An investigation was carried out to determine whether there were significant changes in the intake of haem and non-haem Fe of adult men and women in the UK from 1982 (aged 36 years) to 1999 (aged 53 years). The 1253 subjects studied were members of the Medical Research Council National Survey of Health and Development; a longitudinal study of a nationally representative cohort of births in 1946. Food intake was recorded in a 5-d diary at age 36 years in 1982, 43 years in 1989 and 53 years in 1999. Outcome measures were mean intakes of total Fe, haem and non-haem Fe, by year, gender and food source. There were significant changes in total Fe, haem Fe and non-haem Fe intake over the three time points. Total Fe intake was significantly higher in 1989 than in 1982 or 1999 for both men and women but haem Fe was significantly lower in 1999 mainly due to a 40 % fall in haem Fe from beef during this period. Haem Fe from processed meats fell by more than 50 % between 1989 and 1999 but that from poultry rose by more than 50 %. Cereal foods remained the most important source of non-haem Fe and the contribution from breakfast cereals rose relative to that of bread over the 17 years. Several factors could be responsible for these changes, particularly the importance of the epidemic of BSE from 1990. The possible advantages of a lower haem Fe intake in older subjects are discussed.

The influence of high CaCO3, intake on the bioavailability of Fe from FeSO4, was assessed during Fe repletion of rats with Fe-deficiency-induced anaemia. Fe-deficient rats with a mean blood haemoglobin concentration of 4. 1 mmol/l were fed on purified Fe-adequate diets containing either 6.2 or 25.0g CaCO,/kg (ten rats per group). Haemoglobin repletion after 14 d was significantly depressed by high CaCO, intake (9.5 v. 9.8 mmol/l for high and low CaCO, intake respectively; P = 0·03), as was apparent Fe retention (367 v. 552 µg/d during days 5–7, P<0·001; 146 v. 196 µg/d during days 19–21, P < 0·001). The concentration of Fe in the liquid phase of the proximal half of the small intestine was significantly lower in the high-CaCO, group (3.71 v. 520 µg/g digesta; P = 0-02). Mucosal uptake and mucosal transfer of Fe were determined with orally administered 59Fe and Cr as a non-absorbable marker. Mucosal transfer was significantly diminished by CaCO, loading (90 v. 100% of mucosal uptake; P = 0·04), whereas mucosal uptake was not. 59Fe retention values at 14 d after administration were not significantly different (57.6 v. 51.9%; P = 0·14). Fe contents of liver and spleen were significantly decreased by high compared with low CaCO, intake (879 v. 590 pg Fe in liver, P < 0·001; 92 v. 63pg Fe in spleen, P <0·001). It is concluded that high intake of CaCO, depresses Fe bioavailability in rats. The CaCO,-induced decrease in Fe solubility in the digesta probably was associated with an increased efficiency of mucosal Fe uptake so that the amount of mucosal uptake remained unaltered. The CaCO,-induced decrease in Fe transfer through the mucosal cytoplasm and/or basolateral membrane may have been responsible for the concurrent decrease in Fe bioavailability.