Effects of lifestyle and genetic polymorphisms on consumption of coffee or black tea and urinary caffeine levels

To find the cause of individual differences in caffeine intake and its metabolism, we investigated the effects of lifestyle and genetic polymorphisms of caffeine metabolic enzymes on coffee or black tea and urinary caffeine levels among 259 male Japanese. It was seen that cigarette smokers drank more coffee or black tea than non-smokers (p < 0.001). There was an inverse correlation between the amount of coffee or black tea consumed and age or the frequency of alcohol drinking (p < 0.05). Genetic polymorphisms of N -acetyltransferase 2 (NAT2), cytochrome P450 (CYP)1A1 and 2E1 did not significantly affect the habit of drinking coffee or black tea. The frequency of allele 1, the NAT2 allele of rapid acetylators, increased according to coffee or black tea consumption (0.05 < p < 0.1). Among lifestyle factors, two factors, i.e. smoking and the amount of coffee or black tea consumed, were related to urinary caffeine levels (p < 0.05). Geometric means of urinary caffeine levels were higher in the group who consumed higher amounts of coffee or black tea (p < 0.05) and those of smokers were lower than non-smokers- approximately 70% of non-smokers (p < 0.05). The genetic polymorphisms of NAT2, CYP1A1 and CYP2E1 were not significantly associated with the urinary caffeine levels according to each consumption level of coffee or black tea. This study suggests that smoking should be considered for the proper appreciation of individual differences in caffeine intake and urinary caffeine levels.     

Exaggeration of Postprandial Hyperglycemia in Patients with type 2 Diabetes by Administration of Caffeine in Coffee

ObjectiveTo test whether caffeine administered in coffee increases postprandial hyperglycemia in patients with type 2 diabetes who are habitual coffee drinkers.MethodsThe study used a within-subject, double-blind, placebo-controlled experimental design. Twenty adult coffee drinkers (11 women and 9 men) with type 2 diabetes treated with diet, exercise, orally administered antidiabetic agents, or some combination of these factors completed two mixed-meal tolerance tests (MMTT) after an overnight fast. Before the MMTT, each study participant received 250 mg of caffeine in 16 oz (475 mL) of decaffeinated coffee or decaffeinated coffee alone, with the treatment order counterbalanced in the group. Fasting and 1-hour and 2-hour postprandial blood samples were collected for measurement of plasma glucose and insulin concentrations.ResultsGlucose and insulin responses to the MMTT were quantified by the incremental areas under the 2-hour concentration-time curves (AUC_2h). Administration of caffeine in decaffeinated coffee increased postprandial glucose and insulin responses (both P = 0.02). The mean plasma glucose AUC_2h was 28% larger and the mean plasma insulin AUC_2h was 19% larger after administration of caffeine than after administration of placebo.ConclusionOther constituents in coffee did not prevent the exaggeration of postprandial hyperglycemia by caffeine in these patients with type 2 diabetes, who were habitual coffee drinkers. Repeated on a daily basis, such effects could impair long-term glucose control in those patients with type 2 diabetes who habitually drink coffee or other caffeinated beverages. (Endocr Pract. 2007;13: 239-243)     

Decaf and the Steeplechase Towards Decaffito—the Coffee from Caffeine-Free Arabica Plants

Unquestionably, the popularity of the coffee beverage relies on its alerting attribute caffeine. However, susceptibilities to this purine alkaloid, quite frequently associated with health concerns, encouraged a significant market for decaffeinated coffee. The beans of Coffea arabica render the best beverage and a decaffeinated coffee has to preserve the desired organoleptic characteristics of this species. Consequently, besides technical removal of caffeine, the endeavors to attain a decaffeinated Arabica coffee range from traditional studies on genetic variability to advanced techniques to produce genetic modified coffee. The aim of this review is to recover part of this subject focusing mainly on the natural genetic variation for caffeine content in Arabica. We also present historical information about caffeine discovery and briefly discuss molecular approaches to reduce caffeine. We introduce here the term decaffito for coffee derived from Arabica plants with beans naturally low in or almost devoid of caffeine. In the near future, coffee drinkers avoiding caffeine will have the choice between basically three Arabica coffees, namely decaffeinated by (a) selection and breeding, (b) genetic modification and (c) industrial extraction. Although only the last decaf coffee is available for the consumers, we believe that the size of the market of each type will occupy in the future depend on the price and health aspects related to the way the decaffeinated coffee beans are obtained.     

Caffeine: a well known but little mentioned compound in plant science.

Caffeine, a purine alkaloid, is a key component of many popular drinks, most notably tea and coffee, yet most plant scientists know little about its biochemistry and molecular biology. A gene from tea leaves encoding caffeine synthase, an N-methyltransferase that catalyses the last two steps of caffeine biosynthesis, has been cloned and the recombinant enzyme produced in E. coli. Similar genes have been isolated from coffee leaves but the recombinant protein has a different substrate specificity to the tea enzyme. The cloning of caffeine biosynthesis genes opens up the possibility of using genetic engineering to produce naturally decaffeinated tea and coffee.     

Stimulatory effect of oral administration of green tea and caffeine on locomotor activity in SKH-1 mice

Administration of green tea or caffeine was shown previously to inhibit ultraviolet B light-induced carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study, oral administration of 0.6% green tea (6 mg tea solids/ml) or 0.04% caffeine (0.4 mg/ml; equivalent to the amount of caffeine in 0.6% green tea) as the sole source of drinking fluid to SKH-1 mice for 15 weeks increased total 24 hr locomotor activity by 47 and 24%, respectively (p<0.0001). Oral administration of 0.6% decaffeinated green tea (6 mg tea solids/ml) for 15 weeks increased locomotor activity by 9% (p<0.05). The small increase in locomotor activity observed in mice treated with decaffeinated green tea may have resulted from the small amounts of caffeine still remaining in decaffeinated green tea solutions (0.047 mg/ml). The stimulatory effects of orally administered green tea and caffeine on locomotor activity were paralleled by a 38 and 23% increase, respectively, in the dermal muscle layer thickness. In addition, treatment of the mice with 0.6% green tea or 0.04% caffeine for 15 weeks decreased the weight of the parametrial fat pad by 29 and 43%, respectively, and the thickness of the dermal fat layer was decreased by 51 and 47%, respectively. These results indicate that oral administration of green tea or caffeine to SKH-1 mice increases locomotor activity and muscle mass and decreases fat stores. The stimulatory effect of green tea and caffeine administration on locomotor activity described here may contribute to the effects of green tea and caffeine to decrease fat stores and to inhibit carcinogenesis induced by UVB in SKH-1 mice.     

Gas Chromatography Time-Of-Flight Mass Spectrometry (GC-TOF-MS)-Based Metabolomics for Comparison of Caffeinated and Decaffeinated Coffee and Its Implications for Alzheimer’s Disease

Findings from epidemiology, preclinical and clinical studies indicate that consumption of coffee could have beneficial effects against dementia and Alzheimer’s disease (AD). The benefits appear to come from caffeinated coffee, but not decaffeinated coffee or pure caffeine itself. Therefore, the objective of this study was to use metabolomics approach to delineate the discriminant metabolites between caffeinated and decaffeinated coffee, which could have contributed to the observed therapeutic benefits. Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics approach was employed to characterize the metabolic differences between caffeinated and decaffeinated coffee. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed distinct separation between the two types of coffee (cumulative Q² = 0.998). A total of 69 discriminant metabolites were identified based on the OPLS-DA model, with 37 and 32 metabolites detected to be higher in caffeinated and decaffeinated coffee, respectively. These metabolites include several benzoate and cinnamate-derived phenolic compounds, organic acids, sugar, fatty acids, and amino acids. Our study successfully established GC-TOF-MS based metabolomics approach as a highly robust tool in discriminant analysis between caffeinated and decaffeinated coffee samples. Discriminant metabolites identified in this study are biologically relevant and provide valuable insights into therapeutic research of coffee against AD. Our data also hint at possible involvement of gut microbial metabolism to enhance therapeutic potential of coffee components, which represents an interesting area for future research.     

Coffee and tea consumption during pregnancy and risk of childhood acute myeloid leukemia: A Childhood Leukemia International Consortium (CLIC) study

BackgroundDietary habits during pregnancy have been inconsistently linked to childhood acute myeloid leukemia (AML), given the putative intrauterine onset of the disease as a result of triggering events during the critical period of fetal hematopoiesis. We investigated the potential association of maternal coffee and tea consumption during pregnancy with childhood AML risk, pooling primary data from eight case-control studies participating in the Childhood Leukemia International Consortium.MethodsInformation on coffee and/or tea consumption was available for 444 cases and 1255 age- and sex-matched controls, on coffee consumption for 318 cases and 971 controls and on tea consumption for 388 cases and 932 controls. Categories for cups of daily coffee/tea consumption were created in order to explore potential dose-response associations. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression.ResultsAssociations were found neither in the analysis on coffee or tea nor in the analysis on coffee only consumption (any versus no). A positive association with increasing coffee intake was observed (>1 cup per day; OR: 1.40, 95% CI: 1.03–1.92, increment of one cup per day; OR: 1.18, 95% CI: 1.01–1.39). No associations were observed with tea consumption. Interaction analyses showed non-significant associations between coffee/tea and smoking. Hyperdiploidy was inversely associated with tea consumption, with other cytogenetic markers having no association with coffee/tea.ConclusionGiven the widespread consumption of caffeinated beverages among pregnant women, our finding is of important public health relevance, suggesting adverse effects of maternal coffee consumption during pregnancy in the offspring.     

Suppressive effect of coffee on lipopolysaccharide-induced hepatitis in D-galactosamine-sensitized rats

A coffee extract significantly suppressed lipopolysaccharide (LPS)-induced hepatitis in D-galactosamine-sensitized rats, as assessed by the plasma alanine and aspartate aminotransferase activities, when it was added to the diet (30 g/kg) and fed to rats for 14 days. Its effect was as strong as that of a green tea extract. The coffee extract suppressed LPS-induced hepatitis when singly force-fed (1.2 g/kg) 1.5 h prior to the injection of the drugs, whereas a decaffeinated coffee extract had no significant effect. The hepatoprotective effect of caffeine was stronger than that of theobromine. These results indicate that coffee can protect animals from LPS-induced hepatitis, and that the effect of coffee might be mainly due to caffeine.     

Suppressive Effect of Coffee on Lipopolysaccharide-induced Hepatitis in D-Galactosamine-sensitized Rats

A coffee extract significantly suppressed lipopolysaccharide (LPS)-induced hepatitis in D-galactosamine-sensitized rats, as assessed by the plasma alanine and aspartate aminotransferase activities, when it was added to the diet (30 g/kg) and fed to rats for 14 days. Its effect was as strong as that of a green tea extract. The coffee extract suppressed LPS-induced hepatitis when singly force-fed (1.2 g/kg) 1.5 h prior to the injection of the drugs, whereas a decaffeinated cofee extract had no significant effect. The hepatoprotective effect of caffeine was stronger than that of theobromine. These results indicate that coffee can protect animals from LPS-induced hepatitis, and that the effect of coffee might be mainly due to caffeine.     

Effect of Caffeine-Containing Beverage Consumption on Serum Alanine Aminotransferase Levels in Patients with Chronic Hepatitis C Virus Infection: A Hospital-Based Cohort Study

Introduction

To date, there have been no prospective studies examining the effect of coffee consumption on serum alanine aminotransferase (ALT) level among individuals infected with the hepatitis C virus (HCV). We conducted a hospital-based cohort study among patients with chronic HCV infection to assess an association between baseline coffee consumption and subsequent ALT levels for 12 months.

Materials and Methods

From 1 August 2005 to 31 July 2006, total 376 HCV-RNA positive patients were recruited. A baseline questionnaire elicited information on the frequency of coffee consumption and other caffeine-containing beverages. ALT level as a study outcome was followed through the patients’ medical records during 12 months. The association between baseline beverage consumption and subsequent ALT levels was evaluated separately among patients with baseline ALT levels within normal range (≤45 IU/L) and among those with higher ALT levels (>45 IU/L).

Results

Among 229 patients with baseline ALT levels within normal range, 186 (81%) retained normal ALT levels at 12 months after recruitment. Daily drinkers of filtered coffee were three times more likely to preserve a normal ALT level than non-drinkers (OR=2.74; P=0.037). However, decaffeinated coffee drinkers had a somewhat inverse effect for sustained normal ALT levels, with marginal significance (OR=0.26; P=0.076). In addition, among 147 patients with higher baseline ALT levels, 39 patients (27%) had ALT reductions of ≥20 IU/L at 12 months after recruitment. Daily drinkers of filtered coffee had a significantly increased OR for ALT reduction (OR=3.79; P=0.034). However, in decaffeinated coffee drinkers, OR could not be calculated because no patients had ALT reduction.

Conclusion

Among patients with chronic HCV infection, daily consumption of filtered coffee may have a beneficial effect on the stabilization of ALT levels.     

Vitamin-D pathway genes and HIV-1 disease progression in injection drug users

Vitamin-D has pleiotropic effects on calcium and bone metabolism, cellular growth control, cell differentiation and modulation of both innate and acquired immune response. Previous studies revealed the association of vitamin-D receptor gene (VDR) polymorphism with infection diseases including HIV-1 infection. To assess for association between polymorphisms of vitamin-D pathway genes CYP27B1, vitamin-D binding protein (VDBP) and VDR with HIV-1 infection, disease progression to acquired immunodeficiency syndrome (AIDS) was analysed according to CDC93 criteria in a cohort of 185 HIV-1 seroprevalent patients belonging to the injection drug users. Genotype data was obtained from rs10877012, rs3782130 and rs4646536 markers at CYP27B1 locus; rs7041 and rs4588 at VDBP locus; and rs11568820, rs4516035, rs2228570, rs1544410 and rs17878969 at VDR locus. Distribution of genotypes between patients grouped by outcome was compared by contingency table analysis. Marker–marker interaction was assessed by a MDR analysis. Assuming an additive model for VDR markers, a Kaplan–Meier survival analysis was employed to evaluate association with disease progression. Among vitamin-D pathway genes, VDR locus reveals specific 5′UTR and 3′UTR diplotype combinations associated with both, slower and faster progression to AIDS. Marker–marker interaction analysis indicates a strong interaction between VDR markers and a redundant effect for CYP27B1 markers. According to our results, VDR locus association follows an additive model in which increased genetic risk score for the VDR is directly correlated with AIDS progression rates. Our data supports a role of vitamin-D pathway gene variability on HIV-1 disease progression.     

Association between CYP1A2 and CYP1B1 Polymorphisms and Colorectal Cancer Risk: A Meta-Analysis

Background

The previous published data on the association between CYP1A2*F (rs762551), CYP1B1 Leu432Val (rs1056836), Asn453Ser (rs180040), and Arg48Gly (rs10012) polymorphisms and colorectal cancer risk remained controversial.

Methodology/Principal Findings

The purpose of this study is to evaluate the role of CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly genotypes in colorectal cancer susceptibility. We performed a meta-analysis on all the eligible studies that provided 5,817 cases and 6,544 controls for CYP1A2*F (from 13 studies), 9219 cases and 10406 controls for CYP1B1 Leu432Val (from 12 studies), 6840 cases and 7761 controls for CYP1B1 Asn453Ser (from 8 studies), and 4302 cases and 4791 controls for CYP1B1Arg48Gly (from 6 studies). Overall, no significant association was found between CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly and colorectal cancer risk when all the eligible studies were pooled into the meta-analysis. And in the subgroup by ethnicity and source of controls, no evidence of significant association was observed in any subgroup analysis.

Conclusions/Significance

In summary, this meta-analysis indicates that CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly polymorphisms do not support an association with colorectal cancer, and further studies are needed to investigate the association. In addition, our work also points out the importance of new studies for CYP1A2*F polymorphism in Asians, because high heterogeneity was found (dominant model: I ² = 81.3%; heterozygote model: I ² = 79.0).     

Effects of chronic coffee consumption on glucose kinetics in the conscious rat

Epidemiological studies indicate that regular coffee consumption reduces the risk of developing type 2 diabetes. Despite these findings, the biological mechanisms by which coffee consumption exerts these effects are unknown. The aim of this study was twofold: to develop a rat model that would further delineate the effects of regular coffee consumption on glucose kinetics, and to determine whether coffee, with or without caffeine, alters the actions of insulin on glucose kinetics in vivo. Male Sprague-Dawley rats were fed a high-fat diet for 4 weeks in combination with one of the following: (i) drinking water as placebo (PL), (ii) decaffeinated coffee (2 g/100 mL) (DC), or (iii) alkaloid caffeine (20 mg/100 mL) added to decaffeinated coffee (2 g/100 mL) (CAF). Catheters were chronically implanted in a carotid artery and jugular vein for sampling and infusions, respectively. Recovered animals (5 days postoperative) were fasted for 5 h before hyperinsulinemic-euglycemic clamps (2 mU x kg(-1) x min(-1)). Glucose was clamped at 6 mmol/L and isotopes (2-deoxy-[(14)C]glucose and [3-(3)H]glucose) were administered to obtain indices of whole-body and tissue-specific glucose kinetics. Glucose infusion rates and measures of whole-body metabolic clearance were greater in DC than in PL or CAF, indicating increased whole-body insulin sensitivity. As the only difference between DC and CAF was the addition of alkaloid caffeine, it can be concluded that caffeine antagonizes the beneficial effects of DC. Given these findings, decaffeinated coffee may represent a nutritional means of combating insulin resistance.     

Genome-wide meta-analysis identifies regions on 7p21 (AHR) and 15q24 (CYP1A2) as determinants of habitual caffeine consumption

We report the first genome-wide association study of habitual caffeine intake. We included 47,341 individuals of European descent based on five population-based studies within the United States. In a meta-analysis adjusted for age, sex, smoking, and eigenvectors of population variation, two loci achieved genome-wide significance: 7p21 (P = 2.4 × 10(-19)), near AHR, and 15q24 (P = 5.2 × 10(-14)), between CYP1A1 and CYP1A2. Both the AHR and CYP1A2 genes are biologically plausible candidates as CYP1A2 metabolizes caffeine and AHR regulates CYP1A2.     

Relationship among Habitual Tea Consumption,Percent Body Fat,and Body Fat Distribution

Objective: To disclose the possible relationship between habitual tea consumption and changes in total body fat and fat distribution in humans. Research Methods and Procedures: A cross‐sectional survey of 1210 epidemiologically sampled adults (569 men and 641 women) were enrolled in our study. Tea consumption and other lifestyle characteristics were obtained by structured questionnaires. Percent body fat (BF%) was measured using bioelectrical impedance analysis. Body fat distribution was assessed using waist‐to‐hip ratio (WHR). Results: Among the 1103 analyzed subjects, 473 adults (42.9%) consumed tea once or more per week for at least 6 months. The habitual tea drinkers were male‐dominant, more frequently current smokers, and alcohol or coffee drinkers than the nonhabitual tea drinkers. Habitual tea drinkers for more than 10 years showed a 19.6% reduction in BF% and a 2.1% reduction in WHR compared with nonhabitual tea drinkers. The multiple stepwise regression models revealed that men, older age, higher BMI, and current smokers were positive factors for BF% and WHR. In contrast, longer duration of habitual tea consumption and higher total physical activity were negative factors for BF%. Longer duration of habitual tea consumption, higher socioeconomic status, and premenopausal status were negative factors for WHR. Discussion: An inverse relationship may exist among habitual tea consumption, BF%, and body fat distribution, especially for subjects who have maintained the habit of tea consumption for more than 10 years.     

Role of caffeine and tannin in anti-toxigenic properties of coffee and tea

Aflatoxins B₁, B₂, G₁ and G₂ produced by Aspergillus parasiticus var. globosus IMI 120920 in detannin-caffeinated coffee and black tea were five times more concentrated than in normal tea and coffee. Extracts of normal coffee and tea powders significantly reduced aflatoxins production in liquid broth at 1 and 3 % concentrations, with tea extract. having a more pronounced effect than coffee extract Relevant anti-aflatoxigenic properties appear to be due to tannin and caffeine. These induced 95 % inhibition in aflatoxins at 0.3 % and 0.6 %, respectively. Roasting of contaminated coffee beans at 200 °C for 20 min is effective in the reduction of aflatoxins.     

Identification of a new susceptibility variant for multiple sclerosis in OAS1 by population genetics analysis

Contrasting results have been reported concerning the association of a splice-site polymorphism (rs10774671) in OAS1 with multiple sclerosis (MS). We analysed two OAS1 regions encompassing alternatively spliced exons. While the region carrying the splice-site variant is neutrally evolving, a signature of long-standing balancing selection was observed across an alternative exon 7. Analysis of variants in this exon identified an insertion/deletion polymorphism (rs11352835, A/?) that originates predicted products with distinct C termini. This variant is located along the major branch of the haplotype genealogy, suggesting that it may represent the selection target. A case/control study for MS indicated that rs11352835 is associated with disease susceptibility (for an allelic model with the deleted allele predisposing to MS, OR 1.27, 95% CI 1.072?C1.513, p?=?0.010). No association was found between rs10774671 and MS. As the two SNPs are in linkage disequilibrium in Europeans, the previously reported association between rs10774671 and MS susceptibility might be driven by rs11352835, possibly explaining the contrasting results previously observed for the splice-site polymorphism. Thus, we describe a novel susceptibility variant for MS in OAS1 and show that population genetic analyses can be instrumental to the identification of selection targets and, consequently, of functional polymorphisms with an effect on phenotypic traits.     

Caffeine adsorption of montmorillonite in coffee extracts

The growth in health-conscious consumers continues to drive the demand for a wide variety of decaffeinated beverages. We previously developed a new technology using montmorillonite (MMT) in selective decaffeination of tea extract. This study evaluated and compared decaffeination of coffee extract using MMT and activated carbon (AC). MMT adsorbed caffeine without significant adsorption of caffeoylquinic acids (CQAs), feruloylquinic acids (FQAs), dicaffeoylquinic acids (di-CQAs), or caffeoylquinic lactones (CQLs). AC adsorbed caffeine, chlorogenic acids (CGAs) and CQLs simultaneously. The results suggested that the adsorption selectivity for caffeine in coffee extract is higher in MMT than AC. The caffeine adsorption isotherms of MMT in coffee extract fitted well to the Langmuir adsorption model. The adsorption properties in coffee extracts from the same species were comparable, regardless of roasting level and locality of growth. Our findings suggest that MMT is a useful adsorbent in the decaffeination of a wide range of coffee extracts.     

Bladder cancer: smoking,beverages and artificial sweeteners

A matched patient-control study of bladder cancer examined the relationship of the disease to occupation, smoking and intake of tea, coffee, cola, alcohol and artificial sweeteners.There was no association of disease with occupation for these patients. Heavy smoking gave relative risks of 6.37 and 4.36 for men and women respectively; there was evidence of a dose-response relationship. Tea and coffee intake did not increase the risk of disease nor did prolonged use of artificial sweeteners. Alcohol and cola intake increased the relative risk of bladder cancer among male smokers. There is some suggestion that smoking interacts with both alcohol and cola intake in the production of bladder cancer.     

Body Weight Loss and Weight Maintenance in Relation to Habitual Caffeine Intake and Green Tea Supplementation

Objective: Investigation of the effect of a green tea‐caffeine mixture on weight maintenance after body weight loss in moderately obese subjects in relation to habitual caffeine intake. Research Methods and Procedures: A randomized placebo‐controlled double blind parallel trial in 76 overweight and moderately obese subjects, (BMI, 27.5 ± 2.7 kg/m²) matched for sex, age, BMI, height, body mass, and habitual caffeine intake was conducted. A very low energy diet intervention during 4 weeks was followed by 3 months of weight maintenance (WM); during the WM period, the subjects received a green tea‐caffeine mixture (270 mg epigallocatechin gallate + 150 mg caffeine per day) or placebo. Results: Subjects lost 5.9 ±1.8 (SD) kg (7.0 ± 2.1%) of body weight (p < 0.001). At baseline, satiety was positively, and in women, leptin was inversely, related to subjects’ habitual caffeine consumption (p < 0.01). High caffeine consumers reduced weight, fat mass, and waist circumference more than low caffeine consumers; resting energy expenditure was reduced less and respiratory quotient was reduced more during weight loss (p < 0.01). In the low caffeine consumers, during WM, green tea still reduced body weight, waist, respiratory quotient and body fat, whereas resting energy expenditure was increased compared with a restoration of these variables with placebo (p < 0.01). In the high caffeine consumers, no effects of the green tea‐caffeine mixture were observed during WM. Discussion: High caffeine intake was associated with weight loss through thermogenesis and fat oxidation and with suppressed leptin in women. In habitual low caffeine consumers, the green tea‐caffeine mixture improved WM, partly through thermogenesis and fat oxidation.