Iodine, a mineral present in certain foods, is necessary to produce thyroid hormones in the human body. These hormones play a crucial role in regulating the body’s metabolism, as well as supporting brain and bone development during pregnancy and infancy. Ensuring an adequate intake of iodine is particularly important for infants and pregnant women. Iodine deficiency might result in hypothyroidism, goitre, and impaired child development.
The iodine content of foods can vary due to the amount found in the soil, water, and animal feed. Thus, plant foods may or may not have iodine depending on where they are grown and other factors. Seafood and dairy products are good sources of iodine. Consuming iodised salt is an effective and widely recommended way of getting all the iodine the human body needs. However, salt (also when iodised) can raise blood pressure and have other adverse health impacts, so it is important to not consume more than 5 grams of salt per day (also when iodised). Bread and other manufactured products and organic ones might not contain iodised salt, so it is always better to check the label and choose products with little but iodised salt.
Seaweeds (e.g. kombu, kelp, wakame, nori) are an excellent plant-based dietary source of iodine. Seaweed can be added to salads or consumed as nori sheets in sushi rolls. However, some seaweed products have excessive amounts that exceed the recommended daily iodine intake. Therefore it is a good idea to consume only a little of it. Some foods (e.g. cassava, soy, cabbage, millet) have naturally-occurring compounds called goitrogens, which, if consumed excessively, can potentially interfere with iodine uptake by the thyroid gland. However, this is typically not a concern as long as adequate iodine is consumed and a variety of foods are eaten.
Choosing iodised salt or taking iodine supplements is particularly important in pregnant and breastfeeding women as these groups are more likely to be at risk of iodine deficiency. Iodised salt and iodine supplements might interfere with some commonly prescribed medications. Check with your healthcare provider before taking supplements.
Sources
- ‘Iodine – Health Professional Fact Sheet’. Accessed 26 May 2023. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/#en49.
Eveleigh, Elizabeth R., Lisa J. Coneyworth, Amanda Avery, and Simon J. M. Welham. ‘Vegans, Vegetarians, and Omnivores: How Does Dietary Choice Influence Iodine Intake? A Systematic Review’. Nutrients 12, no. 6 (June 2020): 1606. https://doi.org/10.3390/nu12061606. - Krajcovicová-Kudlácková, M., K. Bucková, I. Klimes, and E. Seboková. ‘Iodine Deficiency in Vegetarians and Vegans’. Annals of Nutrition & Metabolism 47, no. 5 (2003): 183–85. https://doi.org/10.1159/000070483.
- He, Feng J, Yuan Ma, Xiangxian Feng, Wanqi Zhang, Laixiang Lin, Xiaohui Guo, Jing Zhang, Wenyi Niu, Yangfeng Wu, and Graham A MacGregor. ‘Effect of Salt Reduction on Iodine Status Assessed by 24 Hour Urinary Iodine Excretion in Children and Their Families in Northern China: A Substudy of a Cluster Randomised Controlled Trial’. BMJ Open 6, no. 9 (8 September 2016): e011168. https://doi.org/10.1136/bmjopen-2016-011168.
