Effects of oral bovine colostrum supplementation on serum insulin-like growth factor-i levels

Abstract 

OBJECTIVES:

We investigated whether supplementation with 60 g/d of bovine colostrum affects blood levels of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 in relation to doping testing. Nine endurance-trained men ingested 60 g/d of bovine colostrum for 4 wk.

METHODS:

Blood and urine were sampled before starting supplementation. After 4 wk urine and blood samples were taken after an overnight fast and 2 h after ingestion of the last portion to study possible acute effects.

RESULTS:

Blood IGF-I levels before supplementation were (mean ± standard deviation) 31 ± 13 nM/L, and no acute effects were observed after 4 wk of supplementation (33 ± 9 nM/L). Levels of IGF-binding protein-3 were 136 ± 11 nM/L before supplementation and 135 ± 16 nM/L after 4 wk of supplementation. Two hours after ingestion of the last portion, the level of IGF binding protein-3 was 131 ± 19 nM/L, which was not different from baseline values. Drug testing in a laboratory accredited by the International Olympic Committee did not show any forbidden substance before or after 4 wk of supplementation.

CONCLUSIONS:

Daily supplementation with 60 g of bovine colostrum for 4 wk does not change blood IGF-I or IGF binding protein-3 levels and does not elicit positive results on drug tests.

Keywords:  colostrum supplementation, growth factors, doping test