whereRU: Aresty Poster78 - Effect of Diet and Protein on IGF-1 and IGF-BP3 by Aresty Posters 2009

The Effect of Caloric Restriction and Protein Intake on Insulin-like growth factor and Insulin-like growth factor binding protein-3

Previous studies have shown that dietary protein is important for bone health. In addition insulin like growth factor (IGF-1) and IGF-binding protein-3 (IGFBP-3) are essential for bone growth and maintenance. Weight loss due to normal caloric restriction can result in a decrease in IGF-1/IGF-binding protein which can have an adverse effect on bone health. The aim of this study was to determine whether IGF-1 and binding protein-3 is associated with lean body mass, bone mass and turnover in overweight and obese postmenopausal women and whether it is altered by the level of dietary protein intake during caloric restriction. It is hypothesized that a HP diet compared to a NP diet will prevent a decline in serum IGF-1/binding proteins, normally associated with caloric restriction. In this year- long study postmenopausal women were recruited for weight loss and instructed to follow a reduced calorie, well balanced diet. Participants were placed randomly on either a low-calorie normal protein (NP) or high protein diet (HP) diet (18 vs 30% calories from protein) and consumed the recommended level of calcium and vitamin D. In this analysis, we measured serum IGF-1, IGFBP-3 and body composition (fat, muscle mass, and bone mineral density and content) using dual energy x-ray absorptiometry. We show that there tends to be a greater increase in IGF-1 in HP as compared to the NP diet (p= 0.07). Additionally we also show that the change in IGF-1 in the HP group is positively associated with change in femoral neck bone mineral content. These data suggest that the high protein diet may be associated improved bone health due to an increase in IGF-1 during caloric restriction.

Aakruti Bhalja
abhalja@gmail.com
Department of Nutritional Sciences
Nutrition and Bone Lab