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Biotin Analysis of Commercial Vitamin and Other Nutritional Supplements¹

Divisions of Gastroenterology/Hepatology and Nutrition, Department of Pediatrics, College of Medicine, University of Iowa, Iowa City, IA 52242

Because previous observations suggest that biotin may be present in vitamin preparations not labeled as containing biotin, we determined the biotin content of several over-the-counter vitamin and nutritional supplements said to contain biotin (group 1) and several in which biotin content was not specified (group 2). Biotin concentration was measured using the ¹²⁵I-avidin assay which detects total avidin-binding substances. Water extracts were assayed for free biotin and acid hydrolysates were assayed for total biotin. The results of the ¹²⁵I-avidin assay agreed with the stated biotin content for most vitamin and nutritional supplements in group 1. Biotin was the only avidinbinding substance in the preparations from group 1, based on reversed-phase chromatography. However, some vitamin and nutritional supplements in group 2 contained nutritionally significant amounts of biotin, particularly if the supplement contained liver or yeast extract. Total biotin was significantly higher than free biotin in one supplement; the difference was attributable to release of biotin rather than a biotin analog. We conclude that biotin may be present in some vitamin and nutritional supplements not labeled as containing biotin; biotin intake might be underestimated if the subject is receiving a nutritional supplement containing extracts of liver or yeast.

KEY WORDS: • biotin • acid hydrolysis • high performance liquid chromatography • bovine serum albumin • commercial vitamin supplements

¹ Supported by grant CRCR-1-2331 from the Competitive Research Grants Program of the U.S. Department of Agriculture.

² Recipient of Research Career Development Award K04-DK01810 from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

Manuscript received 8 June 1989. Revision accepted 13 June 1989.

This article has been cited by other articles:

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