Oral bovine colostrum supplementation does not increase circulating insulin-like growth factor-1 concentration in healthy adults: results from short- and long-term administration studies

Purpose: Bovine colostrum is available in health food shops and as a sports food supplement and is rich in antibodies and growth factors including IGF-1. World Anti-Doping Agency advises athletes against taking colostrum for fear of causing increased plasma IGF-1. There are also concerns that colostrum may theoretically stimulate malignancy in organs which express IGF-1 receptors. We, therefore, determined changes in plasma IGF-1 levels in subjects taking colostrum or placebo for 1 day, 4 weeks, and 12 weeks. Methods: Plasma IGF1 levels were determined in healthy males (n = 16) who ingested 40 g bovine colostrum or placebo along with undertaking moderate exercise for total period of 4.5 h. Two further studies followed changes in IGF1 using double-blind, parallel group, placebo-controlled, randomized trials of colostrum or placebo (N = 10 per arm, 20 g/day for 4 weeks and N = 25 colostrum, N = 29 placebo arm 20 g/day for 12 weeks). Results: Baseline IGF1 levels 130 ± 36 ng/ml. 4.5 h protocol showed no effect of colostrum on plasma IGF1 (ANOVA, treatment group: p = 0.400, group × time: p = 0.498, time p = 0.602). Similarly, no effect of colostrum ingestion was seen following 4 week (ANOVA, group: p = 0.584, group × time interaction: p = 0.083, time p = 0.243) or 12 week (ANOVA, group: p = 0.400, group × time interaction: p = 0.498, time p = 0.602) protocol. Conclusions: Ingestion of standard recommended doses of colostrum does not increase IGF-1 levels in healthy adults, providing additional support for the safety profile of colostrum ingestion.