From the Guidelines
Iodized salt is not harmful to health and is actually beneficial for most people, as it helps prevent iodine deficiency disorders, including goiter and hypothyroidism, as supported by the recent espen micronutrient guideline published in Clinical Nutrition in 2022 1. The benefits of iodized salt are well-documented, and its introduction has significantly reduced the incidence of iodine deficiency disorders worldwide. According to the espen micronutrient guideline, iodine deficiency can have severe consequences, including impaired brain development, neurocognitive function, and reduced offspring IQ, especially when it occurs during pregnancy and breastfeeding 1. Some of the key points to consider when evaluating the benefits of iodized salt include:
- Iodine deficiency disorders represent a global health threat, and universal salt iodization is the preferred strategy for prevention 1
- Iodized salt provides a simple way to ensure adequate iodine intake, especially for individuals who may not get enough from their diet alone
- The typical iodization level of 45-76 micrograms of iodine per gram of salt is sufficient to meet the daily needs of most adults, which is about 150 micrograms of iodine per day
- Excessive salt consumption, including iodized salt, can contribute to high blood pressure and cardiovascular issues, so moderation is key, with the World Health Organization recommending a limit of less than 5 grams of total salt intake per day. Overall, the benefits of iodized salt in preventing iodine deficiency disorders far outweigh any potential risks, making it a recommended part of a balanced diet for most people, as supported by the recent evidence from the espen micronutrient guideline 1.
From the Research
Iodized Salt and Health
- Iodized salt is widely used and can be excessively iodized, with potential health impacts 2
- Excessive intake of iodine through iodized salt has been linked to various health problems, including iodine deficiency disorders, hypothyroidism, hyperthyroidism, thyroiditis, thyroid papillary cancer, and thyrotoxicosis 2
Risk of Thyroid Nodules and Cancer
- Daily intake of more than 5g of iodized salt has been found to be an independent risk factor for the occurrence of thyroid nodules and thyroid cancer 3
- A study in China found that the prevalence of thyroid nodules was 40.25% and the prevalence of thyroid cancer was 0.76% among subjects who consumed more than 5g of iodized salt per day 3
- However, increased physical activity and education level have been found to reduce the risk of thyroid nodules and thyroid cancer caused by iodized salt intake 3
Effects of Long-Term Iodized Salt Consumption
- A study in Bangladesh found that long-term consumption of iodized salt increased T3 and T4 levels and decreased TSH levels, but the changes were not statistically significant 4
- The study suggested that mandatory mass iodination of table salt consumption in a hyper-endemic iodine deficient area is safe and does not cause any side effects 4
Excess Iodine Intake and Thyroid Diseases
- A systematic review and meta-analysis found that excess iodine intake was associated with an increased risk of hypothyroidism and hyperthyroidism 5
- The review suggested that monitoring of both iodine concentration in salt and the iodine concentration in local drinking water is essential to preventing thyroid diseases 5
- Another study found that chronic excess iodine intake from iodized salt and/or groundwater iodine had little impact on thyroid function in nonpregnant and pregnant women, infants, and children, but recommended careful evaluation of contributions from both sources before reviewing iodization policy 6