Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism

Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.     

Stop for tea? Enzyme inhibitors from tea – what good are they?

Tea possesses many bioactive components including polyphenols, theanine and caffeine. Inhibitory effect of these components on the various enzymes involved in some chronic diseases was reviewed in this study. Many studies revealed that anti‐obesity of tea was mainly ascribed to the polyphenols which could inhibit the activity of the enzymes related to diet metabolism such as α‐amylase, α‐glucosidase and lipase. Inhibitory effect of catechins and caffeine against β‐ and γ‐secretase, acetylcholinesterase, protein kinase C and histone deacetylase might be responsible for the prevention from nervous system diseases. Cytochrome P450 enzymes, cytosolic sulfotransferases, cyclooxygenase‐2 and phosphoinositide‐3‐kinase could be efficiently suppressed by catechins, which would decrease the risk of cancer initiation and proliferation; theanine could lower the activity of some anticarcinogen‐activated enzymes and alleviate the adverse effect of cancer cure. Catechins and caffeine exhibited significant inhibition against the matrix metalloproteinases, histidine decarboxylase and many kinases related to inflammation. Thus, catechins, theanine and caffeine might be employed as inhibitors of the enzymes associated with these chronic diseases.     

Protective effect of polyphenol‐rich extract prepared from Malaysian cocoa (Theobroma cacao) on glucose levels and lipid profiles in streptozotocin‐induced diabetic rats

BACKGROUND: Cocoa beans are used for preparing cocoa liquor and cocoa powder, which are the main ingredients of cocoa‐based products. Previous studies have reported the health benefits of cocoa polyphenols in reducing the risk of cardiovascular diseases. However, there is no report on the efficacy of cocoa polyphenols on diabetes mellitus. Therefore this study was designed to evaluate the protective effect of cocoa polyphenol‐rich extract (CE) on glucose levels and lipid profiles in streptozotocin (STZ)‐induced diabetic rats. Male Sprague‐Dawley rats were divided into diabetic control, diabetic CE and diabetic glibenclamide groups. RESULTS: Three different dosages of CE (10, 20 and 30 mg per 100 g body weight) were administered orally once a day for 1 week before STZ injection and for 3 weeks thereafter. The results showed that CE could normalise the body weight loss caused by STZ. In the 20 mg CE‐pretreated group there was a 143% increase in plasma glucose levels, compared with a 226% increase in diabetic control rats. CE could also normalise total cholesterol, triglycerides and high‐density lipoprotein cholesterol at the end of the experiment compared with the baseline. CONCLUSION: The present study suggests that pretreatment with CE from roasted cocoa beans could prevent the development of diabetes induced by STZ injection in rats. Copyright © 2008 Society of Chemical Industry     

Changes in polyphenol ability to produce astringency during roasting of cocoa liquor

Polyphenols in cocoa products determine the astringent sensation due to their interaction with salivary proline‐rich protein. Changes in the ability of polyphenols to produce astringency during cocoa roasting have been studied through an evaluation of the polyphenol–protein interaction in cocoa cake/liquor roasted at 120 °C for 45 min, with and without enrichment with polyphenol extract. Roasting decreased the capacity of polyphenols to interact with protein, causing a decrease in astringency. However, the polyphenol–protein interaction products after roasting could still be oxidized enzymatically and most probably would still give cocoa products beneficial effects as functional food. Copyright © 2005 Society of Chemical Industry     

药食两用植物改善饮食诱导代谢性炎症研究进展

代谢性炎症具有缓慢性、隐匿性、持续性、关联性等特点,未加及时防治可能破坏机体稳态,导致代谢紊乱并且干扰能量平衡,继而引发肥胖、代谢综合征、代谢相关脂肪性肝病、动脉粥样硬化、2型糖尿病等难治病症。伴随着人类生活方式和饮食结构的改变,肥胖等慢性代谢性疾病已成为世界公共卫生健康备受关注的焦点,代谢性炎症作为这些疾病发病机制的启动因素,通过阻断其发生发展已成为代谢性疾病的重要防治策略。目前研究发现多种药食两用植物表现出良好的抗炎作用,其具有安全、稳定、易接受、毒副作用小及无耐药性等优势。本文通过从药食两用植物目录中筛选发挥缓解炎症、调节代谢等作用的植物及其有效成分,归纳总结改善饮食诱导代谢性疾病的相关作用机制,以期为深入研究代谢性疾病的预防和治疗提供参考。     

Polyphenols in chocolate: is there a contribution to human health?

Recently, polyphenols have gained much more attention, owing to their antioxidant capacity (free radical scavenging and metal chelating) and their possible beneficial implications in human health, such as in the treatment and prevention of cancer, cardiovascular disease, and other pathologies. Cocoa is rich in polyphenols particularly in catechins (flavan-3-ols) and procyanidins. Polyphenol contents of cocoa products such as dark chocolate, milk chocolate and cocoa powder have been published only recently. However, the data vary remarkably due to the quantity of cocoa liquor used in the recipe of the cocoa products but also due to the analytical procedure employed. For example, results obtained by a colourimetric method were 5–7 times higher for the same type of product than results obtained by high performance liquid chromatography (HPLC). In 1994, the per head consumption of chocolate and chocolate confectionery in the European Union ranged from 1.3 kg/year in Portugal to 8.8 kg/year in Germany. In general, consumers in the Northern countries consume on average more than people in the South. Thus, chocolate can be seen as a relevant source for phenolic antioxidants for some European population. However, this alone does not imply, that chocolate could be beneficial to human health. Some epidemiological evidence suggests a beneficial effect to human health by following a polyphenol-rich diet, namely rich in fruits and vegetables and to a less obvious extent an intake of tea and wine having a similar polyphenol composition as cocoa. In many experiments cellular targets have been identified and molecular mechanisms of disease prevention proposed, in particular for the prevention of cancer and cardiovascular diseases as well as for alleviating the response to inflammation reactions. However, it has to be demonstrated, whether polyphenols exert these effects in vivo. One pre-requisite is that the polyphenols are absorbed from the diet. For monomeric flavonoids such as the catechins, there is increasing evidence for their absorption. For complex phenols and tannins (procyanidins) these questions have to be addressed for the future. Some indication for the absorption of procyanidins derive from studies with the human colon cancer cell line Caco-2, believed to be a valuable model for passive intestinal absorption as proposed for polyphenols. However, it has to be clarified which concentration is effective and what concentrations can be expected from food intake. Another open question is related to polyphenol metabolism. For example, much effort has been invested to show antioxidative effects of free unbound polyphenols, especially of catechins and the flavonol quercetin. However, only a very small part can be found in plasma in the free form but conjugated or even metabolised to several phenolic acids and other ring scission products. From the papers reviewed, it is as yet to early to give an answer to the question, whether chocolate and/or other sources rich in catechins and procyanidins are beneficial to human health. Even though some data are promising and justify further research in the field, it has to be shown in future, whether the intake of these functional compounds and/or their sources is related to measurable effects on human health and/or the development of diseases.     

多酚类化合物对糖脂代谢影响的研究进展

多酚类化合物是植物的次生代谢产物,广泛存在于食物中,包括黄酮类化合物、咖啡酸、绿原酸等。很多研究报道表明,摄入富含多酚类化合物的饮料、水果和蔬菜可以减缓肥胖、心血管疾病、糖尿病等慢性疾病甚至癌症的发生和发展。很大一部分原因在于其中的多酚类化合物具有抗氧化、抗病菌、增强免疫力、参与营养成分代谢调节的生理活性。本文结合近年来国内外的研究概况,从相关代谢酶活性和基因的表达、胰岛素分泌、营养物质的消化和吸收等方面来论述多酚类化合物对糖、脂代谢的影响。     

Impact of dietary polyphenols on human platelet function – A critical review of controlled dietary intervention studies

Cardiovascular disease is a chronic disease influenced by many factors, with activated blood platelets being one of them. Platelets play a central role in the formation of plaques within blood vessels, contributing to early inflammatory events. Consumption of diets rich in plant‐based products protects against the development of cardiovascular disease. Polyphenols, which are secondary plant metabolites found in a wide range of foodstuffs and beverages, may be partially responsible for these effects. Their protective properties include inhibitory effects on platelet function in vitro and in vivo. However, the bioavailability of many polyphenols is poor and it is unclear whether sufficient quantities can be obtained by dietary means to exert protective effects. Consequently, this review summarizes 25 well‐controlled human intervention studies examining the effect of polyphenol‐rich diets on platelet function. These studies report a huge variety of research methods, study designs, and study subjects, resulting in controversial assertions. One consistent finding is that cocoa‐related products, however, have platelet‐inhibiting effects when consumed in moderate amounts. To assess whether other classes of dietary polyphenols, or their metabolites, also beneficially affect platelet function requires more well‐controlled intervention studies as well as the adoption of more uniform methods to assess platelet aggregation and activation.     

茶多酚调节肠道菌群及抗肥胖作用研究进展

茶是世界上最受欢迎的饮料之一,其含有丰富的茶多酚,近来,茶多酚对肠道菌群的调节作用引起了学术界的关注。肥胖可以导致心血管疾病、糖尿病、癌症等慢性疾病,因此抗肥胖物质的研究与开发也是当下的研究热点之一,茶多酚的抗肥胖作用也是其中的重要领域。本综述总结了茶多酚、肠道菌群以及肥胖三者的作用关系,并对近5年相关的非临床以及临床研究进行了总结分析。总结发现茶多酚可以调节肠道菌群组成,而肠道菌群也可以影响茶多酚的吸收与代谢。茶多酚可以通过增加益生菌的丰度以及调节能量消耗、营养物质消化吸收、脂质分解代谢和抑制脂肪细胞合成等方式发挥抗肥胖作用。目前对于茶多酚调节肠道菌群和抗肥胖作用的研究以动物模型为主,且大多实验结果证实了茶多酚的肠道菌群调节作用及抗肥胖作用,但是作用剂量尚不明确,且茶多酚剂量毒性研究不足。另外该领域临床研究不足,需要在未来进行更大样本量和更长时间的研究,以实现茶渣等副产物的高价值利用并减少肥胖相关疾病。     

Protective Effects of Anthocyanins in Obesity‐Associated Inflammation and Changes in Gut Microbiome

Obesity is a complex disease and a major public health epidemic. Chronic, low‐grade inflammation is a common underlying feature of obesity and associated metabolic diseases; adipose tissue is a major contributor to this systemic inflammation. Evidence shows that obesity‐associated inflammation may originate from gut dysfunction, including changes in intestinal bacteria or microbiome profiles. Increasingly, food and plant bioactive compounds with antioxidant and anti‐inflammatory properties are proposed to ameliorate obesity‐associated inflammation. Among these, the health‐promoting effects of anthocyanin‐rich foods are of interest here. Specifically, this review summarizes the reported benefits of anthocyanins in obesity‐associated inflammation and underlying molecular mechanisms, including the role of gut microbiome and cell signaling pathways regulated by anthocyanins both in vivo and in vitro.     

植物多酚降血糖机制的研究进展

多酚类化合物是植物的次生代谢产物,广泛存在于自然界中,包括黄酮类化合物、单宁、绿原酸等。研究表明,经常摄入富含多酚类化合物的蔬菜、水果和饮料可以减缓心脑血管疾病、糖尿病、肥胖等慢性代谢疾病甚至癌症的发生和发展。本文从植物多酚可以通过促进胰岛素合成与分泌、抑制葡萄糖转运、调节肠道菌群等方面对血糖起调节作用进行论述,以期为植物多酚降血糖功能提供理论依据。     

Beneficial Effects of Pomegranate on Lipid Metabolism in Metabolic Disorders

Pomegranate (Punica granatum Linn) is used in the prevention and treatment of metabolic syndrome in recent decades. Imbalances in lipid metabolism are profound features of metabolic disorders. In vivo and in vitro studies have shown that extracts of different pomegranate fractions (peels, flowers, juice, and seeds) regulate lipid metabolism in metabolic‐disorder‐associated diseases such as atherosclerosis, nonalcoholic fatty liver disease, and type 2 diabetes, helping to alleviate the development of diseases. Amelioration of oxidative stress and the inflammatory response is considered an important reason underlying the regulation of lipid metabolism by pomegranate extracts. Mitochondria, the major cellular site for lipid oxidation, are strongly associated with cellular oxidative and inflammatory status and are likely to be a target for pomegranate extract action. This review summarizes the main findings about the effects of different pomegranate fraction extracts on lipid metabolism in metabolic‐disorder‐associated diseases and analyses how pomegranate extracts achieve their effects. Furthermore, it also provides an important basis for the research and development of pomegranate‐related nutrients or drugs.     

Cocoa Phytochemicals: Recent Advances in Molecular Mechanisms on Health

Recent reports on cocoa are appealing in that a food commonly consumed for pure pleasure might also bring tangible benefits for human health. Cocoa consumption is correlated with reduced health risks of cardiovascular diseases, hypertension, atherosclerosis, and cancer, and the health-promoting effects of cocoa are mediated by cocoa-driven phytochemicals. Cocoa is rich in procyanidins, theobromine, (?)-epicatechin, catechins, and caffeine. Among the phytochemicals present in consumed cocoa, theobromine is most available in human plasma, followed by caffeine, (?)-epicatechin, catechin, and procyanidins. It has been reported that cocoa phytochemicals specifically modulate or interact with specific molecular targets linked to the pathogenesis of chronic human diseases, including cardiovascular diseases, cancer, neurodegenerative diseases, obesity, diabetes, and skin aging. This review summarizes comprehensive recent findings on the beneficial actions of cocoa-driven phytochemicals in molecular mechanisms of human health.     

Effects of cocoa extract containing polyphenols and methylxanthines on biochemical parameters of obese‐diabetic rats

BACKGROUND: Previous studies have indicated that cocoa extract possesses hypoglycaemic and hypocholesterolaemic properties in streptozotocin‐induced diabetic rats. However, there has been limited research on the effects of cocoa extract on obese‐diabetic (Ob‐db) rats that mimic human diabetes syndrome. Hence this study was initiated to determine the effect of cocoa extract containing polyphenols and methylxanthines on several biochemical parameters, namely glucose level, insulin sensitivity and lipid profiles of Ob‐db rats. RESULTS: Intake of cocoa extract supplemented with polyphenols (2.17 mg epicatechin, 1.52 mg catechin, 0.25 mg dimer and 0.13 mg trimer g^?1 cocoa extract) and methylxanthines (3.55 mg caffeine and 2.22 mg theobromine g^?1 cocoa extract) for 4 weeks significantly (P < 0.05) reduced the plasma total cholesterol, triglycerides and low‐density lipoprotein cholesterol of obese‐diabetic rats (Ob‐db + cocoa) compared with non‐supplemented animals (Ob‐db). Short‐term (acute) supplementation of cocoa extract significantly (P < 0.05) reduced the plasma glucose level at 60 and 90 min compared with untreated rats as assessed by the oral glucose tolerance test. However, no significant differences were observed in plasma glucose level, insulin level and insulin sensitivity after chronic (4 weeks) cocoa extract supplementation. CONCLUSION: The results of this study suggest that cocoa extract possesses hypocholesterolaemic properties and can exert a transient glucose‐lowering effect but not long‐term glucose control. Copyright © 2008 Society of Chemical Industry     

PPARγ调控脂肪细胞增殖和分化机理研究进展

随着人们生活水平的提高,长期摄取高热量的饮食,加上运动量不足,会造成身体能量过度累积,能量以脂肪的形式贮存,从而导致肥胖。早在1997年,世界卫生组织已经正式将肥胖列为一种慢性疾病。过氧化物酶体增殖物激活受体(peroxisome proliferators-activated receptors,PPARs)通过与靶基因启动子区调控序列结合,调控脂肪的代谢和脂肪细胞的增殖与分化。了解PPARs的结构特征、表达特性和作用机理等,对于控制肥胖及其引起的一系列疾病,具有重要的理论意义和实用价值。本文从PPARγ的结构特征和表达特点、配体对PPARγ的活化、PPARs间的相互作用、PPARγ在脂类代谢中的作用和天然配体对脂肪细胞的分化等进行综述,并从PPARγ调控脂肪细胞增殖的角度,提出了预防肥胖的对策。     

Lemon balm extract causes potent antihyperglycemic and antihyperlipidemic effects in insulin‐resistant obese mice

Over the last decades polyetiological metabolic diseases such as obesity and type 2 diabetes have emerged as a global epidemic. Efficient strategies for prevention and treatment include dietary intervention and the development of validated nutraceuticals. Safe extracts of edible plants provide a resource of structurally diverse molecules that can effectively interfere with multifactorial diseases. In this study, we describe the application of ethanolic lemon balm (Melissa officinalis) leaves extract for the treatment of insulin‐resistance and dyslipidemia in mice. We show that lemon balm extract (LBE) activates the peroxisome proliferator‐activated receptors (PPARs), which have key roles in the regulation of whole body glucose and lipid metabolism. Application of LBE (0.6 mg/mL) to human primary adipocytes resulted in specific peroxisome proliferator‐activated receptor target gene expression. LBE treatment of insulin‐resistant high‐fat diet‐fed C57BL/6 mice (200 mg/kg/day) for 6 weeks considerably reduced hyperglycemia and insulin resistance, plasma triacylglycerol, nonesterified fatty acids and LDL/VLDL cholesterol levels. Taken together, ethanolic lemon balm extract can potentially be used to prevent or concomitantly treat type 2 diabetes and associated disorders such as dyslipidemia and hypercholesterolemia.     

Sugar and cocoa: sweet synergy or bitter antagonisms. Formulating cocoa and chocolate products for health: a narrative review

The potential health effects of cocoa flavanols are well described. Ranging from reducing risk of developing type 2 diabetes and cardiovascular disease at population levels, moderating disease risk factors including endothelial function and lipid metabolism in clinical trials and mechanistic studies in laboratory studies highlighting target tissues and pathways. However, translating these benefits into public health messages is problematic, due to the high energy and sugar content of many cocoa products, including chocolate. This review considered the role of sugar in cocoa products, what are its physiological effects on bioavailability and bioactivity? Considering, then how cocoa products can be reformulated to reduce sugar intake, and the likely effects on beneficial effects of cocoa flavanols and consumer preferences. Ultimately, although interesting physiological effects are seen with cocoa flavanols, their use as a disease‐modifying commodities may be limited the effect such products may have within an individual's and populations overall dietary patterns.