Effects of Polyphenols from Cocoa Powder on Diabetic Syndrome in Obese-Diabetic Rats

This study was carried out to determine the effects of polyphenols from cocoa powder on diabetic syndrome of obese-diabetic (Ob-db) rats. The studied diabetic syndrome are fasting plasma glucose level, oral glucose tolerance test, insulin level and insulin sensitivity, lipid profiles (total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and free fatty acids), oxidative stress biomarker (8-isoprostane), and antioxidant enzymes (superoxide dismutase and catalase). Obese-diabetic (Ob-db) rats were developed using a high-fat diet (49% fat, 32% carbohydrate, and 19% protein from total energy, kcal) for 3 months, followed by a low dose (35 mg/kg body weight) streptozotocin (STZ) injection. Cocoa extract (600 mg/kg body weight) containing both polyphenols (2.17mg epicatechin, 1.52 mg catechin, 0.25 mg dimer and 0.13 mg trimer g/cocoa extract) and methylxanthines (3.55 mg caffeine and 2.22 mg theobromine g/cocoa extract) was given to the rats for 4 weeks. The results indicated that there were no significant differences in fasting plasma glucose, insulin level and insulin sensitivity after 4 weeks of cocoa extracts administration. Oral glucose tolerance test revealed that cocoa supplementation in Ob-db rats significantly (p < 0.05) reduced plasma glucose at 60 and 90 min compared to unsupplemented Ob-db rats. The supplementation 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). Plasma free fatty acid and oxidative stress biomarker (8-isoprostane) were significantly (p < 0.05) reduced after cocoa supplementation. Superoxide dismutase activity was enhanced in Ob-db compared to that in non-supplemented rats. However, no change was observed in catalase activity. Cocoa supplementation had an effect on postprandial glucose control but not for long-term glucose control (4 weeks). Four weeks of cocoa extract supplementation also possess hypocholesterolaemic properties. Moreover, cocoa supplementation could reduce circulating plasma free fatty acid and 8 isoprostane and may enhance the antioxidant defense system

Development of functional bread with beta glucan and black tea and effects on appetite regulation, glucose and insulin responses in healthy volunteers

In the UK, dietary fibre intake is below the recommended level of 30 g/day. The manipulation of behavioural change is challenging, hence finding alternative ways to improve diet is important. The development of functional foods such as bread with added functional ingredients such as β-glucan and black tea may be more feasible and acceptable than changing to a new eating pattern. β-Glucan and black tea are often eaten separately, however there may be a food-matrix interaction between starch, protein (gluten), tea (poly)phenols and β-glucan when added together in a bread. We hypothesise that β-glucan and black tea will be digested slowly and display a blunted postprandial glycaemia. Some undigested residues will reach the colon, where it will be metabolised to short chain fatty acids (SCFA). SCFA, particularly propionate, have the potential to increase satiety by stimulating G protein receptors, however the effects on food intake need to be tested. This project described: i) development of a functional bread containing black tea, BT; β- glucan, βG; β-Glucan and black tea, βGBT) and compare it to normal white bread (WB) (study 1); ii) determination of bread palatability, perceived satiety and subsequent energy intake following ingestion (study 2); iii) determination of postprandial glucose and insulin responses, and appetite hormones (CCK, PYY and GLP-1) among healthy volunteers (study 3 – in vivo study). In study 1, the breads were developed and tested for starch functionality, antioxidant potential and in vitro fermentability mimicking human colonic fermentation. βG and βGBT breads reduced early (10-min) in vitro starch hydrolysis and this could be due to action of β-glucan that ‘protected’ some of the starch granules (microscopic study) against amylolysis. Digestion with α-amylase increased antioxidant potential and total (poly)phenols content of BT and βGBT breads compared with WB. In vitro propionate concentration did not increase significantly when fermented with β-glucan. High inter- individual variation was observed for individual SCFA production. The addition of black tea had no apparent effect on SCFA production. Study 2 is a randomised, crossover study design conducted in healthy volunteers. Breads were given as breakfast and perceived satiety (perceived fullness, hunger, satiety, desire to eat and prospective food intake) was measured postprandially for 3 h. Ad libitum lunch was given after 3 h and energy intake estimated. BT bread was the most acceptable among all breads. βG and βGBT breads showed adverse taste, texture and palatability but showed similar overall acceptability as WB and BT breads. Female subjects showed lower preference for taste, texture and palatability of βG and βGBT compared with WB. βG and βGBT had positive effects on perceived satiety as follows: 1) decreased hunger; 2) increased fullness; and 3) decreased desire to eat. However, eating βG and βGBT at breakfast did not reduce energy intake at lunch compared with WB. Study 3 was similar to study 2. Only βG bread showed significantly lower glucose TAUC0-180 min compared with BT and βGBT but has no apparent effect on insulin response. No significant changes were observed for CCK and GLP-1 responses for all breads. However, βG and βGBT showed lower PYY TAUC0-180 min compared with BT. In vitro starch hydrolysis did not correlate with in vivo postprandial glycaemic responses. In conclusion, these studies suggest that breads with β-glucan and/or black tea have positive effects on perceived satiety in vivo and show good overall acceptability. However, there is no clear evidence that they affect appetite regulation. Breads containing 7 g β- glucan per 50 g of available carbohydrate reduced in vivo glucose response without altering insulin responses. There was no additional effect of adding black tea together with β-glucan to bread on the in vivo postprandial glycaemic response. It is too early to generalise the results from in vitro batch fermentation and starch hydrolysis and this needs to be considered when planning future dietary interventions looking at both in vitro and in vivo studies. Overall this study concluded that adding soluble dietary fibre to bread is feasible in controlling glycaemic responses and may help increase daily dietary fibre intake

Polyphenols in cocoa and cocoa products: is there a link between antioxidant properties and health?.

Cocoa and cocoa products have received much attention due to their significant polyphenol contents. Cocoa and cocoa products, namely cocoa liquor, cocoa powder and chocolates (milk and dark chocolates) may present varied polyphenol contents and possess different levels of antioxidant potentials. For the past ten years, at least 28 human studies have been conducted utilizing one of these cocoa products. However, questions arise on which of these products would deliver the best polyphenol contents and antioxidant effects. Moreover, the presence of methylxanthines, peptides, and minerals could synergistically enhance or reduce antioxidant properties of cocoa and cocoa products. To a greater extent, cocoa beans from different countries of origins and the methods of preparation (primary and secondary) could also partially influence the antioxidant polyphenols of cocoa products. Hence, comprehensive studies on the aforementioned factors could provide the understanding of health-promoting activities of cocoa or cocoa products components

Assessment of antioxidant capacity and phenolic content of selected commercial beverages

This study was aimed at assessing the antioxidant capacity and phenolic (free, bound, and total) contents in selected commercial beverages. Three different types of beverages commonly available in Malaysian supermarkets namely, cocoa, coffee and tea were selected. Phenolic contents were determined using a Folin-Ciocalteu assay. Antioxidant capacity (ferric reducing power and scavenging activity) was determined using FRAP and TEAC assays. Based on analysis of variance, coffee showed the highest amount of free phenolic compounds and antioxidant capacity compared to cocoa and tea (p < 0.05). The major phenolic compound detected in coffee was chlorogenic acid. Cocoa showed higher phenolic content than tea. However, cocoa and tea have similar catechin content and possessed comparable antioxidant capacity. The free phenolic content in the three beverages was found to be highly correlated with antioxidant capacity. In addition, moderate correlation was observed between total phenolic content and antioxidant capacity. On the other hand, there was no significant contribution of bound phenolic compounds towards antioxidant capacity. The contribution of antioxidant capacity in these beverages could be due to phenolic compounds in the free form. The study indicated that the beverages studied possessed varying degrees of antioxidant capacity and phenolic contents

Glycaemic index, palatability, acceptability and perceived satiety of cookies prepared with durian (Durio Zibethinus Murr.) and beta-glucan

Durian is rich in macronutrients and bioactive compounds. β-glucan is a soluble fibre and has the ability to increase perceived satiety and reduce glycaemic response. Hence, durian and β-glucan can be used for the development of functional foods. The aim of this study was to determine the effects of cookies prepared with durian and β-glucan on glycaemic index, acceptability, palatability and perceived satiety. Ten healthy participants with normal BMI completed four trials with a 3-day washout period. Foods were given to the subject after an overnight fast. Blood was sampled at fasting (0 min, baseline) and 120 min after food consumption and assayed for glucose concentration. Acceptability, perceived satiety and palatability were assessed using visual analogue scale. There were no significant differences for acceptability and palatability between control and test cookies. Cookies prepared with durian and/or β-glucan significantly (p < 0.05) increased perceived satiety except for thirstiness and pleasantness compared with control cookies. Durian and β-glucan cookies showed lower glycaemic index compared with other biscuits with 59.4 (14.63). This study suggests that cookies prepared with durian and β-glucan is acceptable and has the potential to reduce GI compared with control. A combination of durian and β-glucan in cookies shows promising health benefits and could be used for the development of functional foods

Phenolic and theobromine contents of commercial dark, milk and white chocolates on the Malaysian market

Chocolate contains a wide range of antioxidants that includes soluble phenolic compounds (phenolic acids, catechin, epicatechin, and proanthocyanidins), insoluble polymeric phenolics and methylxanthines. The objective of this study was to determine phenolic and theobromine contents in dark (DC), milk (MC), and white (WC) chocolates commonly found in the Malaysian marketplace. Total phenolic and flavonoids were determined by means of a spectrometric assay, while catechin, epicatechin and theobromine were quantified using a reverse-phase HPLC method. Dark chocolates exhibited the highest phenolics and flavonoids contents, followed by milk and white chocolates. Catechin and epicatechin were major flavonoids detected in dark chocolates. Theobromine was detected in dark and milk chocolates, but not in white chocolates. A high correlation (r= 0.93) between total phenolic and flavonoid contents, indicating that the major phenolic compounds in dark chocolates belong to the flavonoid class. When nutrition and health promotion are of concern, dark chocolates would be recommended over milk and white chocolates owing to their higher contents of antioxidant phenolic compounds

Glycemic index of starch-based foods commonly consumed in Terengganu, Malaysia

This study was aimed to determine the GI of nine starch-based foods commonly consumed in Terengganu, Malaysia as follows: noodles (fried yellow mi, fried mihun, fried kuay teow), local kuih (akok, apam ayu, mek comel), and local fish snacks (boiled keropok lekor, fried keropok lekor, fried keropok keping). Glycemic index determination was done according to standard GI protocol. Ten healthy subjects completed each category of starch-based foods. i.e. three test foods and one reference food after an overnight fast (10-12 hr). Capillary blood samples were measured at baseline (fasting, 0 min) and at 15, 30, 45, 60, 90 and 120 min thereafter. Glycemic index was determined by expressing the percentage incremental area under the curve of the test food over reference food (glucose). Four foods were categorized as low GI as follows: fried keropok keping, GI = 29.00 (7.5); fried mihun, GI = 45.40 (7.43); akok, GI = 49.34 (5.11) and fried yellow mi, GI = 49.56 (6.77). These foods had significantly lower GI than reference food (glucose; GI = 100) (p < 0.05). The remaining five foods were categorized as high GI as follows: apam ayu, GI = 90.56 (12.0), mek comel; GI = 82.71 (9.42); fried kuay teow, GI = 79.50 (9.34); boiled keropok lekor, GI = 79.00 (9.50) and fried keropok lekor, GI = 70.00 (13.40). This study shows that starch-based foods raised glucose response differently and depends on the factors such as nutrient composition, food structure, processing techniques and cooking methods

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 (2.17mg epicatechin, 1.52mg catechin, 0.25mg dimer and 0.13 mg trimer g-1 cocoa extract) and methylxanthines (3.55 mg caffeine and 2.22mg 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 90min 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

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

Effects of cocoa extract on glucometabolism, oxidative stress, and antioxidant enzymes in obese-diabetic (Ob-db) rats

In this present study, we investigated the effects of cocoa extract containing polyphenols and methylxanthines prepared from cocoa powder on the biochemical parameters of obese-diabetic (Obdb) rats. Obese-diabetic (Ob-db) rats were developed using a high-fat diet (49% fat, 32% carbohydrate, and 19% protein from total energy, kcal) for 3 months, followed by a low dose (35 mg/kg body weight)streptozotocin (STZ) injection. Cocoa extract (600 mg/kg body weight/day) was given to the rats for 4 weeks. The results indicated that there were no significant differences in fasting plasma glucose and insulin level after 4 weeks of cocoa extract administration. Oral glucose tolerance test revealed that cocoa supplementation in Ob-db rats significantly (p < 0.05) reduced plasma glucose at 60 and 90 min compared to unsupplemented Ob-db rats. Plasma free fatty acid and oxidative stress biomarker(8-isoprostane) were significantly (p < 0.05) reduced after cocoa supplementation. Superoxide dismutase activity was enhanced in Ob-db compared to that in nonsupplemented rats. However, no change was observed in catalase activity. The results showed that cocoa supplementation had an effect on postprandial glucose control but not for long term (4 weeks). Moreover, cocoa supplementation could reduce circulating plasma free fatty acid and 8-isoprostane and may enhance the antioxidant defense system