Caffeine Intake among Undergraduate Students: Sex Differences, Sources, Motivations, and Associations with Smoking Status and Self-Reported Sleep Quality.

Due to its stimulatory effects, caffeine is one of the most frequently consumed mood and behavior altering drugs. University students report using caffeine-containing products to enhance mood and performance or for a desire of alertness. The current study investigated caffeine consumption in university undergraduate students, and associations with smoking status, alcohol and cannabis consumption, fruit and vegetable consumption, and sleep quality. Motivations for caffeine intake were also ascertained. A total of 886 undergraduates aged 18−25 years from the University of the Balearic Islands participated in a cross-sectional survey. Caffeine was consumed by 91.1% of participants. Caffeine consumers were more likely to be female, smokers, and alcohol and cannabis consumers. Coffee was found to be the main source of caffeine intake in both men and women (48.9% of total caffeine intake). Higher percentages of women consumed coffee (56.4 vs. 42.1%, p = 0.01) and tea (40.3 vs. 19.8%, p < 0.001), whereas a higher percentage of men consumed energy drinks (18.0 vs. 7.4%, p < 0.001). Main motivations for caffeine intake were those related to cognitive enhancement. Caffeine intake was associated with poorer subjective sleep quality (p < 0.001). In conclusion, undergraduate students that were female and smokers reported higher caffeine intakes. Coffee was found as the main caffeine contributor, with higher contributions of tea in women and energy drinks in men. Universities should consider the implementation of health campaigns and educational programs to educate students of the risks of high caffeine consumption together with associated behaviors such as smoking, alcohol consumption and poor sleep quality to physical health and academic performance.

Blood Cell In Vitro Cytokine Production in Response to Lipopolysaccharide Stimulation in a Healthy Population: Effects of Age, Sex, and Smoking.

Immune system functionality has been commonly assessed by a whole-blood or isolated-cell stimulation assay. The aim of this study was to determine whether cytokine production in whole-blood-stimulated samples is influenced by age, sex, and smoking. A descriptive cross-sectional study in 253 healthy participants aged 18-55 years was conducted. Whole blood samples were stimulated for 24 h with LPS and concentrations of IL-6, IL-10, and TNF-α were determined in the culture media. Among parameters considered, statistical regression analysis indicated that smoking (change in R2 = 0.064, p < 0.001) and sex (change in R2 = 0.070, p < 0.001) were the main predictors for IL-10 production, with higher values for women and non-smokers. Age was also found to be a significant predictor (change in R2 = 0.021, p < 0.001), with higher values for younger ages. Age (change in R2 = 0.089, p = 0.013) and smoking (change in R2 = 0.037, p = 0.002) were found to be negative predictors for IL-6 production. Regarding TNF-α-stimulated production, age (change in R2 = 0.029, p = 0.009) and smoking (change in R2 = 0.022, p = 0.022) were found to be negative predictors. Furthermore, sex (change in R2 = 0.016, p = 0.045) was found to be a significant predictor, with lower values for women. In conclusion, sex, age, and smoking were found to be independent determinants of stimulated cytokine production. While female sex is associated with higher IL-10 and lower TNF-α production, aging and smoking are associated with lower IL-6, IL-10, and TNF-α production.

Caffeine supplementation induces higher IL-6 and IL-10 plasma levels in response to a treadmill exercise test.

BACKGROUND: An acute bout of exercise induces an inflammatory response characterized by increases in several cytokines. Caffeine ingestion could modify this inflammatory response. The aim of this study was to determine the effects of caffeine supplementation on plasma levels of cytokines, mainly IL-10 and IL-6, in response to exercise. METHODS: In a randomized, crossover, double-blinded study design, thirteen healthy, well-trained recreational male athletes performed, on two different occasions, a treadmill exercise test (60 min at 70% VO2max) after ingesting 6 mg/kg body mass of caffeine or placebo. Blood samples were taken before exercising, immediately after finishing and 2 h after finishing the exercise. Plasma concentrations of IL-10, IL-6, IL-1ß, IL-1ra, IL-4, IL-8, IL-12 and IFN-γ, adrenaline, cortisol and cyclic adenosine monophosphate (cAMP) were determined. The capacity of whole blood cultures to produce cytokines in response to endotoxin (LPS) was also determined. Changes in blood variables were analyzed using a time (pre-exercise, post-exercise, recovery) x condition (caffeine, placebo) within-between subjects ANOVA with repeated measures. RESULTS: Caffeine supplementation induced higher adrenaline levels in the supplemented participants after exercise (257.3 ± 53.2 vs. 134.0 ± 25.7 pg·mL- 1, p = 0.03) and higher cortisol levels after recovery (46.4 ± 8.5 vs. 32.3 ± 5.6 pg·mL- 1, p = 0.007), but it did not influence plasma cAMP levels (p = 0.327). The exercise test induced significant increases in IL-10, IL-6, IL-1ra, IL-4, IL-8, IL-12 and IFN-γ plasma levels, with IL-6 and IL-10 levels remaining high after recovery. Caffeine supplementation influenced only IL-6 (3.04 ± 0.40 vs. 3.89 ± 0.62 pg·mL- 1, p = 0.003) and IL-10 (2.42 ± 0.54 vs. 3.47 ± 0.72 pg·mL- 1, p = 0.01) levels, with higher concentrations after exercise in the supplemented condition. No effect of caffeine was observed on the in vitro stimulated cytokine production. CONCLUSIONS: The results of the present study indicate a significant influence of caffeine supplementation increasing the response to exercise of two essential cytokines such as IL-6 and IL-10. However, caffeine did not influence changes in the plasma levels of other cytokines measured and the in vitro-stimulated cytokine production.

Effects of Habitual Caffeine Intake, Physical Activity Levels, and Sedentary Behavior on the Inflammatory Status in a Healthy Population.

Low-grade chronic inflammation is associated with many chronic diseases and pathological conditions. The aim of the present study was to determine the effect of regular caffeine intake, physical activity levels, and sedentary behavior on the inflammatory status in healthy participants. In total, 112 men and 132 women aged 18 to 55 years and belonging to the staff and student population of the University of the Balearic Islands volunteered to participate in this descriptive cross-sectional study. Plasma concentrations of pro-inflammatory and anti-inflammatory markers were measured. Weight, height, and body composition (bioelectrical impedance) were determined. Caffeine intake, physical activity levels and sitting time, and diet quality were determined using questionnaires. Statistical regression analysis showed that caffeine intake was a negative predictor of C-reactive protein (CRP) (p = 0.001). Body fat percentage was positively associated with CRP (p < 0.001) and inversely associated with adiponectin (p = 0.032) and interleukin (IL)-10 levels (p = 0.001). Visceral fat was the main predictor for IL-6 (p < 0.001) and tumor necrosis factor (TNF)-α (p < 0.001). Sitting time was found to be the main, inverse, predictor for IL-10 (p < 0.001), and a positive predictor for TNF-α (p < 0.001). In conclusion, regular caffeine consumption induced very limited anti-inflammatory effects. Sedentary behavior and body fat accumulation induced significant pro-inflammatory effects.

Energy, macronutrient and water intake during a mountain ultramarathon event: The influence of distance.

Adequate dietary strategies are essential for the successful participation in ultra-endurance races. The aim of this study was to evaluate and compare the energy and water intakes of participants during three different mountain ultra-endurance runs. The study took place at the "Ultra Mallorca Serra de Tramuntana" (Mallorca, Spain), an ultra-endurance mountain event with runners participating either in a 44-km (Marathon, n = 51), a 67-km (Trail, n = 109) or a 112-km (Ultra, n = 53) run competition. Participants in the study answered a questionnaire focused on the nutritional intake within an hour after finishing the competition. Mean energy intake during the competitions was 183 kcal · h¯1, with an average carbohydrate intake of 31 g · h¯1 (52.1% of participants consumed less than 30 g · h¯1). No significant differences between competitions were found in these parameters. However, a higher percentage of energy from lipids in participants in the Trail and the Ultra was found (P = 0.034). Furthermore, significant differences were observed in water intake per hour of competition (P = 0.039), with the lowest value for the intake during the Ultra competition. In conclusion, the majority of the participants in the study present low carbohydrate intakes. However, fluid intake seems to be adequate. Different distances did not significantly influence the participants' nutritional strategies.