Iodine is regarded as one of the most important trace minerals for human health and it plays a vital biochemical function in the regulation of hormone levels in the body.
Iodine is essential in the bio-synthesis of the hormone thyroxine, also known as the thyroid hormone. The metabolic rate of the human body is regulated by thyroxine and the secretion of this hormone in the body is directly dependant on the availability of iodine in the body.
Why we need it
The World Health Organisation has recognised that iodine deficiency is the world's greatest single cause of preventable mental retardation. Approximately one-third of the world's population lives in iodine deficient areas and up to 72% of the world's inhabitants is affected by an iodine deficiency disorder.
An iodine deficiency is often compensated for in the human body, by a sudden increase in the secretion of thyroxine hormone. This sudden increase in the secretion of thyroid hormone can cause the gland to become enlarged and swollen, it can become congested and results in the condition called goiter - this disorder is typically seen in individuals affected by a deficient intake of iodine. Physical and mental retardation, also known as cretinism can affect a developing fetus, if the mother’s diet is lacking sufficient iodine.
There are many disease that can affect the functioning of the thyroid gland, this gland is formed by two large lobes lying at the base of the throat; it is an important gland and releases many hormones which are necessary for the proper functioning of the body including the maintenance of cellular machinery in the human body. A condition or disease known as hyperthyroidism can start affecting a person when the thyroid gland produces excess thyroid hormone. In this condition, the body’s metabolic rate runs too fast and metabolism is rapid compared to the normal rate, this situation in the body may be comparable to an overheated engine in an automobile. The secretion of too little of the thyroid hormone will lead to the converse disorder known as hypothyroidism-this disorder is characterized by the sluggish performance of metabolism in the body. The appearance of the symptoms in both of these different but related conditions is very sometimes rapid, and sometimes gradual, the symptoms may be mistaken for the signs signaling long-term mild depression in the individual.
Iodine has other effects
Every cell in the body contains and utilises iodine but it is in the glandular system that it is most concentrated. Large amounts are also found in the salivary glands, the brain and cerebrospinal fluid, gastric mucosa, breasts, ovaries and some parts of the eye.
Although iodine has other positive effects in the body, they are often overlooked or not mentioned. Iodine is not only necessary for the production of the thyroid hormone, but is also responsible for the production of all the other hormones in the body. Adequate levels are required for proper immune system function. Iodine also contains potent antibacterial, antiparasitic, antiviral and anti-cancer properties. It is essential for the normal physical growth & intellectual development of children, with severe deficiency resulting in mental impairment and deafness.
Iodine is an essential element required for thyroid hormone synthesis, believed to impart some of its antioxidant and antiproliferative activity in the prevention of cardiovascular disease and cancer. It is now thought that a lack of iodine can also cause or contribute to the development of certain types of cancer, especially ones involving estrogens.
The prevalence of thyroid disease and the failure to handle it correctly is one of the most important health issue in medical care. It is important that health professionals fully understand the entire process of iodine utilisation by the body, and that they are willing to test how the body performs at each step.
Having enough iodine in the diet is the first step in the resolution of any problems related to iodine deficiency. There is a lot of controversy still on this subject. Iodine has a RDA (adult) of about 150 micrograms or a dose of 0.15 mg per person daily. This is a maintenance dose and a guideline. Given individual body chemistry, toxicities, deficiencies and diet (because some vegetables are thyroid inhibitors), the help & support of a knowledgeable professional is desirable in order to develop a personal plan that will optimise iodine intake & management for each person.
As an example, hormone production from iodine can be impaired by various things including radiation damage, Mercury toxicity, Selenium and zinc deficiencies and the presence of unbalanced levels of copper.
Even if the hormones are produced correctly, the body may show 'Thyroid resistance', which is the inability of the cells to accept & utilise the thyroid hormone. Transport protein is needed for the thyroid hormones to travel through the blood to reach the cells. Protein malnutrition, alcoholism and liver disease can impair the production of these carrier proteins. Also, imbalances in Calcium, Magnesium or omega-3 fatty acids can prevent their release into the cells. At the level of cellular utilization, CoEnzyme Q10, magnesium, manganese and B vitamins are required. B12 deficiency is associated with significant reduction in serum T3.
Then T3 must be absorbed into the mitochondria & Potassium plays a crucial role in sensitizing the mitochondria to the presence of T3. Then ATP and ADP - coenzymes - must be produced, utilised and recycled.
This is to say that many factors may influence the body's performance along the way, and diagnosing where the process breaks down and how to fix it can be tricky.
Sources of Iodine
In many industrialised countries, iodine has also been added to salt products with a goal to prevent goiter. Although the addition of iodine to the salt supply has lessened the prevalence of goiter, it is inadequate to supply the body's need for iodine. Read more about the salt controversy.
Iodine is a relatively rare element, ranking 62nd in abundance amongst the elements of earth and it is not very plentiful in the earth's crust; as a result, unlike other vitamins and minerals, iodine is not present in adequate amounts in most foods. Specific plants absorb iodine when it is present in the soil (which is mostly not). Iodine is primarily found in seawater (but in very small quantities) and solid rock near the ocean. Iodine is found abundantly in sea foods, such as fish and seaweeds of all kinds. Iodine supplementation is normally not required by a person on a diet with plenty of ocean fish and seaweeds. Interesting to note that most of the iodine in fish is found in the thyroid, located in the head of the fish which is NOT commonly eaten.
Seaweeds on the other hand, have the unique ability to concentrate iodine from the ocean, with certain types of brown seaweed accumulating over 30,000 times the iodine concentration of seawater. That is why seaweed are said to be the best source of iodine in nature. The iodine level in seaweed is dependent on the type of seaweed. Kelp has the highest amount of iodine, with some kelp species having 8165 mcg/gm. Most Kelp has about 2500 mcg/gm. Other common seaweeds are much lower; for example, Karengo-wild nori (120 mcg/gm), Wakame (350 mcg/gm), Dulse (925 mcg/gm), Sea Spaghetti (330 mcg/gm), Bladderwrack (260 mcg/gm), Sea Lettuce (68 mcg/gm) and Sea Grapes (36 mcg/gm). Iodine content is reduced by storage (e.g., in paper bags or open to the air) and cooking. Consuming a variety of seaweeds insure optimum nutrient intake of iodine and the multiple cofactors required for its utilisation by the body.
Japanese Iodine Intake
Japanese iodine intake from edible seaweeds is amongst the highest in the world. Predicting the type and amount of seaweed the Japanese consume is difficult due to day-to-day meal variation and dietary differences between generations and regions. In addition, iodine content varies considerably between seaweed species, with cooking and/or processing having an influence on iodine content. By combining information from dietary records, food surveys, urine iodine analysis (both spot and 24-hour samples) and seaweed iodine content, we estimate that the Japanese iodine intake--largely from seaweeds--averages 1,000-3,000 μg/day (1-3 mg/day).
Japanese iodine intake from seaweed is linked to health benefits not seen in cultures with dissimilar diets. Knowing how much iodine the Japanese consume daily is beneficial for people who wish to consume equivalent amounts of iodine or seaweed supplements while avoiding excessive amounts that may adversely affect health.
Note: High iodine intake from seaweed consumption can cause unexpected health problems in a subset of individuals with pre-existing thyroid disorders. Although it is reported that excessive iodine does not cause thyroid antibody positivity, high intake can cause or worsen symptoms for people with previous thyroid autoimmunity or other underlying thyroid issues. In Asian cultures, seaweed is commonly cooked with foods containing goitrogens such as broccoli, cabbage, bok choi and soy . The phytochemicals in these foods can competitively inhibit iodine uptake by the thyroid gland, or inhibit incorporation of iodine into thyroid hormone.
An important concept of nature here is that seaweed is said to 'modulate' the thyroid, meaning that impaired thyroid seem to respond best to the treatment while the same protocol may not promote the same metabolic increases in healthy glands, therefore naturally helping reduce the risks of an overdose. Also the presence of other compounds in the natural seaweed seems to promote better utilisation/neutralisation of possible excess than if the iodine element is taken in isolation.
Iodine supplements administered in excess have often induced cases of thyroid toxicity - known as thyrotoxicosis. The physiological effect of a deficiency of iodine is apparently similar to the effects of an excess amount of iodine - both can induce hyperthyroidism in the affected person. Levels of iodine in the body which are safe for some people may induce adverse effects in many other persons, this suggests a different chemistry in the body or possibly a metabolic defects which can directly interfere with the regulation of the iodine thyroid system inside the body.
Signs & symptoms of iodine toxicity:
Fatigue, heat intolerance, hyperactivity, hypertension, nervousness, palpitations, tremor, weakness, menstrual disturbance, exaggerated hair loss, inability to sleep. A condition or disease known as hyperthyroidism can start affecting a person when the thyroid gland produces excess thyroid hormone. In this condition, the body’s metabolic rate runs too fast and metabolism is rapid compared to the normal rate.
If these symptoms are present, stop consumption of iodine foods until symptoms are gone. Consult with your health practitioner.
"Iodine: Why You Need It"; Dr David Brownstein; 2007
Health Salon: Iodine for Greatest Mental and Physical -- Dr Abraham and Dr Flechas
Your Entire Body, Not Just Your Thyroid, Needs Iodine - Mercola
Assessment of Japanese iodine intake based on seaweed consumption in Japan
Dr Wilson's articles on Thyroid health
Mercola - iodine deficiency
Disclaimer: This material is provided for educational purposes only and IS NOT intended as a substitute for professional medical advice, diagnosis, or treatment. This information is generic and may not include the latest research. We encourage you to do your own research and discuss your findings with a qualified health practitioner who can help you validate the outcomes in the context of your specific & individual health situation.