A study of the pharmacokinetic profile (oral absorption and renal excretion) of inositol hexaphosphate or phytate (IP(6)) is presented. Seven healthy volunteers were following a IP(6) poor diet (IP(6)PD) in a first period, and on IP(6) normal diet (IP(6)ND) in a second one. When following the IP(6)PD they become deficient in IP(6), the basal levels found in plasma (0.07+/- 0.01 mg/L) being clearly lower than those found when IP(6)ND 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 commercial sources and doses. After the IP(6) restriction period, volunteers were on IP(6)ND, reaching normal plasma and urinary IP(6) values in 16 days. Thus, the normal plasma and urinary concentrations, can be obtained either by consumption of a IP(6)ND taking a long time or in a short period by IP(6) supplements.

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The phytate urinary levels in a group of active calcium oxalate stone formers were studied and compared with those found in healthy people. Urinary phytate was significantly lower for stone formers. If deficit of the capacity to inhibit crystallization of calcium salts is considered an important factor related to calcium stone formation, the excretion of low phytate amounts could be an important risk factor in the development of this type of renal calculi. The influence of dietary phytate on urinary excretion was also studied. Clearly maintenance of a phytate-free diet significantly decreased the urinary excretion of phytate (about 50% after 36 h). This demonstrated the importance of dietary phytate in maintaining adequate urinary levels to permit effective crystallization inhibition of calcium salts and consequently preventing renal stone development.

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Objective To study the relationship between the oral intake of inositol hexakisphosphate (InsP 6 , phytic acid, an inhibitor of urinary crystallization) and its urinary excretion, to establish their possible mutual in¯uence. Materials and methods Two groups of male Wistar rats (six animals each) received either; tap water and normal rat food pellets (controls); or a liquid diet in which InsP 6 was absent and which then received gradually increasing amounts of InsP 6 . The urinary levels of InsP 6 were then assessed regularly in both groups. Results When InsP 6 was absent from the diet, urinary excretion declined to undetectable levels after 22 days. The addition of increasing amounts of InsP 6 to the liquid diet caused an increase in its urinary excretion after about 10 days. Adding InsP 6 in amounts >425 mg/L caused no further increases in urinary excretion. Adding inositol (with no InsP 6 ) to the liquid diet caused only a slight increase in the urinary excretion of InsP 6 . Conclusion These results showed that InsP 6 urinary levels were related to its oral intake; consequently, a low consumption of InsP 6 would cause a urinary de®cit of this crystallization inhibitor and thus an increase in the risk of developing urinary calcium stones. Although urinary excretion was dose-dependent, there was an ingested amount (20.9 mg/kg) above which there was no increase in the amount excreted. This intake is easily obtained by consuming a normal diet (rich in InsP 6 ) indicating that to maintain appropriate urinary levels of InsP 6 , the consumption of InsP 6 supplements is only necessary when the diet is particularly poor in InsP 6 .

The effects on the calcium oxalate urolithiasis urinary risk factors of Zeu mays (stigmata maidis), in herb infusion form, combined with different diets (standard, high glucidic, high protein) have been studied using male Wistar rats. From the reported study, the possible antilithiasic effects of Zeu muis infusion can be exclusively assigned to some diuretic activity. Thus, no influence on important urinary risk factors such as citraturia, calciuria or urinary pH values was detected. It is interesting to emphasize that the diuretic effect of the herb infusion was clearly dependent on the diet and was maximum when the rats were fed with the standard one.