Iodine source apportionment in the Malawian diet

The aim of this study was to characterise nutritional-I status in Malawi. Dietary-I intakes were assessed using new datasets of crop, fish, salt and water-I concentrations, while I status was assessed for 60 women living on each of calcareous and non-calcareous soils as defined by urinary iodine concentration (UIC). Iodine concentration in staple foods was low, with median concentrations of 0.01 mg kg(−1) in maize grain, 0.008 mg kg(−1) in roots and tubers, but 0.155 mg kg(−1) in leafy vegetables. Freshwater fish is a good source of dietary-I with a median concentration of 0.51 mg kg(−1). Mean Malawian dietary-Iodine intake from food, excluding salt, was just 7.8 μg d(−1) compared to an adult requirement of 150 μg d(−1). Despite low dietary-I intake from food, median UICs were 203 μg L(−1) with only 12% defined as I deficient whilst 21% exhibited excessive I intake. Iodised salt is likely to be the main source of dietary I intake in Malawi; thus, I nutrition mainly depends on the usage and concentration of I in iodised salt. Drinking water could be a significant source of I in some areas, providing up to 108 μg d(−1) based on consumption of 2 L d(−1).