Inadequate iodine intake during pregnancy increases the risk of neonatal morbidity and mortality. We aimed to evaluate whether prenatal supplements containing iodine affect urinary iodine concentrations (UIC) of pregnant women in Malawi.

A randomised controlled trial. Pregnant women (n 1391) were assigned to consume 60 mg/d Fe and 400 µg/d folic acid (IFA) or 18 vitamins and minerals including 250 µg/d iodine (MMN) or 20 g/d small-quantity lipid-based nutrient supplements (SQ-LNS) with similar nutrient contents as MMN group, plus macronutrients (LNS) until childbirth. In a sub-study (n 317), we evaluated group geometric mean urinary iodine concentration (UIC) (µg/L) at 36 weeks of gestation controlling for baseline UIC and compared median (baseline) and geometric mean (36 weeks) UIC with WHO cut-offs: UIC < 150, 150–249, 250–499 and ≥500 reflecting insufficient, adequate, above requirements and excessive iodine intakes, respectively.

Mangochi District, Malawi.

Women ≤20 weeks pregnant.

Groups had comparable background characteristics. At baseline, overall median (Q1, Q3) UIC (319 (167, 559)) suggested iodine intakes above requirements. At 36 weeks, the geometric mean (95 % CI) UIC of the IFA (197 (171, 226)), MMN (212 (185, 243)) and LNS (220 (192, 253)) groups did not differ (P = 0·53) and reflected adequate intakes.

In this setting, provision of supplements containing iodine at the recommended dose to pregnant women with relatively high iodine intakes at baseline, presumably from iodised salt, has no impact on the women’s UIC. Regular monitoring of the iodine status of pregnant women in such settings is advisable. Clinicaltrials.gov identifier: NCT01239693.

To assess dietary iodine intakes among adults and to investigate the relationships of dietary, lifestyle, demographic and geographical characteristics with dietary iodine status. Adequacy of iodine intakes was also assessed.

Cross-sectional study. Linear regression analyses and logistic regression modelling were used to determine correlates of iodine intakes. Usual iodine mean intake was calculated by averaging six 24 h dietary records completed over a 2-year period.

Females aged 35–60 years (n 2962) and males aged 45–60 years (n 2117) living in France and who participated in the SU.VI.MAX study.

Iodine intakes ranged from 30·0 to 446·3 μg/d. The median iodine intake was 150·7 μg/d for males and 131·4 μg/d for females. High-level (97·5th percentile) intakes were 273·4 μg/d for males and 245·0 μg/d for females. Overall, 8·5 % of males and 20·3 % of females had intakes <100 μg/d (P < 0·001). Alcohol drinkers and smokers tended to have lower iodine intakes than abstainers or non-smokers. Regular physical activity and both intermediate and high education levels were associated with a lower risk of iodine intake of <150 μg/d. For both males and females there were significant overall regional differences (P < 0·001) in multivariate-adjusted iodine intakes, with higher adjusted iodine intakes in Brittany and Normandy than in the north-eastern region.

Our data show a borderline low iodine intake in this middle-aged French population. However, differences in iodine intakes may contribute to explaining only a small part of the effects of sex and age on thyroid disease incidence.