sea kelp, kelp supplement

Thyroid dysfunction is common, so common, in fact, that Synthroid is the most prescribed drug in the country. That is a synthetic thyroid hormone, levothyroxine. But while many people take Synthroid or another form of levothyroxine, many others would prefer a natural approach. Should they take a kelp supplement?

Is a Kelp Supplement the Answer?

Q. When my internist noted a low-normal thyroid value, he suggested a thyroid supplement. I suspected I had an iodine deficiency from years on a low-salt diet. I proposed a trial of sea kelp and he agreed. Two 100 mg tablets a day brought the thyroid value up to normal and warmed my cold toes. I also noted my foot fungus receded 90 percent.

A. Using iodine to treat an underactive thyroid gland is controversial. Very few Americans get too little iodine. Your years of avoiding iodized salt may have resulted in an inadequate iodine intake for you, though.

Kelp Supplement Could Make Thyroid Problem Worse:

In a case report, a woman who used kelp as an iodine supplement aggravated her thyroid disease.  German researchers noted that this woman developed an overactive thyroid after consuming tea containing kelp (Journal of General Internal Medicine, June 2006). The following details have some doctorspeak, but is worth wading through as a cautionary tale:

We report a case of iodine-induced hyperthyroidism due to the ingestion of a kelp-containing tea. A 39-year-old woman with multinodular goiter presented with typical signs of hyperthyroidism…including tachycardia (100 beats/min), palpitations, tremor, nervousness, insomnia, fatigue, increased sweating, diarrhea, secondary amenorrhoea, and weight loss. Laboratory analysis revealed increased levels of fT3 and fT4 as well as a suppressed TSH concentration, anti-thyroid antibodies remained negative…

Considering the average iodine content of kelp of 1,500 to 2,500 μg/g, our patient was taking an estimated 580 to 990 μg iodine daily, i.e., 3.8 to 6.6 times the recommended daily allowance of 150 μg. For comparison, in the United States the estimated average iodine intake of men and women aged 25 to 30 years is 410 and 260 μg/day, respectively. In the literature, several cases of iodine-induced hyperthyroidism after consumption of seaweed have been described, this occurred mainly while taking kelp tablets…

In our patient, hyperthyroidism did not resolve spontaneously following discontinuation of the kelp-containing tea,…but required antithyroid drug therapy.”

Hyperthyroidism due to Kelp Supplement:

Hyperthyroidism is a serious condition that can be challenging to treat. Here is a more recent case report of hyperthyroidism triggered by kelp. It was published in BMJ Case Reports (Oct., 2014):

“Complementary medications and herbal medicine for weight loss have become very popular. We report a case of thyroid dysfunction following the ingestion of a kelp-containing marketed diet in a 45-year-old woman with no previous thyroid disease. Signs of hyperthyroidism occurred shortly after a kelp-containing diet. Hyperthyroidism lasted 2 months and was followed by an over hypothyroidism…

“After 3 months of levothyroxine substitutive therapy, normal thyroid function was recovered after levothyroxine discontinuation. This clinical history is compatible with a case of iodine-induced thyrotoxicosis followed by prolonged block of the sodium-iodide symporter activity as a consequence of excessive iodine consumption from kelp. Consumers of marketed diets containing kelp of other iodine-rich ingredients should be advised of the risk to develop a thyroid dysfunction also in the absence of underlying thyroid disease.”

Contrast CT Scans Can Also Pose a Hyperthyroid Risk

Many physicians are quick to warn about dietary supplements. The authors of the first article from the Journal of General Internal Medicine concluded:

“Dietary supplements and herbal remedies are used by an increasing number of patients without prior medical consultation. Therefore, patients with known thyroid disease should be advised to avoid all complementary and alternative medications that contain iodine. Before starting any such supplements, patients with underlying thyroid disorder should check with their physician or pharmacist.”

What many physicians (and some radiologists) may not realize is that when they order a CT scan with contrast or cardiac catheterization, they could also trigger hyperthyroidism. That’s because the contrast material often contains iodide. Here is just such a case that was reported on our website along with scientific documentation of the link to hyperthyroidism.

The People’s Pharmacy Bottom Line:

We’re glad you worked with your doctor and got good results, but we don’t generally recommend this approach. For one thing it is hard to control the iodine dose with dietary supplements. Some kelp supplement products may contain more iodine than is safe. Too much iodine can trigger hyperthyroidism and that can be a very dangerous situation.

You can learn more about hyperthyroidism, hypothyroidism, thyroid functioning, diagnostic testing and thyroid treatment in our Guide to Thyroid Hormones. In this 25-page downloadable PDF publication you will learn why some people do not do well on levothyroxine (Synthroid) prescriptions and why some people need both T3 and T4 supplementation. You will also learn why taking your thyroid supplement at night before bed might be more effective than taking it around breakfast time.

This article was updated on September 10, 2015. The original article on kelp was published August 9, 2009 but we felt that it was important to update you on the latest scientific findings with regard to kelp, iodine and contrast material. Please vote on this article and share your own story or comment below.

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  1. Susan

    I think that if anyone is confused about iodine, to look up Dr Brownstein for some great information. He is the best!

  2. Carrol

    Your conclusion that very few Americans get too little iodine does not agree with the expert Dr. David Brownstein who states “very few americans have an adequate level of iodine”.

    • Lori

      I agree with you Carrol, the medical world is happy to keep us sick with their lies. My doctor kept saying my tests were normal, not to worry, yet my basal temp was WAYYYY below what it should have been, as well as having dry skin, always cold, weight climbing for no reason, toe nail fungus for YEARS, energy levels very low. I eat very healthy, only real food, no artificial junk, low in carbs, etc. Went to a homeopath who put me on iodine supplements and my life is turning around. Dr. Brownstein is one of the few doctors who actually care about our health and is honest. If I had continued to listen to my western doctor’s advice, my health would have been ruined.

  3. Acie

    What is ug/g? The amount given on my iodine supplement is 30 mg. How do I compare amounts?

  4. J lyngdoh

    Hello. I’m a 38 female and last year my T3 and T4 are normal, however my TSH was 5.6, hence I took homeopathic and Kelp one capsule daily supplement. After 6 month my TSH comes down to 0.93 on January 2016, so I stop taking all the homeopathic and kelp at once. Maybe this is my mistake. I should continue kelp at least once a week or so. But my sudden stop again after 9 month now I tested again and my TSH is 8.6. Please help. Should I repeat the same treatment?

  5. Klee

    In 6 months, my TSH has gone from 5.6 to 7.04. I have been gaining weight and having depression. My doctor wants me to go on Synthroid, but I am scared that my thyroid will get addicted to it and will stop creating what little hormones it is creating naturally. I don’t want to be on medication for the rest of my life. My diet is pretty good–I eat mostly organic except when I go out to eat. I do not eat pasta and very little wheat. I do not eat junk food or fast food, hardly any sugar at all–except in fruit. I do not overeat or consume too many calories. I am starting to take powdered Kelp supplement every other day at 600 mg of kelp/300 mcg of Iodine. I do not eat iodized salt for many years now, except if it is in food when I eat at restaurants. I only keep sea salt in my house. My current plan of action is to start exercising more and keep taking Kelp every other day and get on a Selenium supplement. I have refused fluoride treatments at the dentist for years, and occasionally buy the Tom’s of Maine toothpaste with fluoride. I drink only spring water from a local spring, so I am not getting fluoride in the water I drink. I think my endocrine system has been compromised this year from the formaldehyde in some new furniture I bought. The day it was delivered, I immediately had watery eyes, runny nose, a cough and dizziness for a few months. Formaldehyde is an endocrine disruptor, as so many things are! Hoping to do a cleanse soon to see if it will help my thyroid get working again!

  6. Dawn
    Belice, In the Caribbean.

    Am on Propycil for some years now , sometimes It hard to find it, where we live in the Caribbean, I will try the Kelp to see how it works am sufferings from Sinus, every morning i wake there’s mucus in my eyes, Sweating a lot and also in my head had to cut my hair low, to help to dry, have curly hair.

  7. Dianne

    I recently discovered dried, roasted seaweed snacks, which are high fiber, low calorie (50/5g. pkg) and (relatively) low salt (50mg). I use them as a substitute for potato chips, and to alleviate acid reflux. I do have a multinodular goiter, but my TSH is within normal range (2.6). I am 72. I cannot find out what the iodine content is. Could these be harmful? I eat about 5 g. a day.

  8. Mary

    Since testing for iodine levels is rare, how can I be sure I do have enough in my body?

    The other halogens: bromine, chlorine and fluoride do restrict how much iodine can be utilized by the body.

  9. Mary

    I keep hearing that most of us are not deficient in iodine. With the increase of mercury in seafood, we probably get less iodine than we did in the past.

    Iodize salt is a placebo. Look at how much salt you would need to consume to get much benefit. I purposely went to gourmet salts w/o added iodine.

    Since most of us are exposed to the halogens fluoride, bromine, and chlorine, and all make it impossible for the thyroid to receive iodine, AND we are not being tested for our levels, HOW can they know that most of us get sufficient iodine?

    Iodine is needed throughout the body, not just the thyroid. Breasts are high on the list.

    • The People's Pharmacy

      Iodized salt is an effective public health measure, but we are being admonished to cut back on salt. The high levels of salt in our food come mainly from processed foods, and that salt is not necessarily iodized.

  10. Lyn

    Thank you for this article. It was very informative. Kelp is one of those very touchy supplements. Now I know I will stay away from it.

  11. Penny

    I was taking Kelp for one year and found that my tsh level went from 5 to 9. Should this happen?

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