Abstract
Iodine deficiency in infants and children is associated with hypothyroidism and adverse consequences, including short stature and impaired neurocognitive development. We have recently reported that iodine deficiency in 9-month- to 6-year-old children residing in three Haitian regions (coastal, urban and mountainous) is not a significant public health threat, with only children in the mountainous region having mild iodine deficiency (median urinary iodine content 89 μg/L) compared with normal levels in the coastal and urban regions (median urinary iodine content 145 and 187 μg/L, respectively) (1). Urinary iodine values are the recognized method of evaluating iodine status in populations and values of 100–199 μg/L are considered to be optimal and levels of <100 μg/L, <50 μg/L, and <20 μg/L are defined as mild, moderate, and severe iodine deficiency, respectively.
The absence of iodine deficiency in this Haitian population of young children who have high rates of malnutrition and nutritional deficiencies was rather unexpected, even in light of recent efforts to increase consumption of iodized salt in Haiti. This finding lead us to investigate other potential sources of iodine intake. We hypothesized that the widespread use of bouillon cubes in Haiti may account for the largely normal urinary iodine levels in young children. Locally sold bouillon cubes from a variety of brands are used on a daily basis to prepare soups and other cooked foods in Haiti. Based on local practices, we estimate that the main daily warm meal contains approximately half to one bouillon cube (5–10 grams) per person.
Methods
Eleven different bouillon cubes available in stores throughout Haiti were purchased onsite and shipped to our laboratory at Boston Medical Center. Samples of each of the 11 different cube brands were diluted in water, digested with 3.0 mL chloric acid (30% aqueous solution), and measured in duplicate for iodine content. Total iodine concentrations were measured spectrophotometrically by a modification of the method of Benotti et al. (2).
Results and Conclusion
Two bouillon cubes had a low iodine content, but 9 cubes had values ranging from 45 to 240 μg iodine per cube. The iodine content of the 11 cubes analyzed averaged 109 ± 81.3 μg, which is roughly equivalent to a child's daily requirement (3), and suggests that the recently documented finding of iodine sufficiency in Haiti's young children may, at least in part, be due to high levels of iodine in the bouillon cubes (Table 1). There is no known significant difference in bouillon consumption between the highland versus coastal and rural areas. Verbal communication with one of the bouillon suppliers confirmed that even the most remote regions in Haiti are being supplied with bouillon cubes by means of donkey transport. It seems that iodized salt is generally used in urban populations. Iodized salt is more expensive and thus more likely to be purchased in the less impoverished urban areas, where it is also more accessible. The traditional method of salt preparation, mainly stemming from the salt basins in the Artibonite region, includes a washing process that reduces the amount of iodine in the salt. However, these basins were significantly affected by the 2010 earthquake, and salt production from these sources has decreased. There are now two salt iodization plants near Port-au-Prince that produce sufficient iodized salt to supply the entire country. While there are regional differences in manioc preparations, our recently published population survey of iodine status in Haiti found no significant difference in urinary thiocyanate between urban, rural, and coastal populations (1). Generally, there are two types of manioc preparation: a “bitter” manioc that contains a higher level of cyanogenes and a “sweet” manioc that contains a lower amount of cyanogenes. Tapioca, a “bitter” manioc, and the cooked foods prepared with this flower are traditionally more used in rural areas, where it is a common food for children. These findings suggest that iodine intake may well be improved by sources other than dairy products, iodized salt, and iodine enriched vitamin tablets, although adverse effects of increased salt and trans fat intake due to bouillon cube consumption need to be weighed against the benefit of iodine sufficiency.