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.