Dietary Tea Catechins Increase Fecal Energy in Rats

Gut microbiota as a driver of the interindividual variability of cardiometabolic effects from tea polyphenols

Tea polyphenols have been extensively studied for their preventive properties against cardiometabolic diseases. Nevertheless, the evidence of these effects from human intervention studies is not always consistent, mainly because of a large interindividual variability. The bioavailability of tea polyphenols is low, and metabolism of tea polyphenols highly depends on individual gut microbiota. The accompanying reciprocal relationship between tea polyphenols and gut microbiota may result in alterations in the cardiometabolic effects, however, the underlying mechanism of which is little explored. This review summarizes tea polyphenols-microbiota interaction and its contribution to interindividual variability in cardiometabolic effects. Currently, only a few bacteria that can biodegrade tea polyphenols have been identified and generated metabolites and their bioactivities in metabolic pathways are not fully elucidated. A deeper understanding of the role of complex interaction necessitates fully individualized data, the ntegration of multiple-omics platforms and development of polyphenol-centered databases. Knowledge of this microbial contribution will enable the functional stratification of individuals in the gut microbiota profile (metabotypes) to clarify interindividual variability in the health effects of tea polyphenols. This could be used to predict individual responses to tea polyphenols consumption, hence bringing us closer to personalized nutrition with optimal dose and additional supplementation of specific microorganisms.

Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review

The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.

Preventive effect of small-leaved Kuding tea (Ligustrum robustum) on high-diet-induced obesity in C57BL/6J mice

Small-leaved Kuding tea (SLKDT; Ligustrum robustum) is a traditional Chinese tea. We systematically investigated the effect of SLKDT extract on obesity. SLKDT-controlled weight gain in mice fed a high-fat diet. Tissue specimen results showed that the SLKDT extract alleviated liver damage and fat accumulation. Meanwhile, SLKDT extract improved dyslipidemia by decreasing total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels and increasing high-density lipoprotein cholesterol levels. Furthermore, SLKDT extract reduced alanine aminotransferase, alkaline phosphatase, and aspartate transaminase levels in the serum and liver tissues; decreased inflammatory cytokines, including interleukin (IL)-1β, tumor necrosis factor-α, interferon-γ, and IL-6; and increased the anti-inflammatory cytokines, IL-4 and IL-10. The quantitative PCR results showed that SLKDT extract upregulated the mRNA expressions of peroxisome proliferator-activated receptor (PPAR)-α, lipoprotein lipase, carnitine palmitoyltransferase 1, and cholesterol 7 alpha hydroxylase and downregulated PPAR-γ and CCAAT/enhancer-binding protein-alpha mRNA expressions in the obese mouse livers to reduce adipocyte differentiation and fat accumulation, promote fat oxidation, and improve dyslipidemia, thereby inhibiting the immune response and alleviating liver injury. SLKDT shows a potential for preventing obesity and regulating obesity-related syndrome, so it is possible to be further developed as a novel treatment for fighting obesity.

N-Oleoyl-Phosphatidyl-Ethanolamine and Epigallo Catechin-3-Gallate Mitigate Oxidative Stress in Overweight and Class I Obese People on a Low-Calorie Diet

Oxidative stress and lipid peroxidation are considered key factors linking obesity with its associated complications. Epigallo catechin-3-gallate (EGCG) and oleoylethanolamide, together with its phospholipid precursor N-oleoyl-phosphatidylethanolamine (NOPE), are nutritional compounds that might improve the oxidative stress status of obese people. Unfortunately, the bioavailability of these compounds is low; however, the coadministration of NOPE with EGCG has been shown to ameliorate both the plasma availability of EGCG and the intestinal levels of NOPE in rats. This double-blind placebo-controlled study investigated the effects of 2 months' supplementation with EGCG complexed with NOPE, combined with moderate energy restriction, on plasma oxidative status of overweight and class I obese subjects. A total of 138 subjects (body mass index: 25-35 kg/m²) were recruited and randomized into two groups: the first (n = 67) received caps of placebo and the second (n = 71) caps of an oily dispersion of EGCG complexed with NOPE for 2 months. Subjects' supplementation was combined with moderate energy restriction (-800 kcal/day). Plasma oxidative status was determined by measuring the levels of oxidized low-density lipoprotein (Ox-LDL), malondialdehyde and reactive oxygen metabolites, and by calculating the lag time and the slope of Cu-induced lipid peroxidation kinetics. In total 116 subjects (27 M/89 F) completed the supplementation period, 49 in the placebo group and 67 in the treated group. Treatment induced a similar significant weight reduction in the two groups. Moreover, we found the mean changes of Ox-LDL significantly lower and the mean changes of antioxidant capacity (lag time) significantly higher in NOPE-EGCG group than in placebo group (treatment effect mean difference: -3.15 UL, P < .044 and +5.37 min, P < .0347, respectively). EGCG plasma levels were detectable only after 2 months of NOPE-EGCG diet. The NOPE-EGCG integration to a low-energy diet seems, therefore, useful for ameliorating oxidative stress-related markers, which are concomitant causes of obesity-induced disorders.

Effects of Assam tea extract on growth, skin mucus, serum immunity and disease resistance of Nile tilapia (Oreochromis niloticus) against Streptococcus agalactiae

The present study aimed to assess the possible effects of Assam tea (Camellia sinensis) extract (ATE) on growth performances, immune responses, and disease resistance of Nile tilapia, Oreochromis niloticus against Streptococcus agalactiae. Five levels of ATE were supplemented into the based diet at 0, 1, 2, 4, and 8 g kg^-1 feed of Nile tilapia fingerlings (10.9 ± 0.04 g initial weight) in triplicate. After four and eight weeks of feeding, fish were sampled to determine the effects of the tea supplements upon their growth performance, as well as serum and mucosal immune responses. A disease challenge using S. agalactiae was conducted at the end of the feeding trial. Fish fed ATE revealed significantly improved serum lysozyme, peroxidase, alternative complement (ACH50), phagocytosis, and respiratory burst activities compared to the basal control fed fish (P < 0.05). The mucus lysozyme and peroxidase activities were ameliorated through ATE supplementation in the tilapia diets. Supplementation of ATE significantly (P < 0.05) enhanced final body weight, weight gain, and specific growth rate; while a decreased feed conversion ratio was revealed at 2 g kg^-1 inclusion level, after four and eight weeks. Challenge test showed that the relative percent survival (RSP) of fish in each treatment was 33.33%, 60.00%, 83.33%, 76.68%, and 66.68% in groups fed 0, 1, 2, 4, and 8 g kg^-1, respectively. In summary, diets supplemented with ATE especially at 2 g kg^-1 increased the humoral and mucosal immunity, enhanced growth performance, and offered higher resistance against S. agalactiae infection in Nile tilapia.

Role of the food matrix and digestion on calculation of the actual energy content of food

The energy content of food is calculated on the basis of general factors for fat, protein, and carbohydrates. These general factors were derived by W.O. Atwater in the late 19th century, while additional factors for dietary fiber, polyols, and organic acids were introduced more recently. These factors are applied indiscriminately to all types of foods, yet the same nutrient may be digested to different extents to generate energy, depending on the characteristics of the food matrix, the processing methods applied to foods, and the meal composition. As a consequence, the actual energy content of food may differ from what is theoretically calculated with the Atwater factors. In this review, the relationship of macronutrient digestibility with food structure, macronutrient structure, and food composition is examined, and the implications for the amount of energy achievable through diet are highlighted. Estimates of the discrepancy between calculated energy content and actual energy content are provided for different diets. The findings may have implications for consumer purchasing decisions as well as for the design of dietary interventions.

A Review on the Weight-Loss Effects of Oxidized Tea Polyphenols

The mechanistic systems in the body through which tea causes weight loss are complex and multi-dimensional. Additionally, the bioactive components in tea such as catechins, caffeine, and products of tea polyphenol oxidation vary greatly from one major tea type to the next. Green tea has been the primary subject of consideration for investigation into the preventative health effects of tea because it contains the highest levels of phenolic compounds and retains the highest antioxidant capabilities of any major tea type. However, recent research suggests decreasing body fat accumulation has little to do with antioxidant activity and more to do with enzyme inhibition, and gut microbiota interactions. This paper reviews several different tea polyphenol-induced weight-loss mechanisms, and purposes a way in which these mechanisms may be interrelated. Our original 'short-chain fatty acid (SCFA) hypothesis' suggests that the weight-loss efficacy of a given tea is determined by a combination of carbohydrate digestive enzyme inhibition and subsequent reactions of undigested carbohydrates with gut microbiota. These reactions among residual carbohydrates, tea polyphenols, and gut microbiota within the colon produce short-chain fatty acids, which enhance lipid metabolism through AMP-activated protein kinase (AMPK) activation. Some evidence suggests the mechanisms involved in SCFA generation may be triggered more strongly by teas that have undergone fermentation (black, oolong, and dark) than by non-fermented (green) teas. We discussed the mechanistic differences among fermented and non-fermented teas in terms of enzyme inhibition, interactions with gut microbiota, SCFA generation, and lipid metabolism. The inconsistent results and possible causes behind them are also discussed.

Morinda citrifolia L. leaf extract prevent weight gain in Sprague-Dawley rats fed a high fat diet

Background: Morinda citrifolia L. is widely used as a folk medicinal food plant to manage a panoply of diseases, though no concrete reports on its potential anti-obesity activity. This study aimed to evaluate the potential of M. citrifolia leaf extracts (MLE60) in the prevention of weight gain in vivo and establish its phytochemical profile. Design: Male Sprague-Dawley rats were divided into groups based on a normal diet (ND) or high fat diet (HFD), with or without MLE60 supplementation (150 and 350 mg/kg body weight) and assessed for any reduction in weight gain. Plasma leptin, insulin, adiponectin, and ghrelin of all groups were determined. 1H NMR and LCMS methods were employed for phytochemical profiling of MLE60. Results: The supplementation of MLE60 did not affect food intake indicating that appetite suppression might not be the main anti-obesity mechanism involved. In the treated groups, MLE60 prevented weight gain, most likely through an inhibition of pancreatic and lipoprotein activity with a positive influence on the lipid profiles and a reduction in LDL levels . MLE60 also attenuated visceral fat deposition in treated subjects with improvement in the plasma levels of obesity-linked factors . 1Spectral analysis showed the presence of several bioactive compounds with rutin being more predominant. Conclusion: MLE60 shows promise as an anti-obesity agents and warrants further research.

Natural Products with Anti-obesity Effects and Different Mechanisms of Action

Obesity, a primary influence on health condition, causes numerous comorbidities and complications and, therefore, pharmacotherapy is considered a strategy for its treatment. However, the adverse effects of most chemical drugs targeting weight loss complicate their approval by regulatory authorities. Recently, interest has increased in the development of ingredients from natural sources with fewer adverse effects for preventing and ameliorating obesity. This review provides an overview of current anti-obesity drugs and natural products with anti-obesity properties as well as their mechanisms of action, which include interfering with nutrient absorption, decreasing adipogenesis, increasing energy expenditure (thermogenesis), appetite suppression, modifying intestinal microbiota composition, and increasing fecal fat excretion.

Beneficial Effects of Tea and the Green Tea Catechin Epigallocatechin-3-gallate on Obesity

Green tea has been shown to have beneficial effects against cancer, obesity, atherosclerosis, diabetes, bacterial and viral infections, and dental caries. The catechin (−)-epigallocatechin-3-gallate (EGCG) has shown the highest biological activity among green tea catechins (GTCs) in most of the studies. While several epidemiological studies have shown the beneficial effects of tea and GTCs on obesity, some studies have failed to do this. In addition, a large number of interventional clinical studies have shown these favorable effects, and cellular and animal experiments have supported those findings, and revealed the underlying anti-obesity mechanisms. One of the mechanisms is enhanced cellular production of reactive oxygen species, which is mediated through the pro-oxidant action of EGCG, leading to the activation of adenosine monophosphate-activated protein kinase, which suppresses gene and protein expression of enzymes and transcription factors involved in adipogenesis and lipogenesis, and stimulates those involved in lipolysis. Recently, scientific evidence supporting the beneficial anti-obesity effects of green tea and GTCs has been increasing. However, future investigations are still required to clarify the reasons for the inconsistent results reported in the human studies; to achieve this, careful adjustment of confounding factors will be required.

Nutraceuticals for body-weight management: The role of green tea catechins

Green tea catechins mixed with caffeine have been proposed as adjuvants for maintaining or enhancing energy expenditure and for increasing fat oxidation, in the context of prevention and treatment of obesity. These catechins-caffeine mixtures seem to counteract the decrease in metabolic rate that occurs during weight loss. Their effects are of particular importance during weight maintenance after weight loss. Other metabolic targets may be fat absorption and the gut microbiota composition, but these effects still need further investigation in combination with weight loss. Limitations for the effects of green tea catechins are moderating factors such as genetic predisposition related to COMT-activity, habitual caffeine intake, and ingestion combined with dietary protein. In conclusion, a mixture of green tea catechins and caffeine has a beneficial effect on body-weight management, especially by sustained energy expenditure, fat oxidation, and preservation of fat free body-mass, after energy restriction induced body-weight loss, when taking the limitations into account.

The relationship between phenolic compounds from diet and microbiota: impact on human health

The human intestinal tract is home to a complex microbial community called microbiota.

Effects of (-)-epicatechin on a diet-induced rat model of cardiometabolic risk factors

Overweight and obesity have been associated with increase in cardiometabolic risk. Therapeutics include lifestyle changes and/or pharmacologic agents. However, such interventions are often limited by poor compliance and/or significant side effects. The consumption of certain dietary products, such as cocoa, exerts positive effects on cardiometabolic risk factors. (-)-Epicatechin (EPI), the most abundant flavonoid in cacao has been reported to replicate such effects. However its mechanisms of action have not been fully elucidated.In a rat model of high-fat diet-induced obesity and its associated cardiometabolic risk factors, we administered 1mg/kg of EPI, by gavage, for 2 weeks. Endpoints included weight-gain, glycemia, triglyceridemia, and systolic blood pressure. We also assessed food intake and fecal excretion. Mitochondrial function and structure related proteins were measured by Westerns.Obesity, hyperglycemia, hypertriglyceridemia, and systolic hypertension were developed after the administration of the high-fat diet for five weeks. EPI significantly decreased the rate of weight gain, glycemia and hypertriglyceridemia. The ratio between energy intake and excretion was not significantly modified by treatment. EPI restored the obesity-induced decreases in the levels of skeletal muscle and abdominal tissue sirtuins (SIRTs), peroxisome proliferator-activated receptor coactivator (PGC-1α), mitofilin, transcription factor A mitochondrial (TFAM), uncoupling protein 1 (UCP1), and deiodinase.EPI treatment yielded beneficial effects on high fat diet-induced endpoints thus may be considered as a potential agent for the treatment of obesity and its cardiometabolic associated abnormalities. Mechanism of action may be attributed to the modulation of cellular/mitochondrial function, thus improving overall metabolism.

Catechin- and caffeine-rich teas for control of body weight in humans

Maintaining the level of daily energy expenditure during weight loss and weight maintenance is as important as maintaining satiety while decreasing energy intake. In this context, different catechin- and caffeine-rich teas (CCRTs), such as green, oolong, and white teas, as well as caffeine have been proposed as tools for maintaining or enhancing energy expenditure and for increasing fat oxidation. Tea polyphenols have been proposed to counteract the decrease in metabolic rate that is usually present during weight loss. Their effects may be of particular importance during weight maintenance after weight loss. Although the thermogenic effect of CCRT has the potential to produce significant effects on these metabolic targets as well as on fat absorption and energy intake, possibly via its impact on the gut microbiota and gene expression, a clinically meaningful outcome also depends on compliance by the subjects. Limitations to this approach require further examination, including moderating factors such as genetic predisposition, habitual caffeine intake, and catechin composition and dose. Nevertheless, CCRTs may be useful agents that could help in preventing a positive energy balance and obesity.

Gallic acid glycerol ester promotes weight-loss in rats

Lifestyle-related diseases arise from obesity in 30 - 60% of cases. In recent years, food functions controlling the nutritional physiology of lipids have been a focus of disease prevention. Animal feeding experiments have revealed that esters made from gallic acid (GA) and (-)-epigallo-catechin (EGC) or linoleyl alcohol are more effective in weight-loss promotion and metabolic syndrome management than are intact GA and EGC. In this study, an ester (DOGGA) was chemically synthesized from GA and 1,2-dioleoyl glycerol and its effect was compared to that of octyl gallate (OG) and GA in male Wistar rats fed a powdered standard diet containing 7% frying oil for 12 weeks. Results revealed remarkably low body weight gains and food efficiency ratios in the DOGGA group, and the effects of OG were less pronounced than those of DOGGA. The GA group showed no difference from the control group. In addition, fecal lipid content in the DOGGA group was statistically higher than that in the control group, although organ weights and serum biochemical analyses did not differ between the groups. In conclusion, the data suggested that DOGGA promoted weight-loss more effectively than OG and GA did and that the alcohol moiety of gallate is not necessarily EGC and linoleyl alcohol.

Antidiabetic effects of natural plant extracts via inhibition of carbohydrate hydrolysis enzymes with emphasis on pancreatic alpha amylase

INTRODUCTION

The increasing prevalence of type 2 diabetes mellitus and the negative clinical outcomes observed with the commercially available anti-diabetic drugs have led to the investigation of new therapeutic approaches focused on controlling postprandrial glucose levels. The use of carbohydrate digestive enzyme inhibitors from natural resources could be a possible strategy to block dietary carbohydrate absorption with less adverse effects than synthetic drugs.

AREAS COVERED

This review covers the latest evidence regarding in vitro and in vivo studies in relation to pancreatic alpha-amylase inhibitors of plant origin, and presents bioactive compounds of phenolic nature that exhibit anti-amylase activity.

EXPERT OPINION

Pancreatic alpha-amylase inhibitors from traditional plant extracts are a promising tool for diabetes treatment. Many studies have confirmed the alpha-amylase inhibitory activity of plants and their bioactive compounds in vitro, but few studies corroborate these findings in rodents and very few in humans. Thus, despite some encouraging results, more research is required for developing a valuable anti-diabetic therapy using pancreatic alpha-amylase inhibitors of plant origin.

Does flavor impact function? Potential consequences of polyphenol-protein interactions in delivery and bioactivity of flavan-3-ols from foods

Astringency is a component of the overall flavor experienced when consuming polyphenol rich foods and beverages such as tea, wine, cocoa and select fruits. Following consumption, the astringent sensation results from the well documented ability of polyphenols to bind to salivary proline rich proteins (PRP) and facilitate their precipitation in the oral cavity. In a similar fashion, polyphenols are also known to non-specifically bind food and other biological proteins. While much is known regarding the polyphenol-protein interactions leading to astringency, significantly less information is available regarding the impact of these polyphenol-protein interactions with food or other biological proteins on relevant physiological outcomes. This paper focuses on the interactions between flavan-3-ols, one of the most abundant dietary polyphenol forms, with proteins in food, salivary PRP and other physiological proteins. The physiological implications of these interactions in food and through the gut will be discussed in relation to manipulation of flavan-3-ol bioavailability, metabolism and biological activities including inhibition of digestive enzymes in the gut.

Green tea aqueous extract reduces visceral fat and decreases protein availability in rats fed with a high-fat diet

Green tea is associated with beneficial health effects mainly because of its body fat-reducing and hypocholesterolemic activities, but an effective dose without pronounced influence on protein availability is unknown. The objective of this study was to examine the hypothesis that green tea aqueous extract (GTAE) depending on dose improves cardiovascular risk indicators such as body weight, visceral fat content, and atherogenic index of plasma and does not have unfavorable effect on protein availability in rats fed with a high-fat diet. The rats fed with a high-fat diet enriched with 1.1 and 2.0% GTAE for 8 weeks had significantly (P < .05) lower atherogenic index (in both groups, about 14.3%). Only administration of 2.0% GTAE significantly (P < .05) decreased body weight gain (5.6%) and prevented visceral fat accumulation (17.8%) in rats. However, considerably (P < .05), reduction in the digestion of protein (but not fat) was observed in both GTAE groups (1.1% GTAE: 82.6% ± 1.8%; 2.0% GTAE: 84.3% ± 0.8%) when compared to the control (93.3% ± 1.5%). It was concluded that GTAE may have preventive effects on the accumulation of visceral fat but only in higher doses. Although both doses improved cardiovascular risk indicators, they, in addition, significantly inhibited protein digestion.

Acute effects of epigallocatechin gallate from green tea on oxidation and tissue incorporation of dietary lipids in mice fed a high-fat diet

OBJECTIVE

To examine in mice the acute effects of epigallocatechin gallate (EGCG), a green tea bioactive polyphenol on substrate metabolism with focus on the fate of dietary lipids.

METHODS

Male C57BL/6 mice were fed high-fat diets supplemented with EGCG extracted from green tea (TEAVIGO, DSM Nutritional Products Ltd, Basel, Switzerland) at different dosages up to 1% (w/w). Effects of EGCG on body composition (quantitative magnetic resonance), food intake and digestibility, oxidation and incorporation of exogenous lipids (stable isotope techniques: (13)C-labeled palmitate and diet supplemented with corn oil as a natural source of (13)C-enriched lipids) as well as gene expression (quantitative real-time PCR) in liver and intestinal mucosa were investigated.

RESULTS

Short-term supplementation (4-7 days) of dietary EGCG increased energy excretion, while food and energy intake were not affected. Fecal energy loss was accompanied by increased fat and nitrogen excretion. EGCG decreased post-prandial triglyceride and glycogen content in liver, increased oxidation of dietary lipids and decreased incorporation of dietary 13C-enriched lipids into fat tissues, liver and skeletal muscle. EGCG dose dependently reversed high-fat diet-induced effects on intestinal substrate transporters (CD36, FATP4 and SGLT1) and downregulated lipogenesis-related genes (ACC, FAS and SCD1) in liver in the post-prandial state.

CONCLUSIONS

Anti-obesity effects of EGCG can be explained by a decreased food digestibility affecting substrate metabolism of intestinal mucosa and liver, leading to increased post-prandial fat oxidation and reduced incorporation of dietary lipids into tissues.

Antiobesity effects of green tea catechins: a mechanistic review

Green tea catechins (GTC) are polyphenolic compounds present in the unfermented dried leaves of the plant, Camellia sinensis. Results from a number of randomized, controlled intervention trials have shown that consumption of GTC (270 mg to 1200 mg/day) may reduce body weight and fat. There are several proposed mechanisms whereby GTC may influence body weight and composition. The predominating hypothesis is that GTC influences sympathetic nervous system (SNS) activity, increasing energy expenditure and promoting the oxidation of fat. Caffeine, naturally present in green tea, also influences SNS activity, and may act synergistically with GTC to increase energy expenditure and fat oxidation. Other potential mechanisms include modifications in appetite, up-regulation of enzymes involved in hepatic fat oxidation, and decreased nutrient absorption. This article reviews the evidence for each of these purported mechanisms, with particular reference to studies in humans.