Zinc and calcium apparent absorption from an infant cereal: A stable isotope study in healthy infants

Abstract

Fractional apparent absorption of Zn and Ca from a wheat-milk-based infant cereal was studied in six healthy infants (18-30 weeks old). Mineral absorption was measured by a stable-isotope technique based on faecal excretion of the isotopes. Each test meal (40 g cereal) was extrinsically labelled with 70Zn and 42Ca before intake. All faecal material passed during the 21 d following intake of the labelled test meal was collected on trace-element-free nappies. Individual stool samples were analysed for their content of ' OZn and 42Ca by thermal ionization mass spectrometry. Apparent absorption was calculated as intake minus total faecal excretion of the isotopes over 68-92 h after administration. The fractional apparent absorption values for Zn and Ca were 33.9 (SD 164) YO (range 19.2-639 YO) and 53.5 (SD 12.6) % (range 36.7-71.7 %) respectively. Re-excretion of absorbed 70Zn (> 68-92 h to 21 d after intake of the labelled meal) was 044 (SD 038) % of administered dose while only one infant re-excreted detectable amounts of "Ca (1.74% of administered dose). The analysis of individual stool samples confirmed that 72 h is a sufficient time period for complete collections of non-absorbed isotopes in faecal material from infants during the weaning period and that re-excretion of initially absorbed ' OZn and "Ca (> 68-92 h to 21 d after intake of the labelled meal) is negligible.Zinc: Calcium: Weaning cereal: Stable isotopeThe estimation of mineral and trace element requirements of infants, and the ability to establish dietary recommendations for these nutrients during early life, is limited by the lack of information from studies with infants. Nutrient bioavailability, which includes absorption and retention of the nutrients, is a necessary component in these estimates since only the absorbed and retained fraction of a nutrient can be utilized by the body. The bioavailability of trace elements and minerals varies over a wide range, depending on the amount of the mineral in the diet, the presence of enhancers and inhibitors as well as on the chemical form of the mineral in the diet (Turnlund, 1991). Information on the total content of minerals in the diet is thus only of limited value when evaluating the nutritional impact of different diets.The stable-isotope technique is an excellent tool for studies of absorption and retention of trace elements and minerals, which does not introduce any risk to the subjects Turnlund, 1991 ;Davidsson, 1994). The 'faecal monitoring' method is the most commonly used for studies in infants. Previous studies of Zn and Ca absorption from infant foods by infants, using the stable-isotope technique, have measured absorption by analysing the non-absorbed isotope in faeces . In some studies two isotopes of different elements were added simultaneously to

A Review of Dietary Zinc Recommendations

“…The IZiNCG, 3 however, applied their mean absorption figures generated for adults for each diet type (see Table 3) to all children aged 1 to 18 years, arguing that the figure used by IOM was only based on 2 single-meal studies in infants and young children. 38,39 No allowance for an adaptive response to meet the additional physiological demands for zinc during pregnancy or lactation was made by WHO 5 in view of the paucity of data at that time. Subsequently, IOM, 2 IZiNCG, 3 and EFSA 4 adjusted the figure for FAZ during lactation (but not pregnancy) based on more recent data.…”

A Review of Phytate, Iron, Zinc, and Calcium Concentrations in Plant-Based Complementary Foods Used in Low-Income Countries and Implications for Bioavailability

“…Similarly, iron absorption is not increased in adults consuming high-phytate diets [25], a trend that is probably also apparent in children, given that the effects of enhancers and inhibitors on iron absorption are comparable in adults and infants [26]. Unlike zinc and iron, the high phytate content of cereal-based complementary foods does not have a major impact on calcium status during infancy and early childhood: apparent absorption of calcium was reported to be high (60%) in infants receiving a highphytate complementary food [27]. Instead, calcium deficiency among young children is more likely to be due to a low intake rather than poor absorption [28].…”

Effect of Difructose Anhydride III on Calcium Absorption in Humans

“…Previous other studies on these effects have used radioisotopes or stable isotopes in clearance and other such tests. [8][9][10] We used the urinary calcium excretion as an indicator of calcium absorption. This method is based on the positive correlation between the intestinal calcium absorption and urinary calcium excretion and has often been used.…”