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Type 2 diabetes (T2DM) is a chronic disease characterized by cellular insulin resistance and consequent disturbances in glucose metabolism. Long-term consumption of buckwheat has been previously shown to improve glycemia in individuals with T2DM; however, the underlying mechanisms as well as the contribution of improved acute glycemic responses have not been fully characterized. The current study used cell culture and clinical studies to investigate the mechanisms and effectiveness of common buckwheat for acute modulation of glucose metabolism and glycemia. Glucose uptake was inhibited in H4IIE cells treated with a buckwheat extract (BWE), an effect attributed to the actions of an unknown compound(s). Reduced glucose uptake and transepithelial glucose transport was also present in Caco2 colorectal adenocarcinoma cells and monolayers. The mechanism behind inhibited glucose uptake did not involve modulation of several signaling pathways regulating glucose metabolism, including p38 MAPK, p42/44 ERK, PI3Kγ, PKC, PKA, mTOR and AMPK. Interestingly, BWE treatment was associated with other effects on glucose metabolism, including elevated glucose production and levels of gluconeogenic enzymes. However, these effects were not mediated through the classical pathway of CREB activation involving cyclic AMP and PKA. In a blinded, reference product-controlled study, consumption of a cracker product made from whole grain common buckwheat flour containing 50 grams of available carbohydrate was not associated with changes in post-prandial glucose or insulin concentrations in both healthy individuals and those with diet-controlled T2DM. However, consumption of buckwheat crackers was associated with changes in selected gastrointestinal satiety hormones. Interestingly, several significant correlations observed between fasting concentrations and the overall post-prandial response of these hormones were affected by T2DM. In conclusion, glucose-lowering effects of common buckwheat are not due to the actions of known bioactive compounds, and may involve direct inhibition of facilitative transporters by a novel compound. Although a buckwheat food product did not reduce post-prandial glycemia, identifying the compound responsible for inhibited glucose uptake will allow development of food products enriched with this compound, and may represent a more effective dietary approach to managing glycemia.

Buckwheat ( Fagopyrum esculentum ) derives its name from the likeness of the fruit to a beech-nut (German :Buchweizen). It probably originated in the Himalayas (Stoletova, 1940). The earliest record of buckwheat cultivation was found in Germany in an old register dated 1436 (Hill, 1937; Ames, 1939). It is in no way related to wheat except that it has some importance as a "cereal" and is hence called a pseudo-cereal. [...]

Type 2 diabetes (T2DM) is a chronic disease characterized by cellular insulin resistance and consequent disturbances in glucose metabolism. Long-term consumption of buckwheat has been previously shown to improve glycemia in individuals with T2DM; however, the underlying mechanisms as well as the contribution of improved acute glycemic responses have not been fully characterized. The current study used cell culture and clinical studies to investigate the mechanisms and effectiveness of common buckwheat for acute modulation of glucose metabolism and glycemia. Glucose uptake was inhibited in H4IIE cells treated with a buckwheat extract (BWE), an effect attributed to the actions of an unknown compound(s). Reduced glucose uptake and transepithelial glucose transport was also present in Caco2 colorectal adenocarcinoma cells and monolayers. The mechanism behind inhibited glucose uptake did not involve modulation of several signaling pathways regulating glucose metabolism, including p38 MAPK, p42/44 ERK, PI3Kγ, PKC, PKA, mTOR and AMPK. Interestingly, BWE treatment was associated with other effects on glucose metabolism, including elevated glucose production and levels of gluconeogenic enzymes. However, these effects were not mediated through the classical pathway of CREB activation involving cyclic AMP and PKA. In a blinded, reference product-controlled study, consumption of a cracker product made from whole grain common buckwheat flour containing 50 grams of available carbohydrate was not associated with changes in post-prandial glucose or insulin concentrations in both healthy individuals and those with diet-controlled T2DM. However, consumption of buckwheat crackers was associated with changes in selected gastrointestinal satiety hormones. Interestingly, several significant correlations observed between fasting concentrations and the overall post-prandial response of these hormones were affected by T2DM. In conclusion, glucose-lowering effects of common buckwheat are not due to the actions of known bioactive compounds, and may involve direct inhibition of facilitative transporters by a novel compound. Although a buckwheat food product did not reduce post-prandial glycemia, identifying the compound responsible for inhibited glucose uptake will allow development of food products enriched with this compound, and may represent a more effective dietary approach to managing glycemia.

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Yang, Nan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 94-117). / Abstracts in English and Chinese. / ACKNOWLEDGMENTS --- p.I / ABSTRACT --- p.II / LIST OF ABBREVIATIONS --- p.VII / TABLE OF CONTENTS --- p.IX / Chapter Chapter 1 --- general introduction / Chapter 1.1 --- Cholesterol and cardiovascular disease --- p.1 / Chapter 1.2 --- Functions of cholesterol and lipoprotein --- p.2 / Chapter 1.3 --- Cholesterol metabolism and regulation in the body --- p.5 / Chapter 1.3.1 --- General process of cholesterol metabolism --- p.5 / Chapter 1.3.2 --- Cholesterol metabolism in liver --- p.6 / Chapter 1.3.2.1 --- The uptake of LDL cholesterol into the liver --- p.6 / Chapter 1.3.2.2 --- Cholesterol synthesis --- p.7 / Chapter 1.3.2.3 --- Synthesis of bile acids --- p.8 / Chapter 1.3.2.4 --- RCT pathway --- p.9 / Chapter 1.3.3 --- Lipids absorption in the intestine lumen --- p.9 / Chapter 1.3.3.1 --- Niemann-Pick Cl like 1(NPC1L1) --- p.10 / Chapter 1.3.3.2 --- ABCG5/8 --- p.10 / Chapter 1.3.3.3 --- Acyl-CoA:cholesterol acyltransferase (ACAT) 2 --- p.11 / Chapter 1.3.4 --- Cholesterol homeostasis --- p.11 / Chapter 1.3.5 --- The regulation of the cholesterol metabolism --- p.11 / Chapter 1.3.5.1 --- The role of SREBP-2 --- p.11 / Chapter 1.3.5.2 --- The role of LXR --- p.13 / Chapter 1.3.5.3 --- Feedback regulation of cholesterol --- p.13 / Chapter 1.4 --- Bile acid metabolism --- p.13 / Chapter 1.4.1 --- The function of bile acid --- p.13 / Chapter 1.4.2 --- Bile acid synthesis --- p.14 / Chapter 1.4.3 --- Enterohepatic circulation of bile --- p.14 / Chapter 1.5 --- Effect of Dietary composition on the blood cholesterol --- p.15 / Chapter 1.5.1 --- Dietary cholesterol --- p.15 / Chapter 1.5.2 --- Dietary protein --- p.15 / Chapter 1.5.2.1 --- Research history of dietary protein on the cholesterol --- p.15 / Chapter 1.5.2.2 --- Dietary casein --- p.17 / Chapter 1.5.2.3 --- Soy protein --- p.18 / Chapter 1.5.2.4 --- Buckwheat protein --- p.18 / Chapter 1.5.2.5 --- Mechanism of dietary protein on the cholesterol --- p.18 / Chapter 1.5.3 --- Dietary fiber --- p.18 / Chapter 1.5.4 --- Other functional components in the diet --- p.19 / Chapter 1.5.4.1 --- Phytosterol --- p.19 / Chapter 1.5.4.2 --- Dietary flavonoids --- p.21 / Chapter 1.6 --- Chemical composition of Tartary buckwheat --- p.22 / Chapter 1.6.1 --- Buckwheat protein --- p.22 / Chapter 1.6.2 --- Dietary fiber --- p.23 / Chapter 1.6.3 --- Phytosterols --- p.23 / Chapter 1.6.4 --- Flavonoids --- p.23 / Chapter Chapter 2 --- Effect of Tartary Buckwheat Flour on Blood Cholesterol Level in Male Hamsters / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.2 --- Objective --- p.27 / Chapter 2.3 --- Materials and methods --- p.27 / Chapter 2.3.1 --- Hamsters --- p.27 / Chapter 2.3.2 --- Diets --- p.28 / Chapter 2.3.3 --- "Determination of plasma lipid, lipoproteins" --- p.30 / Chapter 2.3.4 --- Determination of cholesterol concentration in organs --- p.31 / Chapter 2.3.5 --- Determination of fecal neutral and acidic sterols output --- p.31 / Chapter 2.3.6 --- "Western blotting of liver SREBP-2, LDLR, HMGR, LXR and CYP7A1 proteins" --- p.36 / Chapter 2.3.7 --- "Real-Time PCR Analysis of mRNA or Liver SREBP-2, LDLR, HMGR, and CYP7A1 and Small Intestine NPC1L1, ABCG5, ABCG8, ACAT2, and MTP" --- p.37 / Chapter 2.3.8 --- Intestinal ACAT2 activity measurement --- p.37 / Chapter 2.3.9 --- Statistics --- p.39 / Chapter 2.4 --- Results --- p.40 / Chapter 2.4.1 --- Nutritional composition of different flours --- p.40 / Chapter 2.4.2 --- "Growth, food intake and relative organ weights" --- p.44 / Chapter 2.4.3 --- Effect of different flour diets on the plasma lipid profile --- p.44 / Chapter 2.4.4 --- Effect of different flour diets on organ cholesterol of hamsters --- p.44 / Chapter 2.4.5 --- Cholesterol balance and excretion of fecal neutral and acidic Sterols --- p.44 / Chapter 2.4.6 --- "Effect of different flour diets on hepatic SREBP-2, HMGR, LDLR and CYP7A1 immunoreactive mass" --- p.51 / Chapter 2.4.7 --- "Effect of different flour diets on intestinal ABCG5, ABCG8, NPC1L1, MTP, and ACAT2 immunoreactive mass" --- p.54 / Chapter 2.4.8 --- Effect of different diet group on intestinal ACAT activity --- p.54 / Chapter 2.5 --- Discussion --- p.57 / Chapter 2.6 --- Summary --- p.61 / Chapter Chapter 3 --- Effect of DefattedTartary Buckwheat Protein Extract on Blood Cholesterol Level in Male Hamsters / Chapter 3.1 --- Introduction --- p.62 / Chapter 3.2 --- Objective --- p.63 / Chapter 3.3 --- Materials and methods --- p.63 / Chapter 3.3.1 --- Hamsters --- p.63 / Chapter 3.3.2 --- Diets --- p.63 / Chapter 3.3.3 --- "Determination of plasma lipid, lipoproteins" --- p.66 / Chapter 3.3.4 --- Determination of cholesterol concentration in organs and fecal neutral and acidic sterols output --- p.66 / Chapter 3.3.5 --- "Western blotting of liver SREBP-2, LDLR, HMGR and CYP7A1 proteins" --- p.66 / Chapter 3.3.6 --- "Real-Time PCR Analysis of mRNA or Liver SREBP-2, LDLR, HMGR, and CYP7A1 and Small Intestine NPC1L1, ABCG5, ABCG8, ACAT2, and MTP" --- p.66 / Chapter 3.3.7 --- Intestinal ACAT2 activity measurement --- p.67 / Chapter 3.3.8 --- Protein digestibility determination --- p.67 / Chapter 3.3.9 --- Statistics --- p.67 / Chapter 3.4 --- Results --- p.68 / Chapter 3.4.1 --- Diet composition --- p.68 / Chapter 3.4.2 --- "Growth, food intake, fecal excretion" --- p.72 / Chapter 3.4.3 --- Relative organ weights and organ cholesterol concentration --- p.72 / Chapter 3.4.4 --- Effect of different defatted protein extracts on the plasma lipid profile --- p.76 / Chapter 3.4.5 --- Cholesterol Balance and Excretion of Fecal Neutral and Acidic Sterols --- p.76 / Chapter 3.4.6 --- "Apparent protein digestibility in casein, TBP, WP and RP diet groups" --- p.77 / Chapter 3.4.7 --- "Effect of different defatted protein extracts on hepatic SREBP-2, HMGR, LDLR and CYP7A1 immunoreactive mass" --- p.83 / Chapter 3.4.8 --- "Effect of different defatted protein extracts on intestinal ABCG5, ABCG8, NPC1L1, MTP, and ACAT2 immunoreactive mass" --- p.83 / Chapter 3.5 --- Discussion --- p.87 / Chapter 3.6 --- Summary --- p.91 / Chapter Chapter 4 --- Conclusion --- p.92 / References --- p.94

Obesity, glucose intolerance or insulin resistance and elevated blood pressure are now prevalent in the U.S. Increased intake of dietary fiber, omega- 3 fatty acids, and antioxidants may help prevent or manage these diseases. Tortillas are now part of the American diet, and are excellent carriers of higher amounts of fiber and other nutraceutical ingredients. This study was conducted to determine the effects of incorporating nutraceutical ingredients (flaxseed, sorghum bran, oat flour, buckwheat flour) on whole white wheat tortilla quality. Tortillas were prepared using a hot-press, gas-fired oven and were evaluated for physical properties, texture and shelf-stability. Objective and subjective tests demonstrated that whole white wheat and multigrain tortilla doughs were harder, rougher and less extensible than refined flour tortilla dough. Multigrain flour tortillas were thinner, larger and more translucent than the refined flour treatment. Incorporation of whole multigrain flours affected color of the product, giving darker tortillas. Tortilla flexibility decreased over time. After 16 days of storage rollability scores of tortillas decreased drastically. The most pronounced decrease in tortilla flexibility was observed for 5% sorghum bran, 10% buckwheat, and for the treatment prepared with of 5% flax, 5% sorghum, 5% oat, 5% buckwheat. The flexibility loss was higher for whole white wheat and multigrain tortillas than for the refined one which was confirmed with objective and subjective tests. To extend shelf stability of whole multigrain tortillas various amounts of commercial hydrocolloid and ?-amylase were added to the formulation. Tortillas with 75 ppm, 100 ppm of ?-amylase, 1% and 1.5% of gum retained their flexibility during 16 days of storage. Consumer acceptability of the whole multigrain tortillas (5% flaxseed, 5% sorghum bran, 5% oat, 5% buckwheat) was compared with commercial multigrain tortillas and whole white wheat flour tortillas using an untrained sensory panel. The multigrain tortillas were liked by the panel as much as the other samples. Prepared multigrain tortillas had improved nutritional value. Each multigrain treatment contained at least 3 g of dietary fiber, 0.29 g of ?- linolenic fatty acid, lignans and antioxidants. It makes possible to claim them as a ?good source of dietary fiber? and ?an excellent source of ?-linolenic fatty acid?. The formulations tested, together with future refinements, provide more options to consumers seeking healthier alternatives to refined wheat flour tortillas.

There is growing demand for functional foods and ingredients as a result of their health-promoting properties. In this work, the potential of common buckwheat flour (Supreme) and bran (Farinetta) in improving upon the phenolic and antioxidant properties of durum spaghetti was investigated. The effects of processing and cooking on these properties were also studied in addition to the cooking quality and carbohydrate digestibility of spaghetti products. Among uncooked spaghetti samples, there were huge increments of between 114 and 522% for TPC, 50 and 242% for TFC, 359 and 1000% for DPPH antioxidant activity, and 101 and 197% for ORAC values of the experimental spaghetti samples over the control. Farinetta contributed more phenolic and antioxidant compounds than Supreme flour. Processing resulted in losses ranging from 1.2 to 33.7% in TFC and 42.0 to 55.3% in DPPH antioxidant activity. Cooking also resulted in significant losses (p < 0.05) of up to 39% in TPC, 40% in DPPH antioxidant activity, 22% in rutin content, and 55% in TFC in experimental samples. Cooking losses of up to 8.82% were recorded for the experimental samples and were higher in Farinetta-substituted products. These were generally higher than that of the control (6.33%). The introduction of buckwheat increased carbohydrate digestibility of products, but at the same time resulted in an overall lower release of reducing sugars after of 120 min of in vitro hydrolysis. Results show that the phenolic and antioxidant properties of durum spaghetti fortified with buckwheat milling fractions can compare favourably with those of 100% whole buckwheat pasta, and at the same time, maintain a higher cooking quality due to the presence of semolina.

There is growing demand for functional foods and ingredients as a result of their health-promoting properties. In this work, the potential of common buckwheat flour (Supreme) and bran (Farinetta) in improving upon the phenolic and antioxidant properties of durum spaghetti was investigated. The effects of processing and cooking on these properties were also studied in addition to the cooking quality and carbohydrate digestibility of spaghetti products. Among uncooked spaghetti samples, there were huge increments of between 114 and 522% for TPC, 50 and 242% for TFC, 359 and 1000% for DPPH antioxidant activity, and 101 and 197% for ORAC values of the experimental spaghetti samples over the control. Farinetta contributed more phenolic and antioxidant compounds than Supreme flour. Processing resulted in losses ranging from 1.2 to 33.7% in TFC and 42.0 to 55.3% in DPPH antioxidant activity. Cooking also resulted in significant losses (p < 0.05) of up to 39% in TPC, 40% in DPPH antioxidant activity, 22% in rutin content, and 55% in TFC in experimental samples. Cooking losses of up to 8.82% were recorded for the experimental samples and were higher in Farinetta-substituted products. These were generally higher than that of the control (6.33%). The introduction of buckwheat increased carbohydrate digestibility of products, but at the same time resulted in an overall lower release of reducing sugars after of 120 min of in vitro hydrolysis. Results show that the phenolic and antioxidant properties of durum spaghetti fortified with buckwheat milling fractions can compare favourably with those of 100% whole buckwheat pasta, and at the same time, maintain a higher cooking quality due to the presence of semolina.