This study of 65,981 people examines whether vegetarian diets including vegan, lacto-ovo, pesco or semi-vegetarian are associated with prevalence and incidence of hypothyroidism compared to omnivore diets. This is part of the longitudinal Adventist Health Study-2 utilizing self-reported information, with baseline data collected in 2002 and follow-up data in 2008.
Tonstad S, Nathan E, Oda K, Fraser G. Vegan Diets and Hypothyroidism. Nutrients. 2013; 5(11):4642-4652.
Results: Subjects with hypothyroidism tended to be older, female, caucasion and more likely to use salt. There was a higher prevalence of hypothyroidism in people with a higher BMI, lower income and lower amount of education. A lacto-ovo vegetarian diet was associated with increased risk. A vegan versus omnivorous diet tended to be protective, though not statistically significant.
Conclusions: “With the exception of the lacto-ovo vegetarian diet findings in the prevalence study, vegetarian diets were not associated with increased risk of hypothyroidism. Vegan diets which may be expected to lack iodine due to complete exclusion of animal products tended to be protective.”
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