Association Between Dietary Onion Intake and Subclinical Hypothyroidism in Adults: A Population-Based Study From an Lodine-Replete Area

Abstract

Background & AimsThe protective effect of onion against thyroid hypofunction has been reported in animal studies. However, in humans, the association between onion consumption and subclinical hypothyroidism are unclear. The study sought to explore the association between habitual onion intake and subclinical hypothyroidism among adult population from an iodine-replete area.ObjectiveWe aimed to investigate the relationship between dietary onion intake and subclinical hypothyroidism in Chinese populationMethodsA cross-sectional study (6,515 men and 5,290 women) was performed in Tianjin, China. Frequency of onion consumption was assessed using a valid self-administered food frequency questionnaire. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were determined by chemiluminescence immunoassay. Subclinical hypothyroidism was diagnosed with TSH >4.78 IU/mL. Multiple logistic regression was used to evaluate the association of onion intake with subclinical hypothyroidism.ResultsThe prevalence of subclinical hypothyroidism was 2.56% in men and 7.18% in women, respectively. In women, the fully adjusted odds ratios [95% confidence interval (CI)] of having subclinical hypothyroidism across increasing frequency of onion intake were 1.00 (reference) for <1 time/week, 0.99 (0.74-1.34) for 1-3 times/week, 0.73 (0.53-1.01) for 4-6 times/week, and 0.66 (0.46-0.95) for ≥7times/week (P for trend <0.01). However, we observed no significant association between onion intake and subclinical hypothyroidism in men. Stratified analyses suggested a potential effect modification by age; the odds ratios (95% CI) across extreme quartiles was 0.43 (0.20, 0.87) in <40 women and 1.05 (0.49, 2.28) in >60 women.ConclusionsFrequent consumption of onion is inversely associated with subclinical hypothyroidism in adult women from an iodine-replete area. Further studies are needed to explore the casual relationship.

The longitudinal association between onion consumption and risk of depressive symptoms: results from the TCLSIH Cohort study and the UK Biobank

“…Although quercetin conjugates in onions are remarkably resistant to degradation during normal processing operations (e.g., refrigerated storage, oven roasting, moderate microwave, and frying, except boiling), 52,53 culinary treatments, especially heating process, can influence the activity and contents of other nutrients (e.g., folic acid) 54 and may further affect the observed associations. In Tianjin, people often eat raw, cooked, or a mixture of raw and cooked onions, 55 which is similar in UK. [56][57][58] However, because data on onion cooking methods were not available in the present study, it is not possible to determine consumption…”