Oral administration of fermented milk supplemented with synbiotics can influence the physiological condition of Wistar rats in a dose-sensitive and sex-specific manner.

Fermented milk supplemented with two probiotic strains (Bifidobacterium lactis Bi-07 and Lactobacillus acidophilus NCFM) and a prebiotic (isomaltooligosaccharide) was orally administered to Wistar rats for 30 days using three dosages. A commercial yogurt was used as a placebo. After treatment, the total protein, hemoglobin, and albumin levels in serum were significantly increased in female rats compared with those in the control group (p<0.05), whereas no significant change occurred in the male rats. A significant decrease in serum glucose levels was observed in male rats administered a low dosage of the tested fermented milk (p<0.05). The serum triglyceride level was significantly decreased in both male and female rats (p<0.05). No significant differences were found between rats groups in body weight, food intake, food utilization rate, red blood cell counts, white blood cell counts, alanine aminotransferase, aspartate aminotransferase, urea nitrogen, creatinine, and total cholesterol. These results suggest that the fermented milk supplemented with synbiotics altered the nutritive status of the host animal and contributed to their health. However, such potent health-promoting effects could be deeply associated with the dose and sex specific. Therefore, different physiological targets and population characteristics should be managed with different combinations of probiotics and prebiotics.