ASSESSMENT OF THE ROLE OF DAIRY FOODS IN DIABETES AND LACTOSE INTOLERANCE INTERVENTION

Abstract

PART, I Glycemia in Healthy Subjects after Lactose-Equivalent Meals of Milk and Milk Products: In this part, common dietary sources of milk proteins (whey, casein, skim milk, and lactose) were evaluated concerning their influence on postprandial responses of glucose; GI of dairy products was examined blood glucose in response to equal amounts of carbohydrate from a glucose reference meal and test meals was investigated and the obtained results can be summered as follows: - Lactose had lower postprandial glucose responses, expressed as AUC (0-120 min), than did the reference. - Skim milk had lower postprandial glucose responses, expressed as AUC (0-120 min), than did the lactose and reference. - The lowest blood glucose was in response to whey followed by cheese, milk came in third order. - Blood glucose response to whole buffalo milk was lower after 120 minute compared with skim buffalo milk, which can be attributed to presence of fat. Fat has no direct effect on the blood glucose level. - Both blood glucose response to whole milk and skim milk with added fiber was lower compared with skim and whole milk without fiber, which can be attributed to presence of fiber.

Glycemic index and glycemic load of milk and milk products: - Glycemic index is a system of classifying carbohydrate containing foods according to how fast they are digested and absorbed during the postprandial period. - A related concept, glycemic load, also takes into consideration the amount of carbohydrates in portion of food they obtained results revealed glycemic load of milk and milk products ranged from 3 to 11. Whey and Why protein concentrate recorded the lowest GL followed with Whole buffalo’s milk and yoghurt give moderate GL, the highest GL was recorded for ice cream and flavored yogurt due to its high sugar contents. The GI has a value of 100 for glucose, 45 for lactose, 15 for whole buffalo’s milk, 28 for whole cow’s milk, 22 for skim milk, 24 for yoghurt, 43 for flavored yoghurt, 34 for ice cream, 17 for karish cheese and 10 for whey with whey protein. In conclusion, the insulinotropic effect of whey proteins may potentially attenuate the postprandial blood glucose excursions over the day. The present work is an acute study, and further studies are needed to determine possible longer-term effects of whey on blood glucose control. However, recent data suggest that dietary protein might be useful to facilitate blood glucose control in subjects with type 2 diabetes.

PART, II Biological evaluation of administration of dietary lactose and cow's milk in healthy and alloxan-induced diabetic rats: Effect of oral administration of dietary lactose and cow's milk on body weight, serum biochemical profiles and intestinal lactase activity and histopathological examinations in alloxan-induced diabetic rats was studied. The biological assay indicated that:

1- A drastic significant (p<0.05) decrease in body weight was obtained in alloxan-induced diabetic rats fed on standard diet (G4, control +) followed by those fed on dietary lactose (G5) and cow's milk (G6) during 28 days. From the results it could be observed that intraperitoneal injection of rats with alloxan caused significant reduction in body weight gain % (-9.79%) compared to the normal control group (G1, control); However, oral administration of dietary lactose and cow's milk to diabetic rats induced significant improvement in body weight gain % reached 27.64 and 35.12%, respectively. These results indicated that administration either with dietary lactose or cow's milk to diabetic rats had the ability to recover the body weight and protect the diabetic rats from massive body weight loss.

2- Induction of diabetes in rats with alloxan (150 mg/kg body weight) significantly increase serum glucose from 87.69 mg/dl to 381.32 mg/dl after a five days of alloxan injection. The administration of either dietary lactose or cow's milk to rats with hyperglycemia significantly (p<0.05) reduced serum glucose level gradually during 28 days in comparison to those fed on basal diet (G4, positive control). After the 1st, 2nd, 3rd and 4th week of the trial, reduction in serum glucose level in diabetic rats was observed to be (39.40, 44.38, 48.05 and 50.25 %) and (44.08, 49.11, 53.03 and 55.28%) in diabetic rats received dietary lactose (G5) and cow's milk (G6), respectively, when compared with those of rats in positive control group (G6).

3- The rise in blood sugar is accompanied by increase in total cholesterol (TC), Low density lipoprotein-cholesterol (LDL-c), very Low density lipoprotein-cholesterol (VLDL-c), triglycerides (TG) and fall in high density lipoprotein-cholesterol (HDL-c) in alloxan-induced diabetic rats. Significant reduction in serum TC, LDL-c, VLDL-c, TG level and increase in HDL-c concentration was observed in diabetic rats fed with dietary lactose (G5) and cow's milk (G6). A significant reduction was observed to be (40.73, 57.42, 37.71, 37.72 %) and (48.73, 73.7, 46.59, 46.61 %), respectively, and a significant increse (73.1%), (91.76%) in HDL-c fed on dietary lactose and cow's milk for 28 days as compared with positive control (G4).

4- The rise in blood sugar is accompanied by increase in, TC/HDL-c, LDL/HDL-c ratios and AI, while the HTR (%) was decreased, in diabetic rats compared to those of the normal rats (G1, control-). Diabetic rats administrated either with dietary lactose or cow's milk (G5 and G6) for 28 days had a significant (p<0.05) lower ratios of TC/HDL-c, LDL/HDL-c and AI when compared to the diabetic rats, G4, positive control group (2.68, 1.68, 1.68; 2.09, 0.93, 1.09 vs. 7.83, 6.83 and 6.83, respectively), and increase in HTR% (37.33; 47.73; 12.78 respectively). The group of diabetic rats (G4, positive control group) showed highest TC/HDL-c and LDL/HDL-c ratios and lowest increase in HTR % (7.83, 6.83 and 12.78 %, respectively). It could be concluded that, the effect of treatment of diabetic rats either with dietary lactose or cow's milk on TC/HDL-c and LDL/HDL-c ratios and the HTR (%) in descending order was treatment with cow's milk > treatment with dietary lactose.

5- Induction of diabetes in rats resulted in significant increase in the intestinal lactase activity (0.0439 U/ml) compared to (G1, control-) (0.0056 U/ml). The groups of diabetic rats administrated dietary lactose (G5) and cow's milk (G6) showed a significant reduction in the intestinal lactase activity. The reduction in values of the intestinal lactase activity in diabetic rats administrated cow's milk (G6) was significantly (P<0.05) higher (5.16, 61.70, 71.43 and 69.67 %) than that administrated dietary lactose (5.16, 51.06, 59.52, 94.90 %), respectively, after 1st, 2nd, 3rd and 4th weeks of the experimental period as compared with those of rats in positive control group (G4).

6- Histopathological examinations showed that injection the animals with alloxan (G4) resulted in severe cystic dilatation in the pancreatic duct, congestion of main blood vessels and atrophy in the pancreatic exocrine tissue and islets in many areas. However, oral administration of dietary lactose (5 ml/rat/twice daily) to alloxanized diabetic rats (G5) improved injury in pancreatic tissue partially, whereas the pancreatic tissue showed a mild cystic dilatation in the pancreatic exocrine duct while the islets of Langerhans were intact while, oral administration of cow's milk (5 ml/rat/twice daily) to alloxanized diabetic rats (G6) also improved injury in pancreatic tissue and brought back the normal architecture of the pancreatic tissue as the the isets of Langerhans increased in size and the serous acini appeared normal in size and shape and the connective tissue septae were close to normal.