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Evidence summaries

Iodised Salt for Preventing Iodine Deficiency Disorders

Iodised salt appears to be an effective means of improving iodine status, but no conclusions can be made about improvements in patient-oriented outcomes, such as physical and mental development in children and mortality. Level of evidence: "B"

A Cochrane review [Abstract] 1 included 6 prospective controlled trials. Four of these were described as randomised controlled trials, one was a prospective controlled trial that did not specify allocation to comparison groups, and one was a repeated cross-sectional study comparing different interventions. Comparison interventions included non-iodised salt, iodised water, iodised oil, and salt iodisation with potassium iodide versus potassium iodate. Numbers of participants in the trials ranged from 35 to 334; over 20 000 people were included in the cross-sectional study. Three studies were in children only, two investigated both groups of children and adults and one investigated pregnant women. There was a tendency towards goitre reduction with iodised salt, although this was not significant in all studies. There was also an improved iodine status in most studies (except in small children in one of the studies), although urinary iodine excretion did not always reach the levels recommended by the WHO. None of the studies observed any adverse effects of iodised salt.

Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and lack of blinding).

References

  • Wu T, Liu GJ, Li P, Clar C. Iodised salt for preventing iodine deficiency disorders. Cochrane Database Syst Rev 2002;(3):CD003204. [PubMed]

Primary/Secondary Keywords