Health experts often turn to Japan for secrets to a long and healthy life. After all, the Japanese have one of the longest life expectancies on earth, as well as the greatest percentage of people who live past the age of 100.
Conventional wisdom often attributes this longevity to the diet of the Japanese people. To many observers, the fact that the Japanese eat lots of fish and seaweed is why they are so healthy and live so long.
And it may be true that the Japanese diet is at least partially responsible for their health and longevity, but such reasoning can be dangerous, especially when it is based on false and misleading data.
One example of false data is the claim that the Japanese consume more than 13 milligrams of iodine daily in seaweed consumption alone. Some well-known health experts and supplement manufacturers, and retailers have been using this claim.
In fact, some of them have even exaggerated the facts in order to promote the use of iodine supplementation as a means of optimizing one’s health.
Here’s a quote taken from the website of a company that sells an iodine supplement:
In Japan, iodine intake from seaweed is estimated to be as high as 20 mg daily. Seaweed intake has been linked with a lower risk of premature death from any cause. Also, people in Japan have a lower cancer rate and a low rate of fibrocystic breast disease. Though this research can’t prove cause and effect, it’s intriguing.
The fact is, the Japanese don’t consume anything near 20 mg of iodine daily. If they did, they would probably be very ill. The estimate of 20 mg traces back to a misinterpretation of a study published in 1967.
The study stated that the daily average consumption of seaweed in Japan is 4.6 grams (wet weight), which is equivalent to 4,600 mg per day. It also estimated the concentration of iodine in the seaweed (dry weight) is 0.3 percent.
Some people who read the paper simply multiplied 4,600 mg by 0.003 to arrive at the conclusion that the Japanese consume 13.8 mg/day of iodine. However, the 4.6 grams of seaweed was based on wet weight, whereas the estimated 0.3 concentration of iodine in seaweed was based on the dry weight.
Because wet seaweed is probably in excess of 90 percent water, the 13.8 mg/day is a huge overestimate.
Subsequent studies estimate the average daily intake of iodine per person in Japan to be more in the range of 1 to 5 mg/day. According to the United Nations Food and Agriculture Organization and World Health Organization, “The amount of iodine intake by the Japanese is in the range of 2 to 3 mg/day.”
This is significantly higher than the recommended daily allowance (RDA) of 150 micrograms in the U.S., but it’s a far cry from the 13.8 to 20 mg/day recommended by some health gurus and supplement companies.”
The Importance of Iodine for Your Health
It’s true that iodine is essential for good health. In fact, a healthy body contains about 15 to 20 mg of iodine, most of it (70 to 80 percent) stored in the thyroid gland, where it is used to make thyroid hormones — thyroxine (T4) and triiodothyronine (T3). (The thyroid is a small gland at the base of the neck below Adam’s apple.)
Iodine deficiency can result in serious health conditions, including the following:
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Goiter (enlarged thyroid): As it tries to keep up with the demand for thyroid hormone, the thyroid becomes enlarged and nodules may develop.
An enlarged thyroid may cause difficulty breathing and swallowing and even lead to choking, especially when lying down.
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Hypothyroidism (underactive thyroid): The thyroid gland is unable to produce thyroid hormone in sufficient quantities, which can cause a host of symptoms, including fatigue, muscle weakness, increased cold sensitivity, constipation, dry skin, weight gain, puffy face, hoarseness, elevated blood cholesterol, muscle aches, swollen joints, thinning hair, depression, impaired memory, slowed heart rate, and heavier than normal or irregular menstrual periods.
Note: The most common cause of hypothyroidism is Hashimoto’s disease (aka Hashimoto’s thyroiditis), which is an autoimmune condition that features the immune system attacking the thyroid gland.
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Pregnancy-related problems and birth defects: Iodine deficiency during pregnancy can result in miscarriage, stillbirth, preterm delivery, and congenital abnormalities in babies.
Children of mothers with iodine deficiency may have intellectual disabilities and problems with growth (stunted growth), hearing, and speech.
Because iodine is so important for our health, many countries around the world go so far as to supplement iodine in the diet. However, your thyroid needs only about 150 to 250 micrograms of iodine per day to function properly.
As an example, one teaspoon of iodized salt (common table salt in the U.S.) contains about 250 micrograms of iodine. Iodine-rich foods include fish, seaweed, and other seafood; dairy products; grains; eggs; and fruits and vegetables are grown in iodine-rich soil.
The challenge we face today is soils lacking essential nutrients like iodine and magnesium. Additionally, table salt is bad for our health, and many people purposely avoid salt.
One other concern is the level of toxicity from processed foods that contain bromide and fluoride in our drinking water. These compete for the iodine receptors in the body, prompting a greater need for iodine.
So dosing iodine is not as simple as a number we can come up with for the entire population. Iodine dosing needs to be individualized.
The Dangers of Consuming Too Much Iodine
Consuming too much iodine can actually cause additional health problems, including the following:
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Goiter: Yes, too little or too much iodine can cause an enlarged thyroid gland.
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Iodine poisoning: Taking several grams of iodine can cause burning of the mouth, throat, and stomach; fever; stomach pain; nausea; vomiting; diarrhea; weak pulse; and coma.
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Thyroid cancer: Abnormal, uncontrolled growth of thyroid cells.
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Iodine-induced Hashimoto’s disease: Too much iodine may cause or contribute to Hashimoto’s disease (underactive thyroid).
In fact, Hashimoto’s disease is less common among susceptible individuals who live in regions with dietary iodine deficiency. In regions where iodine deficiency has been addressed through supplementation, the prevalence of Hashimoto’s disease has increased.
Excessive dietary iodine affects the thyroid differently in different people. In individuals with underlying inflammation of the thyroid, excess iodine triggers an inflammatory response.
For these individuals, taking iodine supplements is like throwing gasoline on a fire. In fact, individuals with underlying inflammation of the thyroid are particularly susceptible to developing Hashimoto’s thyroiditis as the result of excessive iodine intake.
Optimizing Thyroid Health and Function
Clearly, too little or too much iodine can cause serious health problems, so any attempt to optimize thyroid function merely by supplementing with iodine is a risky approach. Unfortunately, this is an approach that many people try on their own.
The proper way to optimize thyroid health and function is to treat the thyroid holistically and to test first before prescribing any supplements. Here at the BioDesign Wellness Center, the Tampa Functional medicine clinic, we first look for any inflammatory markers — signs of inflammation and, more specifically, inflamed thyroid.
We order a sonogram to get a good look at the thyroid and examine it for any nodules. If our examination reveals signs of inflammation, we test/examine for and treat any and all underlying conditions that may be causing the inflammation, including the following:
- Celiac disease
- Chronic stress
- Environmental toxins, such as toxic mold
- Food sensitivities such as gluten and dairy
- Glutathione deficiency (glutathione is a key antioxidant)
- Gut dysfunction, including small intestinal bacterial overgrowth (SIBO)
- Hormone fluctuations in pregnancy or menopause (and sometimes puberty)
- Medications
- Mercury
- Nutrient deficiencies
- Physical trauma (such as a motor vehicle accident)
- Pituitary gland dysfunction
- Undiagnosed infections, such as the Epstein-Barr Virus, Herpes 6, H. pylori, and Lyme disease
Only after we have the inflammation under control do we consider iodine supplementation. In addition, before prescribing an iodine supplement, we test the urine and the blood for iodine levels to ensure proper dosing.
For more about how we diagnose and treat thyroid dysfunction, see our two-part series on Restoring Thyroid Health.
Before You Supplement Your Iodine Intake
Most importantly, if you’re doing it alone, don’t take an iodine supplement or try to increase your iodine intake by consuming more iodine-rich foods before getting a thorough examination by a doctor who fully understands thyroid health and function and the underlying causes of thyroid dysfunction.
Too much or too little iodine can cause serious health issues, and the daily intake of iodine each person needs for optimal thyroid health and function varies.
If you suspect that you suffer from iodine deficiency, we strongly encourage you to get examined and tested by a doctor who diagnoses and treats not only the symptoms of thyroid dysfunction but also the underlying factors responsible for it.
Iodine levels can be tested using a simple urine test to check your iodine status. By working with your healthcare provider, the correct dosing can be determined.
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Disclaimer: The information in this blog post about iodine is provided for general informational purposes only and may not reflect current medical thinking or practices. No information contained in this post should be construed as medical advice from the medical staff at BioDesign Wellness Center, Inc., nor is this post intended to be a substitute for medical counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible through, this post without seeking the appropriate medical advice on the particular facts and circumstances at issue from a licensed medical professional in the recipient’s state, country or other appropriate licensing jurisdiction.