0
0
May 12, 2025 – A large-scale UK study has found that vegetarians may have a modestly increased risk of developing hypothyroidism compared to high meat-eaters, especially when their iodine intake is low. The findings, published in the journal BMC Medicine, highlight the importance of monitoring thyroid health among those following plant-based diets.
Study Overview
Researchers analyzed data from over 466,000 participants in the UK Biobank, categorizing them into six dietary groups: high meat-eaters, low meat-eaters, poultry-eaters, pescatarians, vegetarians, and vegans. Over a 12-year follow-up, the study identified more than 10,800 new cases of hypothyroidism, a condition where the thyroid gland does not produce enough hormones.
Key Findings
-
Vegetarians: After adjusting for body mass index (BMI), vegetarians showed a slightly higher risk of developing hypothyroidism compared to high meat-eaters. However, the effect was modest and only apparent after statistical adjustment for BMI.
-
Vegans: No statistically significant increase in hypothyroidism risk was observed among vegans, though the sample size for this group was small.
-
Pescatarians: While no increased risk was found for new cases, pescatarians did show a slightly higher prevalence of hypothyroidism at the start of the study after BMI adjustment.
-
Iodine Intake: Analysis revealed that 44% of vegetarians and 92% of vegans failed to meet the recommended daily intake of iodine (150 µg), a nutrient essential for thyroid hormone production.
The Role of BMI and Iodine
The study noted that BMI played a significant role in the observed associations. Since BMI can be influenced by both diet and hypothyroidism, adjusting for it may introduce statistical bias. Additionally, researchers pointed out that many plant-based diets lack key nutrients like iodine, which is crucial for thyroid health. Certain vegetables and soy products can also reduce iodine absorption, further increasing the risk.
Implications and Recommendations
While plant-based diets are linked to numerous health benefits, including lower risks of heart disease and cancer, the authors suggest that vegetarians should pay attention to their iodine intake. Iodine supplementation may be advisable, especially for those not consuming iodized salt or seaweed.
The researchers emphasize that their findings do not prove a direct cause-and-effect relationship. Rather, they highlight the need for further studies that track iodine levels and thyroid function over time.
Disclaimer:
This article summarizes findings from an observational study and is intended for informational purposes only. The study does not establish causality, and the observed associations may be influenced by other factors such as BMI or unmeasured lifestyle variables. Individuals considering dietary changes or concerned about thyroid health should consult a healthcare professional for personalized advice.
Citations:
