An HPLC method was used to quantify contents of inositol hexa-, penta-, tetra-, and triphosphate in various bread, breakfast cereal, pasta, and rye flour samples collected from Finnish commercial mills and retail outlets. The highest contents in breakfast cereals (phytic acid over (10 \mu \mathrm{mol} / \mathrm{g} \mathrm{dry} \mathrm{wt)} \mathrm{were} \mathrm{found} \mathrm{in} \mathrm{whole-meal} \mathrm{porridge} \mathrm{flakes,} \mathrm{followed} \mathrm{by} \mathrm{mΓΌslies.} \mathrm{Inositol}) hexa-, penta-, tetra-, and triphosphate levels in rice crispies and corn flakes were consistently low. Inositol hexaphosphate contents in pastas were about (5 \mu \mathrm{mol} / \mathrm{g}) dry wt. The phytic acid contents in rye flours and whole-meal porridge flakes were on the same level and rye flours had only very low contents of inositol penta- and traces of inositol tetra- and triphosphates. The highest total inositol hexa-, penta-, tetra-, and triphosphate contents in breads were found in crispbreads, breads containing wheat and oat, and Finnish sourdough rye bread. Breads made predominantly of wheat had lower contents. Most of the inositol hexaphosphate in the various sourdough breads studied (rye breads, buckwheat, some domestic crispbreads, and a wheat and potato bread) had hydrolyzed, since the content of inositol hexaphosphate was low compared to that of inositol penta-, tetra-, and triphosphates. The average Finnish per capita intake of phytic acid from cereal products is roughly (370 \mathrm{mg} /) day. Dietary fiber is mainly supplied by cereal products, rye bread being the single most important source therein. Thus these foods were also assumed to be the most important source of phytic acid. However, the share of rye bread (Finnish sourdough dark rye bread) is not a significant source of phytic acid. Cereal products, and rye bread in particular, are very important sources of inositol hexa-, penta-, tetra-, and triphosphates.
c) 1995 Academic Press. Inc.