Iodine & thyroid supplements
Sources
Every numbered claim on the overview and article pages is listed here with the exact passage it rests on. 45 passages were checked word-for-word against the saved copies listed below.
Current evidence
- 1
The body needs iodine to make thyroid hormones, which control metabolism and are needed for bone and brain development in pregnancy and infancy.
“The body needs iodine to make thyroid hormones. These hormones control the body's metabolism and many other important functions.”
“The body also needs thyroid hormones for proper bone and brain development during pregnancy and infancy.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 2
Seafood, dairy products and eggs are good sources of iodine.
“Fish (such as cod and tuna), seaweed, shrimp, and other seafood, which are generally rich in iodine”
“Dairy products (such as milk, yogurt, and cheese) and eggs, which are also good sources of iodine”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 3
Iodized salt is the main food source of iodine; a quarter teaspoon contains 78 micrograms.
“Iodized salt is table salt with iodine added. It is the main food source of iodine.”
“There are 78 micrograms of iodine in 1/4 teaspoon of iodized salt.”
MedlinePlus (U.S. National Library of Medicine) — Iodine in dietPassage verified word-for-word in saved copy
- 4
Processed foods almost never use iodized salt, and sea, kosher and Himalayan salts are not usually iodized.
“Processed foods, such as canned soups, almost never contain iodized salt. In addition, specialty salts, such as sea salt, kosher salt, Himalayan salt, and fleur de sel, are not usually iodized.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 5
Pregnant women need about 50% more iodine than other women.
“Women who are pregnant need about 50% more iodine than other women to provide enough iodine for their baby.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 6
People on a vegan diet, or who eat little dairy, seafood or eggs, may not get enough iodine.
“People who follow a vegan diet or who eat few or no dairy products, seafood, and eggs.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 7
Severe iodine deficiency in pregnancy can permanently harm the baby's growth and development.
“In pregnant women, severe iodine deficiency can permanently harm the fetus by causing stunted growth , intellectual disability, and delayed”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 8
Iodine deficiency is the most common cause of goiter, an enlarged thyroid.
“Iodine deficiency is the most common cause of a goiter.”
MedlinePlus (U.S. National Library of Medicine) — Simple goiterPassage verified word-for-word in saved copy
- 9
Too much iodine can also cause goiter, and high intakes can cause thyroid inflammation and thyroid cancer.
“Getting high levels of iodine can cause some of the same symptoms as iodine deficiency, including goiter (an enlarged thyroid gland). High iodine intakes can also cause thyroid gland inflammation and thyroid cancer.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 10
High-dose iodine with antithyroid medicines such as methimazole can make the body produce too little thyroid hormone.
“Iodine supplements might interact with antithyroid medications such as methimazole (Tapazole), used to treat hyperthyroidism . Taking high doses of iodine with antithyroid medications could cause your body to produce too little thyroid hormone.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 11
Many multivitamins contain iodine, and kelp supplements contain it too.
“Dietary supplements of iodine-containing kelp (a seaweed) are also available.”
“Many multivitamin/mineral supplements contain iodine.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 12
Iodine deficiency is uncommon in the United States.
“Iodine deficiency is uncommon in the United States and Canada.”
NIH Office of Dietary Supplements — Iodine — Fact Sheet for ConsumersPassage verified word-for-word in saved copy
- 13
Nearly 5 in 100 Americans 12 and older have an underactive thyroid, more often women.
“Nearly 5 out of 100 Americans ages 12 years and older have hypothyroidism”
“Women are much more likely than men to develop hypothyroidism.”
NIDDK (U.S. National Institutes of Health) — Hypothyroidism (Underactive Thyroid)Passage verified word-for-word in saved copy
- 14
About 1 in 100 Americans 12 and older have an overactive thyroid.
“About 1 out of 100 Americans ages 12 years and older have hyperthyroidism.”
NIDDK (U.S. National Institutes of Health) — Hyperthyroidism (Overactive Thyroid)Passage verified word-for-word in saved copy
- 15
An underactive thyroid develops slowly; symptoms may go unnoticed for months or years.
“Because hypothyroidism develops slowly, you may not notice symptoms of the disease for months or even years.”
NIDDK (U.S. National Institutes of Health) — Hypothyroidism (Underactive Thyroid)Passage verified word-for-word in saved copy
- 16
Untreated overactive thyroid can cause an irregular heartbeat leading to clots, stroke and heart failure.
“an irregular heartbeat that can lead to blood clots, stroke , heart failure , and other heart-related problems”
NIDDK (U.S. National Institutes of Health) — Hyperthyroidism (Overactive Thyroid)Passage verified word-for-word in saved copy
- 17
Potassium iodide only blocks radioactive iodine from the thyroid in a radiation emergency; it is not a general protection.
“Potassium iodide (KI) works only to prevent the uptake of radioactive iodine into the thyroid gland. It is not a general radioprotective agent.”
U.S. Food and Drug Administration — Frequently Asked Questions on Potassium Iodide (KI)Passage verified word-for-word in saved copy
- 18
Very high iodine intake can reduce thyroid function.
“Iodine poisoning is rare in the US. Very high intake of iodine can reduce the function of the thyroid gland.”
MedlinePlus (U.S. National Library of Medicine) — Iodine in dietPassage verified word-for-word in saved copy
- 19
The FDA does not approve supplements, including kelp and iodine products, before they are sold.
“The FDA does NOT have the authority to approve dietary supplements for safety and effectiveness, or to approve their labeling, before the supplements are sold to the public.”
U.S. Food and Drug Administration — FDA 101: Dietary SupplementsPassage verified word-for-word in saved copy
- 20
A racing or irregular heartbeat, chest pain or fainting — call 911.
“Go to an emergency room or call 911 or the local emergency number if you have:”
“Change in consciousness”
“Dizziness”
“Rapid, irregular heartbeat”
MedlinePlus (U.S. National Library of Medicine) — HyperthyroidismPassage verified word-for-word in saved copy
- 21
A racing or irregular heartbeat, chest pain or fainting — call 911.
“Call 911 or the local emergency number if:”
“You have sudden crushing, squeezing, tightening, or pressure in your chest.”
MedlinePlus (U.S. National Library of Medicine) — Chest painPassage verified word-for-word in saved copy
- 22
A neck swelling that makes it hard to breathe or swallow — contact your provider. If breathing suddenly becomes hard, call 911.
“Breathing difficulties (with very large goiters), especially when lying flat on the back or when reaching up with your arms”
“Swallowing difficulties, especially with solid food”
“Contact your provider if you experience any swelling in the front of your neck or any other symptoms of a goiter.”
MedlinePlus (U.S. National Library of Medicine) — Simple goiterPassage verified word-for-word in saved copy
- 23
A neck swelling that makes it hard to breathe or swallow — contact your provider. If breathing suddenly becomes hard, call 911.
“Go to the emergency room or call the local emergency number (such as 911) if:”
“Breathing difficulty comes on suddenly or seriously interferes with your breathing and even talking”
MedlinePlus (U.S. National Library of Medicine) — Breathing difficultyPassage verified word-for-word in saved copy
- 24
Severe tiredness, confusion or feeling very cold with a known underactive thyroid — seek care promptly.
“If you are being treated for hypothyroidism, contact your provider if:”
“Your symptoms get worse or do not improve with treatment”
“Myxedema crisis is a medical emergency that must be treated in the hospital.”
MedlinePlus (U.S. National Library of Medicine) — HypothyroidismPassage verified word-for-word in saved copy
- 25
New palpitations, weight loss or shakiness after starting iodine or kelp — stop and see a provider.
“eat large amounts of food containing iodine , such as kelp”
“weight loss despite an increased appetite”
“rapid or irregular heartbeat”
“shaky hands, muscle weakness”
NIDDK (U.S. National Institutes of Health) — Hyperthyroidism (Overactive Thyroid)Passage verified word-for-word in saved copy
- 26
New palpitations, weight loss or shakiness after starting iodine or kelp — stop and see a provider.
“Contact your provider if you have symptoms of hyperthyroidism.”
MedlinePlus (U.S. National Library of Medicine) — HyperthyroidismPassage verified word-for-word in saved copy
- 27
New palpitations, weight loss or shakiness after starting iodine or kelp — stop and see a provider.
“If you have side effects, stop taking the supplement and contact your health care provider.”
NCCIH (U.S. National Institutes of Health) — Using Dietary Supplements WiselyPassage verified word-for-word in saved copy
- 28
Pregnant and taking a thyroid medicine — contact your doctor right away about the dose.
“Many women taking thyroid hormone medicine need a higher dose during pregnancy, so contact your doctor right away if you find out you’re pregnant.”
NIDDK (U.S. National Institutes of Health) — Hypothyroidism (Underactive Thyroid)Passage verified word-for-word in saved copy
Source documents
- NIH Office of Dietary Supplements — Iodine — Fact Sheet for Consumers
Saved 2026-10-19 · download · SHA-256f2edbe130c6c3410… - MedlinePlus (U.S. National Library of Medicine) — Iodine in diet
Saved 2026-10-19 · download · SHA-256a3e75127fd50935e… - MedlinePlus (U.S. National Library of Medicine) — Simple goiter
Saved 2026-10-19 · download · SHA-256030abb6452bd4672… - NIDDK (U.S. National Institutes of Health) — Hypothyroidism (Underactive Thyroid)
Saved 2026-10-19 · download · SHA-256049cc3554139ebba… - NIDDK (U.S. National Institutes of Health) — Hyperthyroidism (Overactive Thyroid)
Saved 2026-10-19 · download · SHA-25634ad8b6d8dc45163… - U.S. Food and Drug Administration — Frequently Asked Questions on Potassium Iodide (KI)
Saved 2026-10-19 · download · SHA-256f2db33ace0ed10e0… - U.S. Food and Drug Administration — FDA 101: Dietary Supplements
Saved 2026-10-19 · download · SHA-256a339a330e6d7dbb5… - MedlinePlus (U.S. National Library of Medicine) — Hyperthyroidism
Saved 2026-10-22 · download · SHA-2565edec21d413e4573… - MedlinePlus (U.S. National Library of Medicine) — Chest pain
Saved 2026-10-22 · download · SHA-256368b80496c551edb… - MedlinePlus (U.S. National Library of Medicine) — Breathing difficulty
Saved 2026-10-22 · download · SHA-256713f9d7c4a8372a1… - MedlinePlus (U.S. National Library of Medicine) — Hypothyroidism
Saved 2026-10-22 · download · SHA-25636ef4b40abaac803… - NCCIH (U.S. National Institutes of Health) — Using Dietary Supplements Wisely
Saved 2026-10-22 · download · SHA-2564b6ca4152abde9bd…
Historical perspective: Dr. Majid Ali archive
Historical perspective drawn from the authorized writings of Dr. Majid Ali, preserved in the Clarkson archive. Shown for context; it is not current medical guidance.
- Do Not Take Iodine without Laboratory Test for More Than a Few Weeks, Please. 2015-10-16
Source of the quoted line: his warning against unmonitored iodine. His claims that iodine heals many unrelated disorders are held.
Claims we deliberately did not carry
- His claim that iodine helps heal inflammatory, infectious, immune, cardiovascular, neurological and hormonal disorders.Not supported by the sources used here; high iodine intakes can harm the thyroid.9 Not carried.
- His view that many thyroid patients cannot be optimally managed without iodine supplements, which he prescribed after a 24-hour urine iodine test.
Safety wording awaiting sign-off
The 'When to get help now' list is ProperHealth safety wording. Each line cites the official guidance it follows, and those passages are listed above with the other claims. The wording still needs pharmacist sign-off before public use.