FACTORS AFFECTING IRON STORES IN INFANTS 4-18 MONTHS OF AGE

Objectives: To determine the effects of dietary, physiological or envi ronmental factors on body iron levels in infants aged 4-18 months. Des ign: The daily iron intake of the infants was measured from a diet his tory obtained by interview using a standardised question sheet, previo usly validated against weighed intake (minimum 3 days) in an independe nt sample of 8 and 18 month old infants. Capillary blood samples were analyzed for haemoglobin, mean cell volume, haematocrit, zinc protopor phyrin and plasma ferritin concentration. Ferritin values were log-tra nsformed prior to analysis to give a better approximation to the norma l distribution and forward stepwise multiple linear regression was car ried out using SPSS. Setting: The city of Norwich, UK and some of its suburbs. Subjects: One hundred and eighty-one healthy infants in age g roups 4, 8, 12 and 18 months. Results: Main determinants of iron store s in the 4 month old infants were birth weight (+ve (P < 0.001)) and b ody weight (-ve (P < 0.005)). In the 8 month old infants intake of cow 's milk (-ve (P < 0.05)), belonging to a smoking household (-ve (P ( 0 .05)) and quantity of commercial babyfood consumed (+ve (P < 0.05)) we re significant. In this age group there was a gender effect (girls > b oys (P < 0.01)) and the gender effect remained at 12 months (girls > b oys (P < 0.05)), but at 18 months only non-haem iron intake was a sign ificant factor (-ve (P < 0.05)). Conclusions: At 4 months of age birth weight and body weight exert the greatest influence on iron stores, w hereas by 8 months components of the weaning diet have an effect (comm ercial babyfood (+ve), cow's mill: (-ve)); there is also a gender effe ct (girls > boys), possibly reflecting the different growth rate betwe en boys and girls. At 12 and 18 months the only significant factors ar e gender (girls > boys) and non-haem iron intake (-ve) respectively.