飲食中補充米麩或三價鉻對第二型糖尿病患或STZ誘導的糖尿病大白鼠醣類及脂質代謝之影響

Effect of Dietary Rice Bran or Trivalent Chromium on Carbohydrate and Lipid Metabolism in Type 2 Diabetic Patients or STZ-Induced Diabetic Rats

賴明宏(Lai Ming Hoang)

指導教授 ： 鄭心嫻 博士

臺北醫學大學/藥學院/藥學研究所/博士(2002年)

摘要

中文摘要 為了瞭解第二型糖尿病病人飲食因子中米麩及三價鉻的介入是否能改善其血糖及血脂狀況，本研究先探討糖尿病病人之飲食情況，發現糖尿病患者在平時的飲食狀況符合衛生署建議之飲食原則，但是油脂稍微偏高，粗纖維攝取量偏低。在過年期間第二型糖尿病患的飲食狀況為高油高蛋白質飲食,引起血中三酸甘油酯明顯上升。由醫院營養師設計7天2000大卡之均衡飲食粗纖維量仍嫌不足。因此利用稻米在精白過程中所產生富含纖維的米麩，探討在飲食中補充後對大白鼠及人體之影響，結果顯示：米麩飲食能有效降低STZ誘導的糖尿病大白鼠血中果糖胺值及減緩葡萄糖耐量試驗之血糖反應面積，但並未觀察到有延緩糖尿病腎病變之情形。此外，飲食中補充米麩30 g可降低餐後血糖反應面積達64%，降低餐後胰島素反應面積達38%。在飲食因子三價鉻對人體之影響方面，利用石墨爐式原子吸收光譜儀可精確及準確的分析出血液及尿液中的三價鉻含量。由營養師設計7天2000大卡之均衡飲食，發現每2000大卡可攝取48微克的三價鉻。探討年輕人與中年人血液及尿液中三價鉻濃度之差異，發現40~60歲中年人，血中三價鉻含量會較20~30歲年輕人降低40.1%。探討第二型糖尿病患血中的三價鉻與葡萄糖及脂質濃度之相關性，結果顯示隨著空腹血糖升高，血中三價鉻含量會降低，相關係數高達-0.99。而且血中三價鉻含量降低，會造成胰島素的功能不良，進而引起脂質的代謝異常，相關係數高達-0.98，顯示糖尿病患微量礦物質三價鉻之營養狀況較正常血糖者差。對於由STZ誘導產生的糖尿病大白鼠補充三價鉻四週後，並未觀察到有改善血糖及血脂狀況，且無改善或加速惡化糖尿病腎病變情形。藉由飲食中補充三價鉻觀察對第二型糖尿病患血糖及血脂狀況之影響，經過三個月的補充三價鉻後，能明顯增加嚴重的第二型糖尿病病人胰島素敏感性，達到降低空腹血糖之功效，但是對於血脂狀況並無明顯改善。 飲食因子中的米麩添加可改善糖尿病鼠或正常血糖者餐後血糖變化情形，長期而言對預防及改善糖尿病應有幫助。飲食因子中的三價鉻必須對體內鉻狀況不良造成胰島素敏感性降低者補充才有改善的效果。

關鍵字

米麩 ； 三價鉻 ； 第二型糖尿病患 ； STZ誘導糖尿病大白鼠 ； 醣類代謝 ； 脂質代謝

並列摘要

Abstract To investigate the dietary factors affecting blood glucose and lipid parameters in type 2 diabetes patients, the research was divided into three parts. In the first part, we investigated the dietary pattern of type 2 diabetes. In the second part, we observed the effects of a fiber-rich rice bran diet on carbohydrate and lipid metabolism in STZ-induced diabetic rats and normal subjects. In the third part, we observed the effects of trivalent chromium on carbohydrate and lipid metabolism in patients with type 2 diabetes. First, we investigated the dietary pattern of type 2 diabetes. We investigated the relationship between dietary intake in the usual and blood glucose and lipid concentrations and intake over the Chinese New Year period in normal, mildly hyperglycemic, and severely hyperglycemic subjects. Samples included 22 normal subjects and 62 patients with type 2 diabetes in February and June 2000, respectively. This approach was proceeded by a 24-h dietary recall for collecting subjects’ dietary data, measuring body height and weight and determining fasting plasma glucose, hemoglobin A1c, insulin, cholesterol and triglyceride concentrations. The results show that dietary intake in the usual followed the recommendations of the Department of Health (DOH), but that dietary fiber intake was lower than that recommended by the DOH. Over the Chinese New year holiday, dietary intake was a significant increase in total caloric intake, protein and fat. This change in dietary intake increased diabetic patients’ plasma triglyceride levels. As to food choice and intake by common people, we investigated the dietary fiber content of normal diets designed by a dietitian to meet the recommendations of DOH. We asked that the dietitian design diets which contained 2000 kcal for 7 days, then used a food database for calculation of macronutrients and dietary fiber content. The results showed that the dietary fiber content of the normal diet designed by a dietitian were lower than the recommendation of DOH. Thus, increasing the dietary fiber content in the diets is a big concern. The dietary guidelines for American in 2000 indicate that increasing the whole-grain intake might increase the cereal fiber intake, which would be good for type 2 diabetics. In the second part, we observed the effects of fiber-rich rice bran diets on carbohydrate and lipid metabolism in STZ-induced diabetic rats and normal subjects. A 2 x 2 factorial experimental design was employed to evaluate the effect of a fiber- rich rice bran diet on blood glucose and lipid, and diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats. Forty male adult Wistar rats were randomly divided into four groups, two of which were injected with nicotinamide and STZ to induce diabetes. Both normal and STZ-diabetic rats were fed AIN-76 diets and rice bran diets (20 g/-100 g of diet). After 4 weeks of feeding, a significantly (p < 0.05) change of STZ-diabetic rats both with and without rice bran were hyperglycemic. Blood fructosamine was ameliorated in rice bran diet-fed STZ-diabetic rats, compared with the baseline. STZ-diabetic rats fed a rice bran diet had a significantly lower blood glucose response than did those fed the diet without rice bran. These results suggest that a rice bran diet is effective in lowering blood fructosamine and improving the glucose response, but it cannot retard the development of diabetic nephropathy in STZ-diabetic rats. We further studied the effects of dietary supplementation of rice bran on postpranidal glucose and insulin responses of normal subjects. And rice bran added 30g to the diet might lower 64% the postpranidal glucose response area and lower 38% the postpranidal insulin response of normal subjects. In addition, macronutrients and dietary fiber of the diet might influence carbohydrate and lipid metabolism. Trivalent chromium supplementation in humans has been reported to improve glucose metabolism and serum lipid parameters. In the third part, we investigated the effects of trivalent chromium supplementation on carbohydrate and lipid metabolism in patients with type 2 diabetes. While there is a lower level in biological samples, very few reports have studied chromium concentrations in humans. Thus, we investigated the concentrations of total trivalent chromium in human bodies. The concentrations of total trivalent chromium in human blood and urine were determined by electrothermal atomic absorption spectrometry. We used procedure from the manufacturer and from articles in the literature, and achieved good accuracy and precision. We also analyzed normal diets containing 2000 kcal designed by a dietitian and found that there was an average of 48 ?g trivalent chromium in these diets. The concentration was about the same 50 ?g, which was estimated to be a safe and adequate daily dietary intake in 1989, but higher than 20~35 ?g, which was estimated to be a safe and adequate daily dietary intake in 2000. To investigate the status of young and elderly people, trivalent chromium in the blood and urine were analyzed. The results showed that blood chromium was lower 40.1% in the elderly people (40~60 years-old) than the young people (20~30 years-old). To investigate correlations between blood trivalent chromium level and blood glucose and lipid concentrations in type 2 diabetes. The results suggested that the blood trivalent chromium concentration decreased with increasing blood glucose concentration and serum lipids in diabetes and correlation coefficients were —0.99 and —0.98. A 2 x 2 factorial experimental design was employed to evaluate the effect of a chromium yeast diet on blood glucose and lipid, and diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats. Forty male adult Wistar rats were randomly divided into four groups, two of which were injected with nicotinamide and STZ to induce diabetes. Both normal and STZ-diabetic rats were fed AIN-76 diets and chromium yeast diets (trivalent chromium 200 ?g/day by gavage). After 4 weeks of feeding, a significantly (p < 0.05) change of STZ-diabetic rats both with and without chromium yeast were hyperglycemic. But no significant changes in glucose metabolism and lipid parameters were observed. It cannot retard the development of diabetic nephropathy in STZ-diabetic rats. We investigated the effect of dietary chromium supplementation on glucose and lipid metabolism in patients with type 2 diabetes. After 3 months of supplementation, fasting blood glucose decreased significantly in severe type 2 diabetes. Because insulin sensitivity was lower in severe type 2 diabetes, chromium supplementation might increase insulin sensitivity and improve glucose metabolism. But no significant changes in lipid parameters were observed. In conclusion, rice bran supplementation might improve the glucose response in STZ-diabetic rats and normal subjects. It may prevent and improve the diabetes. Chromium supplementation might increase insulin sensitivity and improve glucose metabolism in severe type 2 diabetes.

並列關鍵字

rice bran ； trivalent chromium ； type 2 diabetic patients ； STZ-induced diabetic rats ； carbohydrate metabolism ； lipid metabolism

參考文獻

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