A possible explanation of the effects of dietary lactose concentration during recovery of protein depletion in growing rats.

It is generally accepted that lactose intolerance is a cause of delayed recovery from malnutrition. To discriminate the true importance of this factor, the effect of dietary lactose concentration on "catch up" growth was studied on rats fed a protein free diet from weaning to 34 days of age and then refed "ad libitum" with diets providing different levels of Protein Calories (P%: 5, 11, 17 and 25%) and Lactose (L%: 0, 1, 15, 27 and 37%) for 4 days. Weight changes, daily dietary intakes and gastrointestinal disorders (GID) were recorded. The growth rate (GR) -g/100g rat/day- showed a direct correlation with P% whereas a decrease in (GR) as well as in Protein Utilization (PU) was associated with increasing L%, the higher the P%, the greater the effect of L%. The observed effect of lactose on (PU) does not correlate with (GID). Analysis of intake data -expressed as calories/day/W0.73- showed that animals ate less diet when lactose was present resulting in energy restriction (ER) from 12 to 62%. A primary effect of food intake might be proposed as a limiting factor for (GR) and (PU) in rats recovering from depletion. The influence of P% on improved lactose tolerance must also be stressed.