Vegetarianism may be associated with a small increased risk of hypothyroidism

1. After controlling for BMI, vegetarians were at a higher risk of hypothyroidism compared to those consuming a high-meat diet. 

Evidence Rating Level: 2 (Good)

Several sources in the literature have reported that plant-based diets are associated with reduced risks of chronic health conditions such as type 2 diabetes and cardiovascular disease. However, consumption of exclusively plant-based diets may also leave an individual at risk of deficiency in essential nutrients such as iodine. This prospective cohort study therefore sought to investigate the risk of hypothyroidism across various dietary groups (including high meat-eaters, low meat-eaters, poultry-eaters, fish-eaters, vegetarians and vegans). 466,362 participants (mean age, 56.41; 52.7% female) across the United Kingdom were included. Prior to adjustment for BMI, none of the dietary groups were significantly associated with increased risk of hypothyroidism. Following adjustment for BMI, there was a significant association between a vegetarian diet and risk of hypothyroidism (HR = 1.23, 95% CI 1.07–1.42). After controlling for BMI, logistic regression analyses revealed increased odds among low meat-eaters with an odds ratio (OR) of 1.05 (95% CI 1.03–1.08), as well as for poultry-eaters (OR = 1.15, 95% CI 1.04–1.28) and pescetarians (OR = 1.10, 95% CI 1.01–1.19). Overall, this study found that following adjustment for BMI, vegetarians were at a higher risk of hypothyroidism compared to those consuming diets higher in meat.

Click to read the study in BMC Medicine

Image: PD

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