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PubMed2026

Genetic and Environmental Influences on Caffeine Intake in Korean Twins.

Caffeine intake may be influenced by both genetic and environmental factors. This study aimed to examine the genetic contribution to variation in coffee and tea drinking, as well as total caffeine intake. A total of 1,106 Korean twins, comprising 456 monozygotic and 97 dizygotic twin pairs aged 30 years or older, from the Healthy Twin Study were included. Structural equation models were used to assess heritability estimates and their 95% confidence intervals (CIs). Heritability (95% CI) was estimated at 0.29 (0.21, 0.37) for coffee drinking, 0.11 (0.02, 0.20) for tea drinking, and 0.27 (0.16, 0.38) for total caffeine intake, with the remaining variance in each trait attributed to unique environmental factors. The unique environmental factors contributed more substantially to coffee drinking than genetic factors during early adulthood, while the genetic contribution to tea drinking remained consistently low across all ages. In conclusion, coffee drinking, tea drinking, and total caffeine intake were partly heritable, with unique environmental factors playing a predominant role.

Humans↗
PubMed1979

Caffeine intake and potential effect on health of a segment of northern Canadian indigenous people.

There are strong indications that the caffeine intake of Canadian Northern Indigenous People is very substantial. Tea is the main contributor. Preliminary calculations show that daily ingestion of caffeine among these groups is much higher than ingestion levels known to have adverse medical and behavioral effects. Of particular concern is the interaction of caffeine and carbohydrate metabolism, already known to be under stress due to increases in sugar and carbohydrate intake. Symptoms characteristic of unduly high intake of caffeine are also found to a large extent in hypoglycemia, mercury intoxication, and various nutritional deficiencies. There is a need for a substantial research effort to further delineate the caffeine problem and to develop alternate beverages containing reduced amounts of caffeine.

Adult↗
PubMed2025

Modifiable risk factors associated with the risk of developing Parkinson's disease: a critical review.

The etiology of Parkinson's disease (PD) is complex and multifactorial, depending on interactions involving environmental/lifestyle and genetic factors. The genetic aspects of the disease are becoming well characterized, while the environmental factors still need further investigation. In the present narrative review, we have described the most concrete evidence of associations between environmental factors and the risk of developing PD. Physical activity, healthy dietary patterns, smoking, and caffeine intake are protective factors against PD. Head trauma, consumption of milk and dairy products, and pesticide exposure were associated with a higher risk of developing PD. The associations of alcohol consumption, living in rural areas, farming, and consumption of well water with PD are still controversial. Results of several studies strongly suggest that diabetes mellitus is a risk factor for the development of PD, as well as the pre-diabetic state. Lower serum levels of uric acid were associated with an increased risk of developing PD and with worse clinical features and faster progression of symptoms. The protective effects of nonsteroidal antiinflammatory drugs use are controversial. Several other factors were potentially associated with the risk of developing PD: environmental pollutants such as organic solvents, exposure to sunlight, vitamin D deficiency, bullous pemphigoid, bipolar disorder, inflammatory bowel disease, irritable bowel syndrome, certain infections and agents, and essential tremor. Environmental factors are important risk markers for the development of PD. Understanding these risks and protective factors could lead to the implementation of risk-modifying actions for PD.

Humans↗
PubMed2026

Comparing genome-wide significant and chemosensory variants as instruments for dietary patterns in Mendelian randomization.

BACKGROUND: Diet is a modifiable risk factor for cardiometabolic disease, yet establishing causality remains challenging. Mendelian randomization (MR) leverages genetic variants as instrumental variables (IVs) to enable causal inference. METHOD: Using two-sample MR, we assessed the causal effects of four principal component-derived dietary patterns (DPs)-Unhealthy, Healthy, Meat-based, Pescatarian-on cardiometabolic outcomes including body mass index, coronary artery disease, blood lipids, blood pressures, type 2 diabetes, fasting glucose and insulin, and glycated haemoglobin. Two sets of IVs were employed: conventional genome-wide significant variants associated with each DP, filtered for pleiotropy and directionality; and biologically informed variants in chemosensory receptor genes, given the role of taste and smell perception in food choice. RESULTS: Using conventional IVs, the Pescatarian DP was associated with reduced fasting insulin (βIVW = -0.10 pmol/L per SD increase in the Pescatarian DP score, 95% confidence interval -0.15, -0.04; P = 1.19 × 10-3), surviving multiple sensitivity analyses. Associations between the Unhealthy DP and elevated blood pressure and glycated haemoglobin should be interpreted cautiously; one of the two filtered IVs was strongly associated with caffeine intake, limiting the attribution of these findings to the DP itself. Chemosensory Receptor IVs yielded null findings, reflecting insufficient power. CONCLUSION: Evidence for causal effects of DPs on cardiometabolic traits was limited, with the strongest support for a protective effect of the Pescatarian DP on fasting insulin. Chemosensory IVs demonstrated limited utility for DPs, likely reflecting the heterogeneous and complex sensory profiles of overall diets. Future efforts should consider guideline-based dietary indices to facilitate interpretability and translation.

Humans↗
PubMed1978

Effects of ethanol, caffeine, and placebo on the auditory evoked response.

A previous paper (Wolpaw and Penry 1975) described separation of the 75-250 msec portion of the AER into N1P2, a product of large areas of cortex, and the T complex, probably a product of secondary auditory cortex. With monaural stimulation, the T complex is larger and earlier on the side contralateral to stimulation and on the right side. Thirty-one normal adults received 3 oz. of ethanol, 300 mg of caffeine, or placebo. Monaural AERs were recorded before intake in all cases, 1 and 4 h after ethanol and 80 min after caffeine or placebo. Blood levels of ethanol and caffeine were measured. Placebo produced mild (20%) decreases in N1P2 amplitude. Caffeine did not decrease N1P2 amplitude. It did produce a statistically significant 2% decrease in Ta peak latency. Ethanol reduced N1P2 amplitude markedly at 1 h and mildly at 4 h. Placebo did not affect hemispheric differences. Caffeine significantly increased the Ta peak ipsilateral vs. contralateral latency difference in 3 of 7 individuals. Ethanol significantly increased it in 3 of 6 subjects at 1 h and in 7 of 10 at 4 h, primarily by increasing ipsilateral latencies.

Adult↗
PubMed1979

Ventricular premature contractions: a randomized non-drug intervention trial in normal men.

The influence of a 6-week intervention on factors thought to be related to ectopic cardiac rhythms was tested in normal men with frequent ventricular premature contractions (VPCs), using a randomized, controlled and partial crossover design. The VPC intervention trial experimental regimen included total abstinence from caffeine and smoking, reduction of alcohol intake, and a physical conditioning program. Effects were studied in detail among 81 healthy men with persistent VPCs. VPCs were measured during standard states of rest, dynamic and isometric exercise and other stresses, and 24-hour ambulatory monitoring. Adherence to the treatment was excellent. The experimental group achieved more than 80% of activities asked of them, and little "contamination" occurred in the control group. VPCs were analyzed according to VPC/min, VPC/man and VPC/total number of heart beats. Moderate changes in VPC rates occurred in both experimental and control groups but no significant group differences were found at rest or during any induction test. This 6-week, multiple-factor "hygienic" intervention program had no significant influence on the frequency or occurrence of VPCs in apparently normal men with persistent and frequent VPCs. Because the mechanisms and the significance of VPCs are different in patients with ischemic heart disease, our approach and methods may be useful for similar trials among cardiac patients of adjunct or non-drug therapy for ectopic rhythms.

Adult↗
PubMed2026

Application of 13C MRS demonstrates carbohydrate feeding spares muscle but not liver glycogen utilization during high-intensity interval exercise.

We examined liver and muscle glycogen utilization during high-intensity interval cycling, and the impact of carbohydrate (CHO) feeding, using noninvasive 13C magnetic resonance spectroscopy (MRS). Following 24 h of standardized dietary intake, nine male cyclists completed 8 &#xd7; 5-min intervals (1-min recovery), ingesting either placebo (PLA), 60 g maltodextrin (CHO), or 60 g maltodextrin plus caffeine, taurine, l-theanine, l-citrulline, and citicoline (CHO+) in a randomized crossover design. 13C MRS and 1H imaging were performed pre- and postexercise to determine liver and muscle glycogen and liver volume, respectively. Liver glycogen utilization was not significantly different between trials (P = 0.101) despite lower postexercise plasma glucagon concentrations in CHO and CHO+ (P = 0.001). In contrast, muscle glycogen utilization was significantly lower (&#x223c;40%) with CHO feeding compared with PLA (P = 0.006), yet this sparing effect was not evident with CHO+ (P = 0.073) in accordance with a higher mean power output during the late intervals (+2.8%, P = 0.046). Plasma glucose was comparable between trials (P = 0.175), whereas plasma lactate was higher in CHO+ versus CHO (P = 0.003), alongside lower blood bicarbonate (P = 0.005), base excess (P < 0.001), and total CO2 (P = 0.004). These findings demonstrate preferential use of skeletal muscle glycogen during high-intensity interval training (HIIT), which is attenuated under conditions of CHO feeding. This sparing effect is, however, not evident with the coingestion of a caffeine-containing multi-ingredient blend, potentially due to an increased capacity to sustain higher power outputs resulting in greater glycogen utilization.NEW & NOTEWORTHY Using 13C MRS, we provide data demonstrating preferential use of skeletal muscle glycogen during HIIT. Furthermore, data show muscle glycogen utilization is attenuated with CHO feeding, yet sparing is not evident when coingesting a caffeine-containing formulation, potentially reflecting increased capacity to perform more total work rather than a direct metabolic effect of caffeine. In contrast, liver glycogen utilization was not significantly different with CHO feeding despite a modest reduction of &#x223c;5 g versus placebo.

Male↗
PubMed2026

Genome-Wide Association Analyses of Bitter Food Preferences Link Genetic Loci to Sensory and Metabolic Pathways.

BACKGROUND: Genetic variation is implicated in individual preferences for bitter-tasting foods. However, previous studies have focused on candidate genes and limited varieties of bitter-tasting foods and have treated food preference scale responses as continuous data. OBJECTIVES: The present investigation aimed to identify genetic variants associated with preferences for bitter-tasting foods using ordinal multinomial regression models in genome-wide association studies (GWAS). In addition, post-GWAS functional annotation and mapping, genetic correlations, and associations with dietary intake were examined. METHODS: Food preference and genome-wide genotyping data were used from the UK Biobank (n = 125,578). Preference data from Likert scale rankings (from 1 to 9) for 12 individual foods were analyzed using ordinal multinomial regression GWAS. In addition, 1 composite continuous variable was created for preference for cruciferous vegetables as a group and analyzed using a linear mixed-model GWAS to enable the calculation of a polygenic score (PGS) for cruciferous vegetable preference. Convergent validity of GWAS results was assessed with dietary intake data for the same food items in the CARTaGENE cohort (n = 8176). Post-GWAS gene-level and pathway-level association analyses were conducted in MAGMA (Multimarker Analysis of GenoMic Annotation). RESULTS: Forty-six single-nucleotide polymorphisms (SNPs) were identified for preferences for 11 bitter-tasting foods at a genome-wide significance level (P < 7.14 &#xd7; 10-9). Gene-set analysis for enrichment identified pathways related to caffeine metabolism and bitter taste perception for preference of coffee without sugar and grapefruit, respectively. Genes with higher expression in brain tissues showed stronger genetic associations with cruciferous vegetable preference. The PGS for cruciferous vegetable preference was weakly correlated with intake (r = 0.05, P < 0.0001), but individual SNPs were not associated with intake in a consistent manner. CONCLUSIONS: Genetic variation contributes to preferences for bitter-tasting foods among adults, and some links with food intake are detectable. Nevertheless, effect sizes are small and inconsistent, reflecting the multifactorial complexity of food intake.

bitter taste↗
PubMed1979

Seasonal variation in the effect of dietary RNA on criteria of energy homoeostasis in the rat.

1. RNA was administered to rats as part of a meal while standardizing food intake and minimizing the effects of psychological stress and diurnal metabolic rhythms. It was demonstrated that circulating levels of glucose and free fatty acids (FFA) in the animals, which were deprived of food for 48 h, were responsive to orally administered caffeine. 2. Inclusion of RNA in the diet slightly but consistently reduced the normal postprandial hyperglycaemia. Its effect on plasma FFA was variable although statistically significant in some experiments. The differences between RNA-and control-fed animals were not attributable to differences in the rate of passage of digesta along the gastrointestinal tract. 3. Evidence was obtained that the variability in the FFA response was related to a seasonally-dependent change in the state of animals. The synchronizer ('Zeitgeber') responsible for this change was not identified and no satisfactory way of suppressing its effect was found. 4. The present findings, taken in conjunction with those of previous workers, suggest that there is a seasonal influence on the sympathetic nervous system manifesting itself as a variable susceptibility to arousal or excitation.

Animals↗
PubMed1979

A model for evaluating the analgesic effect of a new fixed ratio combination analgesic in patients undergoing oral surgery.

A special model designed for evaluating the analgesic effect of oral analgesics was based on a short-time registration period of immediate postoperative pain. One-hour intervals in pain registration and a minimum of 2 h between the tablet intake allowed a good estimation of changes in pain levels. The patient material consisted of 112 patients and from each patient a lower impacted wisdom tooth was removed. The test model was used to compare two analgesic drugs with placebo. The two pharmacologically active preparations were Doleron (dextropropoxyphene, acetylsalicylic acid, phenazone, caffeine and Transergan) and Astra 2167 (dextropropoxyphene and acetylsalicylic acid). The trial was double blind and the tablets were administered according to a crossover design. There was no statistically significant difference in analgesic effect between Astra 2167 and Doleron, and both drugs were superior to placebo. Finally, the trial showed that a reduction of the number of components of a compound analgesic to some degree reduced the pain relieving effect on this particular postoperative pain. This observed reduction was however, not statistically significant.

Adult↗
PubMed1979

[Causes and consequences of long term consumption of phenacetin-containing analgesics, from the urologist's point of view (author's transl)].

In the last two decades reports concerning analgesic nephropathies have been presented from most industrial countries. Today, there is no doubt concerning a causal association between long-term consumption of analgesics and renal failure. In a group of 274 urological patients, the reasons and consequences of long-term intake of phenacetin-containing compounds are herewith demonstrated. The reason for chronic consumption of analgesics is mainly headache, due to psychosomatic causes which had not been adequately treated. After an average latency period of 20 years, renal (papillary necrosis, chronic interstitial nephritis) and extrarenal manifestations appeared. Despite slow progression and low gradient symptoms, severe alterations could be determined at the first examination. Course and prognosis primarily depend on a successful cessation of analgesics and the elimination of the accompanying infection. In the last decade, an increase of transitional cell carcinoma induced by analgesics has been observed. 22 of our patients presented a tumor of the urothelium (i.e. 8%). A further increase of these specific cases is expected.

Analgesics↗