In this prospective, case-control study, a step-wise logistic regression model was used to examine the relationship between the consumption of oral contraceptives before pregnancy and the potential increase in the risk of miscarriage. Consumption of oral contraceptives for more than 2 years before pregnancy is associated with a higher risk of miscarriage.

Caffeine and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study

It is not known whether the consumption of caffeine is associated with excess risk of atrial fibrillation. We evaluated the risk of atrial fibrillation or flutter in association with daily consumption of caffeine from coffee, tea, cola, cocoa, and chocolate. We prospectively examined the association between the amount of caffeine consumed per day and the risk of atrial fibrillation or flutter among 47 949 participants (x age: 56 y) in the Danish Diet, Cancer, and Health Study. Subjects were followed in the Danish National Registry of Patients and in the Danish Civil Registration System. The consumption of caffeine was analyzed by quintiles with Cox proportional-hazard models. During follow-up (x: 5.7 y), atrial fibrillation or flutter developed in 555 subjects (373 men and 182 women). When the lowest quintile of caffeine consumption was used as a reference, the adjusted hazard ratios (95% CIs) in quintiles 2, 3, 4, and 5 were 1.12 (0.87, 1.44), 0.85 (0.65, 1.12), 0.92 (0.71, 1.20), and 0.91 (0.70, 1.19), respectively. Consumption of caffeine was not associated with risk of atrial fibrillation or flutter.

PEDIATRIC HEADACHE

Caffeine is the most widely used behaviourally active substance. Excessive caffeine consumption, mostly in the form of coffee and tea, is a well‐recognized cause of headache or migraine, and withdrawal can cause headache. Nevertheless, caffeine abuse headache is not listed as a separate category in the International Headache Society classification, 1988. We report our experience with children and adolescents with daily or near‐daily headache and excessive consumption of caffeine in the form of cola drinks. Over a period of 5 years we have encountered, in a tertiary headache clinic in a general hospital, 36 children and adolescents (17 girls and 19 boys) with daily or near‐daily headache related to excessive caffeine intake in the form of cola drinks. The mean age of the subjects was 9.2 years (range 6‐18) and mean headache duration was 1.8 years (range 0.6‐5). All were heavy cola drinks consumers; at least 1.5 L of cola drinks per day (192.88 mg of caffeine daily), and an average of 11 (range 10.5‐21) L of cola drinks a week, which amounts to 1414.5 mg of caffeine (range 1350.1‐2700.3). Patients were encouraged to achieve gradual withdrawal from cola drinks, which led to complete cessation of all headaches in 33 subjects, whereas one boy and two adolescent girls continued to suffer from migraine without aura not frequent enough to justify prophylactic medication. Children and adolescents with high daily caffeine consumption in the form of cola drinks may suffer from caffeine‐induced daily headache. Gradual withdrawal can be achieved without withdrawal headache and with complete disappearance of the induced chronic daily headache. Comments: Adolescents get rebound headache, too, and elimination of caffeine is part of the necessary detoxification of medications in teens as well as in adults. I tell my patients that caffeine is just another rebound medication, and I, too, have had excellent results in patients with chronic migraine restored to episodic migraine after decaffeination. SJT I would agree. Another issue always worth exploring with these patients is the use of combination analgesic products; eg, containing caffeine and acetaminophen or aspirin to “enhance the analgesic effects.” These products have also, of course, been implicated in the development of chronic migraine if used on a daily basis. DSM

Caffeine-induced headache in children and adolescents.

Caffeine is the most widely used behaviourally active substance. Excessive caffeine consumption, mostly in the form of coffee and tea, is a well-recognized cause of headache or migraine, and withdrawal can cause headache. Nevertheless, caffeine abuse headache is not listed as a separate category in the International Headache Society classification, 1988. We report our experience with children and adolescents with daily or near-daily headache and excessive consumption of caffeine in the form of cola drinks. Over a period of 5 years we have encountered, in a tertiary headache clinic in a general hospital, 36 children and adolescents (17 girls and 19 boys) with daily or near-daily headache related to excessive caffeine intake in the form of cola drinks. The mean age of the subjects was 9.2 years (range 6-18) and mean headache duration was 1.8 years (range 0.6-5). All were heavy cola drinks consumers; at least 1.5 L of cola drinks per day (192.88 mg of caffeine daily), and an average of 11 (range 10.5-21) L of cola drinks a week, which amounts to 1414.5 mg of caffeine (range 1350.1-2700.3). Patients were encouraged to achieve gradual withdrawal from cola drinks, which led to complete cessation of all headaches in 33 subjects, whereas one boy and two adolescent girls continued to suffer from migraine without aura not frequent enough to justify prophylactic medication. Children and adolescents with high daily caffeine consumption in the form of cola drinks may suffer from caffeine-induced daily headache. Gradual withdrawal can be achieved without withdrawal headache and with complete disappearance of the induced chronic daily headache.

Nicotine and caffeine intake in complex regional pain syndrome

{\it } Nicotine and caffeine are vasoconstrictors. Complex regional pain syndrome (CRPS) is defined to involve disproportionate pain and autonomic dysfunction [1]. The objectives of this study were to identify the prevalence of smoking and caffeine intake in CRPS, to explore the relationship of pain intensity with smoking and caffeine consumption, and to explore the relationship of pain intensity, anxiety and disability among CRPS patients who smoke, use caffeine, or both. {\it } One hundred eleven patients, with CRPS type I or II, from two academic rehabilitation pain clinics were reviewed. Data were collected retrospectively by reviewing CRPS patients' self-reported pain level using visual analogue scales (VAS), Beck Depression Inventory (BDI), Pain Disability Index (PDI), and Pain Anxiety Symptoms Scale (PASS). Status of daily smoking and caffeine consumption were also recorded. {\it } Smoking prevalence among CRPS was significant higher than the national average (p < 0.001). There were no significant relationships between the perceived pain level and either daily smoking, daily caffeine intake, or both (p > 0.430). In patients with CRPS I higher PASS scores were positively associated with dichotomous use of smoking and caffeine (p < 0.05). The PASS scores among patients with CRPS~II were not available for analysis. {\it } The smoking prevalence was higher than the national average among patients with CRPS I and II. Among patients with CRPS~I smoking and caffeine consumption were greater in those who reported more pain-related anxiety, but did not influence pain intensity. The clinical implications of these findings will be discussed.

Human brain metabolic response to caffeine and the effects of tolerance.

Since there is limited information concerning caffeine's metabolic effects on the human brain, the authors applied a rapid proton echo-planar spectroscopic imaging technique to dynamically measure regional brain metabolic responses to caffeine ingestion. They specifically measured changes in brain lactate due to the combined effects of caffeine's stimulation of glycolysis and reduction of cerebral blood flow. Nine heavy caffeine users and nine caffeine-intolerant individuals, who had previously discontinued or substantially curtailed use of caffeinated products because of associated anxiety and discomforting physiological arousal, were studied at baseline and then during 1 hour following ingestion of caffeine citrate (10 mg/kg). To assess state-trait contributions and the effects of caffeine tolerance, five of the caffeine users were restudied after a 1- to 2-month caffeine holiday. The caffeine-intolerant individuals, but not the regular caffeine users, experienced substantial psychological and physiological distress in response to caffeine ingestion. Significant increases in global and regionally specific brain lactate were observed only among the caffeine-intolerant subjects. Reexposure of the regular caffeine users to caffeine after a caffeine holiday resulted in little or no adverse clinical reaction but significant rises in brain lactate which were of a magnitude similar to that observed for the caffeine-intolerant group. These results provide direct evidence for the loss of caffeine tolerance in the human brain subsequent to caffeine discontinuation and suggest mechanisms for the phenomenon of caffeine intolerance other than its metabolic effects on elevating brain lactate.

How Sleep and Mental Disorders Are Related to Complaints of Daytime Sleepiness

Daytime sleepiness is widespread and has negative impacts on the public sector. To ascertain the incidence and prevalence of daytime sleepiness and associated risk factors in the general population. In 1994, a representative sample of the non-institutionalized British population aged 15 years or older was interviewed via telephone using an expert computer-assisted program designed to facilitate surveys of this type (Sleep-Eval, M. M. Ohayon, Montreal, Quebec). Subjects were classified into 3 groups based on the severity of their daytime sleepiness. We completed 4972 interviews (acceptance rate, 79.6%). Severe daytime sleepiness was reported in 5.5% (95% confidence interval, 4.9%-6.1%) of the sample, and moderate daytime sleepiness in another 15.2% (95% confidence interval, 14.2%-16.2%). Associated factors with severe daytime sleepiness included female sex, middle age, napping, insomnia symptoms, high daily caffeine consumption, breathing pauses or leg pain in sleep, depressive disorder (based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria), falling asleep while reading or watching television, and motor vehicle crashes or accidents involving use of machinery. Moderate daytime sleepiness was associated with female sex, napping, insomnia symptoms, arthritis or heart disease, and gross motor movements during sleep. It is likely that daytime sleepiness deleteriously affects work activities, social and/or marital life, and exhibits a negative socioeconomic impact. In addition, the risk of a motor vehicle crash appears to be higher in this specific population: twice as many subjects operating a motor vehicle or using machine tools reported having a crash or accident, respectively, in the previous year in the groups with severe daytime sleepiness or moderate daytime sleepiness than did the general population with no daytime sleepiness. The high prevalence rates of daytime sleepiness and multiplicity of related factors mandate further scrutiny by public health officials.

Absorption and Subjective Effects of Caffeine from Coffee, Cola and Capsules

Coffee is often perceived as producing greater pharmacological effects than cola. The present study compared the magnitude and rapidity of peak caffeine levels and subjective effects between coffee and cola. Thirteen users of both coffee and cola (mean daily caffeine consumption = 456 mg) ingested 400 mg caffeine via 12 oz unsweetened coffee, 24 oz sugar-free cola or 2 capsules in a random, double-blind, placebo-controlled, within-subjects design. Subjects provided a saliva sample and completed subjective effect scales 15 min before and 30, 60, 90, 120, 180 and 240 min after ingestion. Mean peak saliva caffeine levels did not differ between coffee (9.7 ± 1.2 μg/ml) and cola (9.8 ± 0.9 μg/ml) and appeared to be greater with these beverages than with the capsule (7.8 ± 0.6 μg/ml; p = NS). Saliva caffeine levels peaked at similar times for coffee (42 ± 5 min) and cola (39 ± 5 min) but later for capsule (67 ± 7 min; p = 0.004). There was no main effect of vehicle or interaction of vehicle and drug on magnitude of peak effect or time to peak increase on self-report scales. In summary, peak caffeine absorption, time to peak absorption, and subjective effects do not appear to be influenced by cola vs. coffee vehicle. Perceived differences in the effects of coffee vs. cola may be due to differences in dose, time of day, added sweetener, environmental setting or contingencies.