Coffee is one of the most widely consumed beverages across the world. While many beneficial effects of coffee have been studied, its impact on thyroid function remains relatively unknown.

      A recent observational study published in the ‘Nutrition Journal’ had investigated the association between caffeine intake and thyroid function. Data regarding the demographic background, medical conditions, dietary intake, and thyroid function were collected from the National Health and Nutrition Examination Survey (NHANES), a comprehensive health survey conducted in the United States. Subgroups were classified using two-step cluster analysis, with sex, age, body mass index (BMI), hyperglycemia, hypertension, and cardio-cerebral vascular disease (CVD) being used for clustering. Multivariable linear regression was used to evaluate the association between caffeine consumption and thyroid function.

      The study results showed that participants who drank 2-4 cups of coffee per day had significantly lower TSH (Thyroid-Stimulating Hormone) concentrations compared to non-coffee drinkers. Interestingly, in the most metabolically unhealthy group, caffeine intake showed an inverted V-shaped relationship with TSH levels, indicating a complex interplay between caffeine and thyroid function. Caffeine was positively related to TSH levels at minimal doses, while at moderate doses, the association between the two was negative. Also, the level of caffeine intake differed among the subgroups. In addition, coffee consumption was not associated with the risk of hyperthyroidism and hypothyroidism.