Adult dietary patterns and their association with iodine nutrition levels and thyroid function: a cross-sectional study.

OBJECTIVE

To understand the dietary patterns of adults and explore their association with iodine nutritional levels and thyroid function in adults.

DESIGN

We randomly collected 5 ml of adult urine samples and measured urinary iodine concentration (UIC) by cerium arsenate-catalysed spectrophotometry. A serum sample of 5 ml was collected for the determination of free triiodothyronine, free thyroxine and thyrotropin, and diet-related information was collected through a FFQ. Dietary patterns were extracted by principal component analysis, and the relationship between dietary patterns and iodine nutrition levels and thyroid function was explored.

SETTINGS: A cross-sectional study involving adults in Xinjiang, China, was conducted.

PARTICIPANTS

A total of 435 adults were enrolled in the study.

RESULTS

The overall median urinary iodine of the 435 respondents was 219·73 μg/l. The dietary patterns were PCA1 (staple food pattern), PCA2 (fruit, vegetable and meat pattern), PCA3 (fish, shrimp and legume pattern) and PCA4 (dairy-based protein pattern). The correlation analyses showed that PCA1 and PCA3 were positively correlated with the UIC. The results of the multivariable analysis showed that PCA1, Q1, Q2 and Q3 were associated with an increased risk of iodine deficiency compared with Q4 ((OR): 260·41 (95 % CI: 20·16, 663·70)), 59·89 (5·64, 335·81), and 2·01 (0·15, 26·16), respectively). In PCA2, Q3 was associated with an increased risk of iodine deficiency compared with Q4 (OR: 0·16 (0·05, 0·53)). In PCA3, Q3 was associated with an increased risk of iodine deficiency compared with Q4 (OR: 0·23 (0·06, 0·90)). In PCA4, Q1 was associated with an increased risk of iodine deficiency compared with Q4 (OR: 31·30 (4·88, 200·64)).

CONCLUSION

This study demonstrated that of the four dietary patterns, the least dependent staple food pattern (Q1) had a higher risk of iodine deficiency compared with the most dependent staple food pattern (Q4). However, the current evidence on the effect of dietary patterns on thyroid function needs to be validated by further longitudinal studies that include long-term follow-up, larger sample sizes and repeated measures.