Effect of bitter gourd (Momordica charantia) on glycaemic status in streptozotocin induced diabetic rats.

Bitter gourd (Momordica charantia), a commonly consumed vegetable is used as an adjunct in the management of diabetes mellitus. A study was carried out to examine the effect of edible portion of bitter gourd at 10% level in the diet in streptozotocin induced diabetic rats. To evaluate the glycaemic control of bitter gourd during diabetes, diet intake, gain in body weight, water intake, urine sugar, urine volume, glomerular filtration rate and fasting blood glucose profiles were monitored. Water consumption, urine volume and urine sugar were significantly higher in diabetic controls compared to normal rats and bitter gourd feeding alleviated this rise during diabetes by about 30%. Renal hypertrophy was higher in diabetic controls and bitter gourd supplementation, partially, but effectively prevented it (38%) during diabetes. Increased glomerular filtration rate in diabetes was significantly reduced (27%) by bitter gourd. An amelioration of about 30% in fasting blood glucose was observed with bitter gourd feeding in diabetic rats. These results clearly provided experimental evidence that dried bitter gourd powder in the diet at 10% level improved diabetic status signifying its beneficial effect during diabetes.

Supplementation and delivery of n-3 fatty acids through spray-dried milk reduce serum and liver lipids in rats.

Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18:2n-6) but fail to deliver adequate amounts of n-3 FA. Consumption of long-chain n-3 PUFA such as EPA (20:5n-3) and DHA (22:6n-3) is restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary sources of n-3 PUFA. The present work was designed to use n-3 FA-enriched spray-dried milk powder to provide n-3 FA. Whole milk was supplemented with linseed oil to provide alpha-linolenic acid (LNA, 18:3n-3), with fish oil to provide EPA and DHA, or with groundnut oil (GNO), which is devoid of n-3 PUFA, and then spray-dried. Male Wistar rats were fed the spray-dried milk formulations for 60 d. The rats given formulations containing n-3 FA showed significant increases (P < 0.001) in the levels of LNA or EPA/DHA in the serum and in tissue lipids as compared with those fed the GNO control formulation. Rats fed formulations containing n-3 FA had 30-35% lower levels of serum total cholesterol and 25-30% lower levels of serum TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n-3 FA were lower by 18-30% and 11-18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented with n-3 FA are an effective means of improving dietary n-3 FA intake, which may decrease the risk factors associated with cardiovascular disease.

Effect of dietary fibres on constituents of complex carbohydrates in streptozotocin induced diabetic rat tissues.

The effect of dietary fibres on constituents of complex carbohydrates in various tissues of streptozotocin induced diabetic rats is presented by analysing different constituents of complex carbohydrates in presence and absence of dietary fibre. Wheat bran was effective in preventing the decrease (14%) in total sugars in spleen and an increase in total sugars in stomach (33%) during diabetes. Decrease in uronic acid content during diabetes in spleen was prevented to the extent of 25% by the presence of wheat bran in the diet. The other parameters which were affected by the presence of wheat bran in the diet during diabetes are amino sugar (brain and stomach), sulphates (liver) and protein (lungs and stomach). Guar gum was effective in preventing the decrease in total sugar content in spleen by 28% and sulphate content in liver by 14% during diabetes. Variation in protein content in lungs was observed in diabetes. The results indicated beneficial role of dietary fibres like wheat bran and guar gum on complex carbohydrates to varying extents in different tissues.

Hypocholesterolemic effect of anhydrous milk fat ghee is mediated by increasing the secretion of biliary lipids.

The anhydrous milk fat ghee is one of the important sources of fat in the Indian diet. Our earlier studies showed that rats fed diets containing greater than 2.5 wt% of ghee had lower levels of serum cholesterol compared with rats fed diets containing groundnut oil. To evaluate the mechanism of the hypocholesterolemic effect of ghee, male Wistar rats were fed a diet containing 2.5 or 5.0 wt% ghee for a period of 8 weeks. The diets were made isocaloric with groundnut oil. Both native and ghee heated at 120 degrees C containing oxidized lipids were included in the diet. The ghee in the diet did not affect the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity in the liver microsomes, but it significantly increased biliary excretion of cholesterol, bile acids, uronic acid, and phospholipids. The rats fed ghee had lower levels of cholesterol esters in the serum as well as in the intestinal mucosa. Both native and oxidized ghee influenced cholesterol metabolism. These results indicate that supplementation of diets with ghee lipids would increase the excretion of bile constituents and lower serum cholesterol levels.

The anhydrous milk fat, ghee, lowers serum prostaglandins and secretion of leukotrienes by rat peritoneal macrophages.

Ghee, the anhydrous milk fat, is one of the most important sources of dietary fat in India. Male Wistar rats were fed diets containing 2.5, 5.0 and 10 wt% ghee for a period of 8 weeks. The diets were made isocaloric with groundnut oil. The results showed that serum thromboxane levels decreased by 27-35%, and 6-keto-prostaglandin F1alpha by 23-37% when ghee was incorporated at level of 10% in the diet. Prostaglandin E2 levels in serum and secretion of leukotrienes B4, C4 and D4 by peritoneal macrophages activated with calcium ionophore decreased when increased amounts of ghee from 2.5 to 10% were included in the diet. Arachidonic acid levels in macrophage phospholipids decreased when incremental amounts of ghee were fed to rats. These studies indicate that ghee in the diet not only lowers the prostaglandin levels in serum but also decreases the secretion of leukotrienes by macrophages.

Nutritional properties of trans fatty acids.

The role of trans fatty acids (TFA) present in partially hydrogenated fats widely consumed in food and their link with coronary heart disease has been examined in this review. Most of the studies carried out have been on the effects of TFA on blood-lipid profile. The perceived effects of TFA intake depend on the fat or oil with which they are compared and appears to be in between that of dietary saturated fats and monounsaturated fatty acids. When compared to saturated fat, TFA intake shows lower levels of total and LDL-cholesterol in blood. But when both TFA and saturated fatty acids are compared with cis fatty acids or native unhydrogenated oil, increase in total and LDL-cholesterol are noted. The effects of TFA on HDL-cholesterol and Lp(a) are not clearly established. The undesirable effects of TFA can be overcome by inclusion of essential fatty acids at a minimum of 2 energy per cent level in the diet. The link between trans fatty acid intake and coronary heart disease (CHD) are not unequivocally established.

Effect of dietary ghee--the anhydrous milk fat, on blood and liver lipids in rats.

Dairy products are important sources of dietary fat in India. Anhydrous milk fat, viz., ghee, is consumed as such in the diet and also is used for frying the dishes. Ghee contains high levels of saturated fatty acids and cholesterol, which are considered risk factors for cardiovascular diseases. In the present study, ghee, at levels ranging from 0.25 to 10%, was included in a nutritionally balanced AIN-76 diet fed to Wistar rats for a period of 8 weeks. The serum lipid profiles of these animals showed a dose dependent decrease in total cholesterol, low density lipoproteins and very low density lipoproteins cholesterol, and triglyceride levels when ghee was present at levels greater than 2.5% in the diet. Liver cholesterol and triglycerides also were decreased in these animals. When ghee was included as a sole source of fat at a 10% level, polyunsaturated fatty acids in the serum and liver lipids were reduced significantly. Similar results were observed when ghee was subjected to a higher temperature (120 degrees C) to generate cholesterol oxidation products and fed to the animals. Although cholesterol oxidation products were not accumulated in serum, significant amounts were accumulated in liver only when ghee was fed as a sole source of fat at a 10% level. This study revealed that the consumption of ghee up to a 10% level in the diet altered blood lipid profiles in such a manner as not to elevate the risk factors for cardiovascular diseases.

Inhibitory effect of Garcinia kola on lipid peroxidation in rat liver homogenate.

Garcinia kola, (a herb grown in Nigeria; calorific value 358.54 k.cal/100 g) inhibited in vitro lipid peroxidation of rat liver homogenate in a dose dependent manner. The inhibitory activity of G.kola was not affected by heating (100 degrees C/10 min). The antioxidant component of G.kola was soluble in aqueous and ethanolic media. The active component(s) in G. kola responsible for its inhibitory activity on lipid peroxidation is tentatively identified as isoflavones.

Effect of cumin, cinnamon, ginger, mustard and tamarind in induced hypercholesterolemic rats.

The effect of a few common spices--cumin (Cuminum cyminum, cinnamon (Cinnamomum zeylanicum), ginger (Zingiber officinale), mustard (Brassica nigra) and tamarind (Tamarindus indica)--added to normal and hypercholesterolemia inducing diet on serum and liver cholesterol levels in rats was studied. These spices did not show any cholesterol lowering effect when included in the diet at about 5-fold the normal human intake level.

The effect of spices on cholesterol 7 alpha-hydroxylase activity and on serum and hepatic cholesterol levels in the rat.

The effect of feeding curcumin, capsaicin, ginger, mustard, black pepper and cumin on cholesterol and bile acid metabolism was studied in rats. The activity of hepatic cholesterol-7 alpha-hydroxylase, the rate-limiting enzyme of bile acid biosynthesis, was significantly elevated in curcumin (turmeric), capsaicin (red pepper), ginger and mustard treated animals. The enzyme activity was comparable to controls in black pepper and cumin fed rats. Serum and liver microsomal cholesterol contents were significantly higher in the curcumin and capsaicin treated animals. Thus, this study has suggested that the spices--turmeric, red pepper, ginger and mustard can stimulate the conversion of cholesterol to bile acids, an important pathway of elimination of cholesterol from the body. However, simultaneous stimulation of cholesterol synthesis by the spice principles--curcumin and capsaicin suggests that there may not be any significant contribution of stimulation of bile acid biosynthesis to the hypocholesterolemic action of these spices, and the latter action may solely be due to interference with exogenous cholesterol absorption.

Influence of spices and spice principles on hepatic mixed function oxygenase system in rats.

The status of hepatic mixed function oxygenase system (MFOS) was investigated in rats fed spice principles: capsaicin, piperine and curcumin, as well as spices: cumin, ginger, fenugreek, cinnamon, asafoetida, mustard and tamarind at two dietary levels each. Liver microsomal cytochrome P450-dependent aryl hydroxylase was generally stimulated by these spice principles and spices. Cumin, ginger and fenugreek also stimulated the levels of cytochrome P450 and cytochrome b5 and cumin and tamarind stimulated N-demethylase activity. NADPH-cytochrome c reductase and glucuronyl transferase activities, however, remained unaffected by the spices tested.

Effect of capsaicin on triglyceride accumulation & secretion in ethanol fed rats.

Rats fed capsaicin (0.15, 1.5 and 15 mg%) containing diets were able to counter by about 30 per cent of the hepatic lipid accumulation caused by a single dose administration of ethanol (6 g/kg body weight). The rate of triglyceride secretion in capsaicin fed animals from liver to plasma was also elevated as judged by Triton WR-1339 induced hypertriglyceridemia. The results suggest a possible mechanism by which capsaicin counters ethanol induced hepatic lipid accumulation in rats.