ESPE Abstracts

Background and Aims: The most effective environmental factor that affect longitudinal growth is nutrition, but the exact composition and the relative benefits of specific dietary proteins in supporting linear growth is unknown. In the current study, we compared the effect of whey and soy proteins on linear growth and bone strength in young fast growing male rats. Both proteins contain all essential amino acids and are considered the best proteins in their categories according to the protein digestibility-corrected amino acids score. Soy ranks second after whey as a complete food protein and is the most popular plant proteins utilized in the production of newborn formulas and dietary supplements.

Methods: Young male Sprague Dawley rats, fed ad libitum with either Whey or Soy based diets (matched for calories, macro- and micro-nutrients), were followed for short (11d, 24d) or long (74d) term experiments. At sacrifice, humeri length and growth plate (GP) height were measured and blood was taken. Micro CT analysis was used to evaluate effect on bone structure and mineralization

Results: In the short-term experiments, we found that the soy fed group consumed more food, and were heavier, with longer humeri, while GP height was greater in the whey fed group. Interestingly, the effect on weight and humeri length was diminished at 74 days; however, the GP height of the whey fed group was still greater. Furthermore, the GP was better organized with more cells and more proliferative columns compared to the soy fed rats. Micro CT analysis showed that in short-term experiments, the diaphysis diameter of the humeri was greater in the soy fed rats. In the long-term study, the humeri of the whey fed rats had greater bone mineral density and cortical thickness.

Conclusions: The results suggest a differential growth rate, with the soy fed rats growing faster. Although both groups reached the same length at the age of 100 days, the increased GP height of the whey group, suggest a better growth potential. A longer follow up may indicate if the potential is translated to differences in length. Studying the interaction between skeletal growth and nutritional factors