How does it work?
At least seven human enzymes require biotin in order to function. Five have biotin integrated within their structure as a coenzyme, and these all belong to the carboxylase category. Measuring the activities of these carboxylase enzymes gives a more accurate picture of the body’s biotin status than measuring blood biotin levels. The activity of each carboxylase enzyme can be conveniently assessed by measuring the level of its specific end product in the urine. Of the five known biotin carboxylases, three are located in the mitochondria, the microscopic energy generators within our cells. Carboxylases that reside in the mitochondria help make heme, a protein that contains iron and is essential for the mitochondria’s energy generation functions. Consequently, biotin deficiency can impair the functioning of heme proteins in the mitochondria, which in turn can create a free radical challenge for the cell. The sixth biotin enzyme is biotinidase, which functions to release biotin from its linkages to proteins or other biomolecules and thereby make it available for utilization as a carboxylase coenzyme. Mutations in biotinidase can markedly lower biotin absorption from the foods and contribute to depletion of the body’s biotin stores.