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The effect of alginate on ileostomy excretion of sterols and nutrients was investigated in six ileostomy subjects fed a constant low-fiber diet with or without supplementation with 7.5 g sodium alginate. A mean of 95% of uronic acids derived from the sodium alginate was recovered in the ileostomy contents. Supplementation with alginate increased fat excretion by 140% and decreased bile acids excretion by 12%. Sodium and potassium excretion were significantly increased whereas starch and nitrogen excretion were unchanged. Five of six subjects showed a decreased apparent absorption of iron and manganese with alginate, which, however, was not statistically significant. Absorption of phosphorus, calcium, magnesium, and zinc were unchanged. Almost no digestion of sodium alginate occurs in the stomach and small intestine. The increased fatty acids excretion may be explained by the binding or trapping of fatty acids in the gel matrix formed by alginate, which may also cause a reduced bile flow. Am J Clin Nutr 1994;60:751-6.

Background: Inositol hexaphosphate ([IP.sub.6]) is a well-known inhibitor of iron absorption, whereas the effects of the less-phosphorylated derivatives of [IP.sub.6] are less known. Objectives: The objective was to investigate the effects of inositol tri-, tetra-, and pentaphosphates ([IP.sub.3], [IP.sub.4], and [IP.sub.5], respectively) on iron absorption in humans. Design: Iron absorption was measured in 5 experiments from single meals by extrinsic labeling with [sup.55]Fe and [sup.59]Fe and determination of whole-body retention and the erythrocyte uptake of isotopes. In experiments 1-3 the meals contained white-wheat rolls to which 10 mg P as [IP.sub.5], [IP.sub.4], or [IP.sub.3], respectively, was added. Inositol 1,2,6-triphosphate [Ins(1,2,6)[P.sub.3]] and a mixture of isomers of [IP.sub.4] and [IP.sub.5] were studied. White-wheat rolls contained 10 mg P as [IP.sub.3] + [IP.sub.4] and 2 mg P as [IP.sub.5] + [IP.sub.6] in experiment 4 and 20 mg P as [IP.sub.3] + [IP.sub.4] and 3 mg P as [IP.sub.5] + [IP.sub.6] in experiment 5; inositol phosphates were obtained via fermentation of sodium phytate. Each experiment had 8-11 subjects. Results: In experiment 1, iron absorption was reduced by 39%, whereas there was no significant effect on iron absorption in experiments 2 and 3. In experiments 4 and 5, iron absorption was reduced by 54% and 64%, respectively, suggesting that [IP.sub.3] and [IP.sub.4] contributed to the inhibitory effect. Conclusions: [IP.sub.5] has an inhibitory effect on iron absorption, whereas [IP.sub.3] and [IP.sub.4] in isolated form have no such effect. [IP.sub.3] and [IP.sub.4] in processed food contribute to the negative effect on iron absorption, presumably by binding iron between different inositol phosphates. To improve iron absorption from cereals and legumes, degradation of inositol phosphates needs to be to less-phosphorylated inositol phosphates than [IP.sub.3]. Am J Clin Nutr 1999;70:240-6.