Lifestyle factors related to iodine intakes in French adults.

OBJECTIVE: 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.

DESIGN: 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.

SUBJECTS: 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.

RESULTS: Iodine intakes ranged from 30.0 to 446.3 microg/d. The median iodine intake was 150.7 microg/d for males and 131.4 microg/d for females. High-level (97.5th percentile) intakes were 273.4 microg/d for males and 245.0 microg/d for females. Overall, 8.5 % of males and 20.3 % of females had intakes <100 microg/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 microg/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.

CONCLUSIONS: 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.