Biosea Health

Seaweed Iodine Levels

Seaweed iodine levels are often high especially in kelps and brown seaweeds. Red seaweed has only moderate levels of iodine so you can eat 2 to 5 grams of dry Pacific Seamoss without any issues, but gain benefits of adequate levels of iodone and nutrients.

Seaweed iodine levels are good and are an excellent source of dietary iodine intake necessary for production of the thyroid hormone. Many people globally suffer from marginal deficiencies and where you live makes a big difference [1]. Pacific Seamoss has levels sufficient to meet any deficiencies but not too much. The label is here. There is ongoing research on levels of iodine and safety [3] [4] of seaweeds.

Iodine is a trace element required for the synthesis and function of triiodothyronine (T3) and thyroxine (T4) thyroid hormones. In Japan, where approximately 20 different types of seaweed are consumed, the majority being wakame (Undaria spp), kombu (Laminaria spp), and nori (Porphyra spp), iodine intake varies from 0.1 to 20 mg/d (average intake, 1–3 mg/d), which can exceed the upper tolerable limits of 600 µg/d (EFSA) and 1100 µg/d (World Health Organization)

The consequences of iodine deficiency include goiter, intellectual impairments, growth retardation, neonatal hypothyroidism, and increased pregnancy loss and infant mortality.

10 Reasons You need Iodine

These are the 10 reasons often provided – but simplification hides complexity! A question is how much is enough, and how much is too much, and it depends on the form of the iodine, the source of your food, additives in food and health.

  • Necessary for metabolism and thyroid function
  • Helps your brain stay sharp
  • Protects the body from toxins
  • Protects from radiation
  • A natural antiseptic
  • A powerful antioxidant
  • Ensures reproductive health
  • Helps prevent hair loss
  • Maintains strong teeth and bones
  • Helps stabilize your mood
  • Iodine is the food of the thyroid, and the thyroid is the “command center” of all your metabolism.

Eliminating Iodine Deficiency Globally

Both insufficient and excessive iodine intake can result in thyroid disease. The term “iodine deficiency disorders” refers to all of the consequences of iodine deficiency, which depend on its severity and the age of the affected subject. When severe iodine deficiency occurs during pregnancy, it is associated with fetal hypothyroidism, mental impairment, and increased neonatal and infant mortality. In adults, iodine-induced hypothyroidism is rare, while the most common manifestation is goiter that progresses to nodular goiter and eventually to thyroid autonomy and hyperthyroidism.

The United Nations World Summit for Children established the goal of eliminating iodine deficiency worldwide in 1990 (30 years ago!) In 2018, Unicef reported progress mostly through programs of universal salt iodization. Approximately 86% of all households worldwide currently have access to adequately iodized salt.

This improvement in iodine nutrition translates into a near elimination globally of new cases of cretinism, the most serious form of iodine deficiency. It has decreased the incidence of goiter and adverse pregnancy outcomes such as stillbirths, while protecting the intellectual capacity of hundreds of millions of children worldwide, with a significant impact on the lives of future generations.

Back in 2013, as defined by a national or subnational median urinary iodine concentration of 100-299 μg/L in school-aged children, 111 countries have sufficient iodine intake. Thirty countries remain iodine-deficient; 9 are moderately deficient, 21 are mildly deficient, and none are currently considered severely iodine-deficient. Ten countries have excessive iodine intake. In North America, both the United States and Canada are generally iodine-sufficient, although recent data suggest pregnant U.S. women are mildly iodine-deficient. Emerging issues include discrepancies between urinary iodine status in pregnant women compared to school-aged children in some populations, the problem of re-emerging iodine deficiency in parts of the developed world, the importance of food industry use of iodized salt, regions of iodine excess, and the potential effects of initiatives to lower population sodium consumption on iodine intake.

In Australia, even though iodized salt is used in bread, the Australian Thyroid Foundation says more than 50% of children and pregnant or breastfeeding women living in Australia have been shown to be iodine deficient, and are at risk of developing thyroid disease.

Salt is needed, but as intake of salt is reduced then people run the risk of iodine deficiency

Beware High Iodine in Kelp

Kombu kelp can contain up to 2.9mg of iodine per seaweed sheet (1 gram). This provides almost 2,000% of the recommended daily intake (6). Excess iodine consumption is well-tolerated in the majority of people but could result in thyroid dysfunction for those who are susceptible. In contrast red seaweeds have “low” iodine.

Type of Iodine

In dietary supplements, iodine is often present as potassium iodide or sodium iodide. In seaweeds, iodide serves the function of an antioxidant, protecting the apoplast (cell wall space) of the cortical cell layers. The iodide was probably the first inorganic and the chemically simplest antioxidant known from a living system. [7]. It mops up H2O2The iodide may change to a potassium iodide salt with the drying process, but there is no literature we have found.

How Much Iodine Do Japanese Eat

Researchers frequently overestimate, or underestimate, Japanese iodine intake from seaweeds, which results in misleading and potentially dangerous diet and supplementation recommendations for people aiming to achieve the same health benefits seen by the Japanese. Zava estimated in detail that the Japanese iodine intake–largely from seaweeds–averages 1,000-3,000 μg/day (1-3 mg/day). Boiling reduces iodine levels.


Although substantial progress has been made over the last several decades, iodine deficiency remains a significant health problem worldwide and affects both industrialized and developing nations. Monitoring of population iodine status remains important. There are vulnerable populations, such as pregnant women and infants. There is also need for ongoing monitoring of iodized salt and other dietary iodine sources in order to prevent excess as well as insufficient iodine nutrition.

Daily eating of seaweed provides iodine in amounts to ensure adequate levels of iodine nutrition as salt intake declines.


[1]Aghini-Lombardi F, Vitti P, Antonangeli L, et al. The size of the community rather than its geographical location better defines the risk of iodine deficiency: results of an extensive survey in Southern Italy. J Endocrinol Invest. 2013;36(5):282-286. (Pubmed)

[2] BRIGHTER FUTURES Protecting early brain development through salt iodization UNICEF

[3] Kumar M & Sharma S (2020) Toxicological effects of marine seaweeds: a cautious insight for human consumption, Critical Reviews in Food Science and Nutrition, DOI: 10.1080/10408398.2020.1738334

[4] Cherry P, O’Hara C, Magee PJ, McSorley EM, Allsopp PJ. Risks and benefits of consuming edible seaweeds. Nutrition Reviews. 2019 May;77(5):307-329. DOI: 10.1093/nutrit/nuy066.

[5] Iodine Fact Sheet, Office of Dietary Supplements, National Institute of Health (Google Link)

[6] Zava, T.T., Zava, D.T. Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis. Thyroid Res 4, 14 (2011).

[7] Küpper, Frithjof. (2015). Iodine in seaweed: Two centuries of research. 591-596. 10.1007/978-3-642-53971-8_23.