More biotin, more IGF-1
The concentration of the growth factor IGF-1 rises and falls in accordance with fluctuations in the concentration of the B-vitamin biotin [see structure below] in the blood. Researchers at the Universidad Nacional Autonoma de Mexico have published an article on this in the European Journal of Nutrition, but it's not yet clear whether athletes will benefit from these findings.Biotin
If you give laboratory animals too little biotin their growth is retarded. But how come? What's the mechanism at work here? This is the question the Mexicans set out to answer in an animal study where they gave mice a diet lacking in biotin from three weeks of age on.

The supplements industry regards biotin as a vitamin that strengthens nails, skin and hair. To nutritionists, biotin is a co-factor for processes in the body through which energy is extracted from food. Under normal conditions you are only likely to develop a biotin deficiency if you eat large amounts of egg protein. Protein in eggs contains avidin, a peptide that neutralises biotin. The longer you cook egg protein, the more inactive the avidin becomes. In some experiments, researchers cook egg protein for as long as an hour to make 100 percent sure that they have deactivated the avidin.Animal study
The researchers gave one group of mice a standard diet, and gave two experimental groups a diet containing 30 percent egg protein. One of the experimental groups got food containing no biotin, the other got food to which biotin had been added. As the researchers expected, the mice with a biotin deficiency grew less fast.

When they examined the blood of the no-biotin mice the researchers discovered how the deficiency had caused the retarded growth. Although the growth hormone concentration was normal, the IGF-1 level in the mice's blood was reduced.

The researchers speculate that biotin does something with the DNA, RNA and the proteins that 'read' the genetic material. Biotin gets cells to produce more IGF-1, but how this happens the researchers do not go into.

Nor did the Mexicans examine what happens to the IGF-1 level if you put the mice back on a normal diet, and give them a high dose of biotin on top of that.
Eur J Nutr. 2009 Apr;48(3):137-44.