Protein supplements increase serum insulin-like growth factor-I levels and attenuate proximal femur bone loss in patients with recent hip fracture. A randomized, double-blind, placebo-controlled trial

Abstract

Background: Elderly persons who have osteoporotic hip fracture are often undernourished, particularly with respect to protein. Protein malnutrition may contribute to the occurrence and outcome of hip fracture.

Objective: To investigate whether oral protein supplements benefit bone metabolism in patients with recent hip fracture.

Design: 6-month, randomized, double-blind, placebo-controlled trial with a 6-month post-treatment follow-up.

Setting: University orthopedic ward.

Patients: 82 patients (mean age, 80.7 +/- 7.4 years) with recent osteoporotic hip fracture. Patients received calcium supplementation, 550 mg/d, and one dose of vitamin D, 200,000 IU (at baseline).

Intervention: Protein supplementation, 20 g/d, or isocaloric placebo (among controls).

Measurements: Bone mineral density, biochemical markers of bone remodeling, calciotropic hormone levels, biochemically evaluated nutritional and immunologic status, and muscle strength were measured every 6 months.

Results: Compared with controls, patients who received protein supplements had significantly greater increases in serum levels of insulin-like growth factor-I (85.6% +/- 14.8% and 34.1% +/- 7.2% at 6 months; difference, 51.5 percentage points [95% CI, 18.6 to 84.4 percentage points]; P = 0.003) and an attenuation of the decrease in proximal femur bone mineral density (-2.29% +/- 0.75% and -4.71% +/- 0.77% at 12 months; difference, 2.42 percentage points [CI, 0.26 to 4.59 percentage points]; P = 0.029). Seven and 13 new vertebral deformities were found among patients who received protein supplements and controls, respectively (P > 0.2). Median stay in rehabilitation wards was shorter for patients who received protein supplements than for controls (33 days [CI, 29 to 56 days] and 54 days [CI, 44 to 62 days]; difference, 21 days [CI, 4 to 25 days]; P = 0.018).

Conclusion: Protein repletion after hip fracture was associated with increased serum levels of insulin-like growth factor-I, attenuation of proximal femur bone loss, and shorter stay in rehabilitation hospitals.