Application of in vitro bioaccessibility and bioavailability methods for calcium, carotenoids, folate, iron, magnesium, polyphenols, zinc, and vitamins B(6), B(12), D, and E.

A review of in vitro bioaccessibility and bioavailability methods for polyphenols and selected nutrients is presented. The review focuses on in vitro solubility, dialyzability, the dynamic gastrointestinal model (TIM)™, and Caco-2 cell models, the latter primarily for uptake and transport, and a discussion of how these methods have been applied to generate data for a range of nutrients, carotenoids, and polyphenols. Recommendations are given regarding which methods are most justified for answering bioaccessibility or bioavailability related questions for specific nutrients.

Production of stable-isotope-labeled bovine heme and its use to measure heme-iron absorption in children.

Background: The use of stable isotopes has provided valuable insights into iron absorption in humans, but the data have been limited to nonheme iron.

Objective: Our objectives were to produce heme iron enriched in (58)Fe and to use it to study the absorption of heme iron and the effect of iron and zinc intakes on heme-iron absorption in children.

Design: Labeled bovine heme was produced in a bovine model.

Effect of beef and soy proteins on the absorption of non-heme iron and inorganic zinc in children.

Background: Iron and zinc deficiency remain substantial problems in small children in both developed and developing nations. Optimizing mineral absorption is an important strategy in minimizing this problem.

Objectives: To assess the effects of beef and soy proteins on the bioavailability of non-heme iron and zinc in children.

The effect of calcium salts, ascorbic acid and peptic pH on calcium, zinc and iron bioavailabilities from fortified human milk using an in vitro digestion/Caco-2 cell model.

The calcium, zinc, and iron bioavailabilities of human milk with commercial and noncommercial human milk fortifiers (HMFs) were evaluated under a variety of conditions: peptic digestion at pH 2 and pH 4, supplementation of ascorbic acid, and addition of three calcium salts. The noncommercial HMFs consisted of casein phosphopeptides (CPPs), alpha-lactalbumin, colostrum, and hydrolyzed whey protein concentrate (WPC). They were mixed with human milk (HM) and calcium, zinc, and iron were added.

A low-molecular-weight factor in human milk whey promotes iron uptake by Caco-2 cells.

The iron bioavailability of human milk (HM) is substantially greater than that of cow's milk (CM), but the factor responsible for this high bioavailability is unknown. This study evaluated the effects of various HM and CM fractions on iron bioavailability. Milk was separated into fat, casein and whey fractions by ultracentrifugation.

Simultaneous determination of (45)calcium and (65)zinc uptake by caco-2 cells.

A simple method for simultaneously determining cell-associated Ca and Zn in Caco-2 cells is described. Calcium and zinc uptake was measured via radioisotopes (45)Ca and (65)Zn. Preliminary studies revealed that (65)Zn, a positron (beta(+)) and gamma emitter, contributed to (45)Ca counts in a liquid scintillation counter (LSC).