Green tea for weight loss and weight maintenance in overweight or obese adults

Dietary Supplement-Induced Hepatotoxicity: A Clinical Perspective

The consumption of dietary supplements (DS) has resulted in a significant and escalating number of cases involving liver injury. It is crucial for clinicians and consumers to be well informed about the adverse effects of such products, leading to their discontinuation and timely reporting of any harmful cases. This article delves into the clinical perspective of DS-related hepatotoxicity, highlighting key concepts such as a systematic diagnostic approach. The discussion extends to notable examples of both currently popular and potential future dietary supplements, such as garcinia cambogia, turmeric, and ashwagandha, accompanied by an overview of recent findings. Causality assessment tools play a crucial role in establishing a connection between these products and instances of liver injury, with consideration of the advantages and disadvantages associated with their use. Fostering a comprehensive understanding of regulatory standards, coupled with a solid foundation of knowledge of DS, will prove instrumental in preventing DS-related hepatotoxicity. Achieving this goal requires collaborative efforts from both consumers and clinicians.

A Comprehensive Review on the Use of Herbal Dietary Supplements in the USA, Reasons for Their Use, and Review of Potential Hepatotoxicity

Herbal and dietary supplement (HDS) use has grown exponentially in the United States. Unfortunately, the incidence of HDS-related liver injury has proportionally increased. Despite the potential for certain HDSs to cause clinically significant liver injury, they are not regulated by the Food and Drug Administration. Recent efforts have been made to regulate HDSs but are far removed from the scrutiny of prescription medications. Scant literature exists on HDSs and their risks of causing liver injury. In this comprehensive review, we examine trends of HDS use in the United States and the pathophysiologic mechanisms of drug-induced liver injury (DILI) of certain HDSs. Finally, we review usage rates; benefits, if any; purported pathophysiology of DILI; and propensity for progression to fulminant hepatic failure of nine HDSs linked to clinically significant DILI.

Targeting skeletal muscle mitochondrial health in obesity

Metabolic demands of skeletal muscle are substantial and are characterized normally as highly flexible and with a large dynamic range. Skeletal muscle composition (e.g., fiber type and mitochondrial content) and metabolism (e.g., capacity to switch between fatty acid and glucose substrates) are altered in obesity, with some changes proceeding and some following the development of the disease. Nonetheless, there are marked interindividual differences in skeletal muscle composition and metabolism in obesity, some of which have been associated with obesity risk and weight loss capacity. In this review, we discuss related molecular mechanisms and how current and novel treatment strategies may enhance weight loss capacity, particularly in diet-resistant obesity.

A Mild Causal Relationship Between Tea Consumption and Obesity in General Population: A Two-Sample Mendelian Randomization Study

Evidence from observational studies for the effect of tea consumption on obesity is inconclusive. This study aimed to verify the causal association between tea consumption and obesity through a two-sample Mendelian randomization (MR) analysis in general population-based datasets. The genetic instruments, single nucleotide polymorphisms (SNPs) associated with tea consumption habits, were obtained from genome-wide association studies (GWAS): UK Biobank, Nurses’ Health Study, Health Professionals Follow-up Study, and Women’s Genome Health Study. The effect of the genetic instruments on obesity was analyzed using the UK Biobank dataset (among ∼500,000 participants). The causal relationship between tea consumption and obesity was analyzed by five methods of MR analyses: inverse variance weighted (IVW) method, MR-Egger regression method, weighted median estimator (WME), weighted mode, and simple mode. Ninety-one SNPs were identified as genetic instruments in our study. A mild causation was found by IVW (odds ratio [OR] = 0.998, 95% confidence interval [CI] = 0.996 to 1.000, p = 0.049]), which is commonly used in two-sample MR analysis, indicating that tea consumption has a statistically significant but medically weak effect on obesity control. However, the other four approaches did not show significance. Since there was no heterogeneity and pleiotropy in this study, the IVW approach has the priority of recommendation. Further studies are needed to clarify the effects of tea consumption on obesity-related health problems in detail.

Using partial least squares to identify a dietary pattern associated with obesity in a nationally-representative sample of Canadian adults: Results from the Canadian Community Health Survey-Nutrition 2015

BACKGROUND

Hybrid methods of dietary patterns analysis have emerged as a unique and informative way to study diet-disease relationships in nutritional epidemiology research.

OBJECTIVE

To identify an obesogenic dietary pattern using weighted partial least squares (wPLS) in nationally representative Canadian survey data, and to identify key foods and/or beverages associated with the defined dietary pattern.

DESIGN

Data from one 24-hr dietary recall data from the cross-sectional Canadian Community Health Survey-Nutrition (CCHS) 2015 (n = 12,049) were used. wPLS was used to identify an obesogenic dietary pattern from 40 standardized food and beverage categories using the variables energy density, fibre density, and total fat as outcomes. The association between the derived dietary pattern and likelihood of obesity was examined using weighted multivariate logistic regression. Key dietary components highly associated with the derived pattern were identified.

RESULTS

Compared to quartile one (i.e. those least adherent to an obesogenic dietary pattern), those in quartile four had 2.40-fold increased odds of being obese (OR = 2.40, 95% CI = 1.91, 3.02, P-trend< 0.0001) with a monotonically increasing trend. Using a factor loading significance cut-off of ≥|0.17|, three food/beverage categories loaded positively for the derived obesogenic dietary pattern: fast food (+0.32), carbonated drinks (including energy drinks, sports drinks and vitamin water) (+0.30), and salty snacks (+0.19). Seven categories loaded negatively (i.e. in the protective direction): whole fruits (-0.40), orange vegetables (-0.32), "other" vegetables (-0.32), whole grains (-0.26), dark green vegetables (-0.22), legumes and soy (-0.18) and pasta and rice (-0.17).

CONCLUSION

This is the first study to apply weighted partial least squares to CCHS 2015 data to derive a dietary pattern associated with obesity. The results from this study pinpoint key dietary components that are associated with obesity and consumed among a nationally representative sample of Canadians adults.

Baseline drinking water consumption and changes in body weight and waist circumference at 2-years of follow-up in a senior Mediterranean population

BACKGROUND & AIMS

The association between drinking water consumption and adiposity has been poorly explored. Therefore, we aimed to analyse the associations between the frequency of drinking water consumption and body weight and waist circumference changes in an elderly Mediterranean cohort.

METHODS

A total of 1832 elderly participants (aged 55-75 years) with metabolic syndrome from the PREDIMED-Plus study with baseline data on drinking water and other beverages assessed by a validated 32-item Spanish fluid-intake questionnaire and with data on body weight (BW) and waist circumference (WC) at 1-year and 2-year were included in these prospective analyses. Multivariable linear regression models were fitted to assess the β-coefficients and 95% confidence interval (CI) for BW and WC changes in terms of categories of baseline drinking water consumption (tap water and bottled water). The theoretical effect on BW and WC of replacing several beverages with drinking water was assessed using mathematical models.

RESULTS

The baseline frequency of drinking water consumption was inversely associated with 1-year and 2-year changes in BW. β-coefficients (95%CI) across categories of water consumption (<2.5, 2.5 to <5, 5 to < 7.5, ≥7.5 servings/d) expressed in % of weight changes at 2 years of follow-up were 0.0, -0.80 (-1.48, -0.12), -1.36 (-2.18, -0.54), and -1.97 (-3.09, -0.86), respectively. Individuals in the two highest categories of drinking water consumption (5 to < 7, and ≥7.5 servings/d) also showed a higher decrease in WC (expressed as % of change) after 2 years of follow-up: -1.11 (-1.96, -0.25) and -1.45 (-2.66, -0.24) compared to the reference intake (<2.5 servings/day), after adjustment for potential confounding factors. The theoretical replacement of soups, beers, spirits, hot beverages, dairy beverages, and other beverages group with drinking water was associated with greater reductions in BW at one- and two-years of follow-up.

CONCLUSIONS

Drinking water consumption was inversely associated with 2-year adiposity changes in an elderly Mediterranean cohort at high cardiovascular risk. Our results also suggest that the consumption of drinking water instead of energy-containing beverages is associated with lower weight gain.

THE TRIAL REGISTRATION

ISRCTN89898870.

Providing food to patients in primary care to induce weight loss: a systematic literature review

Purpose

Primary care is the ideal setting to promote weight management, warranting innovative ways to support patients. This systematic review aimed to determine whether providing food to patients in primary care can help to reduce body weight.

Methods

Four databases were searched for studies that aimed to elicit weight loss by directly providing foodstuffs and/or supplements to patients in primary care settings. Interventions with adults of any gender or race were included. Interventions that involved other components such as exercise classes or education sessions were excluded. The methodological quality of each study was appraised using the Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies.

Results

Four heterogeneous studies met the eligibility criteria, representing 476 adults. Two studies used meal-replacement products but differed in length and intensity, another study provided green tea and vitamin E supplementation, and the final study provided vouchers for use at a farmers’ market hosted at a primary care clinic. Interventions ranged in length from 4 to 13 weeks. Three of the four studies observed weight loss in some form and all studies observed at least one other improvement in a health outcome such as waist circumference, blood pressure or fasting insulin levels.

Conclusions

A small yet notable body of literature supports the concept of providing food to patients in primary care settings to support weight loss. Further, high-quality research is needed on the efficacy and cost-effectiveness of this approach to ultimately inform policy initiatives for primary care.

Effect of Acute and Chronic Dietary Supplementation with Green Tea Catechins on Resting Metabolic Rate, Energy Expenditure and Respiratory Quotient: A Systematic Review

The consumption of green tea catechins (GTC) is associated with modulations of fat metabolism and consequent weight loss. The aim of this systematic review was to investigate the effect of GTC on resting metabolic rate (RMR), energy expenditure (EE), and respiratory quotient (RQ). Eligible studies considered both the chronic and acute intake of GTC-based supplements, with epigallocatechin gallate (EGCG) doses ranging between 100–800 mg. Findings from 15 studies (n = 499 participants) lasting 8–12 weeks (for chronic consumption) or 1–3 days (for acute intake) are summarized. This review reveals the positive effects of GTC supplementation on RQ values (272 subjects). Regarding the effects of acute and chronic GTC supplementation on RMR (244 subjects) and EE (255 subjects), the results did not allow for a definitive conclusion, even though they were promising, because some reported a positive improvement (two studies revealed an increase in RMR: one demonstrated an RMR increase of 43.82 kcal/day and another demonstrated an increase of 260.8 kcal/day, mainly when subjects were also engaged in resistance training exercise). Considering GTC daily dose supplementation, studies in which modifications of energetic parameters occurred, in particular RQ reduction, considered GTC low doses (100–300 mg). GTC may be useful for improving metabolic profiles. Further investigations are needed to better define adequate doses of supplementation.

Effects of Oil Tea on Obesity and Dyslipidemia: A Cross-Sectional Study in China

BACKGROUND

Animal experiments have found that oil tea reduces body weight and improves blood lipid levels. However, the effect of oil tea on human health has not been confirmed yet. This study aims to explore the relationship between oil tea consumption and obesity and dyslipidemia.

METHODS

In a cross-sectional population study in Guangxi, China, a semi-quantitative questionnaire was used to investigate the oil tea consumed and food consumption frequency in adults aged 30 years and over. Anthropometric variables and serum biochemical indicators were measured. A total of 2001 adults were divided into five groups based on their non-consumption status and quartile of consumption (groups non-drink oil tea, Q1-Q4).

RESULTS

The risk of abdominal obesity tended to decrease significantly with increasing consumption of oil tea (P for trend< 0.05) in the overall participants (Q3 group, OR = 0.545, 95% CI = 0.336-0.884; Q4 group, OR = 0.520, 95% CI = 0.311-0.871) and in women (Q2 group, OR = 0.502, 95% CI = 0.274-0.920; Q3 group, OR = 0.397, 95% CI = 0.213-0.740; Q4 group, OR = 0.421, 95% CI = 0.228-0.780). Oil tea consumption Q1, Q2, Q3 and Q4 group significantly reduced the risk of abnormal HDL-cholesterol (P < 0.05). Oil tea consumption Q2 group significantly increased the risk of abnormal LDL-cholesterol (OR = 2.600, 95% CI = 1.033-6.546) in women. Oil tea consumption Q1 (OR = 0.081, 95% CI =0.008-0.864) and Q3 (OR = 0.057, 95% CI = 0.004-0.913) groups significantly reduced the risk of abnormal HDL-cholesterol in women.

CONCLUSION

Oil tea consumption may be associated with a low risk of abdominal obesity. High-dose oil tea consumption may be associated with a low risk of abnormal HDL-cholesterol. Prospective studies with large sample sizes would be required to further investigate this association.

Daily Consumption of Coffee and Eating Bread at Breakfast Time Is Associated with Lower Visceral Adipose Tissue and with Lower Prevalence of Both Visceral Obesity and Metabolic Syndrome in Japanese Populations: A Cross-Sectional Study

BACKGROUND

The study aimed to investigate the association between daily consumption of coffee or green tea, with and without habitual bread consumption for breakfast, and components and prevalence of metabolic syndrome in Japanese populations.

METHODS

The study population consisted of 3539 participants (1239 males and 2300 females). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression analyses to evaluate the associations of daily coffee and green tea consumption with the prevalence of obesity, visceral obesity, and metabolic syndrome.

RESULTS

Coffee consumption was associated with significantly lower proportions of visceral obesity (OR: 0.746, CI: 0.588-0.947) and metabolic syndrome (OR: 0.706, CI: 0.565-0.882). On the other hand, green tea was not associated with visceral obesity (OR: 1.105, CI: 0.885-1.380) or metabolic syndrome (OR: 0.980, CI: 0.796-1.206). The combination of daily drinking coffee and eating bread at breakfast time was associated with significantly lower proportions of obesity (OR: 0.613, CI: 0.500-0.751) (p = 0.911 for interaction), visceral obesity (OR: 0.549, CI: 0.425-0.710) (p = 0.991 for interaction), and metabolic syndrome (OR: 0.586, CI: 0.464-0.741) (p = 0.792 for interaction).

CONCLUSION

Coffee consumption was significantly associated with lower visceral adipose tissue and lower proportions of visceral obesity, but the same was not true for green tea consumption. Furthermore, in combination with coffee consumption, the addition of eating bread at breakfast time significantly lowered proportions of visceral obesity and metabolic syndrome, although there was no interaction between coffee and bread.

Green tea and cancer and cardiometabolic diseases: a review of the current epidemiological evidence

Green tea is commonly consumed in China, Japan, and Korea and certain parts of North Africa and is gaining popularity in other parts of the world. The aim of this review was to objectively evaluate the existing evidence related to green tea consumption and various health outcomes, especially cancer, cardiovascular disease and diabetes. This review captured evidence from meta-analyses as well as expert reports and recent individual studies. For certain individual cancer sites: endometrial, lung, oral and ovarian cancer, and non-Hodgkins lymphoma the majority of meta-analyses observed an inverse association with green tea. Mixed findings were observed for breast, esophageal, gastric, liver and a mostly null association for colorectal, pancreatic, and prostate cancer. No studies reported adverse effects from green tea related to cancer although consuming hot tea has been found to possibly increase the risk of esophageal cancer and concerns of hepatotoxity were raised as a result of high doses of green tea. The literature overall supports an inverse association between green tea and cardiovascular disease-related health outcomes. The evidence for diabetes-related health outcomes is less convincing, while the included meta-analyses generally suggested an inverse association between green tea and BMI-related and blood pressure outcomes. Fewer studies investigated the association between green tea and other health outcomes such as cognitive outcomes, dental health, injuries and respiratory disease. This review concludes that green tea consumption overall may be considered beneficial for human health.

Anti-Obesity Effects of Polyphenol Intake: Current Status and Future Possibilities

The prevalence of obesity has steadily increased worldwide over the past three decades. The conventional approaches to prevent or treat this syndrome and its associated complications include a balanced diet, an increase energy expenditure, and lifestyle modification. Multiple pharmacological and non-pharmacological interventions have been developed with the aim of improving obesity complications. Recently, the use of functional foods and their bioactive components is considered a new approach in the prevention and management of this disease. Due to their biological properties, polyphenols may be considered as nutraceuticals and food supplement recommended for different syndromes. Polyphenols are a class of naturally-occurring phytochemicals, some of which have been shown to modulate physiological and molecular pathways involved in energy metabolism. Polyphenols could act in the stimulation of β-oxidation, adipocyte differentiation inhibition, counteract oxidative stress, etc. In this narrative review, we considered the association between polyphenols (resveratrol, quercetin, curcumin, and some polyphenolic extracts) and obesity, focusing on human trials. The health effects of polyphenols depend on the amount consumed and their bioavailability. Some results are contrasting, probably due to the various study designs and lengths, variation among subjects (age, gender, ethnicity), and chemical forms of the dietary polyphenols used. But, in conclusion, the data so far obtained encourage the setting of new trials, necessary to validate benefic role of polyphenols in obese individuals.

Nutraceuticals: Reviewing their Role in Chronic Disease Prevention and Management

Over half the adult population in many Western countries consume nutraceuticals because of their purported therapeutic benefits, accessibility and convenience. Several studies have demonstrated that they may also serve as a useful adjunct to pharmaceuticals to better manage chronic conditions or offset negative side effects. Individuals are advised to consult their physician before using nutraceuticals, but this advice is often overlooked. Thus, the community pharmacist plays an increasingly important role in assisting consumers with selecting a nutraceutical that is safe and for which there is evidence of therapeutic efficacy. Therefore, the aim of this review is to summarise the clinical evidence, safety and purported mechanisms of action for selected nutraceuticals in the management of chronic diseases, including obesity, diabetes, hypertension, hypercholesterolemia and inflammatory-based diseases.

A Critical Review on the Role of Food and Nutrition in the Energy Balance

The mass media has increasingly frequently suggested to the general population that specific foods or nutritional schemes are able to affect both human metabolism and energy expenditure, thus facilitating weight loss. This critical review is aimed at assessing available evidence on the roles of nutrients, food and dietary regimens in energy intake and energy expenditure. We queried the National Library of Medicine, the Cochrane Library, Excerpta Medica dataBASEand the Cumulative Index to Nursing and Allied Health Literature database, and a search strategy was performed by using database-specific subject headings and keywords. We found that available scientific evidence on these topics is scarce, and that the limited number of available studies often have poor methodological quality. Only a few foods show beneficial effects on metabolism and energy expenditure, as the human energy balance is complex and multifactorial. Finally, microbiota may interfere with the intake, use and expenditure of energy in the human body. Conclusive evidence is still lacking, and, at present, it is not possible to identify a food or a diet with a significant impact on human energy expenditure.

United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts

As part of the United States Pharmacopeia's ongoing review of dietary supplement safety data, a new comprehensive systematic review on green tea extracts (GTE) has been completed. GTEs may contain hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids and elemental impurities, but no evidence of their involvement in GTE-induced liver injury was found during this review. GTE catechin profiles vary significantly with manufacturing processes. Animal and human data indicate that repeated oral administration of bolus doses of GTE during fasting significantly increases bioavailability of catechins, specifically EGCG, possibly involving saturation of first-pass elimination mechanisms. Toxicological studies show a hepatocellular pattern of liver injury. Published adverse event case reports associate hepatotoxicity with EGCG intake amounts from 140 mg to ∼1000 mg/day and substantial inter-individual variability in susceptibility, possibly due to genetic factors. Based on these findings, USP included a cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph that reads as follows: "Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes)."

Does green tea extract enhance the anti-inflammatory effects of exercise on fat loss?

AIMS

Green tea extract (GTE) can exert antiobesity and anti-inflammatory effects. Our study determined whether the benefits of GTE are summative with exercise-induced changes in anthropometric indices, and the levels of inflammatory cytokines, adiponectin and irisin in inactive overweight women.

METHODS

Thirty overweight female participants were randomized to 3 groups: endurance training + placebo (ET + P); endurance training + GTE (ET + GTE); and Control (no exercise) + placebo (Control, n = 10). The exercise intervention consisted of an 8-week endurance-training programme of 3 sessions per week (aerobics, aerobic circuit training, and fast walking or jogging at a moderate intensity of 40-59% of the heart rate reserve). The dose of GTE used was 500 mg/day in the form of a green tea capsule.

RESULTS

Body weight, body mass index, waist to hip ratio and body fat percentage were decreased in both ET + P and ET + GTE interventions (P < .001 for both interventions). The reduction of anthropometric values in the ET + GTE group was significantly higher than ET + P interventions (P < .001). Both exercise interventions also significantly (P < .001) increased adiponectin (ET + GTE = 5.28 mg/mL [95% confidence interval {CI}, 4.48 to 6.08] and ET + P = 3.34 mg/mL [95% CI, 2.76 to 3.92]) and decreased high-sensitivity C-reactive protein (hs-CRP; ET + GTE = -0.95 mg/L [95% CI, -1.15 to -0.75] and ET + P = -0.35 mg/L [95% CI, -0.46 to -0.24]). Changes in adiponectin and hs-CRP were greater (P < .05) in ET + GTE compared to ET + P. There were no significant differences in irisin, interleukin-6 or tumour necrosis factor-α between the 3 groups (P > .05).

CONCLUSIONS

GTE improves exercise-induced body composition by further decreasing exercise-induced changes in weight, body mass index, waist to hip ratio and body fat percentage. The combination of GTE and exercise also produced greater changes in anti-inflammatory (increases in adiponectin) and metabolic (decreases in hs-CRP) markers than exercise alone.

Tea Compounds and the Gut Microbiome: Findings from Trials and Mechanistic Studies

In recent years, the gut microbiome has become a focal point of interest with growing recognition that a well-balanced gut microbiota composition is highly relevant to an individual’s health status and well-being. Its profile can be modulated by a number of dietary factors, although few publications have focused on the effects of what we drink. The present review performed a systematic review of trials and mechanistic studies examining the effects of tea consumption, its associated compounds and their effects on the gut microbiome. Registered articles were searched up to 10th September 2019, in the PubMed and Cochrane library databases along with references of original articles. Human trials were graded using the Jadad scale to assess quality. Altogether 24 publications were included in the main review—six were human trials and 18 mechanistic studies. Of these, the largest body of evidence related to green tea with up to 1000 mL daily (4–5 cups) reported to increase proportions of Bifidobacterium. Mechanistic studies also show promise suggesting that black, oolong, Pu-erh and Fuzhuan teas (microbially fermented ‘dark tea’) can modulate microbial diversity and the ratio of Firmicutes to Bacteroidetes. These findings appear to support the hypothesis that tea ingestion could favourably regulate the profile of the gut microbiome and help to offset dysbiosis triggered by obesity or high-fat diets. Further well-designed human trials are now required to build on provisional findings.

Cardiovascular Effects of Flavonoids

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Cardiovascular Disease (CVD) is the major cause of death worldwide, especially in Western society. Flavonoids are a large group of polyphenolic compounds widely distributed in plants, present in a considerable amount in fruit and vegetable. Several epidemiological studies found an inverse association between flavonoids intake and mortality by CVD. The antioxidant effect of flavonoids was considered the main mechanism of action of flavonoids and other polyphenols. In recent years, the role of modulation of signaling pathways by direct interaction of flavonoids with multiple protein targets, namely kinases, has been increasingly recognized and involved in their cardiovascular protective effect. There are strong evidence, in in vitro and animal experimental models, that some flavonoids induce vasodilator effects, improve endothelial dysfunction and insulin resistance, exert platelet antiaggregant and atheroprotective effects, and reduce blood pressure. Despite interacting with multiple targets, flavonoids are surprisingly safe. This article reviews the recent evidence about cardiovascular effects that support a beneficial role of flavonoids on CVD and the potential molecular targets involved.

Relationship between Mediterranean Dietary Polyphenol Intake and Obesity

Obesity is a multifactorial and complex disease defined by excess of adipose mass and constitutes a serious health problem. Adipose tissue acts as an endocrine organ secreting a wide range of inflammatory adipocytokines, which leads to systemic inflammation, insulin resistance, and metabolic disorders. The traditional Mediterranean diet is characterized by a high phenolic-rich foods intake, including extra-virgin olive oil, nuts, red wine, vegetables, fruits, legumes, and whole-grain cereals. Evidence for polyphenols’ effect on obesity and weight control in humans is inconsistent and the health effects of polyphenols depend on the amount consumed and their bioavailability. The mechanisms involved in weight loss in which polyphenols may have a role are: activating β-oxidation; a prebiotic effect for gut microbiota; inducing satiety; stimulating energy expenditure by inducing thermogenesis in brown adipose tissue; modulating adipose tissue inhibiting adipocyte differentiation; promoting adipocyte apoptosis and increasing lipolysis. Even though the intake of some specific polyphenols has been associated with body weight changes, there is still no evidence for the effects of total polyphenols or some polyphenol subclasses in humans on adiposity.

Acute Epigallocatechin 3 Gallate (EGCG) Supplementation Delays Gastric Emptying in Healthy Women: A Randomized, Double-Blind, Placebo-Controlled Crossover Study

Background: Epigallocatechin 3 Gallate (EGCG) appears to act in appetite control through hormonal modulation. However, there is a lack of elucidation of EGCG's action mechanisms, especially in humans. The aim of this study was to evaluate the effects of acute EGCG supplementation on gastric emptying and its relation to blood hormones, glucose and appetite perceptions in healthy women. Methods: 22 healthy adult women were included in a randomized, double-blind, placebo-controlled crossover study. On two separate occasions, 1 week apart from each other, we offered 800 mg of corn starch (placebo) or 752 mg of EGCG. Appetite was assessed through gastric emptying; perceptions of hunger, desire to eat and satiation; and plasma insulin, adiponectin, leptin and glucose concentrations. The evaluations were carried out in fasting, 30, 90 and 150 min after supplementation. Results: EGCG supplementation induced higher relative gastric volume at 30 and 90 min. Satiation at 90 min was higher in the EGCG group. Adiponectin concentrations at 150 min were higher with EGCG, but no difference was found for glucose, insulin and leptin concentrations. Conclusions: Acute EGCG supplementation is able to delay gastric emptying in healthy women to a small, but statistically significant extent. This study was registered at the Brazilian Registry of Clinical Trials (ReBEC) as RBR-9svwrv.

IOC consensus statement: dietary supplements and the high-performance athlete

Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the management of micronutrient deficiencies, (2) supply of convenient forms of energy and macronutrients, and (3) provision of direct benefits to performance or (4) indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can benefit the athlete, but others may harm the athlete's health, performance, and/or livelihood and reputation (if an antidoping rule violation results). A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome and habitual diet. Supplements intended to enhance performance should be thoroughly trialled in training or simulated competition before being used in competition. Inadvertent ingestion of substances prohibited under the antidoping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete's health and awareness of the potential for harm must be paramount; expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.

Dietary Supplement of Large Yellow Tea Ameliorates Metabolic Syndrome and Attenuates Hepatic Steatosis in db/db Mice

Yellow tea has been widely recognized for its health benefits. However, its effects and mechanism are largely unknown. The current study investigated the mechanism of dietary supplements of large yellow tea and its effects on metabolic syndrome and the hepatic steatosis in male db/db mice. Our data showed that dietary supplements of large yellow tea and water extract significantly reduced water intake and food consumption, lowered the serum total and low-density lipoprotein cholesterol and triglyceride levels, and significantly reduced blood glucose level and increased glucose tolerance in db/db mice when compared to untreated db/db mice. In addition, the dietary supplement of large yellow tea prevented the fatty liver formation and restored the normal hepatic structure of db/db mice. Furthermore, the dietary supplement of large yellow tea obviously reduced the lipid synthesis related to gene fatty acid synthase, the sterol regulatory element-binding transcription factor 1 and acetyl-CoA carboxylase α, as well as fatty acid synthase and sterol response element-binding protein 1 expression, while the lipid catabolic genes were not altered in the liver of db/db mice. This study substantiated that the dietary supplement of large yellow tea has potential as a food additive for ameliorating type 2 diabetes-associated symptoms.

Principles of pharmacological research of nutraceuticals

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Evaluation of Endometrial Angiogenesis in Mice Uterus Before Implantation in Natural Cycles Followed by Use of Human Menopausal Gonadotropin - Human Chorionic Gonadotropin Drugs and Epigallocatechin Gallate

Background:

Angiogenesis plays a major role in endometrial receptivity and thickening of the endometrium immediately before implantation. The aim of the present work was to evaluate the antiangiogenic properties of epigallocatechin-3-gallate (EGCG) from green tea in angiogenesis of endometrium.

Materials and Methods:

In this study, forty adult female NMARI mice randomly divided into four groups. Control group received vehicle; human menopausal gonadotropin/human chorionic gonadotropin (HMG/HCG) group received 7.5 IU HMG intraperitoneal (IP) and 48 h later 7.5 IU HCG was injected (IP) for ovarian stimulation; HMG/HCG + EGCG group received HMG and HCG in the same manner as the previous group and also received 5 mg/kg EGCG at 0, 24, 48, and 72 h after injection of HMG; and the group EGCG received 5 mg/kg EGCG. A male mouse was kept with two female animals in the same cage for mating. Mice were dissected 96 h after administration of HMG (immediately before implantation) and tissue processing was carried out for the uterine specimens. CD31-positive cells were counted by use of histological and immunohistochemical methods.

Results:

Angiogenesis in EGCG-treated group was less than that of control and gonadotropin group (P < 0.05). The number of endothelial cells was counted by CD31 marker under a light microscope and showed significant differences between all groups (P < 0.05).

Conclusion:

EGCG significantly inhibited the angiogenesis in endometrium (in natural cycles) through antiangiogenic effects.

Comparison of the Effects of Goat Dairy and Cow Dairy Based Breakfasts on Satiety, Appetite Hormones, and Metabolic Profile

The satiating effects of cow dairy have been thoroughly investigated; however, the effects of goat dairy on appetite have not been reported so far. Our study investigates the satiating effect of two breakfasts based on goat or cow dairy and their association with appetite related hormones and metabolic profile. Healthy adults consumed two breakfasts based on goat (G-Breakfast) or cow (C-Breakfast) dairy products. Blood samples were taken and VAS tests were performed at different time points. Blood metabolites were measured and Combined Satiety Index (CSI) and areas under the curves (AUC) were calculated. Desire to eat rating was significantly lower (breakfast &amp; time interaction p < 0.01) and hunger rating tended to be lower (breakfast &amp; time interaction p = 0.06) after the G-breakfast. None of the blood parameters studied were different between breakfasts; however, AUC_GLP-1 was inversely associated with the AUC_hunger and AUC_{desire-to-eat} after the G-Breakfast, whereas triglyceride levels were directly associated with AUC_CSI after the C-Breakfast. Our results suggest a slightly higher satiating effect of goat dairy when compared to cow dairy products, and pointed to a potential association of GLP-1 and triglyceride levels with the mechanisms by which dairy products might affect satiety after the G-Breakfast and C-Breakfast, respectively.

A Balanced Risk-Benefit Analysis to Determine Human Risks Associated with Pyrrolizidine Alkaloids (PA)-The Case of Tea and Herbal Infusions

Humans are exposed to pyrrolizidine alkaloids (PA) through different sources, mainly from contaminated foodstuff. Teas and herbal infusions (T&HI) can be contaminated by PA producing weed. PA can possess toxic, mutagenic, genotoxic, and carcinogenic properties. Thus, possible health risks for the general population are under debate. There is a strong safety record for T&HI and additionally epidemiological evidence for the preventive effects of regular tea consumption on cardiovascular events and certain types of cancer. There is no epidemiological evidence, however, for human risks of regular low dose PA exposure. Recommended regulatory PA-threshold values are based on experimental data only, accepting big uncertainties. If a general risk exists through PA contaminated T&HI, it must be small compared to other frequently accepted risks of daily living and the proven health effects of T&HI. Decision making should be based on a balanced riskbenefit analysis. Based on analyses of the scientific data currently available, it is concluded that the benefits of drinking T&HI clearly outweigh the negligible health risk of possible PA contamination. At the same time, manufacturers must continue their efforts to secure good product quality and to be transparent on their measures of quality control and risk communication.

Long-term supplementation of decaffeinated green tea extract does not modify body weight or abdominal obesity in a randomized trial of men at high risk for prostate cancer

Background

Evidence continues to demonstrate the role of obesity in prostate carcinogenesis and prognosis, underscoring the need to identify and continue to evaluate the effective interventions to reduce obesity in populations at high risk. The aim of the study was to determine the effect of daily consumption of decaffeinated green tea catechins (GTC) formulation (Polyphenon E^® (PolyE)) for 1 year on biomarkers of obesity in men who are at high risk for prostate cancer.

Materials and Methods

A randomized, double-blinded trial was conducted targeting 97 men diagnosed with HGPIN or ASAP. Subjects were randomized to receive GTC (PolyE) (n = 49) or placebo (n = 48) for 1 year. Anthropometric data were collected at baseline, 6 and 12 months and data analyzed to observe change in weight, body mass index (indicator of obesity) and waist: hip ratio (indicator of abdominal obesity).

Results

Decaffeinated GTC containing 400 mgs of the bioactive catechin, EGCG administered for 1 year to men diagnosed with ASAP and HGPIN appears to be bioavailable, well tolerated but not effective in reducing biomarkers of obesity including body weight, body mass index and waist: hip ratio.

Conclusions

The results of our trial demonstrates that men who are obese and at high risk for prostate cancer should resort to effective weight management strategies to reduce obesity and not resort to ineffective measures such as taking supplements of green tea to reduce biomarkers of obesity. Changes in body mass index and abdominal obesity seen in other studies were potentially due to caffeine and not GTC.

Protective effects of tea polyphenols on exhaustive exercise-induced fatigue, inflammation and tissue damage

Background: The beneficial properties of tea polyphenols have been extensively studied; however, less attention has been paid to their effects, especially anti-inflammatory effect during exhaustive exercise.

Objective: The present study assessed the potential protective effects of tea polyphenols against the fatigue, inflammation and tissue injury caused by an exhaustive exercise bout in rats.

Design: Twenty-four healthy male rats were divided into three groups. Group C was a sedentary control group, Groups E+TP and Group E performed a single exhaustive swimming test; all groups had normal diets, but Group E+TP was supplemented with tea polyphenols. All rats were immediately euthanized after exhaustive exercise, and biochemical and inflammatory parameters, including lactic acid (LA), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), lactic dehydrogenase (LDH), and creatine kinase (CK) activity levels, were measured. Reverse transcription (RT) and Real-Time PCR was employed to evaluate the mRNA expression of IL-1β in the liver.

Results: The results showed a decrease in serum LA levels (22%, p < 0.05) in rats that consumed dietary tea polyphenols. Interestingly, dietary tea polyphenols decreased the serum levels of pro-inflammatory factors (TNF-α: 13%, p < 0.05; IL-1β: 10%, p < 0.05; and IL-6: 48%, p < 0.05) and shifted the serum IL-10/TNF-α ratio to a predominantly anti-inflammatory milieu (0.52 ± 0.07 vs. 0.67 ± 0.10, p < 0.01). Furthermore, the polyphenols effectively inhibited the release of tissue damage markers (CK: 24%, p < 0.05 and LDH: 28%, p < 0.05) in the serum and decreased IL-1β mRNA expression in the liver.

Conclusions: This study indicated that tea polyphenols could significantly protect rats from the fatigue, inflammation and tissue damage induced by acute exhaustive exercise.

A systematic review and narrative synthesis of interventions for uncomplicated obesity: weight loss, well-being and impact on eating disorders

OBJECTIVE

Most weight loss research focuses on weight as the primary outcome, often to the exclusion of other physiological or psychological measures. This study aims to provide a holistic evaluation of the effects from weight loss interventions for individuals with obesity by examining the physiological, psychological and eating disorders outcomes from these interventions.

METHODS

Databases Medline, PsycInfo and Cochrane Library (2011-2016) were searched for randomised controlled trials and systematic reviews of obesity treatments (dietary, exercise, behavioural, psychological, pharmacological or surgical). Data extracted included study features, risk of bias, study outcomes, and an assessment of treatment impacts on physical, psychological or eating disorder outcomes.

RESULTS

From 3628 novel records, 134 studies met all inclusion criteria and were evaluated in this review. Lifestyle interventions had the strongest evidence base as a first-line approach, with escalation to pharmacotherapy and bariatric surgery in more severe or complicated cases. Quality of life was the most common psychological outcome measure, and improved in all cases where it was assessed, across all intervention types. Behavioural, psychological and lifestyle interventions for weight loss led to improvements in cognitive restraint, control over eating and binge eating, while bariatric surgery led to improvements in eating behaviour and body image that were not sustained over the long-term.

DISCUSSION

Numerous treatment strategies have been trialled to assist people to lose weight and many of these are effective over the short-term. Quality of life, and to a lesser degree depression, anxiety and psychosocial function, often improve alongside weight loss. Weight loss is also associated with improvements in eating disorder psychopathology and related measures, although overall, eating disorder outcomes are rarely assessed. Further research and between-sector collaboration is required to address the significant overlap in risk factors, diagnoses and treatment outcomes between obesity and eating disorders.

Green tea extract and catechol-O-methyltransferase genotype modify the post-prandial serum insulin response in a randomised trial of overweight and obese post-menopausal women

BACKGROUND

Green tea extract (GTE) may be involved in a favourable post-prandial response to high-carbohydrate meals. The catechol-O-methyltransferase (COMT) genotype may modify these effects. We examined the acute effects of GTE supplementation on the post-prandial response to a high-carbohydrate meal by assessing appetite-associated hormones and glucose homeostasis marker concentrations in women who consumed 843 mg of (-)-epigallocatechin-3-gallate (EGCG) or placebo capsules for 11-12 months.

METHODS

Sixty Caucasian post-menopausal women (body mass index ≥ 25.0 kg m^-2 ) were included in a randomised, double-blind feeding study. GTE was consumed with a breakfast meal [2784.0 kJ (665.4 kcal); 67.2% carbohydrate]. Blood samples were drawn pre-meal, post-meal, and every 30 min for 4 h. Participants completed six satiety questionnaires.

RESULTS

Plasma leptin, ghrelin and adiponectin did not differ between GTE and placebo at any time point; COMT genotype did not modify these results. Participants randomised to GTE with the high-activity form of COMT (GTE-high COMT) had higher insulin concentrations at time 0, 0.5 and 1.0 h post-meal compared to all COMT groups randomised to placebo. Insulin remained higher in the GTE-high COMT group at 1.5, 2.0 and 2.5 h compared to Placebo-low COMT (P < 0.02). GTE-high COMT had higher insulin concentrations at times 0, 0.5, 1.0, 1.5 and 2.0 h compared to the GTE-low COMT (P ≤ 0.04). Area under the curve measurements of satiety did not differ between GTE and placebo.

CONCLUSIONS

GTE supplementation and COMT genotype did not alter acute post-prandial responses of leptin, ghrelin, adiponectin or satiety, although it may be involved in post-meal insulinaemic response of overweight and obese post-menopausal women.

Effects of Greenselect Phytosome® on weight maintenance after weight loss in obese women: a randomized placebo-controlled study

Background

Most subjects regain weight after weight loss due to compensatory adaptations finalized to maintain stable body energy stores. Green tea (GT) preparations, which help maintain energy expenditure while dieting could be a useful strategy to facilitate weight maintenance. The usefulness of GT preparations in weight maintenance has been poorly studied so far with conflicting results. This study evaluated if a supplement of GSP and piperine helps obese women to maintain the weight loss obtained with a 3-month lifestyle intervention.

Methods

In a randomized placebo-controlled study, we examined whether a highly bioavailable GT extract may counteract weight regain after weight loss. Forty obese women (age 50.1 ± 10.1 years, Body Mass Index (BMI) 36.3 ± 2.7 kg/m²) underwent a 3-month lifestyle intervention. At the end of the intervention, the women were randomized in two groups for the weight-maintenance phase: 20 of them were prescribed twice a day, for 3 months, with a formula containing 150 mg/dose of Greenselect Phytosome® and 15 mg/dose of pure piperine (GSP group), and 20 were given placebo (P group). Anthropometric measures and body composition were measured before (V-3) and after lifestyle intervention (V0), 1 (V1), 2 (V2), and 3 (V3) months after prescribing supplements and 3 months following the discontinuation of supplements (V6).

Results

Lifestyle intervention induced a significant weight reduction in both groups with similar weight change (−6.2 ± 2.6 in GSP group vs. −4.8 ± 3.1 % in P group). In the GSP group, V1 in comparison to V0, had further reduction in weight and fat mass, which remained stable at V2 and V3 and increased at V6. In the P group, weight and fat mass increased from V2 onwards. Weight changes in GSP group and P group from V0 to V3 were −1.0 kg (95 % CI −2.5 to +0.5) and + 0.3 kg (95 % CI −0.9 to +1.6), respectively.

The proportion of women with weight loss ≥ 5 % was greater in the GSP group than in the P group (75 % vs. 45 % at V1, and 60 % vs. 30 % at V6, p < 0.05 for both groups).

Conclusions

Greenselect Phytosome® devoid of caffeine may have a clinical potential for the maintenance of weight after intentional weight loss.

Trial registration

Clinicaltrials.gov NCT02542449 (September 2015)

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1214-x) contains supplementary material, which is available to authorized users.

Effects of microalgal polyunsaturated fatty acid oil on body weight and lipid accumulation in the liver of C57BL/6 mice fed a high fat diet

Dietary polyunsaturated fatty acids (PUFAs), which are abundant in marine fish oils, have recently received global attention for their prominent anti-obesogenic effects. Among PUFAs, eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), which are n-3 long-chain PUFAs widely referred to as omega-3 oils, were reported to prevent the development of obesity in rodents and humans. In the present study, we evaluated the anti-obesity effects of microalgal oil on high-fat induced obese C57BL/6 mice, compared with commercial omega-3 fish oil and vegetable corn oil. Microalgal oil is an inherent mixture of several PUFAs, including EPA, DHA and other fatty acids produced from a marine microalgal strain of Thraustochytriidae sp. derived mutant. It was found to contain more PUFAs (>80%) and more omega-3 oils than commercial omega-3 fish oil (PUFAs >31%) and corn oil (PUFAs 59%). All three types of oils induced weight loss in high-fat-induced obese mice, with the loss induced by microalgal oil being most significant at 9 weeks (10% reduction). However, the oils tested did not improve blood lipid levels, although microalgal oil showed an apparent inhibitory effect on lipid accumulation in the liver. These findings may be attributed to the higher PUFA content, including omega-3 oils of microalgal oil than other oils. Collectively, these findings suggest that microalgal oil, derived from Thraustochytriidae sp. derived mutant, is a prominent candidate for replacement of omega-3 fish oils based on its apparent anti-obesity effect in vivo.

Hypokalaemia and drinking green tea: a literature review and report of 2 cases

We report the association between excessive consumption of green tea and hypokalaemia in an Oriental couple. Both patients were asymptomatic and the abnormal electrolyte level was only detected on routine blood tests. When they were advised to reduce the consumption of green tea, the abnormally low potassium level was reversed. We have not found such an association reported in the medical literature. The health benefits of green tea consumption are well publicised but the potential side-effects of overconsumption are less well known. We would like to report this association to alert clinicians about this potentially serious complication. This is especially relevant for those who are also taking prescribed medications that can lower potassium levels and/or sensitise patients to potential harm from hypokalaemia.

Long-Term Supplementation of Green Tea Extract Does Not Modify Adiposity or Bone Mineral Density in a Randomized Trial of Overweight and Obese Postmenopausal Women

BACKGROUND

Green tea extract (GTE) consumption has been linked to favorable changes in adiposity and bone mineral density (BMD), although it is unknown if these effects are due to green tea catechins or caffeine. The catechol-O-methyltransferase (COMT) genotype may also modify these associations.

OBJECTIVE

We examined the impact of decaffeinated GTE on body composition (using dual-energy X-ray absorptiometry) and obesity-associated hormones.

METHODS

The Minnesota Green Tea Trial was a 12-mo randomized, double-blind, placebo-controlled clinical trial in 937 postmenopausal women (aged 50-70 y) assigned to receive either GTE containing 843 mg (-)-epigallocatechin-3-gallate or placebo. This substudy was conducted in 121 overweight/obese participants [body mass index (BMI) (kg/m(2)) ≥25.0].

RESULTS

There were no differences in changes in BMI (-0.13 ± 0.11 compared with -0.05 ± 0.11; P = 0.61), total fat mass (-0.30 ± 0.16 compared with -0.12 ± 0.15 kg; P = 0.40), percentage of body fat (-0.15% ± 0.17% compared with -0.15% ± 0.16%; P = 0.99), or BMD (-0.006 ± 0.002 compared with -0.003 ± 0.002 g/cm(2); P = 0.49) over 12 mo between women taking GTE (n = 61) and those taking a placebo (n = 60). Interactions were observed between treatment and time for gynoid percentage of fat (%fat) and tissue %fat. Gynoid %fat increased from baseline to month 12 in the placebo group as baseline BMI increased and decreased over time as baseline BMI increased in the GTE group (P-interaction = 0.02). Tissue %fat increased from baseline to month 12 in the placebo group as baseline BMI increased. In the GTE group, tissue %fat decreased during the intervention as baseline BMI increased (P-interaction = 0.04). No changes were seen in circulating leptin, ghrelin, adiponectin, or insulin concentrations. COMT genotype did not modify the effect of GTE on any variable.

CONCLUSIONS

Decaffeinated GTE was not associated with overall reductions in adiposity or improvements in BMD in overweight/obese postmenopausal women. However, GTE may be beneficial for reduction in tissue and gynoid %fat in individuals with higher BMI. This clinical trial was registered at www.clinicaltrials.gov as NCT00917735.

Green Tea Extract and Catechol-O-Methyltransferase Genotype Modify Fasting Serum Insulin and Plasma Adiponectin Concentrations in a Randomized Controlled Trial of Overweight and Obese Postmenopausal Women

BACKGROUND

Green tea consumption has been associated with favorable changes in body weight and obesity-related hormones, although it is not known whether these changes result from green tea polyphenols or caffeine.

OBJECTIVE

We examined the impact of decaffeinated green tea extract (GTE) containing 843 mg of (-)-epigallocatechin-3-gallate on anthropometric variables, obesity-associated hormones, and glucose homeostasis.

METHODS

The Minnesota Green Tea Trial was a 12-mo randomized, double-blind, placebo-controlled clinical trial of 937 healthy postmenopausal women assigned to either decaffeinated GTE (1315 mg total catechins/d) or a placebo, stratified by catechol-O-methyltransferase (COMT) genotype. This study was conducted in a subset of 237 overweight and obese participants [body mass index (BMI) ≥25 kg/m(2)].

RESULTS

No changes in energy intake, body weight, BMI, or waist circumference (WC) were observed over 12 mo in women taking GTE (n = 117) or placebo (n = 120). No differences were seen in circulating leptin, ghrelin, adiponectin, or glucose concentrations at month 12. Participants randomly assigned to GTE with baseline insulin ≥10 μIU/mL (n = 23) had a decrease in fasting serum insulin from baseline to month 12 (-1.43 ± 0.59 μIU/mL), whereas those randomly assigned to placebo with baseline insulin ≥10 μIU/mL (n = 19) had an increase in insulin over 12 mo (0.55 ± 0.64 μIU/mL, P < 0.01). Participants with the homozygous high-activity (G/G) form of COMT had significantly lower adiponectin (5.97 ± 0.50 compared with 7.58 ± 0.53 μg/mL, P = 0.03) and greater insulin concentrations (7.63 ± 0.53 compared with 6.18 ± 0.36 μIU/mL, P = 0.02) at month 12 compared with those with the low-activity (A/A) genotype, regardless of treatment group.

CONCLUSIONS

Decaffeinated GTE was not associated with reductions in body weight, BMI, or WC and did not alter energy intake or mean hormone concentrations in healthy postmenopausal women over 12 mo. GTE decreased fasting insulin concentrations in those with elevated baseline fasting concentrations. The high-activity form of the COMT enzyme may be associated with elevations in insulin and a reduction in adiponectin concentrations over time. This trial was registered at http://www.clinicaltrials.gov as NCT00917735.

Cardiotoxicodynamics: Toxicity of Cardiovascular Xenobiotics

Maintaining adequate tissue perfusion depends on a variety of factors, all of which can be influenced by xenobiotics (substances foreign to the body, including pharmaceuticals, chemicals, and natural compounds). Volume status, systemic vascular resistance, myocardial contractility, and cardiac rhythm all play a significant role in ensuring hemodynamic stability and proper cardiovascular function. Direct effects on the nervous system, the vasculature, or the heart itself as well as indirect metabolic effects may play a significant role in the development of cardiotoxicity. This article is dedicated to discussion of the disruption of cardiovascular physiology by xenobiotics.

Short-term weight-centric effects of tea or tea extract in patients with metabolic syndrome: a meta-analysis of randomized controlled trials

To evaluate the weight-centric effect of tea or tea extract in participants with metabolic syndrome (MetS), we performed electronic searches in PubMed, EmBase and the Cochrane Library to identify eligible randomized controlled trials (RCTs) comparing tea or tea extract vs a control group. A direct meta-analysis using random-effects model was conducted to pool the standardized mean difference regarding body mass index (BMI), body weight and waist circumference. Study quality was assessed by using the Jadad scale. Pre-specified subgroup and sensitivity analyses were conducted to explore potential heterogeneity. A total of five RCTs involving 338 adult individuals were included. Given the high heterogeneity observed in the overall pooled analysis, we separated the included subjects into two subgroups. Ingestion of tea or tea extract significantly reduced BMI (subgroup 1: -1.60, 95% confidence interval (CI), -2.05 to -1.14; subgroup 2: -0.40, 95% CI, -0.69 to -0.12) and body weight (subgroup 1: -4.14, 95% CI, -4.85 to -3.43; subgroup 2: -0.35, 95% CI, -0.68 to -0.02). This meta-analysis suggests that tea or tea extract has favorable weight-centric effects in MetS patients. Additional large RCTs specifically designed to evaluate the effect on anthropometric measurements are needed to further confirm these findings.

Complementary and alternative medicine for the treatment of obesity: a critical review

CONTEXT

Obesity and its associated morbidities pose a major health hazard to the public. Despite a multiplex of available diet and exercise programs for losing and maintaining weight, over the past years, interest in the use of complementary and alternative medicine (CAM) for obesity treatment has greatly increased.

EVIDENCE ACQUISITION

We searched PubMed, Google scholar and the Cochrane databases for systemic reviews, review articles, meta-analysis and randomized clinical trials up to December 2013.

RESULTS

In this review, the efficacy and safety of the more commonly used CAM methods for the treatment of obesity, namely herbal supplements, acupuncture, and non-invasive body-contouring, are briefly discussed. The evidence supporting the effectiveness and safety of these methods is either lacking or point to a negligible clinical benefit, barely surpassing that of the placebo. Furthermore, several limitations are observed in the available scientific literature. These shortcomings include, without being limited to, uncontrolled trial designs, non-random allocation of subjects to treatment arms, small number of patients enrolled, short durations of follow-up, and ambiguous clinical and laboratory endpoints.

CONCLUSIONS

Further investigations are necessary to accurately determine the efficacy, safety, standard dosage/procedure, and potential side effects of the various CAM methods currently in use.

Influence of diet supplementation with green tea extract on drug-metabolizing enzymes in a mouse model of monosodium glutamate-induced obesity

PURPOSE

Consumption of dietary supplements with green tea extract (GTE) is popular for weight management, but it may be accompanied by various side effects, including interactions with drugs. The aim of the present in vivo study was to evaluate the effect of defined GTE (Polyphenon 60) in three dosage schemes on insulin, leptin and drug-metabolizing enzymes in obese mice.

METHODS

Experimental obesity was induced by repeated s.c. application of monosodium glutamate to newborn mice. Green tea extract was administered in three dosage schemes in chow diet. The plasmatic levels of insulin and leptin were assayed using enzyme-linked immunosorbent assay. Enzyme activities and mRNA expressions of drug-metabolizing enzymes (totally 13) were analyzed in liver and small intestine using spectrophotometric and HPLC assays and RT-PCR, respectively.

RESULTS

GTE-treatment decreased insulin and leptin levels. Eleven enzymes were significantly affected by GTE-treatment. Long-term administration of 0.01% GTE caused increase in the activity and mRNA level of cytochrome P450 3A4 (CYP3A4) ortholog in the liver as well as in the small intestine. Interestingly, short-term overdose by GTE (0.1%) had more pronounced effects on enzyme activities and mRNA expressions than long-term overdose.

CONCLUSIONS

GTE-mediated induction of CYP3A4 ortholog, the main drug-metabolizing enzyme, could result in decreased efficacy of simultaneously or subsequently administered drug in obese individuals.

The role of catechol-O-methyl transferase Val(108/158)Met polymorphism (rs4680) in the effect of green tea on resting energy expenditure and fat oxidation: a pilot study

Introduction

Green tea(GT) is able to increase energy expenditure(EE) and fat oxidation(FATox) via inhibition of catechol-O-methyl transferase(COMT) by catechins. However, this does not always appear unanimously because of large inter-individual variability. This may be explained by different alleles of the functional COMT Val108/158Met polymorphism that are associated with COMT enzyme activity; high-activity enzyme, COMT^H(Val/Val genotype), and low-activity COMT^L(Met/Met genotype).

Methods

Fourteen Caucasian subjects (BMI: 22.2±2.3 kg/m², age: 21.4±2.2 years) of whom 7 with the COMT^H-genotype and 7 with the COMT^L-genotype were included in a randomized, cross-over study in which EE and substrate oxidation were measured with a ventilated-hood system after decaffeinated GT and placebo(PL) consumption.

Results

At baseline, EE, RQ, FATox and carbohydrate oxidation(CHOox) did not differ between groups. Significant interactions were observed between COMT genotypes and treatment for RQ, FATox and CHOox (p<0.05). After GT vs. PL, EE(GT: 62.2 vs. PL: 35.4 kJ.3.5 hrs; p<0.01), RQ(GT: 0.80 vs. PL: 0.83; p<0.01), FATox(GT: 18.3 vs. PL: 15.3 g/d; p<0.001) and CHOox(GT: 18.5 vs. PL: 24.3 g/d; p<0.001) were significantly different for subjects carrying the COMT^H genotype, but not for subjects carrying the COMT^L genotype (EE, GT: 60.3 vs. PL: 51.7 kJ.3.5 hrs; NS), (RQ, GT: 0.81 vs. PL: 0.81; NS), (FATox, GT: 17.3 vs. PL: 17.0 g/d; NS), (CHOox, GT: 22.1 vs. PL: 21.4 g/d; NS).

Conclusion

Subjects carrying the COMT^H genotype increased energy expenditure and fat-oxidation upon ingestion of green tea catechins vs, placebo, whereas COMT^L genotype carriers reacted similarly to GT and PL ingestion. The differences in responses were due to the different responses on PL ingestion, but similar responses to GT ingestion, pointing to different mechanisms. The different alleles of the functional COMT Val108/158Met polymorphism appear to play a role in the inter-individual variability for EE and FATox after GT treatment.

Trial Registration

Nederlands Trial register NTR1918

Novel insights of dietary polyphenols and obesity

The prevalence of obesity has steadily increased over the past three decades both in the United States and worldwide. Recent studies have shown the role of dietary polyphenols in the prevention of obesity and obesity-related chronic diseases. Here, we evaluated the impact of commonly consumed polyphenols, including green tea catechins, especially epigallocatechin gallates, resveratrol and curcumin, on obesity and obesity-related inflammation. Cellular studies demonstrated that these dietary polyphenols reduce viability of adipocytes and proliferation of preadipocytes, suppress adipocyte differentiation and triglyceride accumulation, stimulate lipolysis and fatty acid β-oxidation, and reduce inflammation. Concomitantly, the polyphenols modulate signaling pathways including the adenosine-monophosphate-activated protein kinase, peroxisome proliferator activated receptor γ, CCAAT/enhancer binding protein α, peroxisome proliferator activator receptor gamma activator 1-alpha, sirtuin 1, sterol regulatory element binding protein-1c, uncoupling proteins 1 and 2, and nuclear factor-κB that regulate adipogenesis, antioxidant and anti-inflammatory responses. Animal studies strongly suggest that commonly consumed polyphenols described in this review have a pronounced effect on obesity as shown by lower body weight, fat mass and triglycerides through enhancing energy expenditure and fat utilization, and modulating glucose hemostasis. Limited human studies have been conducted in this area and are inconsistent about the antiobesity impact of dietary polyphenols probably due to the various study designs and lengths, variation among subjects (age, gender, ethnicity), chemical forms of the dietary polyphenols used and confounding factors such as other weight-reducing agents. Future randomized controlled trials are warranted to reconcile the discrepancies between preclinical efficacies and inconclusive clinic outcomes of these polyphenols.

Effect of green tea supplementation on blood pressure among overweight and obese adults: a protocol for a systematic review

INTRODUCTION

Emerging randomised controlled trials (RCTs) exploring the effect of green tea (GT) supplementation or GT extract (GTE) on blood pressure (BP) among overweight and obese adults yielded inconclusive results. We aim to conduct a systematic review to summarise the evidence of RCTs until now, to clarify the efficacy of GT supplementation or GTE in BP in overweight and obese populations.

METHODS AND ANALYSIS

The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and ClinicalTrials.gov will be searched to retrieve potential RCTs. Unpublished studies will be identified by searching the abstract books or websites of the three major conference proceedings: the International Society of Hypertension, the Nutrition & Health Conference and the World Congress of Nutrition and Health. A random-effects meta-analysis will be performed to pool the mean difference for the change in BP from baseline (ie, postintervention BP minus baseline BP) between intervention groups and placebo groups of the included studies, presenting the pooled results with 95% CIs. Subgroups analyses will be conducted according to different doses of GT or GTE, trial duration, geographic regions, overweight versus obese participants, and participants with versus without change in body weight after intervention. Sensitivity analysis will be performed by excluding studies classified as having a high risk of bias, applying a fixed-effects model, using the postintervention BP for analyses and excluding trials with non-study cointerventions.

ETHICS AND DISSEMINATION

This systematic review will be published in a peer-reviewed journal. It will be disseminated electronically and in print. Summarising the RCT evidence to clarify the efficacy in BP among overweight and obese adults will aid in making the dietary recommendation of GT and improving the clinical management of hypertension.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014007273.