Self-report reliability and symptomatology of habitual caffeine consumption

Association of urinary caffeine and caffeine metabolites with bone mineral density in children and adolescents

In epidemiological research, the link between coffee consumption and bone mineral density (BMD) is still debated. Moreover, there hasn't been any research on the relationship between urine caffeine and caffeine metabolites and BMD. This study aimed to investigate if there was a connection between urine caffeine and its metabolites and BMD in people between the ages of 8 and 19. Using data from the National Health and Nutrition Examination Survey 2009 to 2014, multivariate logistic regression models were utilized to investigate the association between urinary caffeine and caffeine metabolites and total BMD. Fitted smoothing curves and generalized additive models were also used. A total of 1235 adolescents were included in this analysis, after controlling for various variables, we found that the association between urinary theophylline and total BMD was negative, whereas the association between urinary paraxanthine, theobromine and caffeine and total BMD was positive. In our study, an inverted U-shaped association between urinary paraxanthine and urinary caffeine was found with BMD in women. In this cross-sectional study, the correlation between urinary caffeine and its metabolites and total BMD differed by sex and race. More studies are needed to confirm the results of this study and to investigate the underlying causes.

Time to Recover From Daily Caffeine Intake

Caffeine elicits widespread effects in the central nervous system and is the most frequently consumed psychostimulant worldwide. First evidence indicates that, during daily intake, the elimination of caffeine may slow down, and the primary metabolite, paraxanthine, may accumulate. The neural impact of such adaptions is virtually unexplored. In this report, we leveraged the data of a laboratory study with N = 20 participants and three within-subject conditions: caffeine (150 mg caffeine × 3/day × 10 days), placebo (150 mg mannitol × 3/day × 10 days), and acute caffeine deprivation (caffeine × 9 days, afterward placebo × 1 day). On day 10, we determined the course of salivary caffeine and paraxanthine using liquid chromatography-mass spectrometry coupled with tandem mass spectrometry. We assessed gray matter (GM) intensity and cerebral blood flow (CBF) after acute caffeine deprivation as compared to changes in the caffeine condition from our previous report. The results indicated that levels of paraxanthine and caffeine remained high and were carried overnight during daily intake, and that the levels of paraxanthine remained elevated after 24 h of caffeine deprivation compared to placebo. After 36 h of caffeine deprivation, the previously reported caffeine-induced GM reduction was partially mitigated, while CBF was elevated compared to placebo. Our findings unveil that conventional daily caffeine intake does not provide sufficient time to clear up psychoactive compounds and restore cerebral responses, even after 36 h of abstinence. They also suggest investigating the consequences of a paraxanthine accumulation during daily caffeine intake.

Lifetime caffeine intake and the risk of epithelial ovarian cancer

BACKGROUND

Caffeine intake has been inconsistently associated with the risk of ovarian cancer in previous studies. The measure of caffeine in these studies has not always distinguished between caffeinated and decaffeinated sources, and the time for which intake was assessed was often for late adulthood and thus may have excluded the etiologic window. We investigated lifetime caffeine intake from caffeinated coffee, black tea, green tea and cola sodas in relation to ovarian cancer risk.

METHODS

Among 497 cases and 904 controls in a population-based case-control study in Montreal, Canada, lifetime intake of caffeinated coffee, black tea, green tea and cola sodas was assessed and used to calculate lifetime total intake of caffeine. Unconditional multivariable logistic regression was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for the association between caffeine intake and ovarian cancer risk overall, as well as by menopausal status. Multivariable polytomous logistic regression was used to estimate the associations for invasive and borderline ovarian cancers separately.

RESULTS

Almost all participants (98.4% of cases and 97.5% of controls) had consumed caffeine in their lifetime. The mean (standard deviation) daily consumption of caffeine over the lifetime was of 117 (89) mg/day among cases and 120 (118) mg/day among controls. The OR (95% CI) of ovarian cancer for the highest versus lowest quartile of lifetime caffeine intake was 1.17 (0.83-1.64). According to menopausal status, the OR (95% CI) was 1.56 (0.85-2.86) for premenopausal women and 0.94 (0.66-1.34) for postmenopausal women, comparing the highest to lowest tertiles of intake. Associations for invasive and borderline ovarian cancers separately were similar to that observed for ovarian cancer overall.

CONCLUSION

Lifetime caffeine intake was not strongly associated with ovarian cancer risk. A difference in relationship by menopausal status is possible.

Association of urinary caffeine and caffeine metabolites with cardiovascular disease risk in adults

OBJECTIVES

Studies have shown that the consumption of a moderate amount of caffeine is associated with a reduced risk of cardiovascular disease (CVD) and may even be protective against CVD. The purpose of the current study was to evaluate the association between urinary caffeine and its related metabolites and CVD risk in a national representative sample of US adults.

METHODS

We analyzed cross-sectional data from the US National Health and Nutrition Examination Survey from 2009 and 2010. The associations between the levels of urinary caffeine metabolites and self-reported CVD, including congestive heart failure, coronary heart disease, angina, heart attack, and stroke, were examined separately in men and women using multivariate logistic regression models adjusted for covariates.

RESULTS

In total, 1916 participants (910 men and 1006 women) were included in the analysis. Among women, the odds ratios of CVD in the highest quartiles of 1,3-dimethylxanthine and 1,3,7-trimethylxanthine were 0.33 (95% confidence interval [CI], 0.12-0.92) and 0.35 (95% CI, 0.13-0.93), respectively, compared with the lowest quartiles. Each one-unit (µmol/L) increase in theophylline concentration was associated with a 0.24-mg/dL increase in high-density lipoprotein cholesterol in the fully adjusted model. Among men, no significant association was observed between urinary caffeine metabolites and CVD. Regarding the subtypes of CVD, compared with women in the lowest quartile for 1,3-dimethylxanthine and 1,3,7-trimethylxanthine, the odds of coronary heart disease decreased by 90% (95% CI, -99% to -11%) and 97% (95% CI, -99% to -47%), respectively, in those in the highest quartile.

CONCLUSIONS

Urinary 1,3-dimethylxanthine and 1,3,7-trimethylxanthine were significantly and inversely associated with CVDs in women. Additional studies are needed to further confirm the results of this study and explore the underlying mechanisms.<END ABSTRACT>.

Lifetime coffee consumption, pineal gland volume, and sleep quality in late life

Study Objectives

Previous studies have shown that coffee consumption may suppress the production of melatonin in pinealocytes through competitive inhibition of adenosine A2 receptors by caffeine. We investigated the impact of lifetime coffee consumption on pineal gland volume and the resulting effects on sleep quality.

Methods

We enrolled 162 cognitively normal elderly individuals among the participants in the Korean Longitudinal Study on Cognitive Aging and Dementia. We evaluated the patterns and amounts of coffee consumption using a study-specific standardized interview and assessed sleep quality using the Pittsburgh Sleep Quality Index. We measured the volume of pineal parenchyma (VPP) by manually segmenting the pineal gland on high-resolution three-dimensional T1-weighted magnetic resonance images. We examined the impact of lifetime coffee consumption on the VPP and the resulting effects on sleep quality using analysis of covariance, multiple linear regression, and mediation analyses.

Results

We found that smaller VPP was associated with higher cumulative lifetime coffee consumption. Participants who consumed more than 60 cup-years of coffee had VPPs that were smaller by about 20% than individuals who consumed less than 60 cup-years of coffee. The VPP mediated the association between lifetime coffee consumption and sleep efficiency and quality.

Conclusions

Our findings suggest that high lifetime coffee consumption may reduce VPP, and that this reduction in VPP may impair the quality of sleep in late life.

Maternal, but not paternal or grandparental, caffeine intake is associated with childhood obesity and adiposity: The Lifeways Cross-Generation Cohort Study

BACKGROUND

Maternal caffeine intake is associated with adverse birth outcomes, but its long-term influence on offspring adiposity outcomes is not well studied. Furthermore, few studies have investigated paternal and grandparental caffeine intake in relation to offspring outcomes.

OBJECTIVE

To study the associations between maternal, paternal, and grandparental caffeine intake and offspring childhood adiposity.

DESIGN

The core study sample consists of 558 mother-child pairs from the Lifeways Study. Caffeine intake was derived from relevant food items in a self-administered validated food frequency questionnaire in early pregnancy. Children's body mass index (BMI) and waist circumference (WC) were measured at 5- and 9-y follow-up. Childhood overall and central obesity were defined as age- and sex-specific BMI z-score > International Obesity Task Force cut-off and WC z-score > 90th percentile, respectively. Multiple linear and logistic regressions were used to assess associations.

RESULTS

Study mothers had a mean age of 30.8 y and a mean prepregnancy BMI (kg/m2) of 23.7. In adjusted models, maternal caffeine intake was associated with a higher offspring BMI z-score [β (95% CI): 0.13 (0.06, 0.21) for year 5 and 0.17 (0.04, 0.29) for year 9; per 100 mg/d increment in maternal caffeine intake], WC z-score [β (95% CI): 0.09 (0.01, 0.17) for year 5 and 0.19 (0.05, 0.32) for year 9], and a higher risk of offspring overall obesity [OR (95% CI): 1.32 (1.11, 1.57) for year 5 and 1.44 (1.10, 1.88) for year 9] and central obesity [1.28 (1.02, 1.60) for year 5 and 1.62 (1.12, 2.34) for year 9]. The influence was stronger for coffee caffeine than tea caffeine. No consistent associations were observed for paternal and grandparental caffeine intake.

CONCLUSIONS

Maternal antenatal, but not paternal or grandparental, caffeine intake is associated with higher offspring adiposity and obesity risk at age 5 and 9 y, with stronger associations observed for coffee caffeine. This prospective observational study was registered at the ISRCTN Registry as ISRCTN16537904.

Inverse association between caffeine intake and depressive symptoms in US adults: data from National Health and Nutrition Examination Survey (NHANES) 2005-2006

The objective of this study was to examine the association between caffeine consumption and depressive symptoms. We used data from the 2005-06 National Health and Nutritional Examination Surveys (NHANES). A total of 4737 individuals aged ≥ 18 years who answered the caffeine intake and PHQ-9 questionnaires were selected for this study. Depressive symptoms were assessed using the 9-item Patient Health Questionnaire (PHQ-9) with total scores between 0 and 27. Those with PHQ-9 total scores ≥ 10 were considered as having clinically relevant depression. To investigate the association of caffeine intake and PHQ-9 scores, a multiple logistic regression was used in different models. The overall weighted prevalence of depression was 5.5% (4.3% in men and 6.6% in women). After controlling for potential confounders (age, sex, family PIR, education, marital status, disease history, sleep disorders, thyroid problems, physical activity, social support, smoking, total energy, and cholesterol, retinol, vitamin A, beta-carotene, beta-criptoxanthin, vitamin B1, iron, and phosphorus levels), a significant nonlinear inverse association between caffeine consumption and PHQ-9 scores was observed. In conclusion, caffeine's psychostimulant properties appear to protect against depressive symptoms; however, additional prospective studies are required to ascertain whether or not caffeine consumption can lead to a decrease in depressive symptoms.

Associations of maternal caffeine intake with birth outcomes: results from the Lifeways Cross Generation Cohort Study

Background

Maternal caffeine intake is associated with adverse birth outcomes, but in most studies the primary caffeine source is coffee; the influence of tea caffeine remains unclear.

Objective

The aim of the study was to examine the association between maternal caffeine intake and birth outcomes in a population with tea as the predominant caffeine source.

Design

Data from 941 Irish mother-child pairs of the Lifeways Cross Generation Cohort Study were examined. Maternal dietary intakes in early pregnancy were assessed using a validated food-frequency questionnaire. Caffeine intake was derived from coffee, tea, soft drinks, and cocoa-containing foods and beverages. Associations of maternal caffeine intake with continuous (birth weight, birth length, and gestational age) and binary [low birth weight (LBW) (<2500 g) and preterm birth (PB) (<37 wk gestational age)] birth outcomes were investigated using multiple linear and logistic regressions, respectively, with adjustment for potential confounders.

Results

Tea was the predominant caffeine source (48%), followed by coffee (39%). In the fully adjusted model, maternal caffeine intake was associated with lower birth weight [β (95% CI): -71.9 (-105.4, -38.4) g · 100 mg-1 · d-1 caffeine increment], shorter birth length [-0.30 (-0.49, -0.11) cm], smaller head circumference [-0.12 (-0.24, -0.01) cm], and shorter gestational age [-0.13 (-0.25, -0.02) wk]; higher risks for LBW [OR (95% CI): 1.47 (1.14, 1.90)] and PB [1.36 (1.07, 1.74)] were also observed (all P < 0.05). The associations were robust to the exclusion of participants with pregnancy complications and in never smokers. Similar higher risks of adverse birth outcomes were observed for the highest caffeine intake categories from coffee [ORLBW: 3.10 (1.08, 8.89); ORPB: 2.74 (1.05, 7.16)] and tea [ORLBW: 2.47 (1.02, 6.01); ORPB: 2.56 (1.14, 5.75)], compared with the lowest intake categories (all P < 0.05).

Conclusions

Maternal caffeine intake from both coffee and tea is associated with adverse birth outcomes. This prospective observational study was registered at ISRCTN Registry as ISRCTN16537904.

Associations of Urinary Caffeine and Caffeine Metabolites With Arterial Stiffness in a Large Population-Based Study

OBJECTIVE

To assess the influence of caffeine on arterial stiffness by exploring the association of urinary excretion of caffeine and its related metabolites with pulse pressure (PP) and pulse wave velocity (PWV).

PARTICIPANTS AND METHODS

Families were randomly selected from the general population of 3 Swiss cities from November 25, 2009, through April 4, 2013. Pulse pressure was defined as the difference between the systolic and diastolic blood pressures obtained by 24-hour ambulatory monitoring. Carotid-femoral PWV was determined by applanation tonometry. Urinary caffeine, paraxanthine, theophylline, and theobromine excretions were measured in 24-hour urine collections. Multivariate linear and logistic mixed models were used to explore the associations of quartiles of urinary caffeine and metabolite excretions with PP, high PP, and PWV.

RESULTS

We included 863 participants with a mean ± SD age of 47.1±17.6 years, 24-hour PP of 41.9±9.2 mm Hg, and PWV of 8.0±2.3 m/s. Mean (SE) brachial PP decreased from 43.5 (0.5) to 40.5 (0.6) mm Hg from the lowest to the highest quartiles of 24-hour urinary caffeine excretion (P<.001). The odds ratio (95% CI) of high PP decreased linearly from 1.0 to 0.52 (0.31-0.89), 0.38 (0.22-0.65), and 0.31 (0.18-0.55) from the lowest to the highest quartile of 24-hour urinary caffeine excretion (P<.001). Mean (SE) PWV in the highest caffeine excretion quartile was significantly lower than in the lowest quartile (7.8 [0.1] vs 8.1 [0.1] m/s; P=.03). Similar associations were found for paraxanthine and theophylline, whereas no associations were found with theobromine.

CONCLUSION

Urinary caffeine, paraxanthine, and theophylline excretions were associated with decreased parameters of arterial stiffness, suggesting a protective effect of caffeine intake beyond its blood pressure-lowering effect.

A case-control field study on the relationships among type 2 diabetes, sleepiness and habitual caffeine intake

OBJECTIVES

The purpose of this study was to examine the possible links between type 2 diabetes, daytime sleepiness, sleep quality and caffeine consumption.

METHODS

In this case-control field study, comparing type 2 diabetic ( n=134) and non-type 2 diabetic ( n=230) participants, subjects completed detailed and validated questionnaires to assess demographic status, health, daytime sleepiness, sleep quality and timing, diurnal preference, mistimed circadian rhythms and habitual caffeine intake. All participants gave saliva under standardised conditions for CYP1A2 genotyping and quantification of caffeine concentration. Hierarchical linear regression analyses examined whether type 2 diabetes status was associated with caffeine consumption.

RESULTS

Type 2 diabetic participants reported greater daytime sleepiness ( p=0.001), a higher prevalence of sleep apnoea ( p=0.005) and napping ( p=0.008), and greater habitual caffeine intake ( p<0.001), derived from the consumption of an extra cup of coffee each day. This finding was confirmed by higher saliva caffeine concentration at bedtime ( p=0.01). Multiple regression analyses revealed that type 2 diabetes status was associated with higher self-reported caffeine consumption ( p<0.02) and higher salivary caffeine ( p<0.02). Next to male sex, type 2 diabetes status was the strongest predictor of caffeine intake. Subjective sleep and circadian estimates were similar between case and control groups.

CONCLUSIONS

Type 2 diabetic patients may self-medicate with caffeine to alleviate daytime sleepiness. High caffeine intake reflects a lifestyle factor that may be considered when promoting type 2 diabetes management.

Caffeine Consumption and General Health in Secondary School Children: A Cross-sectional and Longitudinal Analysis

Although caffeine is sometimes associated with beneficial effects in adults, the substance may be dangerous if intake is too high. This concern is particularly relevant in regards to children and adolescents, as consumption of energy drinks may be particularly high in such populations. For this reason, the current study examined data from the Cornish Academies Project to determine whether caffeine intake in secondary school children was related to responses to a single-item measure of general health. Two cross-sections of data were available: questionnaires were completed by 2030 at baseline, by 2307 at 6-month follow-up, and by 1660 at both time-points. Relationships were, therefore, explored both cross-sectionally and longitudinally. High caffeine consumption (i.e., 1000 mg/week) was associated with low general health in both cross-sections of data, and analyses of individual caffeine sources suggested that the effects related specifically to cola and energy drinks. However, after controlling for additional aspects of diet, demography, and lifestyle, total weekly intake only remained significantly associated with general health at the latter time-point. Further to this, null findings from cross-lag and change-score analyses suggest that caffeine and general health were unlikely to be causally linked in this sample. However, due to methodological limitations, such as the two cross-sections of data being collected only 6 months apart, it is suggested that further longitudinal and intervention studies are required in order for firm conclusions to be drawn.

The consumption of coffee and black tea and the risk of lung cancer

PURPOSE

Coffee and black tea are among the most consumed beverages worldwide. Although their potential role in lung cancer occurrence has been investigated in several studies, results have been inconclusive. We investigated the associations between intake of coffee and black tea with lung cancer in a population-based case-control study in Montreal, Canada.

METHODS

These analyses included 1130 cases and 1483 controls. Adjusted odds ratios (ORs) were estimated between four metrics of coffee and black tea consumption (frequency, average daily amount, duration, and cumulative amount) and lung cancer, using unconditional logistic regression.

RESULTS

The adjusted ORs (95% confidence intervals) for lung cancer comparing daily to never consumers were 0.73 (0.49-1.10) for coffee and 1.05 (0.85-1.31) for black tea. Analyses of other metrics did not reveal any clear patterns of increasing or decreasing risk with increasing amounts or duration of consumption. There was no strong evidence of OR modification by sex or smoking level. The OR estimates did not materially differ by histological subtype for either of the beverages.

CONCLUSION

Our results do not provide strong support for associations between consumption of coffee and black tea and lung cancer.

Alcohol, caffeine, and nicotine consumption in adolescents: hair analysis versus self-report

BACKGROUND

Clinical reliability of self-reported data for alcohol, caffeine, and nicotine consumptions is lacking, particularly in adolescents.

OBJECTIVES

To compare a self-report questionnaire and hair analysis to assess the reliability and effectiveness of the self-report.

METHODS

A cross-sectional study on 14-15-year-old Italian students (n = 874, 38% males, 62% females) was performed comparing self-reported data to hair analysis. The latter quantified hair concentrations of caffeine, nicotine, cotinine, ethyl glucuronide (EtG), and fatty acid ethyl esters (FAEEs) using mass spectrometry.

RESULTS

Concordance between self-report and hair testing ranged from good to poor across substances and levels of use: poor for heavy alcohol intake (EtG: k = 0.36, 20 positive cases by hair analysis, false negative by self-report, 2.3% of total sample; FAEE k = 0.31, 25 positive cases, 2.9% of total sample); fair to poor for active smokers (k = 0.40, 125 positive cases, 14.3% of total sample); and moderate for caffeine (k = 0.57, 56 positive cases, 6.4% of total sample).

CONCLUSIONS

Epidemiological studies on alcohol, caffeine, and nicotine consumption in adolescents may benefit from the inclusion of toxicological analysis on hair samples to overcome the under-reporting phenomenon of questionnaires and detect more cases of problematic substance use.

Caffeine consumption and self-assessed stress, anxiety, and depression in secondary school children

Previous research suggests that effects of caffeine on behaviour are positive unless one is investigating sensitive groups or ingestion of large amounts. Children are a potentially sensitive subgroup, and especially so considering the high levels of caffeine currently found in energy drinks. The present study used data from the Cornish Academies Project to investigate associations between caffeine (both its total consumption, and that derived separately from energy drinks, cola, tea, and coffee) and single-item measures of stress, anxiety, and depression, in a large cohort of secondary school children from the South West of England. After adjusting for additional dietary, demographic, and lifestyle covariates, positive associations between total weekly caffeine intake and anxiety and depression remained significant, and the effects differed between males and females. Initially, effects were also observed in relation to caffeine consumed specifically from coffee. However, coffee was found to be the major contributor to high overall caffeine intake, providing explanation as to why effects relating to this source were also apparent. Findings from the current study increase our knowledge regarding associations between caffeine intake and stress, anxiety, and depression in secondary school children, though the cross-sectional nature of the research made it impossible to infer causality.

Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose-response meta-analysis of prospective studies

OBJECTIVE

To assess the association between maternal caffeine intake and risk of pregnancy loss using a systematic review and meta-analysis.

DESIGN

Categorical and dose-response meta-analysis of prospective studies.

SETTING

Relevant articles were identified by searching MEDLINE and SCOPUS databases through 30 January 2015. Two authors independently extracted information from eligible studies. Random-effects models were used to derive the summary relative risks (RR) and corresponding 95% CI for specific categories of caffeine consumption and for a continuous association using generalized least-squares trend estimation.

SUBJECTS

A total of 130 456 participants and 3429 cases in fourteen included studies.

RESULTS

Compared with the reference category with no or very low caffeine intake, the RR (95% CI) of pregnancy loss was 1·02 (0·85, 1·24; I(2)=28·3%) for low intake (50-149 mg/d), 1·16 (0·94, 1·41; I 2=49·6%) for moderate intake (150-349 mg/d), 1·40 (1·16, 1·68; I(2)=18·6%) for high intake (350-699 mg/d) and 1·72 (1·40, 2·13; I(2)=0·0%) for very high intake (≥ 700 mg/d). In the dose-response analysis, each 100 mg/d increment in maternal caffeine intake (~1 cup of coffee) was associated with 7% (95% CI 3%, 12%) higher risk of pregnancy loss. Our results may have been affected by publication bias, but the association remained significant for the subset of larger studies. Furthermore, adjustment for smoking and pregnancy symptoms may have been incomplete, potentially resulting in residual confounding.

CONCLUSIONS

Albeit inconclusive, higher maternal caffeine intake was associated with a higher risk of pregnancy loss and adherence to guidelines to avoid high caffeine intake during pregnancy appears prudent.

Maternal caffeine intake during pregnancy is associated with risk of low birth weight: a systematic review and dose-response meta-analysis

BACKGROUND

Considerable controversy exists regarding the relation between maternal caffeine intake during pregnancy and risk of low birth weight (birth weight <2,500 g). We aim to assess this association using a systematic review and dose-response meta-analysis of prospective studies.

METHODS

Potential articles were identified by searching MEDLINE and SCOPUS databases through 17 July 2013. Two authors independently extracted information on study design, participant characteristics and estimates of associations. Random-effects models were used to derive the summary relative risks (RRs) and corresponding 95% confidence intervals (CIs). Dose-response relationships were assessed using generalized least-squares trend estimation.

RESULTS

In our meta-analysis, we included 13 prospective studies: 9 with low birth weight as a binary outcome variable (90,747 participants and 6,303 cases) and 6 with birth weight as a continuous outcome variable (10,015 participants; 2 studies reported both types of outcomes). Compared with the reference category with no or very low caffeine intake, the RR (95% CI) of low birth weight was 1.13 (1.06 to 1.21; I 2 0.0%) for low intake (50 to 149 mg/day), 1.38 (1.18 to 1.62; I 2 31.9%) for moderate intake (150 to 349 mg/day), and 1.60 (1.24 to 2.08; I 2 65.8%) for high intake (≥350 mg/day). In the dose-response analysis, each 100-mg/day increment in maternal caffeine intake (around one cup of coffee) was associated with 13% (RR 1.13, 1.06 to 1.21) higher risk of low birth weight. The association persisted in strata defined according to various study characteristics. Moderate (-33 g, 95% CI -63 to -4; I 2 0.3%) and high (-69 g, 95% CI -102 to -35; I 2 0.0%) caffeine intakes were also associated with a significantly lower birth weight as compared with the reference category.

CONCLUSIONS

Higher maternal caffeine intake during pregnancy was associated with a higher risk of delivering low birth weight infants. These findings support recommendations to restrict caffeine intake during pregnancy to low levels.

Determination of the caffeine contents of various food items within the Austrian market and validation of a caffeine assessment tool (CAT)

The caffeine content of 124 products, including coffee, coffee-based beverages, energy drinks, tea, colas, yoghurt and chocolate, were determined using RP-HPLC with UV detection after solid-phase extraction. Highest concentrations of caffeine were found for coffee prepared from pads (755 mg l⁻¹) and regular filtered coffee (659 mg l⁻¹). The total caffeine content of coffee and chocolate-based beverages was between 15 mg l⁻¹ in chocolate milk and 448 mg l⁻¹ in canned ice coffee. For energy drinks the caffeine content varied in a range from 266 to 340 mg l⁻¹. Caffeine concentrations in tea and ice teas were between 13 and 183 mg l⁻¹. Coffee-flavoured yoghurts ranged from 33 to 48 mg kg⁻¹. The caffeine concentration in chocolate and chocolate bars was between 17 mg kg⁻¹ in whole milk chocolate and 551 mg kg⁻¹ in a chocolate with coffee filling. A caffeine assessment tool was developed and validated by a 3-day dietary record (r²= 0.817, p < 0.01) using these analytical data and caffeine saliva concentrations (r²= 0.427, p < 0.01).

Pilot Study of Caffeine Abstinence for Control of Chronic Glucose in Type 2 Diabetes

BACKGROUND: A growing body of evidence suggests that caffeinated beverages may impair chronic glucose control in type 2 diabetes. This pilot study tested the chronic effects of caffeine abstinence on glucose control in type 2 diabetic patients who were daily coffee drinkers. METHODS: Twelve coffee drinkers (six males) with established type 2 diabetes participated. Seven (five males) completed 3 months of total caffeine abstinence. Measures of chronic glucose control, long-term (hemoglobin A1c [HbA1c]) and short-term (1,5-anhydroglucitol [1,5-AG]), were collected at baseline and during follow-up. Abstinence was established by diaries confirmed by saliva caffeine assays. RESULTS: Abstinence produced significant decreases in HbA1c and increases in 1,5-AG, both indicating improvements in chronic glucose control. Fasting glucose and insulin did not change, nor were changes in body weight observed. CONCLUSIONS: Although preliminary, these results suggest that caffeine abstinence may be beneficial for patients with type 2 diabetes. This hypothesis should be confirmed in larger controlled clinical trials.

Greater coffee intake in men is associated with steeper age-related increases in blood pressure

BACKGROUND

Administration of caffeine or caffeinated coffee in laboratory and ambulatory settings results in small to moderate acute increases in blood pressure (BP). However, habitual coffee intake has not been linked conclusively to long-term increases in basal BP, and findings are inconsistent by sex. This study examined longitudinal relations of habitual coffee use to resting BP and pulse pressure.

METHODS

In a sample of 2,442 participants from the Baltimore Longitudinal Study of Aging (BLSA), coffee consumption was used to predict resting systolic and diastolic BP and pulse pressure using longitudinal mixed-effects regression models adjusted for age, education, antihypertensive, and antihyperlipidemic use, smoking, and body mass index (BMI). Analyses were stratified by sex (865 women and 1,577 men), and age and BMI were examined as possible effect modifiers.

RESULTS

In men, we identified a significant three-way interaction among coffee intake (nonlinear), baseline age, and length of follow-up for systolic BP (SBP) and pulse pressure. A significant interaction of coffee intake and BMI (nonlinear) was also noted for SBP in men. There were no significant relations of coffee intake to BP or pulse pressure in women.

CONCLUSION

Greater coffee intake in men was associated with steeper age-related increases in SBP and pulse pressure, particularly beyond 70 years of age and in overweight to obese men.

Coffee consumption and CYP1A2 genotype in relation to bone mineral density of the proximal femur in elderly men and women: a cohort study

Background

Drinking coffee has been linked to reduced calcium conservation, but it is less clear whether it leads to sustained bone mineral loss and if individual predisposition for caffeine metabolism might be important in this context. Therefore, the relation between consumption of coffee and bone mineral density (BMD) at the proximal femur in men and women was studied, taking into account, for the first time, genotypes for cytochrome P450 1A2 (CYP1A2) associated with metabolism of caffeine.

Methods

Dietary intakes of 359 men and 358 women (aged 72 years), participants of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), were assessed by a 7-day food diary. Two years later, BMD for total proximal femur, femoral neck and trochanteric regions of the proximal femur were measured by Dual-energy X-ray absorptiometry (DXA). Genotypes of CYP1A2 were determined. Adjusted means of BMD for each category of coffee consumption were calculated.

Results

Men consuming 4 cups of coffee or more per day had 4% lower BMD at the proximal femur (p = 0.04) compared with low or non-consumers of coffee. This difference was not observed in women. In high consumers of coffee, those with rapid metabolism of caffeine (C/C genotype) had lower BMD at the femoral neck (p = 0.01) and at the trochanter (p = 0.03) than slow metabolizers (T/T and C/T genotypes). Calcium intake did not modify the relation between coffee and BMD.

Conclusion

High consumption of coffee seems to contribute to a reduction in BMD of the proximal femur in elderly men, but not in women. BMD was lower in high consumers of coffee with rapid metabolism of caffeine, suggesting that rapid metabolizers of caffeine may constitute a risk group for bone loss induced by coffee.

Methodological considerations for the quantification of self-reported caffeine use

RATIONALE

The field of research regarding the effects of habitual caffeine use is immense and frequently utilizes self-report measures of caffeine use. However, various self-report measures have different methodologies, and the accuracy of these different methods has not been compared.

MATERIALS AND METHODS

Self-reported caffeine use was estimated from two methods (a retrospective interview of weekly caffeine use and a 7-day prospective diary; n = 79). These estimates were then tested against salivary caffeine concentrations in a subset of participants (n = 55).

RESULTS

The estimates of caffeine use (mg/day) from the interview- and diary-based methods correlated with one another (r = 0.77) and with salivary caffeine concentrations (r = 0.61 and 0.68, respectively). However, almost half of the subjects who reported more than 600 mg/day in the interview reported significantly less caffeine use in the diary.

CONCLUSIONS

Self-report measures of caffeine use are a valid method of predicting actual caffeine levels. Estimates of high caffeine use levels may need to be corroborated by more than one method.

Assessing caffeine exposure in pregnant women

Studies on the effects of caffeine on health, while numerous, have produced inconsistent results. One of the most uncertain and controversial effects is on pregnancy outcome. Studies have produced conflicting results due to a number of methodological variations. The major challenge is the accurate assessment of caffeine intake. The aim of the present study was to explore different methods of assessing caffeine exposure in pregnant women. Twenty-four healthy pregnant women from the UK city of Leeds completed both a detailed questionnaire, the caffeine assessment tool (CAT) designed specifically to assess caffeine intake and a prospective 3 d food and drink diary. The women also provided nine saliva samples over two consecutive days for estimation of caffeine and a metabolite (paraxanthine). Caffeine intakes from the CAT and diary showed adequate agreement (intra-class correlation coefficient of 0·5). For saliva caffeine and paraxanthine measures, the between-sample variation (within the same woman) was greater than between-woman and between-day variation. However, there was still adequate agreement between these measures and the CAT. The CAT is a valuable tool that is now being used in a large prospective study investigating caffeine's role in pregnancy outcome.

Effect of Caffeine on Leg Muscle Pain during Cycling Exercise among Females

PURPOSE

This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain during moderate-intensity cycling exercise among females.

METHODS

Low-caffeine-consuming college-aged females (N = 11) ingested one of two doses of caffeine (5 or 10 mg x kg(-1) body weight) or a placebo and 1 h later completed 30 min of cycling on an ergometer at approximately 60% VO2peak. The conditions were completed in a counterbalanced order. Perceptions of leg muscle pain as well as power output, heart rate, systolic blood pressure, and oxygen consumption (VO2) were recorded during exercise.

RESULTS

Caffeine had a significant effect on leg muscle pain ratings [F (2,20) = 10.63, P = 0.001, n2 = 0.52]. The mean pain intensity scores during exercise after ingesting 10 mg x kg(-1) body weight caffeine, 5 mg x kg(-1) body weight caffeine, and placebo were 1.6 +/- 1.1, 1.3 +/- 0.7, and 2.4 +/- 1.1, respectively.

CONCLUSION

The results support that caffeine ingestion has a large effect on reducing leg muscle pain during exercise among females, but this effect does not appear to be dose-dependent between 5 and 10 mg.kg body weight caffeine.

Psychophysiological effects of habitual caffeine consumption

Caffeine is the most widely consumed pharmacologically active substance in the world, and a key issue concerning its possible implications for human health is whether it has persistent (i.e., chronic) physiological effects on habitual consumers. This study examined blood pressure, heart rate (HR), electromyogram (EMG), and skin conductance level (SCL) in 36 healthy men and women exposed to a pattern of moderate intake. A double-blind placebo-controlled crossover design with counterbalancing was used in which all subjects participated in four experimental conditions involving the ingestion of placebo or caffeine three times daily for 6 days followed by a seventh ("challenge") day of placebo or caffeine ingestion. Results confirmed that caffeine has significant pressor effects, and these were found to he additive to the pressor action of a laboratory stressor. Following habitual consumption of the drug. pressor effects were diminished (indicative of tolerance) but not eliminated. Effects of caffeine on other parameters were either modest (HR and EMG) or negligible (SCL). Considering (he near-universal use of caffeine. the persistent pressor effects observed in this study have important implications for clinical practice and public health.

Dietary caffeine, performance and mood: enhancing and restorative effects after controlling for withdrawal reversal

This study aimed to determine whether sustained (i.e. dietary) use of caffeine has net effects on performance and mood compared with sustained abstinence, and whether dietary caffeine restores performance and mood adversely affected by sleep restriction. Participants (n = 96) alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while either rested or sleep restricted. Performance involved either a single task requiring sustained vigilance or a varied battery of brief psychomotor and cognitive tasks, and mood was assessed using the Profile of Mood States. Caffeine had no significant net enhancing effects for either performance or mood when participants were rested, and produced no net restorative effects when performance and mood were degraded by sleep restriction.

Hemodynamic effects of dietary caffeine, sleep restriction, and laboratory stress

This study examined the separate and interactive effects of caffeine, sleep restriction, and task-induced laboratory stress in 96 healthy male and female volunteers. Participants alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while being either rested or sleep restricted. Finapres measurements of blood pressure, cardiac output, and total peripheral resistance showed that caffeine produced persistent blood pressure increases with a vascular hemodynamic profile. Sleep restriction produced a pronounced vascular response not associated with appreciable changes in blood pressure, whereas blood pressure increases induced by cognitive activity showed mixed cardiac and vascular responses. The findings suggest that life-long dietary caffeine may contribute significantly to the development of cardiovascular disease.

Effects of dietary caffeine on mood when rested and sleep restricted

Prolonged use of caffeine can lead to physical dependence evidenced by characteristic withdrawal symptoms during abstinence. Debate exists as to whether mood enhancement by caffeine represents a net effect or merely the restoration of abstinence-induced mood decrements. One aim of this study was to determine the net effects on mood of dietary caffeine compared with prolonged abstinence. In addition, the study aimed to determine whether caffeine restores mood degraded by a non-caffeine source, namely, sleep restriction. A double-blind placebo-controlled cross-over design was employed in which 48 male and female volunteers alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while being either rested or sleep restricted. Mood was assessed using a computerized version of the profile of mood states (POMS), giving scores for overall mood and six mood dimensions. Gender had small effects on mood, whereas all mood dimensions were markedly adversely affected by sleep restriction. Caffeine had no significant net enhancing effects on mood when participants were rested, and produced no net restorative effects when mood was degraded by sleep restriction. On the contrary, caffeine-induced decrements in mood were observed during both conditions of rest and sleep restriction.

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure

This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain and blood pressure during moderate intensity cycling exercise. Low caffeine consuming college-aged males (N=12) ingested one of two doses of caffeine (5 or 10 mg.kg(-1) body weight) or placebo and 1 h later completed 30 min of moderate intensity cycling exercise (60% VO2peak). The order of drug administration was counter-balanced. Resting blood pressure and heart rate were recorded immediately before and 1 h after drug administration. Perceptions of leg muscle pain as well as work rate, blood pressure, heart rate, and oxygen uptake (VO2) were recorded during exercise. Caffeine increased resting systolic pressure in a dose-dependent fashion but these blood pressure effects were not maintained during exercise. Caffeine had a significant linear effect on leg muscle pain ratings [F(2,22)=14.06; P < 0.0001; eta2=0.56 ]. The mean (+/-SD) pain intensity scores during exercise after ingesting 10 mg.kg(-1) body weight caffeine, 5 mg.kg(-1) body weight caffeine, and placebo were 2.1+/-1.4, 2.6+/-1.5, and 3.5+/-1.7, respectively. The results support the conclusion that caffeine ingestion has a dose-response effect on reducing leg muscle pain during exercise and that these effects do not depend on caffeine-induced increases in systolic blood pressure during exercise.

Effects of acute exercise on the soleus H-reflex and self-reported anxiety after caffeine ingestion

The effects of moderate intensity cycling exercise on the soleus H-reflex and state anxiety were examined among 16 individuals whose anxiety was experimentally manipulated by consumption of a large dose of caffeine. The soleus H-reflex and state anxiety were measured before and 1 h after consuming caffeine or placebo and then again 10 min after 30 min of either cycling at an intensity of 60% VO(2peak) or quiet rest. We found that (1) caffeine consumption did not influence the amplitude of the soleus H-reflex, but it did increase state anxiety; (2) acute exercise reduced the soleus H-reflex after consumption of either caffeine or placebo, but it reduced state anxiety only after consumption of caffeine; and (3) there was no evidence of a relationship between changes in the soleus H-reflex and state anxiety. Exercise-induced anxiolysis does not appear to underlie the postexercise reduction of the soleus H-reflex.

Effect of caffeine on perceptions of leg muscle pain during moderate intensity cycling exercise

This double-blind, within-subjects experiment examined the effect of ingesting a large dose of caffeine on perceptions of leg muscle pain during moderate intensity cycling exercise. Low-caffeine-consuming college-aged males (n = 16) ingested either caffeine (10 mg x kg(-1) body weight) or placebo and 1 hour later completed 30 minutes of moderate intensity cycling exercise (60% VO(2peak)). The order of drug administration was counter-balanced. Perceptions of leg muscle pain as well as work rate, heart rate, and oxygen uptake (VO(2)) were recorded during exercise. Leg muscle pain ratings were significantly and moderately reduced after a high dose of caffeine. This observation suggests that prior reports showing caffeine improves endurance exercise performance might be partially explained by caffeine's hypoalgesic properties. It also suggests that moderate intensity cycling exercise has promise as a useful experimental model for the study of naturally occurring muscle pain.

The relationship between hostility and behavioral risk factors for poor health in women veterans

BACKGROUND

While previous research has generally supported a relationship between hostility and health risk behaviors, the majority of this research has been conducted in predominately male, highly educated, Caucasian samples. The current study was designed to further examine the relationship between hostility and health risk behaviors in a sample of women.

METHODS

Measures of health risk behavior and scores from the Cook-Medley hostility scale were obtained from 409 women veterans. Linear and logistic regression analyses were used to examine the relationship between hostility and health behaviors including tobacco smoking, alcohol use, body-mass index, caffeine use, and level of physical activity, after sociodemographic factors were accounted for.

RESULTS

In a cohort of women veterans using VA health care, ages 35-81, hostility was significantly associated with tobacco smoking (OR = 2.10; 95% CI = 1.34 to 3.30), caffeine use (OR = 2.12; 95% CI = 1.16 to 3.85), and the number of alcoholic beverages consumed by women who drink alcohol. Hostility was not associated with body mass index (OR = 1.15; 95% CI = 0.77 to 1.72) or a lack of physical exercise (OR = 0.89; 95% CI = 0.55 to 1.43).

CONCLUSIONS

Results are generally consistent with previous research and support the relationship between hostility and health risk behaviors. Awareness that hostility contributes to risk behaviors and disease may help in the design of interventions aimed at risk reduction.

Association between coffee drinking and K-ras mutations in exocrine pancreatic cancer. PANKRAS II Study Group

STUDY OBJECTIVE

To analyse the relation between coffee consumption and mutations in the K-ras gene in exocrine pancreatic cancer.

DESIGN

Case-case study. Consumption of coffee among cases with the activating mutation in the K-ras gene was compared with that of cases without the mutation.

SETTING AND PATIENTS

All cases of pancreatic cancer newly diagnosed at five hospitals in Spain during three years were included in the PANKRAS II Study (n = 185, of whom 121 whose tissue was available for molecular analysis are the object of the present report). Over 88% were personally interviewed in hospital. DNA was amplified from paraffin wax embedded tissues, and mutations in codon 12 of K-ras were detected by the artificial RFLP technique.

MAIN RESULTS

Mutations were found in tumours from 94 of 121 patients (77.7%). Mutations were more common among regular coffee drinkers than among non-regular coffee drinkers (82.0% v 55.6%, p = 0.018, n = 107). The odds ratio adjusted by age, sex, smoking and alcohol drinking was 5.41 (95% CI 1.64, 17.78). The weekly intake of coffee was significantly higher among patients with a mutated tumour (mean of 14.5 cups/week v 8.8 among patients with a wild type tumour, p < 0.05). With respect to non-regular coffee drinkers, the odds ratio of a mutated tumour adjusted by age, sex, smoking and alcohol drinking was 3.26 for drinkers of 2-7 cups/week, 5.77 for drinkers of 8-14 cups/week and 9.99 for drinkers of > or = 15 cups/week (p < 0.01, test for trend).

CONCLUSIONS

Pancreatic cancer cases without activating mutations in the K-ras gene had drank significantly less coffee than cases with a mutation, with a significant dose response relation: the less they drank, the less likely their tumours were to harbour a mutation. In exocrine pancreatic cancer the K-ras gene may be activated less often among non-regular coffee drinkers than among regular drinkers. Caffeine, other coffee compounds or other factors with which coffee drinking is associated may modulate K-ras activation.

Hemodynamic profile of stress-induced anticipation and recovery

Systolic and diastolic blood pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance were measured in 100 healthy men and women with the aim of investigating hemodynamic profile during anticipation of, and recovery from, exposure to active and passive laboratory stressors. A 5-min anticipatory period preceded two tasks, both of which lasted 2.5 min. The tasks were mental arithmetic ('beta-adrenergic' stress) and the cold pressor test ('alpha-adrenergic' stress). Each task was followed by a 5-min recovery period. Blood pressure and heart rate were measured with a FinaPres 2300e, and stroke volume, cardiac output, and total peripheral resistance were computed from these parameters. Salivary cortisol was measured in relation to both tasks, and participants completed tests of state and trait anxiety, locus of control, and hostility. As expected, mental arithmetic and the cold pressor test elicited myocardial and vascular patterns of reactivity, respectively. However, contrary to expectations, anticipatory and recovery hemodynamic profile involved essentially vascular responding for both stressors. Salivary cortisol increased in response to both tasks but only weakly correlated with hemodynamic changes. None of the subjective measurements was a strong predictor of physiological reactivity. The findings suggest that stress-induced anticipatory and recovery reactivity may be generally vascular rather than myocardial. This could have important implications in light of suggestions that anticipatory and recovery responses may be better predictors of subsequent cardiovascular disease than direct stress-induced reactivity.

Caffeine intake, tolerance, and withdrawal in women: a population-based twin study

OBJECTIVE

Caffeine is by far the most commonly consumed psychoactive substance. The use and abuse of most other licit and illicit psychoactive drugs have been shown to be substantially heritable. However, the impact of genetic factors on caffeine consumption, heavy use, intoxication, tolerance, and withdrawal is largely unknown.

METHOD

Caffeine consumption, in the form of brewed coffee, instant coffee, tea, and caffeinated soft drinks, as well as caffeine intoxication, tolerance, and withdrawal, were assessed by personal interviews of 1,934 individual twins from female-female pairs ascertained from the population-based Virginia Twin Registry. The sample included both members of 486 monozygotic and 335 dizygotic pairs. Twin resemblance was assessed by probandwise concordance, odds ratios, and tetrachoric correlations. Biometrical model fitting was also performed.

RESULTS

The resemblance in twin pairs for total caffeine consumption, heavy caffeine use, caffeine intoxication, caffeine tolerance, and caffeine withdrawal was substantially greater in monozygotic than in dizygotic twin pairs. Model fitting suggested that twin resemblance for these measures could be ascribed solely to genetic factors, with estimated broad heritabilities of between 35% and 77%.

CONCLUSIONS

Caffeine is an addictive psychoactive substance. Similar to previous findings with other licit and illicit psychoactive drugs, individual differences in caffeine use, intoxication, tolerance, and withdrawal are substantially influenced by genetic factors.

Serum caffeine and paraxanthine as markers for reported caffeine intake in pregnancy

PURPOSE

Previous studies of maternal caffeine use and pregnancy outcome have relied on self-reported use. Even if these were perfectly accurate, inter-individual differences in caffeine metabolism result in a relatively weak correlation between caffeine intake and serum concentration. The purpose of this study was to determine whether the serum concentration of caffeine or its primary metabolite, paraxanthine, obtained at an unknown time during working hours, is useful to distinguish between pregnant women who report consuming small and large amounts of caffeine.

METHODS

We selected from the Birmingham fetal growth study 60 women with normal pregnancy outcomes who reported consuming < or = 0.8 mg/kg/day of caffeine in a 24-hour dietary recall, 60 who consumed 0.81-2.5 mg/kg/day, 60 who consumed 2.51-5.0 mg/kg/day and 59 who consumed > or = 5.01 mg/kg/day. These women had serum drawn for storage during regular clinic hours on the same day as the recall interview. Caffeine and paraxanthine were measured in the stored serum using high performance liquid chromatography.

RESULTS

The weighted kappa coefficient between strata of caffeine intake and quartiles of serum paraxanthine was 0.58 among smokers and 0.53 among nonsmokers, versus 0.44 and 0.51, respectively, for quartiles of serum caffeine. The Pearson correlation coefficient between intake and paraxanthine was 0.50 for smokers and 0.53 for nonsmokers, and 0.37 and 0.51, respectively, for serum caffeine. These values are comparable to the correlation between reported smoking and serum cotinine in pregnancy.

CONCLUSIONS

The serum concentrations of paraxanthine, and to a lesser degree, caffeine are useful to distinguish between women with varying levels of caffeine intake.

The impact of caffeine use on tobacco cessation and withdrawal

Continuous caffeine consumption with smoking cessation has been associated with more than doubled caffeine plasma levels. Such concentrations may be sufficient to produce caffeine toxicity symptoms in smoking abstinence conditions. To test whether caffeine abstinence influences smoking cessation, 162 caffeine-using smokers were enlisted from American Lung Association smoking cessation programs. Volunteers were randomly assigned by clinic to caffeine-use and caffeine-abstinence conditions and measured for 3 weeks post-smoking cessation, at 6 months and one year. Results showed a significant linear increase in caffeine sputum levels across 3 weeks post cessation for those who quit smoking and continued using caffeine. Three weeks after cessation, concentrations reached 203% of baseline for the caffeine user. Typical nicotine withdrawal symptoms occurred during the first 16 days of cessation. The caffeine abstainers, but not continued users of caffeine, reported increased fatigue during the first 3 days of cessation. Among complete caffeine abstainers, compared with caffeine users, there was a significant increase in fatigue, a decrease in stimulation, and a marginal increase in caffeine craving immediately following tobacco cessation. There were no differences between the groups on other withdrawal symptoms or in cessation success at 16 days, 6 months, or 12 months.

Bone mineral density and hormone levels in menopausal Australian women

To assess the relationships between bone mineral density (BMD) at the lumbar spine and femoral neck and menopausal status, age, physical variables, and lifestyle and gynecological factors. BMD and follicle-stimulating hormone (FSH), estradiol and inhibin levels were measured in 167 women born in Australia, aged 46-57 years, who had no record of receiving hormone replacement therapy. Using the premenopausal group as a baseline, the FSH level was higher in peri- and postmenopausal subjects (p < 0.0005), and estradiol and inhibin levels in the postmenopausal women were lower (p < 0.0005). Mean (+/- SE) lumbar spine and femoral neck BMD were 15 +/- 3% and 10 +/- 3% lower, respectively, in postmenopausal than in premenopausal women. Lumbar spine BMD decreased with increasing age in perimenopausal women only (p < 0.005), and femoral neck BMD decreased with increasing age in the pre-, peri-(p < 0.05) and postmenopausal women. The difference between femoral neck BMD in the pre- and postmenopausal women was explained by the difference in age between these groups, whereas for lumbar spine BMD the menopausal status was an additional determining factor. There was a negative effect of smoking on femoral neck BMD (p < 0.05) in postmenopausal women. In the perimenopausal decade the femoral neck BMD is primarily dependent on age, whereas lumbar spine BMD is dependent on both age and menopausal status.

Effects of caffeine deprivation on complex human functioning

Twenty-five managers who reported an average daily caffeine consumption of 575 mg participated in two complex simulations. A double-blind cross-over design was employed to assess the effects of normal caffeine consumption versus caffeine deprivation upon seven validated measures of managerial effectiveness. Data from a Caffeine Withdrawal Questionnaire indicated discomfort upon deprivation. Systolic blood pressure increased during "normal" caffeine consumption levels but fell quickly and remained lower during deprivation. Several measures of managerial performance indicated decreased effectiveness upon caffeine deprivation. In contrast to prior research from simpler task settings, cognitive effectiveness (during complex task performance) was diminished. However, a measure of strategic performance which requires a relatively high level of cognitive effort showed no impact of caffeine deprivation.

Caffeinated coffee and tea intake and its relationship to cigarette smoking: an analysis of the Second National Health and Nutrition Examination Survey (NHANES II)

Recent studies have shown that smokers' intake of caffeine is higher than nonsmokers. This investigation evaluated the relationships between smoking status and self-reported caffeine intake from both coffee and tea. Subjects were adults who participated in the Second National Health and Nutrition Examination Survey (NHANES II). Results indicated that subjects who ingested caffeine from tea were more likely to be female, less educated, younger, non-Caucasian, and lighter drinkers. In contrast, those who ingested caffeine from coffee were more likely to be older, Caucasian, heavier drinkers, and have higher incomes. Smokers were not more likely to drink caffeinated tea. In contrast, smokers were much more likely to drink caffeinated coffee, and a dose-response relationship between caffeine from coffee and smoking intake was observed. These results clarify the relationship between smoking and caffeine intake. Implications for intervention efforts are discussed.

Nicotine and caffeine use in cocaine-dependent individuals

Nicotine and caffeine use in 87 cocaine-dependent persons seeking treatment at an outpatient clinic were compared to use of those substances in a matched general population sample (n = 78). The prevalence of cigarette smoking was significantly greater in the cocaine-dependent sample (75% vs. 22%). Within the cocaine-dependent sample, smokers were younger, less educated, employed in lesser skilled jobs, and reported an earlier onset and more frequent use of cocaine. The prevalence of caffeine use was significantly less in the cocaine-dependent group (68% vs. 83%), although, among caffeine users, the cocaine group drank significantly more caffeinated beverages per day than matched controls (4.9 vs. 3.3). Interestingly, regular caffeine use was associated with less frequent cocaine use within the cocaine-dependent sample. To our knowledge, this study is the first to report on prevalence of smoking and caffeine use among cocaine-dependent individuals, and suggests that use of these other substances may influence the onset and pattern of cocaine use.

Validity of self-reports of caffeine use

The relationship between self-reports of caffeine ingestion on two occasions and measured plasma concentrations of caffeine and its major metabolites was examined. A subject population [25 men and 25 women, age 20-45 years (mean: 28.7 yr)] that was enrolled in a benzodiazepine pharmacokinetic study underwent general medical screening on two occasions, each including detailed caffeine histories. Before beginning their scheduled study, plasma samples were obtained and evaluated by HPLC for caffeine, paraxanthine, theophylline, and theobromine. These values were compared with estimates of caffeine consumption in mg/day generated from both histories. There was no significant difference between plasma levels of caffeine, metabolites, or caffeine plus metabolites for categories corresponding to reports of low, intermediate or high caffeine use. A self-reported caffeine consumption of greater than 300 mg/day (high) did correlate, however, with a significant smoking history. The authors conclude that self-reports of caffeine ingestion do not accurately reflect acute exposure, and that if caffeine use is of importance in a given setting, reports should be confirmed by biochemical means.