The above image is from [7]
Iodine is an element that occurs naturally in the soil landmass as well as ocean waters on earth. Moreover, it is a vital trace mineral that is required by the human body, for performing various central roles including synthesis of thyroid hormones and preservation of brain functions [3]. Iodine deficiency can lead to serious health problems, including goiter (enlarged thyroid gland), intellectual disability and cretinism. Getting enough iodine is important for everyone, especially infants and women who are pregnant[2].
How much iodine do I need?
The amount of iodine you need each day depends on your age. Average daily recommended amounts are listed below in micrograms (mcg).[2]
Birth to 6 months: 110 mcg
Infants 7–12 months:130 mcg
Children 1–8 years: 90 mcg
Children 9–13 years:120 mcg
Teens 14–18 years:150 mcg
Adults:150 mcg
Pregnant teens and women: 220 mcg
Breastfeeding teens and women:290 mcg
The above table is from [2]
Roles of Iodine:
1. Promoting thyroid health:
To make thyroid hormones, your thyroid takes up iodine in small amounts. Without iodine, thyroid hormone production can decrease. A “low” or underactive thyroid gland can lead to a condition called hypothyroidism. While iodine promotes overall thyroid health, too much iodine can have a negative effect on the thyroid gland. That’s why you shouldn’t take iodine supplements without your doctor’s recommendation.[4]
2. Reducing risk for some goiters:
A goiter is an enlarged thyroid gland. Your thyroid may become enlarged as a result from either hypothyroidism or hyperthyroidism. Hyperthyroidism is an overactive thyroid gland. Non-cancerous thyroid nodules (cysts) can also cause thyroid gland enlargement.
Sometimes a goiter develops as a direct response to iodine deficiency. This is the most common cause of goiter worldwide. Iodine-induced goiters may be reversed by adding iodine-rich foods or supplements in the diet.[4]
3. Managing overactive thyroid gland:
Your doctor may recommend a special type of iodine called radioactive iodine to treat an overactive thyroid gland. Also called radioiodine, this medication is taken by mouth. It’s used to destroy extra thyroid cells to help reduce excessive amounts of thyroid hormone.
The risk with radioactive iodine is that it can destroy too many thyroid cells. This can decrease the amount of hormone production, leading to hypothyroidism. For this reason, radioactive iodine is usually only recommended after anti-thyroid drugs have failed.[4]
Note: Radioactive iodine is not the same thing as iodine supplements. You should never take iodine supplements for hyperthyroidism.
4. Treating thyroid cancer:
Radioiodine may also be a possible treatment option for thyroid cancer. It works in much the same way as hyperthyroid treatment.
When you take radioactive iodine orally, the medication destroys thyroid cells, including cancerous ones. It may be used as a treatment following thyroid surgery to make sure all cancerous cells have been removed from the body.[4]
5. Neurodevelopment during pregnancy:
You need more iodine in pregnancy. That’s because iodine intake during pregnancy is linked to brain development in fetuses.[4]
The recommended daily intake Trusted Source of iodine during pregnancy is 220 mcg. By comparison, the recommended amount in non-pregnant adults is 150 mcg a day.
If you’re pregnant, ask your doctor about iodine supplementation, especially if your prenatal vitamin doesn’t have iodine (many do not). Iodine supplements may also be necessary if you’re deficient in the mineral.[4]
You’ll also need to continue monitoring your iodine intake if you’re breastfeeding. The recommended daily amount of iodine while nursing is 290 mcg. That’s because the iodine you take up from diet and supplementation is transferred via breast milk to your nursing infant. This is a crucial brain developmental period, so infants need 110 mcg per day until they’ve reached 6 months of age Trusted Source.[4]
6. Improving cognitive function:
The same neurological benefits of iodine during pregnancy may extend to healthy brain function during childhood. This also includes a reduced risk Trusted Source of intellectual disability.
It is likely your child gets all the iodine they need through their diet, but if you have any questions about their iodine intake, talk to their pediatrician.[4]
7. Improving birth weight:
As with brain development, iodine during pregnancy is associated with a healthy birth weight. One study Trusted Source of pregnant women with goiters found that 400 mg of iodine taken daily for six to eight weeks was helpful in correcting goiters related to iodine deficiency. In turn, there was an overall improvement in birth weight in newborns.
While iodine intake can impact a baby’s birth weight and overall development, it’s important to note that the above study focused on women in developing areas who were already deficient in iron.
Unless your doctor has determined you are iodine deficient, taking supplements aren’t likely to impact your baby’s weight at birth. In fact, taking iodine unnecessarily can cause health issues.[4]
What happens if I don’t get enough iodine?
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Iodine regulates metabolism, the conversion of energy obtained from food into energy to help cells function and grow. A deficiency of iodine can therefore prevent normal growth and development. This is especially dangerous in pregnant women and infants, in which miscarriage, stillbirth, stunted growth, and cognitive impairments (difficulties with reading, writing, talking, problem solving, social skills) can occur. In adults, an iodine deficiency of less than 10-20 mcg a day can lead to inadequate thyroid hormone production, called hypothyroidism, which disrupts normal metabolic functions like regulating heart rate, body temperature, and body weight. A lump or swelling in the neck, called goiter, often accompanies hypothyroidism. Other signs of hypothyroidism include:[1]
Fatigue, lethargy
Weakness
Sensitivity to cold
Constipation
Dry skin and hair
Weight gain
People at risk for iodine deficiency include those who do not use iodized salt or supplements containing iodine, pregnant women, vegans who do not eat any animal foods, and those living in areas with low levels of iodine in the soil (e.g., mountainous regions)[1] .
Iodine rich food:
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Iodine is found in soil and the ocean, which varies in amount and will affect how much of the mineral is contained in a food. Iodine is found mainly in animal protein foods and sea vegetables, and to a lesser extent in fortified foods like breads, cereals, and milk.[1]
Seaweed (nori, kelp, kombu, wakame)
Fish, shellfish (cod, canned tuna, oysters, shrimp)
Table salts labeled “iodized”
Dairy (milk, cheese, yogurt)
Eggs
Beef liver
Chicken
Fortified infant formula
What happens when we consume too much iodine?
The highest level of daily iodine intake must not exceed 1100 micrograms for adults, as per medical experts. Nevertheless, instances of iodine overdose invariably damage thyroid functions and lead to similar symptoms of iodine deficiency, such as goiter, a decline in the body’s defense abilities and low stamina.[3]
Sometimes, iodine is consumed in huge amounts for a prolonged period of time, which causes excess accumulation of the mineral in the body. This results in serious inflammatory conditions of thyroiditis and even thyroid papillary cancer.[3]
In rare occasions, iodine poisoning happens in the system, which gives rise to painful, burning sensations in the mouth, throat, stomach, abdominal complications of diarrhoea, vomiting and grave complications including a weakened pulse and coma. It is hence always recommended to seek professional medical advise from a doctor before taking iodine supplements and limit consuming surplus iodine through diet as well.[3]
Does iodine interact with medications or other dietary supplements?
Yes. Iodine supplements can interact or interfere with medicines that you take. Here are several examples [2] :
Iodine supplements might interact with anti-thyroid medications such as methimazole (Tapazole®), used to treat hyperthyroidism. Taking high doses of iodine with anti-thyroid medications could cause your body to produce too little thyroid hormone.
Taking potassium iodide with medicines for high blood pressure known as ACE inhibitors could raise the amount of potassium in your blood to an unsafe level. ACE inhibitors include benazepril (Lotensin®), lisinopril (Prinivil® and Zestril®), and fosinopril (Monopril®).
The amount of potassium in your blood can also get too high if you take potassium iodide with potassium-sparing diuretics, such as spironolactone (Aldactone®) and amiloride (Midamor®).
Tell your doctor, pharmacist, and other healthcare providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if these dietary supplements might interact with your medicines. They can also explain whether the medicines you take might interfere with how your body absorbs or uses iodine or other nutrients.[2]
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