Effect of Green Tea Supplements on Liver Enzyme Elevation: Results from a Randomized Intervention Study in the United States

A green tea extract confection decreases circulating endotoxin and fasting glucose by improving gut barrier function but without affecting systemic inflammation: A double-blind, placebo-controlled randomized trial in healthy adults and adults with metabolic syndrome

Anti-inflammatory activities of catechin-rich green tea extract (GTE) in obese rodents protect against metabolic endotoxemia by decreasing intestinal permeability and absorption of gut-derived endotoxin. However, translation to human health has not been established. We hypothesized that GTE would reduce endotoxemia by decreasing gut permeability and intestinal and systemic inflammation in persons with metabolic syndrome (MetS) compared with healthy persons. A randomized, double-blind, placebo-controlled, crossover trial in healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years) examined 4-week administration of a decaffeinated GTE confection (890 mg/d total catechins) on serum endotoxin, intestinal permeability, gut and systemic inflammation, and cardiometabolic parameters. Compared with the placebo, the GTE confection decreased serum endotoxin (P = .023) in both healthy persons and those with MetS, while increasing concentrations of circulating catechins (P < .0001) and γ-valerolactones (P = .0001). Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status. Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status. No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass nor were plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected. However, fasting glucose in both study groups was decreased (P = .029) by the GTE confection compared with within-treatment arm baseline concentrations. These findings demonstrate that catechin-rich GTE is effective to decrease circulating endotoxin and improve glycemic control in healthy adults and those with MetS, likely by reducing gut inflammation and small intestinal permeability but without affecting systemic inflammation.

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.

Investigating the Immune Basis of Green Tea Extract Induced Liver Injury in Healthy Donors Expressing HLA-B*35:01

Epigallocatechin-3-O-gallate (EGCG) is the major component of green tea extract, commonly found in dietary supplements, and has been associated with immune-mediated liver injury. The purpose of this study was to investigate the immunogenicity of EGCG in healthy donors expressing HLA-B*35:01, and characterize EGCG responsive T-cell clones. We have shown that EGCG can prime peripheral blood mononuclear cells and T-cells from donors with and without the HLA-B*35:01 allele. T-cell clones were CD4+ve and capable of secreting Th1, Th2, and cytolytic molecules. These data demonstrate that EGCG can activate T-cells in vitro, suggesting a significant role in the pathogenesis of green tea extract induced liver injury.

Green Tea and Benign Gynecologic Disorders: A New Trick for An Old Beverage?

Green tea is harvested from the tea plant Camellia sinensis and is one of the most widely consumed beverages worldwide. It is richer in antioxidants than other forms of tea and has a uniquely high content of polyphenolic compounds known as catechins. Epigallocatechin-3-gallate (EGCG), the major green tea catechin, has been studied for its potential therapeutic role in many disease contexts, including pathologies of the female reproductive system. As both a prooxidant and antioxidant, EGCG can modulate many cellular pathways important to disease pathogenesis and thus has clinical benefits. This review provides a synopsis of the current knowledge on the beneficial effects of green tea in benign gynecological disorders. Green tea alleviates symptom severity in uterine fibroids and improves endometriosis through anti-fibrotic, anti-angiogenic, and pro-apoptotic mechanisms. Additionally, it can reduce uterine contractility and improve the generalized hyperalgesia associated with dysmenorrhea and adenomyosis. Although its role in infertility is controversial, EGCG can be used as a symptomatic treatment for menopause, where it decreases weight gain and osteoporosis, as well as for polycystic ovary syndrome (PCOS).

Assessing the Hepatic Safety of Epigallocatechin Gallate (EGCG) in Reproductive-Aged Women

A similar abstract of the interim analysis was previously published in Fertility and Sterility. EPIGALLOCATECHIN GALLATE (EGCG) FOR TREATMENT OF UNEXPLAINED INFERTILITY ASSOCIATED WITH UTERINE FIBROIDS (PRE-FRIEND TRIAL): EARLY SAFETY ASSESSMENT. Uterine fibroids are the most common cause of unexplained infertility in reproductive-aged women. Epigallocatechin gallate (EGCG), a green tea catechin, has demonstrated its ability to shrink uterine fibroids in prior preclinical and clinical studies. Hence, we developed an NICHD Confirm-funded trial to evaluate the use of EGCG for treating women with fibroids and unexplained infertility (FRIEND trial). Prior to embarking on that trial, we here conducted the pre-FRIEND study (NCT04177693) to evaluate the safety of EGCG in premenopausal women. Specifically, our aim was to assess any adverse effects of EGCG alone or in combination with an ovarian stimulator on serum liver function tests (LFTs) and folate level. In this randomized, open-label prospective cohort, participants were recruited from the FRIEND-collaborative clinical sites: Johns Hopkins University, University of Chicago, University of Illinois at Chicago, and Yale University. Thirty-nine women, ages ≥18 to ≤40 years, with/without uterine fibroids, were enrolled and randomized to one of three treatment arms: 800 mg of EGCG daily alone, 800 mg of EGCG daily with clomiphene citrate 100 mg for 5 days, or 800 mg of EGCG daily with Letrozole 5 mg for 5 days. No subject demonstrated signs of drug induced liver injury and no subject showed serum folate level outside the normal range. Hence, our data suggests that a daily dose of 800 mg of EGCG alone or in combination with clomiphene citrate or letrozole (for 5 days) is well-tolerated and is not associated with liver toxicity or folate deficiency in reproductive-aged women.

Hepatotoxicity with High-Dose Green Tea Extract: Effect of Catechol-O-Methyltransferase and Uridine 5'-Diphospho-glucuronosyltransferase 1A4 Genotypes

The predominant catechin in green tea, epigallocatechin gallate (EGCG), may be hepatotoxic in high doses. Our objective was to investigate the influence of catechol-O-methyltransferase (COMT) and uridine 5'-diphospho-glucuronosyltransferase 1A4 (UGT1A4) genotypes on changes in liver injury biomarkers in response to long-term, high-dose green tea extract (GTE) supplementation among postmenopausal women. A secondary analysis was conducted using data from the Minnesota Green Tea Trial (N = 1,075), in which participants were randomized to consume high-dose GTE (843 mg/day EGCG) or placebo capsules for 12 months. Analysis of covariance adjusting for potential confounders was performed to examine changes in aspartate aminotransferase (AST), alanine aminotransferase (ALT), AST: ALT ratio, and alkaline phosphatase from baseline to months 3, 6, 9, and 12 across COMT and UGT1A4 genotypes. Mean age and BMI within the GTE group (n = 400) were 59.8 yrs and 25.1 kg/m2, respectively, and 98% of subjects were white. From baseline to month 3, mean AST: ALT ratio change was +1.0% in the COMT (rs4680) A/G genotype versus -4.8% in the A/A genotype (p = 0.03). From baseline to months 6 and 9, respectively, mean ALT change was +78.1% and +82.1% in the UGT1A4 (rs6755571) A/C genotype versus +28.0% and +30.1% in the C/C genotype (p < 0.001 and p = 0.004, respectively). The UGT1A4 (rs6755571) A/C genotype may be an important risk factor for clinically-relevant serum transaminase elevations with 6-9 months of high-dose GTE supplementation among postmenopausal women. Understanding the genetic underpinnings of GTE-related hepatotoxicity may allow for a genetically-informed paradigm for therapeutic use of GTE.

Effects of Green Tea Catechins on Prostate Cancer Chemoprevention: The Role of the Gut Microbiome

Accumulating evidence supports green tea catechins (GTCs) in chemoprevention for prostate cancer (PCa), a leading cause of cancer morbidity and mortality among men. GTCs include (-)-epigallocatechin-3-gallate, which may modulate the molecular pathways implicated in prostate carcinogenesis. Prior studies of GTCs suggested that they are bioavailable, safe, and effective for modulating clinical and biological markers implicated in prostate carcinogenesis. GTCs may be of particular benefit to those with low-grade PCas typically managed with careful monitoring via active surveillance (AS). Though AS is recommended, it has limitations including potential under-grading, variations in eligibility, and anxiety reported by men while on AS. Secondary chemoprevention of low-grade PCas using GTCs may help address these limitations. When administrated orally, the gut microbiome enzymatically transforms GTC structure, altering its bioavailability, bioactivity, and toxicity. In addition to xenobiotic metabolism, the gut microbiome has multiple other physiological effects potentially involved in PCa progression, including regulating inflammation, hormones, and other known/unknown pathways. Therefore, it is important to consider not only the independent roles of GTCs and the gut microbiome in the context of PCa chemoprevention, but how gut microbes may relate to individual responses to GTCs, which, in turn, can enhance clinical decision-making.

Green Tea Polyphenol (-)-Epigallocatechin-3-Gallate (EGCG): A Time for a New Player in the Treatment of Respiratory Diseases?

(-)-Epigallocatechin-3-gallate (EGCG) is a major polyphenol of green tea that possesses a wide variety of actions. EGCG acts as a strong antioxidant which effectively scavenges reactive oxygen species (ROS), inhibits pro-oxidant enzymes including NADPH oxidase, activates antioxidant systems including superoxide dismutase, catalase, or glutathione, and reduces abundant production of nitric oxide metabolites by inducible nitric oxide synthase. ECGC also exerts potent anti-inflammatory, anti-fibrotic, pro-apoptotic, anti-tumorous, and metabolic effects via modulation of a variety of intracellular signaling cascades. Based on this knowledge, the use of EGCG could be of benefit in respiratory diseases with acute or chronic inflammatory, oxidative, and fibrotizing processes in their pathogenesis. This article reviews current information on the biological effects of EGCG in those respiratory diseases or animal models in which EGCG has been administered, i.e., acute respiratory distress syndrome, respiratory infections, COVID-19, bronchial asthma, chronic obstructive pulmonary disease, lung fibrosis, silicosis, lung cancer, pulmonary hypertension, and lung embolism, and critically discusses effectiveness of EGCG administration in these respiratory disorders. For this review, articles in English language from the PubMed database were used.

Herb-Drug Interaction in Inflammatory Diseases: Review of Phytomedicine and Herbal Supplements

Many people worldwide use plant preparations for medicinal purposes. Even in industrialized regions, such as Europe, where conventional therapies are accessible for the majority of patients, there is a growing interest in and usage of phytomedicine. Plant preparations are not only used as alternative treatment, but also combined with conventional drugs. These combinations deserve careful contemplation, as the complex mixtures of bioactive substances in plants show a potential for interactions. Induction of CYP enzymes and pGP by St John's wort may be the most famous example, but there is much more to consider. In this review, we shed light on what is known about the interactions between botanicals and drugs, in order to make practitioners aware of potential drug-related problems. The main focus of the article is the treatment of inflammatory diseases, accompanied by plant preparations used in Europe. Several of the drugs we discuss here, as basal medication in chronic inflammatory diseases (e.g., methotrexate, janus kinase inhibitors), are also used as oral tumor therapeutics.

Anti-inflammatory Effects of GTE in Eye Diseases

Ocular inflammation is a common complication of various eye diseases with wide consequences from irritations to potentially sight-threatening complications. Green tea is a popular beverage throughout the world. One of the proven health benefits of consuming green tea extract (GTE) is anti-inflammation. Catechins are the biologically active constituents of GTE. In in vitro and in vivo studies, GTE and catechins present inhibition of inflammatory responses in the development of ocular inflammation including infectious, non-infectious or autoimmune, and oxidative-induced complications. Research on the ocular inflammation in animal models has made significant progress in the past decades and several key disease mechanisms have been identified. Here we review the experimental investigations on the effects of GTE and catechins on various ocular inflammation related diseases including glaucoma, age-related macular degeneration, uveitis and ocular surface inflammation. We also review the pharmacokinetics of GTE constituents and safety of green tea consumption. We discuss the insights and perspectives of these experimental results, which would be useful for future development of novel therapeutics in human.

Liver biomarkers in adults: Evaluation of associations with reported green tea consumption and use of green tea supplements in U.S. NHANES

Some events of hepatotoxicity have been linked to consumption of green tea supplements. The association between consumption of green tea or green tea supplements and abnormal liver biomarkers in adults was investigated using cross-sectional data from the 2009-2014 United States National Health and Nutrition Examination Survey (U.S. NHANES). Individuals with levels of either bilirubin or GGT, ALT, AST, and/or ALP in excess of the age- and gender-specific upper limits of normal ranges were classified as having abnormal liver biomarkers. Associations between green tea or green tea supplement use (consumption vs. not) and liver function were determined using multiple logistic regression modelling. 12,289 persons were included in the green tea analyses and 12,274 in the green tea supplement analyses. The odds of having one or more abnormal liver biomarkers were significantly reduced (p = 0.01) with consumption of green tea (OR: 0.49; 95% CI: 0.28, 0.85), while no significant association (p = 0.78) was determined for consumption of green tea supplements (OR: 0.92; 95% CI: 0.52, 1.64). Based on data from the 2009-2014 U.S. NHANES, green tea consumption was associated with reduced odds of having one or more abnormal liver biomarkers; whereas, no significant association was determined with consumption of green tea supplements.

Green Tea Extract Increases Soluble RAGE and Improves Renal Function in Patients with Diabetic Nephropathy

One of the proposed mechanisms for the development of diabetic nephropathy (DN) is the increase of end products of advanced glycosylation (AGEs), which bind to its receptor (RAGE), favoring nephron cellular damage. An isoform of this receptor is soluble RAGE (sRAGE), which can antagonize AGE-altered intracellular signaling. It has known that green tea extract (GTE) increases the expression of sRAGE, but it is unknown whether this could improve kidney function. The objective of this study was to evaluate the effect of the administration of GTE on the concentrations of sRAGE, renal function, and metabolic profile in patients with type 2 diabetes mellitus (T2DM) and DN. A randomized, double-blinded, placebo-controlled clinical trial was carried out in 39 patients who received GTE (400 mg every 12 h) or placebo for 3 months. sRAGE levels, renal function, and metabolic parameters were determined before and after the intervention. In the GTE group, there were statistically significant increase on sRAGE (320.55 ± 157.63 pg/mL vs. 357.59 ± 144.99 pg/mL; P = .04) and glomerular filtration rate (GFR; 66.44 ± 15.17 mL/min/1.73 m² vs. 71.70 ± 19.33 mL/min/1.73 m²; P = .04), and a statistically significant decrease in fasting serum glucose (7.62 ± 3.00 mmol/L vs. 5.86 ± 1.36 mmol/L; P ≤ .01) and triacylglycerols (1.91 ± 0.76 mmol/L vs. 1.58 ± 0.69; P = .02). Administration of GTE increases the serum concentration of sRAGE and the GFR and decreases the concentration of fasting serum glucose and triacylglycerols. The study was registered in ClinicalTrials.gov with the identifier NCT03622762.

The role of biofactors in the prevention and treatment of age-related diseases

The present demographic changes toward an aging society caused a rise in the number of senior citizens and the incidence and burden of age-related diseases (such as cardiovascular diseases [CVD], cancer, nonalcoholic fatty liver disease [NAFLD], diabetes mellitus, and dementia), of which nearly half is attributable to the population ≥60 years of age. Deficiencies in individual nutrients have been associated with increased risks for age-related diseases and high intakes and/or blood concentrations with risk reduction. Nutrition in general and the dietary intake of essential and nonessential biofactors is a major determinant of human health, the risk to develop age-related diseases, and ultimately of mortality in the older population. These biofactors can be a cost-effective strategy to prevent or, in some cases, even treat age-related diseases. Examples reviewed herein include omega-3 fatty acids and dietary fiber for the prevention of CVD, α-tocopherol (vitamin E) for the treatment of biopsy-proven nonalcoholic steatohepatitis, vitamin D for the prevention of neurodegenerative diseases, thiamine and α-lipoic acid for the treatment of diabetic neuropathy, and the role of folate in cancer epigenetics. This list of potentially helpful biofactors in the prevention and treatment of age-related diseases, however, is not exhaustive and many more examples exist. Furthermore, since there is currently no generally accepted definition of the term biofactors, we here propose a definition that, when adopted by scientists, will enable a harmonization and consistent use of the term in the scientific literature.

HLA-B*35:01 and Green Tea-Induced Liver Injury

BACKGROUND AND AIMS

Herbal supplements, and particularly multi-ingredient products, have become increasingly common causes of acute liver injury. Green tea is a frequent component in implicated products, but its role in liver injury is controversial. The aim of this study was to better characterize the clinical features, outcomes, and pathogenesis of green tea-associated liver injury.

APPROACH AND RESULTS

Among 1,414 patients enrolled in the U.S. Drug-Induced Liver Injury Network who underwent formal causality assessment, 40 cases (3%) were attributed to green tea, 202 to dietary supplements without green tea, and 1,142 to conventional drugs. The clinical features of green tea cases and representation of human leukocyte antigen (HLA) class I and II alleles in cases and control were analyzed in detail. Patients with green tea-associated liver injury ranged in age from 17 to 69 years (median = 40) and developed symptoms 15-448 days (median = 72) after starting the implicated agent. The liver injury was typically hepatocellular (95%) with marked serum aminotransferase elevations and only modest increases in alkaline phosphatase. Most patients were jaundiced (83%) and symptomatic (88%). The course was judged as severe in 14 patients (35%), necessitating liver transplantation in 3 (8%), but rarely resulting in chronic injury (3%). In three instances, injury recurred upon re-exposure to green tea with similar clinical features, but shorter time to onset. HLA typing revealed a high prevalence of HLA-B*35:01, found in 72% (95% confidence interval [CI], 58-87) of green tea cases, but only 15% (95% CI, 10-20) caused by other supplements and 12% (95% CI, 10-14) attributed to drugs, the latter rate being similar to population controls (11%; 95% CI, 10.5-11.5).

CONCLUSIONS

Green tea-related liver injury has distinctive clinical features and close association with HLA-B*35:01, suggesting that it is idiosyncratic and immune mediated.

Effect of natural leaf extracts as phytomedicine in curing geriatrics

Old age is viewed as an unavoidable, undesirable, and problem-ridden phase of life. As people age, they become more susceptible to disease and disability due to various factors like low immunity, decreased functionality of cells, DNA damage, higher incidence of inflammation, etc. Healthy aging is very important. The nutrition and health of the elderly is often neglected. Nutritional interventions could play an important part in the prevention of degenerative conditions of the elderly and an improvement of their quality of life. The medicinal properties of plants are always believed for its therapeutic effect and its efficiency in treating many without adverse effects. The role of phytomedicine in aging is very crucial as it possesses important bioactive compounds and constituents (such as polyphenols, flavonoids, phenolic acids, and others) which are considered to provide anti-aging properties as well as helps in reducing age-associated problems. Some natural leaves such as Moringa oleifera, curry leaves, guava leaves, green tea, olive leaves, Ginkgo biloba, thankuni leaves, grape leaves, vasaka leaves, and kulekhara leaves are found to have therapeutic effects against diseases like cancer, diabetes, immunosuppression, hepatic damage, and neurodegenerative disorders. Hence, this review aims at understanding the effectiveness of these natural products in curing the geriatric population and the mechanism by which the therapeutic effects are exerted by them.

Functional beverages improve insulin resistance and hepatic steatosis modulating lysophospholipids in diet-induced obese rats

Hypercaloric beverages increase the prevalence of insulin resistance and nonalcoholic fatty liver disease (NAFLD), diets with polyphenolic compounds improved these alterations. The study aimed to evaluate the effect of the consumption of three functional beverages (prepared with: Roselle, green tea, cinnamon, Malabar tamarind, and peppermint in different proportions) on insulin resistance and NAFLD and their relation to liver phospholipid regulation in Wistar rats fed with a high-fat and fructose (HFF) diet. The consumption of beverages showed lower liver triglycerides compared to HFF control group, being the called beverage B the successful triggering up to 30.1%. The consumption of functional beverages improved insulin resistance and decreased the abundance of LysoPC (20:2), LysoPC (16:0), LysoPC (14:0), LysoPE (18:0), LysoPC (15:0), and LysoPC (20:1), with beverage C being the one with the meaningful effect. The results indicate that the functional beverage consumption improves insulin resistance, and decrease the degree of NAFLD, these through modifications of lysophosphatidylcholines, and lipids metabolism.

Liver Injury Caused by Green Tea Extract in PD-1-/- Mice: An Impaired Immune Tolerance Model for Idiosyncratic Drug-Induced Liver Injury

Idiosyncratic drug-induced liver injury (IDILI) is an idiosyncratic drug reaction that is specific to an individual and can lead to liver failure and even death. The mechanism of IDILI remains poorly understood, but most IDILI appears to be immune-mediated. We have developed the first validated animal model by using a PD-1^-/- mouse model in combination with anti-CTLA-4 to block immune checkpoints and impair immune tolerance. Treatment of these mice with drugs that cause IDILI in humans led to delayed-onset liver injury with characteristics similar to IDILI in humans. The current study investigates the effects of green tea extract, a weight-loss dietary supplement that has been reported to cause IDILI in humans. Green tea extracts contain a highly variable content of catechins including (-)-epigallocatechin gallate, the major catechin in green tea formulations. If the liver injury caused by green tea extract in humans is immune-mediated, it may occur in our impaired immune tolerance model. Female PD-1^-/- mice treated with anti-CTLA-4 antibody and green tea extract (500 mg/kg), a dose that is considered a no-observed-adverse-effect level for liver in rodents, produced a delayed onset increase in serum alanine transaminase levels and an increase in hepatic CD8⁺ T cells. In contrast, the response in male PD-1^-/- mice was less pronounced, and there was no evidence of liver injury in wild-type mice. These findings are consistent with the hypothesis that the IDILI caused by green tea extract is immune-mediated and is similar to IDILI caused by medications that are associated with IDILI.

Epigallocatechin gallate decreases plasma triglyceride, blood pressure, and serum kisspeptin in obese human subjects

Obesity is one of major risk factors increasing chronic diseases including type II diabetes, cardiovascular diseases, and hypertension. The effects of epigallocatechin gallate (EGCG), the major active compound in green tea, on reduced obesity and improved metabolic profiles are still controversial. Furthermore, the effects of EGCG on human adipocyte lipolysis and browning of white adipocytes have not been elucidated. This study aimed to investigate the effects of EGCG on obesity, lipolysis, and browning of human white adipocytes. The results showed that, when compared to the baseline values, EGCG significantly decreased fasting plasma triglyceride levels (P < 0.05), systolic blood pressure (P < 0.05), diastolic blood pressure (P < 0.05), and serum kisspeptin levels (P < 0.05) after 8 weeks of supplement. On the other hand, supplement of EGCG in obese human subjects for 4 or 8 weeks did not decrease body weight, body mass index, waist and hip circumferences, nor total body fat mass or percentage when compared to their baseline values. The study in human adipocytes showed that EGCG did not increase the glycerol release when compared to vehicle, suggesting that it had no lipolytic effect. Furthermore, treatment of EGCG did not enhance uncoupling protein 1 (UCP1) mRNA expression in human white adipocytes when compared with treatment of pioglitazone, the peroxisome proliferator-activated receptor γ (PPAR-γ) agonist, suggesting that EGCG did not augment the browning effect of PPAR-γ on white adipocytes. This study revealed that EGCG reduced 2 metabolic risk factors which are triglyceride and blood pressure in the human experiment. We also showed a novel evidence that EGCG decreased kisspeptin levels. However, EGCG had no effects on obesity reduction in humans, lipolysis, nor browning of human white adipocytes.

Gut/Oral Bacteria Variability May Explain the High Efficacy of Green Tea in Rodent Tumor Inhibition and Its Absence in Humans

Consumption of green tea (GT) and GT polyphenols has prevented a range of cancers in rodents but has had mixed results in humans. Human subjects who drank GT for weeks showed changes in oral microbiome. However, GT-induced changes in RNA in oral epithelium were subject-specific, suggesting GT-induced changes of the oral epithelium occurred but differed across individuals. In contrast, studies in rodents consuming GT polyphenols revealed obvious changes in epithelial gene expression. GT polyphenols are poorly absorbed by digestive tract epithelium. Their metabolism by gut/oral microbial enzymes occurs and can alter absorption and function of these molecules and thus their bioactivity. This might explain the overall lack of consistency in oral epithelium RNA expression changes seen in human subjects who consumed GT. Each human has different gut/oral microbiomes, so they may have different levels of polyphenol-metabolizing bacteria. We speculate the similar gut/oral microbiomes in, for example, mice housed together are responsible for the minimal variance observed in tissue GT responses within a study. The consistency of the tissue response to GT within a rodent study eases the selection of a dose level that affects tumor rates. This leads to the theory that determination of optimal GT doses in a human requires knowledge about the gut/oral microbiome in that human.

Safety issues and harmful pharmacological interactions of nutritional supplements in Duchenne muscular dystrophy: considerations for Standard of Care and emerging virus outbreaks

At the moment, little treatment options are available for Duchenne muscular dystrophy (DMD). The absence of the dystrophin protein leads to a complex cascade of pathogenic events in myofibres, including chronic inflammation and oxidative stress as well as altered metabolism. The attention towards dietary supplements in DMD is rapidly increasing, with the aim to counteract pathology-related alteration in nutrient intake, the consequences of catabolic distress or to enhance the immunological response of patients as nowadays for the COVID-19 pandemic emergency. By definition, supplements do not exert therapeutic actions, although a great confusion may arise in daily life by the improper distinction between supplements and therapeutic compounds. For most supplements, little research has been done and little evidence is available concerning their effects in DMD as well as their preventing actions against infections. Often these are not prescribed by clinicians and patients/caregivers do not discuss the use with their clinical team. Then, little is known about the real extent of supplement use in DMD patients. It is mistakenly assumed that, since compounds are of natural origin, if a supplement is not effective, it will also do no harm. However, supplements can have serious side effects and also have harmful interactions, in terms of reducing efficacy or leading to toxicity, with other therapies. It is therefore pivotal to shed light on this unclear scenario for the sake of patients. This review discusses the supplements mostly used by DMD patients, focusing on their potential toxicity, due to a variety of mechanisms including pharmacodynamic or pharmacokinetic interactions and contaminations, as well as on reports of adverse events. This overview underlines the need for caution in uncontrolled use of dietary supplements in fragile populations such as DMD patients. A culture of appropriate use has to be implemented between clinicians and patients' groups.

Profile of herbal and dietary supplements induced liver injury in Latin America: A systematic review of published reports

Hepatotoxicity related to HDS is a growing global health issue. We have undertaken a systematic review of published case reports and case series from LA from 1976 to 2020 to describe the clinical features of HDS related hepatotoxicity in this region. We search in PubMed, Web of Science, Scopus and specific LA databases according to PRISMA guidelines. Only HILI cases published in LA that met criteria for DILI definition were included. Duplicate records or reports that lacked relevant data that precluded establishing causality were excluded. Finally, 17 records (23 cases) were included in this review. Centella asiatica, Carthamus tinctorius, and Herbalife® were the most reported HDS culprit products, the main reason for HDS consumption was weight loss. The clinical characteristics of HDS hepatotoxicity in our study were compared to those of other studies in the USA, Europe and China showing a similar signature with predominance of young females, hepatocellular damage, a high rate of ALF and mortality, more frequent inadvertent re-challenge and chronic damage. This study underscores the challenge in causality assessment when multi-ingredients HDS are taken and the need for consistent publication practice when reporting hepatotoxicity cases due to HDS, to foster HDS liver safety particularly in LA.

Drug-Induced Liver Injury in GI Practice

Although drug-induced liver injury (DILI) is a rare clinical event, it carries significant morbidity and mortality, leaving it as the leading cause of acute liver failure in the United States. It is one of the most challenging diagnoses encountered by gastroenterologists. The development of various drug injury networks has played a vital role in expanding our knowledge regarding drug-related and herbal and dietary supplement-related liver injury. In this review, we discuss what defines liver injury, epidemiology of DILI, its biochemical and pathologic patterns, and management.

Epigallocatechin Gallate Induces Hepatic Stellate Cell Senescence and Attenuates Development of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly morbid condition with lack of effective treatment options. HCC arises from chronically inflamed and damaged liver tissue; therefore, chemoprevention may be a useful strategy to reduce HCC incidence. Several reports suggest that epigallocatechin gallate (EGCG), extracted from green tea, can suppress liver inflammation and fibrosis in animal models, but its role in HCC chemoprevention is not well established. In this study, male Wistar rats were injected with diethylnitrosamine at 50 mg/kg for 18 weeks to induce cirrhosis and HCC, and EGCG was given in drinking water at a concentration of 0.02%. Clinically achievable dosing of EGCG was well-tolerated in diethylnitrosamine-injured rats and was associated with improved serum liver markers including alanine transaminase, aspartate transaminase, and total bilirubin, and reduced HCC tumor formation. Transcriptomic analysis of diethylnitrosamine-injured hepatic tissue was notable for increased expression of genes associated with the Hoshida high risk HCC gene signature, which was prevented with EGCG treatment. EGCG treatment also inhibited fibrosis progression, which was associated with inactivation of hepatic stellate cells and induction of the senescence-associated secretory phenotype. In conclusion, EGCG administered at clinically safe doses exhibited both chemopreventive and antifibrotic effects in a rat diethylnitrosamine liver injury model.

Green tea (Camellia sinensis) for the prevention of cancer

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews (2009, Issue 3).Tea is one of the most commonly consumed beverages worldwide. Teas from the plant Camellia sinensis can be grouped into green, black and oolong tea, and drinking habits vary cross-culturally. C sinensis contains polyphenols, one subgroup being catechins. Catechins are powerful antioxidants, and laboratory studies have suggested that these compounds may inhibit cancer cell proliferation. Some experimental and nonexperimental epidemiological studies have suggested that green tea may have cancer-preventative effects.

OBJECTIVES

To assess possible associations between green tea consumption and the risk of cancer incidence and mortality as primary outcomes, and safety data and quality of life as secondary outcomes.

SEARCH METHODS

We searched eligible studies up to January 2019 in CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and reference lists of previous reviews and included studies.

SELECTION CRITERIA

We included all epidemiological studies, experimental (i.e. randomised controlled trials (RCTs)) and nonexperimental (non-randomised studies, i.e. observational studies with both cohort and case-control design) that investigated the association of green tea consumption with cancer risk or quality of life, or both.

DATA COLLECTION AND ANALYSIS

Two or more review authors independently applied the study criteria, extracted data and assessed methodological quality of studies. We summarised the results according to diagnosis of cancer type.

MAIN RESULTS

In this review update, we included in total 142 completed studies (11 experimental and 131 nonexperimental) and two ongoing studies. This is an additional 10 experimental and 85 nonexperimental studies from those included in the previous version of the review. Eleven experimental studies allocated a total of 1795 participants to either green tea extract or placebo, all demonstrating an overall high methodological quality based on 'Risk of bias' assessment. For incident prostate cancer, the summary risk ratio (RR) in the green tea-supplemented participants was 0.50 (95% confidence interval (CI) 0.18 to 1.36), based on three studies and involving 201 participants (low-certainty evidence). The summary RR for gynaecological cancer was 1.50 (95% CI 0.41 to 5.48; 2 studies, 1157 participants; low-certainty evidence). No evidence of effect of non-melanoma skin cancer emerged (summary RR 1.00, 95% CI 0.06 to 15.92; 1 study, 1075 participants; low-certainty evidence). In addition, adverse effects of green tea extract intake were reported, including gastrointestinal disorders, elevation of liver enzymes, and, more rarely, insomnia, raised blood pressure and skin/subcutaneous reactions. Consumption of green tea extracts induced a slight improvement in quality of life, compared with placebo, based on three experimental studies. In nonexperimental studies, we included over 1,100,000 participants from 46 cohort studies and 85 case-control studies, which were on average of intermediate to high methodological quality based on Newcastle-Ottawa Scale 'Risk of bias' assessment. When comparing the highest intake of green tea with the lowest, we found a lower overall cancer incidence (summary RR 0.83, 95% CI 0.65 to 1.07), based on three studies, involving 52,479 participants (low-certainty evidence). Conversely, we found no association between green tea consumption and cancer-related mortality (summary RR 0.99, 95% CI 0.91 to 1.07), based on eight studies and 504,366 participants (low-certainty evidence). For most of the site-specific cancers we observed a decreased RR in the highest category of green tea consumption compared with the lowest one. After stratifying the analysis according to study design, we found strongly conflicting results for some cancer sites: oesophageal, prostate and urinary tract cancer, and leukaemia showed an increased RR in cohort studies and a decreased RR or no difference in case-control studies.

AUTHORS' CONCLUSIONS

Overall, findings from experimental and nonexperimental epidemiological studies yielded inconsistent results, thus providing limited evidence for the beneficial effect of green tea consumption on the overall risk of cancer or on specific cancer sites. Some evidence of a beneficial effect of green tea at some cancer sites emerged from the RCTs and from case-control studies, but their methodological limitations, such as the low number and size of the studies, and the inconsistencies with the results of cohort studies, limit the interpretability of the RR estimates. The studies also indicated the occurrence of several side effects associated with high intakes of green tea. In addition, the majority of included studies were carried out in Asian populations characterised by a high intake of green tea, thus limiting the generalisability of the findings to other populations. Well conducted and adequately powered RCTs would be needed to draw conclusions on the possible beneficial effects of green tea consumption on cancer risk.

Effects of green tea or green tea catechin on liver enzymes in healthy individuals and people with nonalcoholic fatty liver disease: A systematic review and meta-analysis of randomized clinical trials

The therapeutic potential of green tea as a rich source of antioxidants and anti-inflammatory compounds has been investigated by several studies. The present study aimed to systematically review and analyze randomized clinical trials (RCTs) assessing the effects of green tea, catechin, and other forms of green tea supplementation on levels of liver enzymes. PubMed, SCOPUS, EMBASE, and Cochrane databases were searched until February 2019. All RCTs investigating the effect of green tea or its catechin on liver enzymes including alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin were included. A total of 15 RCTs were included. The overall effect of green tea on liver enzymes was nonsignificant (ALT [Standardized mean difference (SMD)= -0.17, CI -0.42 to 0.08, p = .19], AST [SMD = -0.07, CI -0.43 to 0.29, p = .69], and ALP [SMD = -0.17, CI -0.45 to 0.1, p = .22]). However, subgroup analyses showed that green tea reduced the levels of liver enzymes in participants with nonalcoholic fatty liver disease (NAFLD) but in healthy subjects, a small significant increase in liver enzymes was observed. In conclusion, the results of this study suggest that the effect of green tea on liver enzymes is dependent on the health status of individuals. While a moderate reducing effect was observed in patients with NAFLD, in healthy subjects, a small increasing effect was found.

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)."

Coffee, green tea and liver cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND

Coffee and green tea, two popular drinks in the Japanese, have recently drawn much attention as potential protective factors against the occurrence of liver cancer.

METHODS

We systematically reviewed epidemiologic studies on coffee, green tea and liver cancer among Japanese populations. Original data were obtained by searching the MEDLINE (PubMed) and Ichushi databases, complemented with manual searches. The evaluation was performed in terms of the magnitude of association in each study and the strength of evidence ('convincing', 'probable', 'possible', or 'insufficient'), together with biological plausibility.

RESULTS

We identified four cohort and four case-control studies on coffee and liver cancer and six cohort and one case-control studies on green tea and liver cancer. All cohort and case-control studies on coffee reported a weak to strong inverse association, with a summary relative risk (RR) for one cup increase being 0.72 (95% confidence interval [CI] 0.66-0.79). Conversely, all studies but two cohort studies on green tea reported no association, with a corresponding summary RR of 0.99 (95% CI 0.97-1.01, P = 0.37).

CONCLUSION

Coffee drinking 'probably' decreases the risk of primary liver cancer among the Japanese population whereas the evidence on an association between green tea and liver cancer is 'insufficient' in this population.

Drug-induced Liver Injury Secondary to Herbal and Dietary Supplements

The use of herbal and dietary supplements (HDS) is increasing in the United States and worldwide. Its significant association with liver injury has become a concern, particularly because rates of hepatotoxicity caused by HDS are increasing. There are variety of HDS available, ranging from multi-ingredient substances, to anabolic steroids for bodybuilding purposes, to individual ingredients for purposes of supplementing a diet. This article reviews the impact of liver injury cause by HDS and explores the hepatotoxic potential of such products and their individual ingredients.

Dietary natural flavonoids treating cancer by targeting aryl hydrocarbon receptor

The role of aryl hydrocarbon receptor (AhR) as a ligand-activated transcription factor in the field of cancer has gradually been unveiled. A strong body of evidence indicated that AhR is implicated in cell proliferation and apoptosis, immune metabolism and other processes, which further affected tumor growth, survival, migration, and invasion. Therefore, AhR targeted therapy may become a new method for cancer treatment and provide a new direction for clinical tumor treatment. Astonishingly, the largest source of exposure of animals and humans to AhR ligands (synthetic and natural) comes from the diet. Myriad studies have described that various natural dietary chemicals can directly activate and/or inhibit the AhR signaling pathway. Of note, numerous natural products contribute to AhR active, of which dietary flavonoids are the largest class of natural AhR ligands. As interest in AhR and its ligands increases, it seems sensible to summarize current research on these ligands. In this review, we highlight the role of AhR in tumorigenesis and focus on the double effect of AhR in cancer therapy. We explored the molecular mechanism of AhR ligands on cancer through a few AhR agonists/antagonists currently in clinical practice. Ultimately, we summarize and highlight the latest progression of dietary flavonoids as AhR ligands in cancer inhibition, including the limitations and deficiencies of it in clinical research. This review will offer a comprehensive understanding of AhR and its dietary ligands which may dramatically pave the way for targeted cancer treatment.

Studies on the Prevention of Cancer and Cardiometabolic Diseases by Tea: Issues on Mechanisms, Effective Doses, and Toxicities

This article presents a brief overview of studies on the prevention of cancer and cardiometabolic diseases by tea. The major focus is on green tea catechins concerning the effective doses used, the mechanisms of action, and possible toxic effects. In cancer prevention by tea, the laboratory results are strong; however, the human data are inconclusive, and the effective doses used in some human trials approached toxic levels. In studies of the alleviation of metabolic syndrome, diabetes, and prevention of cardiovascular diseases, the results from human studies are stronger in individuals who consume 3-4 cups of tea (600-900 mg of catechins) or more per day. The tolerable upper intake level of tea catechins has been set at 300 mg of (-)-epigallocatechin-3-gallate in a bolus dose per day in some European countries. The effects of doses and dosage forms on catechin toxicity, the mechanisms involved, and factors that may affect toxicity are discussed.

Scientific opinion on the safety of green tea catechins

The EFSA ANS Panel was asked to provide a scientific opinion on the safety of green tea catechins from dietary sources including preparations such as food supplements and infusions. Green tea is produced from the leaves of Camellia sinensis (L.) Kuntze, without fermentation, which prevents the oxidation of polyphenolic components. Most of the polyphenols in green tea are catechins. The Panel considered the possible association between the consumption of (-)-epigallocatechin-3-gallate (EGCG), the most relevant catechin in green tea, and hepatotoxicity. This scientific opinion is based on published scientific literature, including interventional studies, monographs and reports by national and international authorities and data received following a public 'Call for data'. The mean daily intake of EGCG resulting from the consumption of green tea infusions ranges from 90 to 300 mg/day while exposure by high-level consumers is estimated to be up to 866 mg EGCG/day, in the adult population in the EU. Food supplements containing green tea catechins provide a daily dose of EGCG in the range of 5-1,000 mg/day, for adult population. The Panel concluded that catechins from green tea infusion, prepared in a traditional way, and reconstituted drinks with an equivalent composition to traditional green tea infusions, are in general considered to be safe according to the presumption of safety approach provided the intake corresponds to reported intakes in European Member States. However, rare cases of liver injury have been reported after consumption of green tea infusions, most probably due to an idiosyncratic reaction. Based on the available data on the potential adverse effects of green tea catechins on the liver, the Panel concluded that there is evidence from interventional clinical trials that intake of doses equal or above 800 mg EGCG/day taken as a food supplement has been shown to induce a statistically significant increase of serum transaminases in treated subjects compared to control.

The safety of green tea and green tea extract consumption in adults - Results of a systematic review

A systematic review of published toxicology and human intervention studies was performed to characterize potential hazards associated with consumption of green tea and its preparations. A review of toxicological evidence from laboratory studies revealed the liver as the target organ and hepatotoxicity as the critical effect, which was strongly associated with certain dosing conditions (e.g. bolus dose via gavage, fasting), and positively correlated with total catechin and epigallocatechingallate (EGCG) content. A review of adverse event (AE) data from 159 human intervention studies yielded findings consistent with toxicological evidence in that a limited range of concentrated, catechin-rich green tea preparations resulted in hepatic AEs in a dose-dependent manner when ingested in large bolus doses, but not when consumed as brewed tea or extracts in beverages or as part of food. Toxico- and pharmacokinetic evidence further suggests internal dose of catechins is a key determinant in the occurrence and severity of hepatotoxicity. A safe intake level of 338 mg EGCG/day for adults was derived from toxicological and human safety data for tea preparations ingested as a solid bolus dose. An Observed Safe Level (OSL) of 704 mg EGCG/day might be considered for tea preparations in beverage form based on human AE data.