Chikowore, Tinashe Shawn
(2021)
Iodine deficiency: a nutritional crisis or a matter of speculation? : the perfect discourse.
MRes thesis, University of Nottingham.
Abstract
During pregnancy, an increase in dietary iodine intake arises due to physiologic adaptation, a phenomenon that is characterised by complex effects that increase metabolic demands and incite hormonal changes. The presence of iodine deficiency (ID) during critical stages of gestation is associated with neurodevelopmental deficits and poses as a risk factor to the development of postpartum depression that can disrupt early mother-infant interaction. A pertinent question is at what stage of pregnancy should pregnant women be advised to take iodine-containing supplements.
The narrative review aims to evaluate the recommended level of iodine supply of childbearing age, pregnant and lactating women in relation to foetal brain development and pursues to demonstrate the nutraceutical properties of seaweed as a complimentary supplement for maintaining iodine sufficiency. To achieve this, PICO was used for synthesising foreground research questions, and this was followed up by an electronic search of published data in Embase. As part of the search strategy the exclusion and inclusion criteria for eligible articles took place in Embase. To increase the variation in resources PubMed, Google Scholar, Annual Reviews and Semanticscholar were utilised.
Results indicate that the dietary iodine recommendations for pregnant and lactating women are ambiguous, as they fluctuate between 150-300 μg/d and interestingly, the reference urinary iodine concentration (UIC) value of 150 µg/L is not based on direct experimental evidence; this amount is simply the best estimate for ensuring optimal iodine intake. Further observations revealed that children exposed to severe ID are liable to a 12.45 IQ points loss using the Binet or Raven Scales compared to those in iodine sufficient areas (UIC >100 µg/g UI/Cr), were the use of iodine supplementation prior to and during pregnancy could result in an 8.7 IQ point recovery. Relatedly, seaweed supplementation markedly increased urinary iodine excretion from ~266µg/d (SD:155.8) in the control group to ~567µg/d (SD:177.8, p<0.01) post consumption. Importantly these results confirm the bioavailability of iodine in seaweed. Notably, cytoarchitectural development is not exclusive to in utero and exposure to postpartum ID is associated with behavioural disorders (ADHD), learning difficulties and subtle decrements in working memory and auditory processing speed.
Overall, a glut of complexities governing ID, emerging themes (dietary trends, metabolic syndrome, psycho-nutrition) and brief encounters (seaweed toxicity, processing and cooking methods) are discussed. In closing, a possible long-term indicator of iodine status is evaluated alongside the novel use of iodised food biofortification to tackle emerging micronutrient deficiencies.
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