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.