The Association Between the Consumption of Iodine-Rich Foods and the Risk of Thyroid Cancer

by | May 7, 2024 | 2024, Cancer, Recent Articles, Thyroid

Written by Harold Oster, MD. Results suggest that increased consumption of seaweed and dairy products, both rich in iodine, is associated with a decreased risk of thyroid cancer.

thyroidThe incidence of thyroid cancer has increased in the United States and the developed world. The increase in thyroid cancer has been linked to environmental, dietary, and genetic factors, though overdiagnosis may also be occurring1. Iodine, a trace element, is essential for producing thyroid hormone. Inadequate intake of iodine leads to hypothyroidism2, while excessive consumption may increase the risk of thyroid cancer3.

Yu-Jin Kwon et al. studied the association between the consumption of three iodine-rich food groups and the prevalence of thyroid cancer in adults over forty. The authors analyzed data collected between 2001 and 2013 for the Korean Genome and Epidemiology Study (KoGES), a population-based study evaluating risk factors for various non-communicable diseases4. The intake of eggs, dairy products, and seaweed, three common sources of iodine in South Korea, was assessed by dietary questionnaires and categorized as less than one serving per week, 1-2 per week, 3-4 per week, and five or more per week. Participants were evaluated for confounding variables, including demographics, medical history, body mass index, and lifestyle factors. The diagnosis of thyroid cancer was determined by questionnaire and confirmed by follow-up interview.

The authors noted the following:

  • Based on inclusion criteria, data from 169,057 participants was analyzed.
  • Nine hundred thirty participants were diagnosed with thyroid cancer, of whom 91.9% were women.
  • After adjusting for covariables, participants who consumed seaweed 1-2 times per week, 3-4 times per week, and five or more times per week had a decreased prevalence of thyroid cancer compared to those who ate seaweed less than once per week. (Odds ratio of 0.68, 0.57, and 0.42, respectively)
  • Compared to participants who consumed dairy products 3-4 times per week, those who consumed them less than once per week had a higher prevalence of thyroid cancer. (Odds ratio 1.32)
  • In subgroup analysis, higher seaweed consumption was associated with a lower prevalence of thyroid cancer in those 60 years and older and those with a body mass index of 25 and above.
  • Compared to participants who consumed dairy products 3-4 times per week, consumption of dairy products less than once per week was associated with an increased prevalence of thyroid cancer in participants younger than 60, those with a body mass index lower than 25, and women.
  • No association was found between egg consumption and thyroid cancer.

Results suggest that increased consumption of seaweed and dairy products, both rich in iodine, is associated with a decreased prevalence of thyroid cancer. The study’s limitations include its observational design, the lack of biochemical testing to confirm the amount of iodine intake, and the possibility of residual confounding.

Source: Kwon, Yu-Jin, Hye-Sun Lee, Sang-Wook Kang, and Ji-Won Lee. “Association between Consumption of Iodine-Rich Foods and Thyroid Cancer Prevalence: Findings from a Large Population-Based Study.” Nutrients 16, no. 7 (2024): 1041.

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/
4.0/).

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Posted May 7, 2024.

Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.

References:

  1. Olson E, Wintheiser G, Wolfe KM, Droessler J, Silberstein PT. Epidemiology of Thyroid Cancer: A Review of the National Cancer Database, 2000-2013. Cureus. Feb 24 2019;11(2):e4127. doi:10.7759/cureus.4127
  2. Hatch-McChesney A, Lieberman HR. Iodine and Iodine Deficiency: A Comprehensive Review of a Re-Emerging Issue. Nutrients. Aug 24 2022;14(17)doi:10.3390/nu14173474
  3. Kim K, Cho SW, Park YJ, Lee KE, Lee DW, Park SK. Association between Iodine Intake, Thyroid Function, and Papillary Thyroid Cancer: A Case-Control Study. Endocrinol Metab (Seoul). Aug 2021;36(4):790-799. doi:10.3803/EnM.2021.1034
  4. Kim Y, Han BG. Cohort Profile: The Korean Genome and Epidemiology Study (KoGES) Consortium. Int J Epidemiol. Apr 1 2017;46(2):e20. doi:10.1093/ije/dyv316