Objectives: To determine the effects of dietary, physiological or environmental factors on body iron levels in infants aged 4±18 months. Design: The daily iron intake of the infants was measured from a diet history obtained by interview using a standardised question sheet, previously validated against weighed intake (minimum 3 days) in an independent sample of 8 and 18 month old infants. Capillary blood samples were analyzed for haemoglobin, mean cell volume, haematocrit, zinc protoporphyrin and plasma ferritin concentration. Ferritin values were log-transformed prior to analysis to give a better approximation to the normal distribution and forward stepwise multiple linear regression was carried out using SPSS. Setting: The city of Norwich, UK and some of its suburbs. Subjects: One hundred and eighty-one healthy infants in age groups 4, 8, 12 and 18 months. Results: Main determinants of iron stores in the 4 month old infants were birth weight ( ve (P`0.001)) and body weight (7ve (P`0.005)). In the 8 month old infants intake of cow's milk (7ve (P`0.05)), belonging to a smoking household (7ve (P`0.05)) and quantity of commercial babyfood consumed ( ve (P`0.05)) were signi®cant. In this age group there was a gender effect (girls b boys (P`0.01)) and the gender effect remained at 12 months (girls b boys (P`0.05)), but at 18 months only non-haem iron intake was a signi®cant factor (7ve (P`0.05)). Conclusions: At 4 months of age birth weight and body weight exert the greatest in¯uence on iron stores, whereas by 8 months components of the weaning diet have an effect (commercial babyfood ( ve), cow's milk (7ve)); there is also a gender effect (girls b boys), possibly re¯ecting the different growth rate between boys and girls. At 12 and 18 months the only signi®cant factors are gender (girls b boys) and non-haem iron intake (7ve) respectively. Sponsorship: Ministry of Agriculture, Fisheries and Food and the Biotechnology and Biological Sciences Research Council.

Caseinophosphopeptides (CPP) were detected for the first time in ileostomy fluid, collected at 2 h intervals for 10 h post milk and CPP ingestion, from human volunteers with an ileostomy. The level of CPP present in ileostomy fluid obtained from milk-fed volunteers was markedly higher than that from volunteers fed with selected CPP preparations. The findings are based on HPLC analysis in combination with peptide-bound P determination, thin-layer electrophoresis and amino acid analysis, together with ELISA studies using polyclonal antibodies raised against a set of CPP to detect immunoreactive CPP in ileostomy fluid. These procedures allowed the detection of nM concentrations of CPP. CPP, which can be released during intestinal digestion, may function as bioactive constituents and carriers for different minerals, especially Ca, and may be used as ingredients in functional foods or pharmaceutical preparations.

The effect of calcium intake on the calcium absorption efficiency from 100 mL cow milk was measured in lactating Gambian mothers habituated to a low-calcium diet [mean intake 7.08 mmol (283 mg)/d], and compared with UK lactating mothers consuming high-calcium diets [mean intake 29.2 mmol (1168 mg)/d] by using a double stable-isotope technique (oral 44Ca and intravenous 42Ca). In a double-blind trial starting 9 d postpartum, Gambian mothers were given a calcium supplement [17.85 mmol (714 mg)/d] or placebo for 12 mo. At 3 and 12 mo postpartum, mean (+/- SEM) calcium absorption from isotopically enriched milk was 52.3 +/- 3.1% (n = 25) and 47.2 +/- 4.8% (n = 24) in the unsupplemented Gambian mothers and 48.8 +/- 2.8% (n = 28) and 42.9 +/- 3.7% (n = 24) in the supplemented mothers, respectively. There was no effect of supplementation or stage of lactation on the efficiency of calcium absorption. At 3 mo postpartum the UK mothers absorbed 32.2 +/- 3.8% of the isotopically enriched calcium added to milk, which was significantly less than that of the Gambian mothers (P < 0.01).