Tissue iron deficiency and adiposity-related inflammation in disadvantaged preschoolers from NE Brazil

BACKGROUND/OBJECTIVES: Earlier we reported an association between iron deficiency and overweight in Brazilian preschoolers. Here, we investigate whether this is the result of adipose-related inflammation. SUBJECTS/METHODS: Fasting serum C-reactive protein, alpha-1-acid glycoprotein (AGP), hepcidin, interleukin-6 (IL-6) and leptin, together with two iron biomarkers (serum ferritin and transferrin receptor (sTfR)), were measured in 364 disadvantaged preschoolers with a mean BMIZ (standardised Z-score for BMI) of 0.015, aged 3-6 years and attending day care in Salvador, Brazil. The role of genetic haemoglobin (Hb) disorders, intestinal parasites and dietary iron supply (calculated from serving sizes of 20 weekday menus) were also examined. RESULTS: Forty-eight children (13%) were overweight (BMIZ >1). Prevalence of tissue iron deficiency (sTfR >113.3 nmol/l; 30.6 vs 12.5%; P=0.002) and chronic inflammation (AGP >25 mu mol/l; 19 vs 10%; P=0.025) were higher in overweight than in normal-weight children. From multiple regression, BMIZ was a positive predictor of log serum sTfR, ferritin and leptin, but not of log hepcidin or IL-6. Instead, major positive predictors of log hepcidin were log IL-6, followed by an elevated AGP and sex (male), whereas for log IL-6 elevated AGP was the only significant predictor. Besides BMIZ, sex (female) was also a major positive predictor of leptin. Heterozygous variant of sickle cell Hb (n=20), but not helminths, was also a positive predictor of log sTfR. Median dietary iron supply (mg/day) was above the WHO Recommended Nutrient Intake assuming moderate bioavailability and appeared adequate. CONCLUSIONS: The role of adiposity-related inflammation in tissue iron deficiency should be considered even when the prevalence of overweight is relatively low.