Development of an outpatient biotin feeding protocol for studies of biotin requirements in adults

Abstract

Human biotin requirements are unknown. Previous studies of biotin metabolism at physiologically relevant levels, ranging from moderate deficiency to moderate excess, required costly inpatient settings. We sought to develop a cost‐efficient outpatient protocol based on feeding egg white shakes. In this protocol, subjects are required to consume an egg white shake with every major meal. The avidin protein in spray‐dried egg white binds biotin and prevents its absorption, i.e., egg white can be used to titrate the amount of available biotin in the diet. The following three levels of biotin supply were tested. (a) Deficiency = sufficient egg white to saturate all the biotin in a typical American diet. (b) Control = biotin‐saturated egg white plus 30 μg biotin/d. (c) Supplemented = biotin‐saturated avidin plus 600 μg biotin/d. As of today, 11 adults have completed the study. The abundance of biotinylated carboxylases and the urinary excretion of biotin (0.26±0.15 vs 0.35±0.15 vs 3.2±0.67 nmol biotin/μmol creatinine) depended on the amount of free biotin in test diets, suggesting efficacy of treatment. We conclude that the new outpatient protocol is an effective and cost‐efficient alternative to costly in‐patient protocols. (UNL ARD Hatch Act, NIH DK063945, DK077816, and DK082476)