BioFactors 15 (2001) 53–61 53 IOS Press Absorption and excretion of orally administered inositol hexaphosphate (IP 6 or phytate) in humans Felix Grases a,∗ , Bartolom´ e M. Simonet a , Ivana Vucenik b , Rafel M. Prieto a , Antonia Costa-Bauz´ a a , Joan G. March a and Abulkalam M. Shamsuddin c a Laboratory of Renal Lithiasis Research, Faculty of Science, University of Illes Balears, 07071 Palma de Mallorca, Spain b Department of Medical and Research Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA c Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA Received 7 February 2001 Accepted 28 June 2001 Abstract. A study of the pharmacokinetic profile (oral absorption and renal excretion) of inositol hexaphosphate or phytate (IP6) is presented. Seven healthy volunteers were following a IP6 poor diet (IP6PD) in a first period, and on IP6 normal diet (IP6ND) in a second one. When following the IP6PD they become deficient in IP6, the basal levels found in plasma (0.07 ± 0.01 mg/L) being clearly lower than those found when IP6ND was consumed (0.26 ± 0.03 mg/L). During the restriction period the maximum concentration in plasma were obtained 4 h after the ingestion of a single dose of IP 6, observing almost the same renal excretion profiles for the three different comercial sources and doses. After the IP 6 restriction period, volunteers were on IP6ND, reaching normal plasma and urinary IP6 values in 16 days. Thus, the normal plasma and urinary concentrations, can be obtained either by comsumption of a IP 6ND taking a long time or in a short period by IP6 supplements. 1. Introduction Inositol hexaphosphate (InsP6 or IP 6 or phytate) has been an important dietary component of humans from ancient ages; high amounts of this substance are present in legumes, non-refined cereal derivatives, corn, whole grain cereals and all types of nuts. Nevertheless, for a long time IP 6 was considered as an antinutrient due to its capacity to form insoluble complexes with trace elements, such as zinc, iron and copper in vitro, and, as a consequence, perhaps to a decrease in the bioavailability of these elements in vivo. However, recent studies demonstrate that this “antinutrient” effect of IP 6 is only manifested when large quantities of IP 6 are consumed in combination with oligoelements-poor diet [2,10,14,23]; the daily consumption of 1–2 g IP 6 with balanced diets did not affect the mineral status in humans [2,23]. * Corresponding author: Prof. Dr. F. Grases, Laboratory of Renal Lithiasis Research, Faculty of Sciences, University of Illes Balears, Ctra. Valldemossa Km 7,5, 07071 Palma de Mallorca, Spain. Tel.: +31 971 17 32 57; Fax: +31 971 17 34 26; E-mail: dqufgf0@ps.uib.es. 0951-6433/01/$8.00  2001 – IOS Press. All rights reserved