Flaws of universal salt iodization programmes in nutrition transition contexts: is there a risk of a double burden of inadequate iodine intake and excess adiposity? A case study in Tunisia

Abstract

Background In the Middle East and North Africa (MENA) region, universal salt iodization (USI) programs defaults were sometimes shown to increase the risk of iodine excess. Also, the nutrition transition which underlies the obesity epidemic in the MENA region is characterized by salt-rich diets, so that there could be a cumulative effect with respect to iodine status. We assess the within-subject co-existence of overweight and inadequate iodine intake, and associated factors.Methods A national cross-sectional study used a stratified, clustered random sample and conducted among Tunisian school-age children aged from 6 to 12 y. (n = 1560). Overweight (Ow) was body mass index (BMI)-for-age ≥ + 1z. Iodine deficiency was UIC (Urinary Iodine Content) < 100 µg/L and iodine intake above requirements (IAR) UIC ≥ 200 µg/L. Association of covariables with the within-subject double burden Ow–IAR was assessed by multinomial regression.Results The prevalences of Ow-ID or Obe-ID were marginal, but not so for excess adiposity and IAR as for example prevalence of Ow-IAR was 9.8% (95% CI:[7.7–12.3]). OW and IAR were found to co-occur independently (P = 0.29). Socio-economic patterning of Ow-IAR was mild. Nevertheless, prevalence were the lowest among children of mother with no formal schooling and in the South-East region. Beyond school-age children, we estimated that this double burden of overweight and excess iodine could concern a third of Tunisian adults (all the more for women).Conclusions Among Tunisian children, iodine deficiency coupled with excess adiposity was quite marginal. Coexistence of overweight and excess iodine may affect a tenth of these children. More data would be needed to document a possibly even higher rate among adults. Cumulative effects of unhealthy lifestyle due to the nutrition transition interacting with metabolic pathways may be involved in this potential overweight-high iodine intake double burden. In the MENA region, obesity and salt reduction policies should continue to be monitored.