"The results confirmed that the dahi containing probiotic bacteria Lactobacillus acidophilus and Lactobacillus casei exhibited a significant delaying effect on the progression of diabetes induced by high fructose administration in rats," wrote lead author Hariom Yadav from India's National Dairy Research Institute.
Interest in more exotic probiotic sources has been increasing as consumer awareness and acceptance of probiotics increases. Indeed, kefir, popular in Eastern and Central Europe but increasingly in West European, was recently reported to decrease the allergic response to ovalbumin (egg white) in mice, and offer hope to preventing food allergies (Journal of the Science of Food and Agriculture, doi: 10.1002/jsfa.2649).
Traditionally dahi has been made in the home from cow or buffalo milk, but the present economic boom is creating a middle class, which, in turn, is said to be driving increasing demand for packaged foods.
Dahi, the closest India comes to the Western yoghurt, is not specifically classed as a health food but is more of a basic food in the Indian diet, although the manner in which it is consumed varies. In the North it is consumed for breakfast with paranthas bread, whereas in the South it is mixed with rice or served as a side dish for lunch or dinner.
The new research, published in the journal Nutrition (doi: 10.1016/j.nut.2006.09.002), reports that male albino Wistar rats, fed a fructose solution (21 per cent in water) and low-fat (2.5 per cent) dahi containing Lactobacillus acidophilus and Lactobacillus casei had improved levels of markers for type-2 diabetes.
The rats were divided into three diet groups, one eating the normal control diet (NCG), one fed the diet plus the fructose solution (HFCG) and the last fed the diet plus the fructose solution and supplemented with dahi (DHFG).
After eight weeks of supplementation, the researchers report that fasting blood glucose levels had increased in both fructose-fed groups, compared to control, but this increase was significantly less in the dahi supplemented group (53 versus 16 per cent increases for HFCG and DFCG, respectively.
Liver plasma insulin levels also significantly increased (19 per cent) in the HFCG group and 14 per cent higher in the DHFG than in the NCG group.
While plasma lipid levels were significantly higher in the HFCG rats, compared to the control group - total cholesterol (18 per cent), triacylglycerol (45 per cent), and LDL-C (23 per cent), similar values in the dahi-supplemented group were significantly lower - total cholesterol (16 per cent), triacylglycerol (28 per cent), and LDL-C (23 per cent) than the HFCG group, said the researchers.
"Insulin is the leading hormone that regulates blood glucose and fat metabolism, and insulin resistance is a condition in which circulating insulin decreases its response to target tissues, namely skeletal muscle, adipose tissues, and the liver," explained Yadav.
"In the present study, insulin resistance developed by the administration of a high fructose diet, which was significantly inhibited by feeding of dahi. Diabetes-induced dyslipidemia is a common and most prevalent character in type 2 diabetes, which is the leading cause of cardiovascular diseases (CVDs) in diabetic populations," he said.
The mechanism by which dahi may decrease the risk of diabetes may be multiple and complementary, suggest the researchers, and significant further studies are needed to investigate if such observations are also observed in a human populations in free-living conditions.
"The probiotic dahi-supplemented diet significantly delayed the onset of glucose intolerance, hyperglycemia, hyperinsulinemia, dyslipidemia, and oxidative stress in high fructose-induced diabetic rats, indicating a lower risk of diabetes and its complications," they concluded.
An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132bn, with $92bn being direct costs from medication, according to 2002 American Diabetes Association figures.