Are you getting enough iodine?
When you hear the word iodine, you may think of the tablets used to disinfect water on camping trips or the yellow liquid used for disinfecting cuts and grazes when we were younger. Or you may just remember it from the periodic table in chemistry class.
Iodine is one of the most important life-sustaining elements. For more than 100 years, it has been known as the element that is necessary for thyroid hormone production. However, it is so much more than that.
Iodine is found in each and every one of the trillions of cells in the body, and responsible for the production of all the other hormones in the body.
It is a powerful antibiotic, and has potent antibacterial, antiviral properties.
It has strong anti-inflammatory effects by neutralising free radicals and is necessary for proper immune system function. Working together with other minerals like Selenium, it has many therapeutic benefits for a range of modern illnesses and diseases.
It is estimated by the World Health Organisation (WHO) that more than half of the world’s population live in an area of iodine deficiency, and that this has risen 400% in the last few decades due to soil depletion and an increase in environmental contaminants that have replaced it.
Our body does not make iodine, so we need to access it from the foods we eat. But if the nutrients are not in the soil to begin with, it cannot be in the food we eat, and this can lead to common deficiencies.
Iodine deficiency in New Zealand
Soil in coastal areas are naturally iodine-rich, as are the dairy products produced by the cows that graze there. Fresh produce such as fruits and vegetables that are grown in coastal areas are also rich in iodine.
Despite being a coastal nation, New Zealand soils are low in iodine, and this is reflected in our locally grown produce.
This can be due to intensive farming, lack of crop rotation and the use of fertilisers. Coupled with changes to our diet, the reduced use of iodised salt in the household, the prevalence of processed foods, many New Zealanders are now lacking important nutrients such as iodine that are key to good health.
The WHO’s research has suggested deficiencies in both Australia and New Zealand are re-emerging, when they were previously thought to be iodine sufficient.
This research suggests that we may be consuming less than 60% of what is recommended. While we all need iodine, it is especially important for women who are trying to fall pregnant, are currently pregnant or who are breastfeeding, as the body demands more during this time due to increased thyroid hormone production, and the requirements of the developing baby.
Properly evaluating and treating iodine deficiency will help people support thyroid health and immune system function, increase their energy levels, and help improve general health and wellbeing. This can be achieved by some simple changes to their diet or daily supplementation in consultation with their health practitioner. It can be as little as a couple of drops of potassium iodide in a glass of water each day to get you feeling better, and help you avoid some of the common but serious health problems we are seeing today in New Zealand and around the world.
The best results are seen with a holistic approach, and increasing the intake of important vitamins, minerals and electrolytes through a wholefood diet.
The hungry thyroid
The thyroid is often referred to as a ‘hungry’ part of the body, in reference to its high nutritional demands.
This butterfly-shaped endocrine gland surrounds the windpipe and is important for metabolism, regulating digestion and your heart rate. It facilitates energy production and mental agility. The thyroid also helps with fat burning too, by determining how quickly and efficiently kilojoules are burned up, and it assists in the breakdown of proteins. Thyroid function also assists the suppleness and strength of our hair, skin and nails.
Iodine is an essential ingredient in all thyroid hormones, including T4 (thyroxine) and T3 (triiodothyronine). It is important to maintain sufficient amounts of iodine, and they are required to be synthesised in adequate amounts. In a low thyroid state, known as hypothyroidism, the thyroid gland can’t make enough thyroid hormone to keep the body running normally. The metabolic state is therefore reduced which can lead to weight gain.
When the thyroid gland is releasing excess amounts of thyroid hormone, it is known as hyperthyroidism, which is an overactive or elevated metabolic state which can result in fatigue, irregular heartbeat, unexplained weight loss and brain fog.
When you have an adequate intake of iodine, your body contains 20-50g, and 75% of that amount is stored in the thyroid. However large amounts are also stored in other parts of the body, including the salivary glands, the breasts, ovaries, and the brain. In the brain it concentrates in the substantia nigra, the part of the brain that is associated with Parkinson’s disease.
One of the first signs of deficiency is an enlarged thyroid gland.
The lack of iodine causes the gland to expand in an attempt to extract as much iodine in the bloodstream as possible. If your iodine intake is low, this will be reflected in low levels of thyroid hormone. You may then experience fatigue, dry skin, constipation, systemic inflammation, a hoarse voice, delayed reflexes and some cognitive impairment.
It is best to consult your doctor or health professional should you identify any of these symptoms. Anybody taking thyroid medication should always discuss their condition with a health professional before taking supplementary iodine.
The role of selenium
Selenium, another important mineral and antioxidant, plays a significant role in regulating thyroid function and iodine metabolism. The thyroid contains more selenium by weight than any other organ in the body.
Selenium is a required component for the production of the enzyme glutathione peroxidase, which protects the body from damage with antioxidant capabilities.
Without this enzyme, the thyroid gland is susceptible to damage from oxidants, there would be no activation of thyroid hormone without selenium.
The need for iodine before pregnancy
The consequences of iodine deficiency are most serious for women who are trying to fall pregnant, who are currently pregnant or are breastfeeding.
Thyroid hormones balance the function and development of the body’s major organs and influence the progress of the developing baby.
Research has shown that a lack of iodine can cause fetal and neonatal mental disabilities and growth problems, along with speech and hearing issues. Cognitive function and neurological development can be impaired when iodine levels are low.
Pregnant and breastfeeding women also require more iodine due to increased thyroid hormone production.
It is recommended that women take iodine supplements from the point of planned pregnancy and through the full duration of pregnancy as well as breastfeeding. Avoid kelp or seaweed supplements as they may be contaminated with heavy metals such as mercury. Multi-vitamin, multi-mineral and pre-natal supplements may or may not contain enough iodine, so it’s best to check.
Women with pre-existing thyroid conditions should always check with their health professional before taking a supplement.
How do I know if I’m deficient?
Under most states of iodine sufficiency, approximately 90% of dietary iodine eventually is excreted in the urine, with exception being the lactating female due to iodine excretion in the breast milk. Because of this, urine is the best biological fluid to use for assessment of deficiency.
If you are concerned there may be deficiency, you could undertake an iodine-loading test, otherwise known as a urinary iodine concentration (UIC) where you take a prescribed dose of iodine, then collect 24 hours of urine to undergo analysis with a health professional.
The principle of this test is that if you’re iodine sufficient, most of the dose will be excreted, and if there is a deficiency present, it will be instead be absorbed by the body.
Can I get enough iodine from salt?
Iodised table salt was implemented in many regions and countries around the world when iodine deficiency was recognised. In New Zealand in the 1920’s, the government allowed manufacturers to voluntarily add iodine to table salt. This was mainly to safeguard against thyroid enlargement (goitre) and the severe mental retardation of cretinism, although the incidence of these conditions was very rare in New Zealand.
In recent decades we have seen people consume less salt due to health concerns, while some avoid salt entirely. Salt used in processed foods is often non-iodised to save on costs, so is not a source of iodine despite the sodium content.
In recent times we are seeing a prevalence of sea salt, or kosher salt, promoted as a healthier alternative. However, sea salt is a poor source of iodine, and we should look for unrefined, unprocessed sea salt, with some products now enriched with New Zealand sea kelp. The iodine in salt is not very bioavailable in our bodies, it is better absorbed through liquid and food sources.
Other sources of dietary iodine
It can be difficult to identify sources and the quantity of iodine in most foods. However, it is naturally present in seawater, so therefore seafood is a good source, especially seaweed, shellfish and saltwater fish. It’s also naturally present in soil, and found in eggs and dairy, including yoghurt, cow’s milk, ice cream and cheese.
If you don’t have access to shellfish or other seafood, or if the soil is deficient due to intensive farming, you’ll need to access it from other sources.
Iodine levels in milk can vary according to the soils in which the animals have grazed and factors such as the groundwater used in irrigation, fertilisers used and the feed for the livestock. Interestingly, organic milk is estimated to contain roughly 30-40% less iodine than conventional milk, owing to alternative processing methods.
It is difficult for most people to obtain adequate iodine by eating foods that are natural sources of iodine.
That said, in 2009, Iodine fortification of bread became mandatory with the exception of organic bread, non-yeast-leavened bread and bread mixes. When salt was iodised in the 20th century, this significantly improved the iodine levels within the New Zealand population, but recently deficiencies have again become apparent, hence the need for the fortification of foods.
Iodine dosage guidelines
There is no single dose of iodine that is effective for everyone. The best approach is working with a health professional that is knowledgeable about iodine.
If you eat seafood and other iodine-rich foods, use iodised salt, take a multi-vitamin or mineral supplement, you may be able to obtain adequate levels.
Recommended daily allowances range from 100-250mcg a day, with the exception of pregnant or breastfeeding women, who may require more than 300mcg per day due to increased hormone production in early pregnancy, increased urinary iodine excretion, and the transfer of iodine to the fetus or the nursing infant when feeding.
Some leading iodine experts suggest significantly larger daily doses, even up to 12mg. In Japan, the average daily intake is 12-13 milligrams due to increased consumption of seaweed and other seafood.
Iodine is one the most basic elements of all life on earth, it is present in the ocean, marine life and in every one of the trillions of cells in our body. The role it plays in our everyday wellbeing cannot be overstated. As our bodies can’t produce iodine, there are simple steps we can take to make sure we can rebalance and replenish our mineral levels, and avoid deficiencies.
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Ministry of Health Manatū & Australian National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary Intakes. 2006, updated 2017.