| Popis: |
This thesis aims to examine factors influencing the solubility of oxalate from dietary sources, namely cereal brans and legumes, and strategies to reduce the bioavailability of oxalate, including the influence of enzymes and a probiotic. Intake of oxalate through diet is a significant factor in the formation of kidney stones, particularly when consumed alongside mineral rich foods, due to the low solubility of calcium oxalate and some other mineral oxalates. Consumption of whole bran cereals and legumes is increasing because of potential nutritional benefits, yet both foods contain significant levels of oxalate, as well as phytate and minerals that can be determinant factors towards the risk of kidney stone formation. Phytate has been reported to form complexes with metal cations, thereby leaving less cations, particularly calcium and magnesium, available to form insoluble oxalate. Therefore, phytate and mineral composition of whole bran cereals (wheat, barley and oat) and legumes were determined, along with soluble and insoluble oxalate concentrations, in order to investigate the effects on oxalate solubility. Phytate concentration in tested food samples ranged from 227•4393 mg/ 100 g and the concentrations of cations were in the range 54•70 mg/IOOg for calcium and 75•398 mg/100g for magnesium. It has been found that soluble oxalate concentration did not increase in proportion to total oxalate, and the phytate concentration in all foods was sufficient to contribute to an increase in soluble oxalate concentration by binding calcium, since the phytate:calcium ratio was greater than 0.24. This value indicates that the phytate concentration is sufficient to reduce the calcium available for binding to oxalate, and thereby contributes to an increase in soluble oxalate. |
