Are You Getting Enough Iodine?
Iodine is an essential nutrient naturally found in earth's soil and ocean water. It’s important to get enough iodine in our diet as it regulates our hormones, fetal development, and more. Generally, you can get enough iodine from your diet by consuming iodized salt, seafood, and certain vegetables like kelp, potatoes, lima beans and green beans.
Strawberries are one of the few fruits that contains high amounts of iodine. A cup of strawberries contains 12.96 mcg of iodine or 8.6% of the RDA.
In some cases, you may need iodine supplementation to help reduce your risk for iodine deficiency, or as a treatment for certain medical conditions, such as under-active thyroid or goiter (enlarged thyroid gland).
The symptoms of low iodine levels are primarily detected through thyroid symptoms, such as fatigue, hair loss, depression, brain fog and unintentional weight gain.
So, is your iodine consumption within the Recommended Daily Intake (RDI)150 µg for adults ?
I did this exercise of actually recording my daily iodine intake to see if I am getting enough. The amount of iodine in foods is in the references I used if you are interested to do the same exercise.
Daily Iodine intake for one day in micrograms:
Seaweed salt 1.3µg
2 eggs 19 µg
Bread 2 slices 28 µg
Cheddar cheese 16g 4 µg
Canned salmon 63 µg
Apple 0.6 µg
Yogurt 200g 32 µg
Total 147.9 µg
Based on the above daily iodine intake for one day, my total is approximately 148 µg per day which is very close to the recommended daily intake of 150 µg. I usually eat these foods on a typical day noting some days iodine intake may be less or more. I don’t experience any side effects of low iodine levels at least nothing I felt I had to visit a health practitioner. On weekends, noting I’m a sushi lover, I eat sushi with seaweed which has a high amount of iodine per serve – 1 sushi roll 100 g has 92 µg. I would eat a couple, so that alone totals 184 µg which is higher than the RDI noting I could eat other foods throughout the day which contain iodine. This is still lower that The World Health Organization proposed a safe limit of 500 μg iodine noting larger dosages have been reported without any adverse effects on human health.
As an example, the Japanese consume dietary iodine from seaweed approximately 4-14 times higher above the upper safety limit of 1 mg by U.S standards. These higher levels appear to have no adverse effects on thyroid function.
Iodine deficiency is a common, global issue and in this case the thyroid hormones T3 and T4 cannot be produced in optimal amounts and thus, the thyroid cannot work to its full potential. This may result in in a hypothyroid state as in Hashimoto’s disease, or a hyperthyroid state as in Graves’ disease. Low iodine levels are often the missing link in correcting thyroid disorders. Iodine is necessary for many biological functions and for maintaining our vitality including proper hormone balance, mental sharpness, mood stability, immune health and thyroid function.
High intakes of iodine can cause some of the same symptoms as iodine deficiency—including goiter, elevated TSH levels, and hypothyroidism—because excess iodine in susceptible individuals inhibits thyroid hormone synthesis and thereby increases TSH stimulation, which can produce goiter. Iodine-induced hyperthyroidism can also result from high iodine intakes, including when iodine is administered to treat iodine deficiency. Studies have also shown that excessive iodine intakes cause thyroiditis and thyroid papillary cancer. Cases of acute iodine poisoning are rare and are usually caused by doses of many grams.
The recommended maximum daily intake of iodine for normal thyroid is approximately 200 μg - 300 μg. However, this is not necessarily the optimal range for other health benefits. There are benefits to using a higher dose of iodine especially for women with disorders such as fibrocystic disease and breast cancer. However, it is important that when prescribing high dosage of iodine, that regular monitoring of TSH, thyroid hormone and thyroid antibodies should be performed. Thus, high dosage of iodine will likely cause toxicity in a significant portion (25%) of the population, but will be safe for most, but not all patients.
References:
Iodine in food and iodine requirements (2016) https://www.foodstandards.gov.au/consumer/nutrition/iodinefood/Pages/default.aspx
Iodine facts (2010) https://nutritionaustralia.org/fact-sheets/iodine-facts/
Food and Your Hormones. Applied Functional Nutrition Course (2019) https://thenutrition.academy/wp-content/uploads/2020/02/Module-3-Lesson-2-V2.2-2019.pdf
Iodine: Fact Sheet for Health Professionals (2020) https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
11 Uses for Iodine: Do Benefits Outweigh the risks? (2019) https://www.healthline.com/health/iodine-uses
Fruits and Vegetables High in Iodine (2011) https://www.healthdiaries.com/eatthis/fruits-and-vegetables-high-in-iodine.html
The Nutrition Academy, Applied Functional Nutrition Course, Module 3: Food and your Hormones