Ultra-processed food consumption and the risk of subclinical thyroid dysfunction: a prospective cohort study.

Background

prospective cohort studies linking ultra-processed foods (UPF) and subclinical thyroid dysfunction (SCTD) are limited, especially in Chinese adults.

Objective

we designed a large-scale cohort study to examine whether UPF consumption is a risk factor for SCTD in adults.

Methods

this prospective cohort study investigated 8732 participants (mean age: 44.7 ± 10.7 years; 53.3% men). UPF consumption was measured at the baseline using a validated food frequency questionnaire and classified according to the NOVA classification system. SCTD was characterized by abnormal serum thyroid-stimulating hormone levels and normal free thyroxine. Cox proportional hazards regression models were used to examine the association of UPF consumption with the risk of various types of SCTD.

Results

during the follow-up period, the incidence rate of subclinical hypothyroidism was 8.3/1000 person-years and that of subclinical hyperthyroidism was 7.0/1000 person-years. After adjusting the potential confounding factors, the multivariable hazard ratios (HRs) (95% confidence intervals) across increasing tertiles of energy-adjusted UPF consumption for subclinical hypothyroidism were 1.00 (reference), 0.82 (0.57, 1.18) and 0.87 (0.60, 1.27) (P for trend = 0.47) and for subclinical hyperthyroidism were 1.00 (reference), 1.09 (0.71, 1.68) and 1.69 (1.12, 2.56) (P for trend = 0.01). Per one standard deviation (58.0 g per 1000 kcal per day) increase in ultra-processed food consumption a 14% increase in risk of subclinical hyperthyroidism was observed (HR = 1.14; 95% CI: 1.00, 1.30; P = 0.04). Further sensitivity analysis showed that the fully adjusted HRs (95% CIs) of subclinical hyperthyroidism across tertiles of the proportion of UPF in weight for subclinical hyperthyroidism were 1.00 (reference), 1.06 (0.69, 1.63) and 1.63 (1.09, 2.46) (P for trend = 0.01).

Conclusions

this population-based prospective cohort study has firstly demonstrated that higher UPF consumption was associated with higher risk of subclinical hyperthyroidism in adults. The UMIN clinical trial registry number is UMIN000027174 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000031137).