Early serum IGF-I response to oral protein supplements in elderly women with a recent hip fracture

Background & aims: In patients with recent hip fracture, reduced serum IGF-I in relation to protein undernutrition is frequent. Elevation of circulating IGF-I in response to a daily oral supplement of 20 g of casein was observed after 6 months. This study determined if the response to casein as compared to whey protein can be observed as early as after one week. Methods: 45 Women were randomized after recent hip fracture in 3 groups receiving a preparation of 20 g of casein, an isocaloric supplement of 20 g of whey protein or an isocaloric supplement of 15 g of whey protein combined with 5 g of essential amino acids (a.a.). Results: A similar significant elevation of serum IGF-I was already observed after 7 days for casein (+37.3 mu g/L), whey (+29.4) and for whey + a.a. (+34.3). From day 7-28, no further significant rise in IGF-I was recorded. Conclusion: After one week of protein supplementation, the percent increase of IGF-I was of similar magnitude to that previously observed after 6 months of protein supplementation. It suggests that in hip fracture patients, long-term effects of various protein preparations on IGF-I could be predicted from changes observed as early as 7 days after the onset of supplementation. (C) 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.