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Vitamin A and iodine supplementation in African children with concurrent vitamin A and iodine deficiency: a randomized, placebo‐controlled trial
Author(s) -
Zimmermann Michael,
Jooste Pieter,
Mabapa Ngoako,
Schoeman Serina,
Biebinger Ralf,
Mushaphi Lindelani
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a724-c
Subject(s) - placebo , medicine , iodine deficiency , iodine , endocrinology , thyroid , thyroglobulin , thyroid function , thyroid stimulating hormone , vitamin , goiter , randomized controlled trial , chemistry , pathology , alternative medicine , organic chemistry
Background Vitamin A (VA) deficiency (VAD) and iodine deficiency (ID) often coexist in children in Africa. VAD may affect thyroid function and response to iodine prophylaxis. Study Aim To investigate the effects of supplementation with iodine or VA alone, and in combination, in children with concurrent VAD and ID. Design A 6‐mo, randomized, double‐blind, 2×2 intervention trial was done in 5–14 y‐old South African children (n=404) with VAD and ID. At baseline and after 3 months, children received either: iodine (191 mg oral iodine) + placebo (IS group), VA (200,000 IU) + placebo (VAS group); both iodine and VA (IS+VAS group); or both placebo. At baseline, 3 and 6 months, thyroid volume, thyrotropin (TSH), total thyroxine (TT4), thyroglobulin (Tg), serum retinol (SR) and retinol‐binding protein (RBP) were measured. Results SR and RBP increased significantly in both the VAS and IS+VAS groups. Compared to placebo, there were significant decreases in TSH, Tg and thyroid volume in the IS, VAS and IS+VAS groups; the decreases were greater in the IS and IS+VAS groups than in the VA group. There were no significant changes in TT4 concentrations in any of the groups. Conclusions VA supplements are effective in treating VAD in areas of mild ID, and have an additional benefit: through suppression of the pituitary TSHβ gene, VAS may decrease excess TSH stimulation of the thyroid and thereby reduce risk for goiter and its sequelae.