Meat, total and haem iron intakes of New Zealand toddlers aged 12-24 months

Abstract

Statement of the problem: It is thought that one third of New Zealand toddlers have suboptimal iron status. This is likely a reflection of the inadequate dietary iron intake reported in this group, in particular the low intake of foods containing haem iron which are a source of highly bioavailable iron. However, the amount of haem iron and animal tissue consumed in the diet is rarely investigated due to a lack of data in food composition databases. Therefore, the aim of this study was to determine the amount of haem iron; meat, fish, poultry (MFP); and red meat in foods in the New Zealand food composition database, then use these values to determine the total, haem iron, MFP and red meat intakes of New Zealand toddlers aged 12-24 months.

Methods and procedures: The amount of total iron was obtained from New Zealand FOODfiles 2010. The amount of haem iron (as mg of haem iron, or % of total iron) in different meats was determined from the literature, and these values were then used to develop two calculations for estimating haem iron intakes in the diet (“Haem iron 2: mg from literature” and “Haem iron 3: % from literature”). The third calculation (“Haem iron 1: 40% of MFP”) was based on the method previously used in the literature where 40% of the iron in MFP is assumed to be haem iron. These calculations were then compared to determine whether either of the simpler calculations (“Haem iron 1: 40% MFP iron” or “Haem iron 2: mg from literature”) could be used instead of the more complex calculation, “Haem iron 3: % from literature”. The grams of animal tissue was used as a proxy for MFP factor content of foods. The amount of red meat (a source of haem iron and MFP factor) in foods was calculated as the grams of beef, veal, lamb or mutton in the food. Five-day weighed food records had been collected for 154 toddlers aged 12-24 months from Wellington, Dunedin and North Canterbury, between September 2011 and March 2012. The values determined above were loaded into the database within the newly developed diet analysis programme Kai-culator to determine the total iron, haem iron, MFP and red meat intakes of the toddlers. Results: The third calculation (“Haem iron 3: % from literature”) was considered to be the most accurate method for estimating the haem iron content of foods as it individually assigns a haem iron value to each food and is less likely to over-estimate haem iron, although in this population there was a statistically significant but very small difference in the results between “Haem iron 1” and “Haem iron 3”. Total iron and haem iron (using “Haem iron 3: % from the literature”) intakes in toddlers were 5.7 (5.2, 6.1) mg/day (geometric mean (lower, upper 95% CI) and 0.19 (0.16, 0.21) mg/day respectively, with haem iron intake 3.3% of total iron intake. Iron intake was inadequate in 47% of toddlers. The main sources of total iron were “breads and cereal” (45.2%) followed by “Infant formulas and toddler milks”. The main sources of haem iron were “Mince and patties” (38.8%) followed by “Beef, lamb, pork, mutton”. Meat, fish, poultry intake was 25.2 (22.4, 27.9) g/day and contributed 10.3% of dietary iron to the toddlers’ diets. Of the MFP eaten, 34.1% was red meat. The main sources of MFP and red meat were “Chicken (non-processed)” (19.1%) and “Mince and patties” (43.5%) respectively. Conclusions: Comparing the 40% of MFP iron method (“Haem iron 1”) to the “Haem iron 3: % from literature” method developed in this study, suggests that using a set value to calculate haem iron can over- or under-estimate intake of haem iron depending on the balance of red and white meat intake in the diet. By assigning a haem iron value to each meat, this problem is eliminated and a more accurate estimate of intake may be obtained. Forty-seven percent of toddlers in this study had inadequate iron intakes. In order to reduce this inadequacy, overall total dietary iron intake needs to be increased. Foods which have a higher bioavailability and which increase non-haem iron absorption such as MFP and red meat should also be promoted to help reduce the prevalence of inadequate iron status.