Who Should Not Use Iodised Salt: A Guide to Dietary Restrictions

December 24, 2025 •

4 min read

According to the NIH, consuming high levels of iodine can cause some of the same symptoms as an iodine deficiency, including goiter. This paradox underscores why certain people with pre-existing conditions must be mindful of their intake. So, who should not use iodised salt? The answer primarily concerns people with thyroid disorders and those undergoing specific medical procedures.

Quick Summary

Certain individuals with underlying thyroid conditions like hyperthyroidism or autoimmune disorders need to avoid iodised salt. Restricting iodine intake is also necessary for patients preparing for radioactive iodine treatment, as excess iodine can interfere with therapy effectiveness. Such dietary changes should always be guided by a healthcare professional.

Key Points

Thyroid Disorders: Individuals with hyperthyroidism, including Graves' disease and toxic nodules, should use non-iodised salt to avoid exacerbating their condition.
Autoimmune Sensitivity: People with Hashimoto's thyroiditis may be sensitive to iodine, and excessive intake can worsen the autoimmune attack on the thyroid.
Radioactive Iodine Therapy: A strict, short-term low-iodine diet, excluding iodised salt, is required before radioactive iodine treatment for thyroid cancer to maximize its effectiveness.
Medical Supervision: Any decision to avoid iodised salt should be made in consultation with a doctor to ensure adequate iodine intake from other sources and avoid deficiency.
Hidden Iodine: Beyond iodised salt, other sources of high iodine include seaweed, dairy products, and certain medications, all of which must be considered during restriction.
Jod-Basedow Effect: The sudden introduction of high iodine, even after deficiency, can trigger hyperthyroidism in susceptible individuals.

The Importance of Iodine and the Dangers of Excess

Iodine is a vital trace mineral essential for the production of thyroid hormones, which regulate metabolism, growth, and development. While many health programs promote iodisation to prevent deficiency, excessive intake can be detrimental, especially for vulnerable populations. A balanced approach is key, and for certain individuals, this means actively avoiding iodised salt and other high-iodine sources.

Medical Conditions That Require Iodine Restriction

For those with existing thyroid abnormalities, the body's normal regulatory mechanisms for iodine can be impaired. This leads to conditions that require a low-iodine diet, which necessitates avoiding iodised salt.

Hyperthyroidism: An overactive thyroid produces too much hormone, and for some, excess iodine can exacerbate this problem. Those with Graves' disease, the most common cause of hyperthyroidism, may be particularly sensitive to increased iodine intake. Nodules on the thyroid can also cause excessive hormone production, which is worsened by a high-iodine diet.

Hashimoto's Thyroiditis: This autoimmune disease causes the immune system to attack the thyroid, leading to hypothyroidism over time. Some individuals with Hashimoto's are sensitive to iodine, and high intake can trigger or aggravate the autoimmune process. Some research also suggests a link between excessive iodine intake and the incidence of Hashimoto's thyroiditis.

Iodine-Induced Hyperthyroidism (Jod-Basedow Effect): This condition occurs when individuals who were previously iodine-deficient or have underlying thyroid issues are exposed to excessive iodine, which can trigger hyperthyroidism. While the effect is often temporary, it can be dangerous for those with underlying heart disease.

Preparing for Radioactive Iodine (RAI) Treatment: Patients with thyroid cancer who are preparing for RAI therapy must follow a strict low-iodine diet for one to two weeks prior to treatment. The purpose is to "starve" the thyroid cells of iodine so they will readily absorb the radioactive iodine, making the treatment more effective. During this period, all iodised salt must be avoided, and dietary intake is typically limited to less than 50 micrograms of iodine per day.

Practical Considerations for a Low-Iodine Diet

Following a low-iodine diet requires vigilance, as iodine can be found in many unexpected places. For those who must avoid it, understanding key sources is crucial.

Foods to Avoid:

Iodised salt: The most obvious source, and a primary ingredient to eliminate.
Seafood: Fish, shellfish, and seaweed are naturally rich in iodine and should be avoided. This includes food additives like carrageenan.
Dairy products: Milk, cheese, and yogurt contain varying levels of iodine, so they are typically restricted on a low-iodine diet.
Egg yolks: The yolk of an egg is a significant source of iodine.
Processed foods: Many commercially prepared and fast foods use iodised salt and other iodine-containing ingredients.
Supplements and Medications: Many multivitamins, supplements containing kelp, and certain medications (like amiodarone) are high in iodine.

Allowed Foods:

Non-iodised salt: Including some kosher salt (check the label) and many sea salts (check for "iodised" label).
Fruits and Vegetables: Most fresh or frozen fruits and vegetables are low in iodine, though iodine content can vary based on soil.
Meats and Poultry: Moderate portions of fresh beef, chicken, and pork are generally allowed.
Grains: Rice, pasta, and bread made without iodate dough conditioners are acceptable.
Nuts and Legumes: Unsalted nuts and nut butters, as well as beans and peas, are good options.

Iodised vs. Non-Iodised Salt: A Comparison Table


Feature	Iodised Salt	Non-Iodised Salt (e.g., Kosher, plain)
Iodine Content	Contains added iodine (e.g., potassium iodide)	Contains no added iodine
Best For	The general population to prevent iodine deficiency	Individuals on a low-iodine diet for medical reasons
Flavor	Some perceive a slightly metallic aftertaste	Offers a pure, straightforward saltiness
Culinary Use	Everyday cooking, baking (less popular)	Baking, canning, pickling, specific finishes
Sodium Content	Similar to non-iodised salt by weight	Similar to iodised salt by weight
Health Impact	Crucial for preventing iodine deficiency disorders	Preferred for managing conditions affected by iodine excess

Seeking Medical Guidance Is Essential

While this information provides a general guide, it is critical to consult a healthcare professional before making any significant dietary changes related to iodine intake. A doctor can confirm your specific medical needs and provide a personalized plan. Following a low-iodine diet without medical supervision can lead to iodine deficiency, which carries its own set of health risks, such as hypothyroidism and goiter. Therefore, this should always be a targeted, medically advised strategy, not a general practice for healthy individuals.

Conclusion

For most people, iodised salt is a beneficial, easy way to ensure adequate iodine intake and prevent deficiency disorders. However, for certain individuals with specific health conditions—namely hyperthyroidism, Hashimoto's thyroiditis, and those undergoing radioactive iodine treatment—avoiding iodised salt is a necessary and important dietary step. Understanding who should not use iodised salt, the reasons behind this restriction, and how to identify alternative food sources is crucial for effective health management. Always prioritize medical advice to ensure dietary changes are safe and appropriate for your health needs. For more details on the role of iodine in diet, refer to resources from the National Institutes of Health.(https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/)

Frequently Asked Questions

No, for most healthy people, iodised salt is not only safe but also recommended. It is an effective way to prevent iodine deficiency disorders, which can lead to conditions like goiter.

Excessive iodine intake can cause symptoms similar to iodine deficiency, including goiter, fatigue, and changes in thyroid function. In high-risk individuals, it can also cause hyperthyroidism or thyroid inflammation.

The Jod-Basedow effect is a form of iodine-induced hyperthyroidism. It can occur in people with pre-existing thyroid abnormalities when they are suddenly exposed to a high iodine load, leading to an overproduction of thyroid hormones.

Patients typically need to follow a strict low-iodine diet, which includes avoiding iodised salt, for one to two weeks before their scheduled radioactive iodine therapy.

No, not all sea salts are non-iodised. While many naturally contain trace amounts of iodine, some brands may add iodine. You must check the label carefully to ensure it explicitly states it is not iodised or contains no added iodine, especially if you are on a restricted diet.

Avoiding iodised salt primarily affects your iodine intake, not your overall sodium consumption. You can use non-iodised salt, but your overall sodium intake from all sources should still remain within recommended daily limits.

Major sources of iodine beyond salt include seaweed and kelp, dairy products (milk, cheese), egg yolks, and seafood. Certain supplements and medications, like amiodarone, are also high in iodine.