The adjustment of sleep-wake patterns and the circadian temperature rhythm was monitored in nine Royal Norwegian Air-force volunteers operating P-3 aircraft during a westward training deployment across nine time zones. Subjects recorded all sleep and nap times, rated nightly sleep quality, and completed personality inventories. Rectal temperature, heart rate, and wrist activity were continuously monitored. Adjustment was slower after the return eastward flight than after the outbound westward flight. The eastward flight produced slower readjustment of sleep timing to local time and greater interindividual variability in the patterns of adjustment of sleep and temperature. One subject apparently exhibited resynchronization by partition, with the temperature rhythm undergoing the reciprocal 15-h delay. In contrast, average heart rates during sleep were significantly elevated only after westward flight. Interindividual differences in adjustment of the temperature rhythm were correlated with some of the personality measures. Larger phase delays in the overall temperature waveform (as measured on the 5th day after westward flight) were exhibited by extraverts, and less consistently by evening types.
Shift work is associated with negative health effects. Increased prevalence of several cardiovascular risk factors among shift workers/night workers compared with day workers have been shown resulting in increased risk of cardiovascular events among shift workers and night workers. Previous studies have taken a dichotomous approach to the comparison between day and night workers. The present study uses a continuous approach and provides such a new perspective to the negative effects of night work load as a possible risk factor for undesirable health effects.
This cross sectional study (The SUrvey of Shift work, Sleep and Health (SUSSH)) uses data collected from December 2008 to March 2009. The study population consists of Norwegian nurses. The study collected information about demographic and lifestyle factors: Body Mass Index (BMI), smoking habits, alcohol consumption, caffeine consumption and exercise habits. The lifestyle parameters were evaluated using multiple hierarchical regression and binary logistic regression. Number of night shifts worked last year (NNL) was used as operationalization of night work load. Adjustment for possible confounders were made. Obesity was defined as BMI > 30. Alcohol Consumption was evaluated using the short form of the Alcohol Use Disorders Identification Test Consumption (AUDIT-C). Data were analyzed using SPSS version 22.
We had data from 2059 nurses. NNL was significantly and positively associated with BMI, both when evaluated against BMI as a continuous parameter (Beta = .055, p
Throughout childhood there is a shift from predominantly milk-based beverage consumption to other types of beverages, including those containing caffeine. Although a variety of health effects in children and adults have been attributed to caffeine, few data exist on caffeine intake in children aged one to five years.
Because beverages provide about 80% of total caffeine consumed in children of this age group, beverage consumption patterns and caffeine intakes were evaluated from two beverage marketing surveys: the 2001 Canadian Facts study and the 1999 United States Share of Intake Panel study.
Considerably fewer Canadian children than American children consume caffeinated beverages (36% versus 56%); Canadian children consume approximately half the amount of caffeine (7 versus 14 mg/day in American children). Differences were largely because of higher intakes of carbonated soft drinks in the US.
Caffeine intakes from caffeinated beverages remain well within safe levels for consumption by young children.
BACKGROUND: It is not known whether the consumption of caffeine is associated with excess risk of atrial fibrillation. OBJECTIVE: We evaluated the risk of atrial fibrillation or flutter in association with daily consumption of caffeine from coffee, tea, cola, cocoa, and chocolate. DESIGN: 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. RESULTS: 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. CONCLUSION: Consumption of caffeine was not associated with risk of atrial fibrillation or flutter.
Comment In: Am J Clin Nutr. 2005 Mar;81(3):539-4015755819
Scientific literature cites a wide range of values for caffeine content in food products. The authors suggest the following standard values for the United States: coffee (5 oz) 85 mg for ground roasted coffee, 60 mg for instant and 3 mg for decaffeinated; tea (5 oz): 30 mg for leaf/bag and 20 mg for instant; colas: 18 mg/6 oz serving; cocoa/hot chocolate: 4 mg/5 oz; chocolate milk: 4 mg/6 oz; chocolate candy: 1.5-6.0 mg/oz. Some products from the United Kingdom and Denmark have higher caffeine content. Caffeine consumption survey data are limited. Based on product usage and available consumption data, the authors suggest a mean daily caffeine intake for US consumers of 4 mg/kg. Among children younger than 18 years of age who are consumers of caffeine-containing foods, the mean daily caffeine intake is about 1 mg/kg. Both adults and children in Denmark and UK have higher levels of caffeine intake.
BACKGROUND: Some epidemiologic studies have suggested that the ingestion of caffeine increases the risk of spontaneous abortion, but the results have been inconsistent. METHODS: We performed a population-based, case-control study of early spontaneous abortion in Uppsala County, Sweden. The subjects were 562 women who had spontaneous abortion at 6 to 12 completed weeks of gestation (the case patients) and 953 women who did not have spontaneous abortion and were matched to the case patients according to the week of gestation (controls). Information on the ingestion of caffeine was obtained from in-person interviews. Plasma cotinine was measured as an indicator of cigarette smoking, and fetal karyotypes were determined from tissue samples. Multivariate analysis was used to estimate the relative risks associated with caffeine ingestion after adjustment for smoking and symptoms of pregnancy such as nausea, vomiting, and tiredness. RESULTS: Among nonsmokers, more spontaneous abortions occurred in women who ingested at least 100 mg of caffeine per day than in women who ingested less than 100 mg per day, with the increase in risk related to the amount ingested (100 to 299 mg per day: odds ratio, 1.3; 95 percent confidence interval, 0.9 to 1.8; 300 to 499 mg per day: odds ratio, 1.4; 95 percent confidence interval, 0.9 to 2.0; and 500 mg or more per day: odds ratio, 2.2; 95 percent confidence interval, 1.3 to 3.8). Among smokers, caffeine ingestion was not associated with an excess risk of spontaneous abortion. When the analyses were stratified according to the results of karyotyping, the ingestion of moderate or high levels of caffeine was found to be associated with an excess risk of spontaneous abortion when the fetus had a normal or unknown karyotype but not when the fetal karyotype was abnormal. CONCLUSIONS: The ingestion of caffeine may increase the risk of an early spontaneous abortion among non-smoking women carrying fetuses with normal karyotypes.
To investigate the CYP1A2 phenotype distribution in a population with an increased exposure to polychlorinated biphenyls (PCBs) that would likely induce an increased activity of this enzyme. Further, to investigate the effect of sex, smoking, and oral contraceptive use on the CYP1A2 activity.
In 305 randomly selected Faroese residents aged 18-60 years, the CYP1A2 activity was determined following oral intake of a caffeine dose and subsequent determination of the urinary metabolites and calculation of the caffeine metabolic ratio (CMR). PCB exposure was assessed by measuring the serum concentration of major congeners.
The CYP1A2 phenotype distribution was unimodal. The CMR was significantly higher both in smoking men and in smoking women, independent of oral contraceptive use, as compared with non-smokers. Among non-smokers, the CMR was significantly higher in women not using oral contraceptives than in those using oral contraceptives; a similar difference could not be established among smokers. The CMR appeared higher in men than in women, but stratified analyses confirmed a significant sex-related difference only among smokers not using oral contraceptives. Overall, the mean CMR in Faroese was significantly higher compared with the mean CMR in Danish historical controls. No association was found with PCB exposure and individual PCB congeners, except for one of three dioxin-like congeners, in confounder-adjusted multiple regression analyses.
The CYP1A2 phenotype in Faroese residents was unimodally distributed and showed the inducing effect of smoking and the inhibiting effect of use of oral contraceptives, but a sex-related difference was not apparent after confounder adjustment. There was no statistically significant association between CMR and PCB exposure.
The role of coffee intake as a risk factor for coronary heart disease (CHD) has been debated for decades. We examined whether the relationship between coffee intake and incidence of CHD events is dependent on the metabolism of circulating catecholamines, as determined by functional polymorphism of the catechol-O-methyltransferase (COMT) gene.
In a cohort of 773 men who were 42 to 60 years old and free of symptomatic CHD at baseline in 1984-89, 78 participants experienced an acute coronary event during an average follow-up of 13 years. In logistic regression adjusting for age, smoking, family history of CHD, vitamin C deficiency, blood pressure, plasma cholesterol concentration, and diabetes, the odds ratio (90% confidence interval) comparing heavy coffee drinkers with the low activity COMT genotype with those with the high activity or heterozygotic genotypes was 3.2 (1.2-8.4). Urinary adrenaline excretion increased with increasing coffee intake, being over two-fold in heavy drinkers compared with nondrinkers (p = 0.008 for trend).
Heavy coffee consumption increases the incidence of acute coronary events in men with low but not high COMT activity. Further studies are required to determine to which extent circulating catecholamines mediate the relationship between coffee intake and CHD.
Cites: J Epidemiol Community Health. 1999 Aug;53(8):481-710562866
Cites: N Engl J Med. 1994 Jun 2;330(22):1549-548177243
A population-based survey of life-style factors and subfecundity (prolonged time to pregnancy) was conducted between 1984 and 1987 in two cities in Denmark. Altogether, 11,888 women filled out a questionnaire in the last trimester of pregnancy (an 86 percent response rate). After exclusion of women who had been treated for infertility or who did not respond to the question on infertility, 10,886 subjects remained. Among nonsmokers, no association was found between subfecundity (defined as a waiting time of 1 year or more from cessation of contraception to achievement of pregnancy) and consumption of hot caffeinated beverages. For women who smoked and also consumed at least 8 cups of coffee per day (or an equivalent amount of tea), a statistically significant association was seen (odds ratio = 1.35, 95% confidence interval 1.02-1.48) for a wait of 1 year or more. Consumption of coffee was closely related to smoking habits and to a number of social factors, such as education and peer group acceptance, which may play a role in subfecundity.