Safety evaluation of lactulose syrup in rats

摘要

The safety of lactulose to be used in infant formula as a bifidogenic factor was assessed. Lactulose syrup (50%) was administered intragastrically to groups of male and female Wistar rats (CFT strain, 50 g) at 2, 4, 8, 12, 24 or 36 g/kg body weightper day in split doses for 20 days. A control group of rats received lactose solution at similar levels. The general condition of animals, their behaviour, food consumption and mortality were recorded. The LD50 values and maximum tolerated dose were calculated. The computed LD50 values for male and female rats were >31 and >21 g/kg body weight, and the maximum tolerated doses were 18 and 10 g/kg body weight, respectively. Concentrations greater than these caused transient diarrhoea, which disappeared within 5 h of feeding of lactulose. Treatment had no effect on food consumption, growth rate or behaviour and no mortality was observed in any of the groups. The incorporation of lactulose at 0.5% in infant formula, as a bifidogenic factor, did not induceany adverse effects on rats. It is concluded that it is safe to use lactulose at low concentrations in infant food formulations.