Monitoring caffeine intake in children with a questionnaire and urine collection: a cross-sectional study in a convenience sample in Switzerland

The association between urinary caffeine and caffeine metabolites and diabetic retinopathy in individuals with diabetes: NHANES 2009-2014

The association between caffeine and diabetic retinopathy (DR) risk remains controversial. This study aims to examine the association between urinary caffeine and caffeine metabolites and self-reported DR risk in US individuals with diabetes. This cross-sectional study enrolled 535 participants with diabetes from the National Health and Nutrition Examination Survey (NHANES) 2009-2014. The high-performance liquid chromatography-electrospray ionization-tandem quadrupole mass spectrometry (HPLC-ESI-MS/MS) and internal standards labeled with stable isotopes were used to measure urinary caffeine and fourteen of its metabolites. Urinary caffeine and its metabolites levels were calibrated with urine creatinine for analysis. Caffeine and its metabolites were analyzed as continuous variables and categorical variables (≤ 50% or > 50%). Weighted logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Subgroup analysis by sex was conducted. After adjusting for age, sex, race, BMI, smoking, alcohol drinking, duration of diabetes, glycated hemoglobin, hypertension, and total energy intake, ln-transformed 1-methyluric acid (1-MU) (OR = 1.27, 95% CI, 1.05 to 1.56, P = 0.016) and 5-acetylamino-6-amino-3-methyluracil (AAMU) (OR = 1.16, 95% CI, 1.01 to 1.34, P = 0.043) were associated with an increased DR risk. In median analysis, compared to lower levels (≤ 50%), higher levels (> 50%) of 1,7-dimethyluric acid (1,7-DMU) (OR = 1.92, 95% CI, 1.20 to 3.09, P = 0.008), caffeine (OR = 2.00, 95% CI, 1.27 to 3.16, P = 0.004), and AAMU (OR = 1.48, 95% CI, 1.04 to 2.10, P = 0.029) were associated with an increased DR risk. Sex-based analysis showed that ln-transformed 1-MU (OR = 1.48, 95% CI, 1.10 to 1.98, P = 0.012), 1,3,7-TMU (OR = 1.24, 95% CI, 1.04 to 1.49, P = 0.018) and caffeine (OR = 1.29, 95% CI, 1.03 to 1.60, P = 0.028) were associated with an increased DR risk in males. Compared to lower levels (≤ 50%), higher levels (> 50%) of 1,7-DMU (OR = 2.75, 95% CI, 1.33 to 5.70, P = 0.008), 1,3,7-TMU (OR = 2.26, 95% CI, 1.02 to 5.01, P = 0.044), caffeine (OR = 3.23, 95% CI, 1.53 to 6.82, P = 0.003), and AAMU (OR = 2.93, 95% CI, 1.16 to 7.40, P = 0.024) were associated with an increased DR risk in males. This study indicated that high urinary levels of 1-MU, 1,7-DMU, 1,3,7-TMU, caffeine and AAMU were associated with an increased risk of DR in US males with DM. Prospective studies are needed to verify these findings.

Urinary Caffeine Levels in Chinese Children: Insights from Diet, Gender, and Regional Variations

BACKGROUND/OBJECTIVES

The consumption of caffeine products among children in China is on the rise, yet there remains a paucity of evidence regarding the variability of caffeine consumption and the influencing factors. Urinary caffeine levels provide a valid indicator of caffeine intake, as it directly reflects the quantitative measure of consumption within the population. This study aimed to investigate the effects of diet, gender, and region on urinary caffeine concentrations in Chinese children and their parents, specifically focusing on participants from Guangdong province and Guangxi province.

METHODS

Morning urine samples were pretreated using liquid-liquid extraction. Caffeine and creatinine concentrations were analyzed using ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS), with quality control measures ensuring method accuracy (recovery rate: 92.8-122%, RSD < 20%). Caffeine exposure was assessed through estimated daily intake (EDI) calculations, and statistical analyses, including weighted regression and Spearman correlation, were conducted to evaluate associations with demographic and dietary variables.

RESULTS

The findings revealed that urinary caffeine levels and detection rates among Chinese children were significantly lower than those observed in the United States (30.1 ng/mL), with a median concentration of 2.18 ng/mL and a detection rate of 45%. Urinary caffeine concentrations in males were slightly higher than in females; however, these gender differences were not statistically significant. Certain dietary habits, particularly milk consumption, were found to influence urinary caffeine levels and detection rates. Using the random forest method, urine caffeine detection was highest (nearly 60%) when milk was consumed three times a week. Regionally, children in Guangdong had marginally higher urinary caffeine concentrations compared to those in Guangxi (median: 5.20 μg/gcrea vs. 1.58 μg/gcrea). The estimated daily caffeine intake suggested that children in China consume less caffeine than their counterparts in other countries.

CONCLUSIONS

These results indicate that dietary habits significantly correlated with caffeine consumption in children, and urinary caffeine concentration serves as a valuable measure for dietary research.

Comprehensive analysis of pharmaceutical and illicit drugs contamination in thermal swimming pools: Occurrence, distribution, and potential impact

The contamination of aquatic environments by micropollutants, including pharmaceuticals and illicit drugs, is a growing global issue with significant implications for environmental and public health. This study addresses a critical knowledge gap by examining pharmaceutical and drug contamination in thermal swimming pools, which are often legally discharged into water bodies without treatment. A total of 49 water samples from 19 distinct thermal pools were analysed, targeting 101 compounds, including pharmaceuticals, illicit drugs, and their metabolites. High-frequency contaminants were identified including caffeine, theophylline, cardiovascular medications (bisoprolol, metoprolol, telmisartan), antidepressants (venlafaxine, citalopram), antihistamines (cetirizine, diphenhydramine), the analgesic tramadol, the antiepileptic carbamazepine, and the illicit drug methamphetamine. The study revealed that these substances were present in more than 30% of the samples, with some occurring at relatively high maximum concentrations, e.g. caffeine (69 μg/L), and methamphetamine (1.8 μg/L). Notably, certain categories of targeted micropollutants, such as cardiovascular medications and illicit drugs, were found to be more prevalent in specific pools. A higher occurrence of cardiovascular drugs has been observed in a pool predominantly designed for relaxation and thus probably preferred by older people. In this pool also notably high levels of illicit drugs were found. The presence of illegal drugs was also confirmed in the children's pool. This study contributes valuable insights into the patterns of micropollutant distribution in thermal pools and emphasises the necessity for enhanced monitoring and management strategies to mitigate environmental and public health risks posed by micropollutants, as well as the possible further impact on aquatic ecosystems.

Urinary caffeine and its metabolites in association with advanced liver fibrosis and liver steatosis: a nationwide cross-sectional study

Aim: This study used urinary caffeine and its metabolites to evaluate their relationships with liver steatosis and advanced liver fibrosis. Methods: A total of 2068 adult participants with required data were filtered from the 2009-2014 National Health and Nutrition Examination Survey (NHANES) cycles. Non-invasive scores were applied to define liver steatosis and advanced liver fibrosis. Logistic regression models, weighted quantile sum (WQS) regression models, quantile-based g-computation (QG-Comp) models, and restricted cubic spline (RCS) regression models were used to assess the associations of urinary caffeine and its metabolites with liver steatosis and advanced liver fibrosis. A series of additional analyses were conducted to examine the subgroup-specific differences and test the robustness of the observed results. Results: The major caffeine metabolite mixture and most individual caffeine metabolites were found to be negatively associated with the risk of advanced liver fibrosis with subgroup-specific variations. Only 7-MX consistently showed a negative association with liver steatosis in all analyses, while no association was observed between the major caffeine metabolite mixture and liver steatosis. Conclusion: The major caffeine metabolite mixture and most individual urinary caffeine metabolites exhibited inverse associations with advanced liver fibrosis with subgroup differences. Further prospective and experimental studies are urgently needed to verify our results and further identify the possible mechanisms.

Overview of Caffeine Effects on Human Health and Emerging Delivery Strategies

Caffeine is a naturally occurring alkaloid found in various plants. It acts as a stimulant, antioxidant, anti-inflammatory, and even an aid in pain management, and is found in several over-the-counter medications. This naturally derived bioactive compound is the best-known ingredient in coffee and other beverages, such as tea, soft drinks, and energy drinks, and is widely consumed worldwide. Therefore, it is extremely important to research the effects of this substance on the human body. With this in mind, caffeine and its derivatives have been extensively studied to evaluate its ability to prevent diseases and exert anti-aging and neuroprotective effects. This review is intended to provide an overview of caffeine's effects on cancer and cardiovascular, immunological, inflammatory, and neurological diseases, among others. The heavily researched area of caffeine in sports will also be discussed. Finally, recent advances in the development of novel nanocarrier-based formulations, to enhance the bioavailability of caffeine and its beneficial effects will be discussed.

Limited caffeine consumption as first-line treatment in managing primary monosymptomatic enuresis in children: how effective is it? A randomised clinical trial

OBJECTIVE

Evidence about the negative caffeine effect on enuresis in children remains understudied or poorly understood. The study aimed to investigate the effect of caffeine restriction on the improvement and severity of primary monosymptomatic nocturnal enuresis (PMNE).

DESIGN

Randomised clinical trial.

SETTING

Two referral hospitals in Tehran, Iran, from 2021 to 2023.

PATIENTS

Five hundred and thirty-four PMNE children aged 6-15 years (each group 267).

INTERVENTIONS

Amount of caffeine consumption was recorded by the feed frequency questionnaire and was estimated by Nutrition 4 software. Caffeine consumption per day in the intervention group was <30 mg, and in the control group, 80-110 mg. All children were asked to return 1 month later to check the recorded data. The ordinal logistic regression analysis was used to assay the effects of caffeine restriction on PMNE by relative risk (RR) at a 95% CI.

MAIN OUTCOME MEASURES

The effect of limited caffeine consumption on the improvement and severity of PMNE.

RESULTS

The mean age of the intervention and control groups was 10.9±2.3 and 10.5±2.5 years, respectively. The mean number of bed-wetting before caffeine restriction in the intervention and control group was 3.5 (SD 1.7) times/week and 3.4 (SD 1.9) times/week (p=0.91) and 1 month after intervention were 2.3 (SD 1.8) times/week and 3.2 (SD 1.9) times/week, respectively (p=0.001). Caffeine restriction significantly reduced the severity of enuresis in the intervention group. Fifty-four children (20.2%) improved (dry at night) in caffeine restriction and 18 children (6.7%) in the control group with RR 0.615 at 95% CI 0.521 to 0.726, p=0.001. The caffeine restriction significantly reduced the enuresis in children with a number-needed-to-treat benefit 7.417. It means you must treat 7.417 PMNE children with caffeine limitation to improve one child with enuresis (become dry).

CONCLUSION

Caffeine restriction can be helpful in reducing PMNE or its severity. Constructive limitation of caffeine is suggested as one of the first-line treatments in the management of PMNE.

TRIAL REGISTRATION NUMBER

IRCT20180401039167N3.

Shifts in Fecal Metabolite Profiles Associated With Ramadan Fasting Among Chinese and Pakistani Individuals

The human gut microbiota has been proposed to serve as a multifunctional organ in host metabolism, contributing effects to nutrient acquisition, immune response, and digestive health. Fasting during Ramadan may alter the composition of gut microbiota through changes in dietary behavior, which ultimately affects the contents of various metabolites in the gut. Here, we used liquid chromatography–mass spectrometry-based metabolomics to investigate the composition of fecal metabolites in Chinese and Pakistani individuals before and after Ramadan fasting. Principal component analysis showed distinct separation of metabolite profiles among ethnic groups as well as between pre- and post-fasting samples. After Ramadan fasting, the Chinese and Pakistani groups showed significant differences in their respective contents of various fecal metabolites. In particular, L-histidine, lycofawcine, and cordycepin concentrations were higher after Ramadan fasting in the Chinese group, while brucine was enriched in the Pakistani group. The KEGG analysis suggested that metabolites related to purine metabolism, 2-oxocarboxylic acid metabolism, and lysine degradation were significantly enriched in the total subject population pre-fasting vs. post-fasting comparisons. Several bacterial taxa were significantly correlated with specific metabolites unique to each ethnic group, suggesting that changes in fecal metabolite profiles related to Ramadan fasting may be influenced by associated shifts in gut microbiota. The fasting-related differences in fecal metabolite profile, together with these group-specific correlations between taxa and metabolites, support our previous findings that ethnic differences in dietary composition also drive variation in gut microbial composition and diversity. This landscape view of interconnected dietary behaviors, microbiota, and metabolites contributes to the future development of personalized, diet-based therapeutic strategies for gut-related disorders.

Nutritional Metabolomics and the Classification of Dietary Biomarker Candidates: A Critical Review

Recent advances in metabolomics allow for more objective assessment of contemporary food exposures, which have been proposed as an alternative or complement to self-reporting of food intake. However, the quality of evidence supporting the utility of dietary biomarkers as valid measures of habitual intake of foods or complex dietary patterns in diverse populations has not been systematically evaluated. We reviewed nutritional metabolomics studies reporting metabolites associated with specific foods or food groups; evaluated the interstudy repeatability of dietary biomarker candidates; and reported study design, metabolomic approach, analytical technique(s), and type of biofluid analyzed. A comprehensive literature search of 5 databases (PubMed, EMBASE, Web of Science, BIOSIS, and CINAHL) was conducted from inception through December 2020. This review included 244 studies, 169 (69%) of which were interventional studies (9 of these were replicated in free-living participants) and 151 (62%) of which measured the metabolomic profile of serum and/or plasma. Food-based metabolites identified in ≥1 study and/or biofluid were associated with 11 food-specific categories or dietary patterns: 1) fruits; 2) vegetables; 3) high-fiber foods (grain-rich); 4) meats; 5) seafood; 6) pulses, legumes, and nuts; 7) alcohol; 8) caffeinated beverages, teas, and cocoas; 9) dairy and soya; 10) sweet and sugary foods; and 11) complex dietary patterns and other foods. We conclude that 69 metabolites represent good candidate biomarkers of food intake. Quantitative measurement of these metabolites will advance our understanding of the relation between diet and chronic disease risk and support evidence-based dietary guidelines for global health.