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10 signs and symptoms of iodine deficiency

Updated on 1 February 2024.

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Symptoms of iodine deficiencyIodine is an essential mineral not synthesized by the body. It is used by the thyroid gland to produce thyroid hormones, which control the growth and repair of damaged cells and promote healthy metabolism.

According to statistics, around a third of the world’s population suffers from iodine deficiency. The people most affected by this deficiency are largely :

  • Pregnant women.
  • Inhabitants of certain countries where there is very little iodine in the soil, such as South Asia, New Zealand and certain European countries.
  • People who use non-iodized salt.
  • Vegetarians or vegans.

On the other hand, in the United States, where the food supply is rich in minerals, cases of iodine deficiency are very rare.

Iodine deficiency can lead to unpleasant and even serious health complications. These include neck swelling, pregnancy-related problems, weight gain and learning difficulties. Its symptoms are very similar to those of hypothyroidism.

Here are 10 signs and symptoms of iodine deficiency not to be overlooked.

1. Neck swelling

neck-swelling-iodine-deficiency-symptomSwelling in the front of the neck is the most common symptom of iodine deficiency. This is called a goiter (an often visible enlargement of the thyroid gland).

When the body lacks iodine, this gland doesn’t produce enough thyroid hormone. To compensate, it doubles its efforts to increase production, resulting in goitre.

Fortunately, these cases can easily be treated by increasing daily iodine intake.

However, if a goiter has not been treated in time (for many years, for example), it could cause permanent damage to the thyroid gland.

2. Rapid, unexplained weight gain

Rapid weight gain is another sign of iodine deficiency. It usually occurs when the body doesn’t have enough iodine to make thyroid hormones.

This is because thyroid hormones are responsible for the speed of basal metabolism, the process by which the body converts food into energy and heat. If levels of these hormones are low, the body burns fewer calories, which are then stored as fat.

Adding iodine to your diet can help reverse the effects of a slow metabolism.

3. Feeling tired and weak

Feeling tired and weak is also a common symptom of iodine deficiency.

One study [1] has shown that nearly 80% of people suffering from low thyroid hormone levels due to iodine deficiency feel tired, lethargic and weak. Thyroid hormones help the body produce energy.

A drop in thyroid hormone levels due to iodine deficiency has a negative impact on the energy reserves produced by the body, resulting in fatigue and weakness.

4. Hair loss

Thyroid hormones help control the growth of hair follicles. Hair follicles stop regenerating if thyroid hormone levels are low. This can lead to hair loss.

According to one study [2] conducted on 700 volunteers, 30% of people with low thyroid hormone levels suffered from hair loss.

However, another study [3] showed that low thyroid hormone levels only appear to cause hair loss in people with a family history of hair loss.

If you suffer from hair loss due to iodine deficiency, sufficient intake of this mineral can help correct thyroid hormone levels and stop hair loss.

5. Dry, scaly skin

Iodine deficiency can lead to dry, flaky skin.

In fact, some studies have revealed that up to 77% of people with low thyroid hormone levels may suffer from dry, flaky skin [4]. Thyroid hormones help skin cells regenerate. Therefore, if their levels are low, this regeneration in turn weakens, which can lead to dry, flaky skin [5].

In addition, thyroid hormones help the body regulate perspiration, which helps keep the skin hydrated.

People with low thyroid hormone levels tend to sweat less than those with normal thyroid hormone levels [6, 7].

6. Abnormal sensation of cold

abnormal-feeling-cold-iodine-deficiency-symptomIodine deficiency can also result in a feeling of cold.

In fact, some studies have revealed that over 80% of people with low thyroid hormone levels may feel more sensitive than normal to cold temperatures.

Reduced thyroid hormone levels lead to a slowdown in metabolism, resulting in lower thermogenesis and therefore lower body heat. [8, 9].

In addition, thyroid hormones help stimulate the activity of your brown fat, a type of fat that is responsible for heat production.

This means that low thyroid hormone levels, which can be caused by iodine deficiency, could prevent brown fat from doing its job [10, 11].

7. Changes in heart rate

Heart rate is the number of heartbeats per minute. This frequency can be affected by iodine levels in the body.

A lack of iodine may cause the heart to beat more slowly than usual, while a high level of iodine may cause it to beat faster than usual. [12, 13].

Severe iodine deficiency can lead to an abnormally slow heart rate. This could lead to feelings of weakness, fatigue and dizziness.

In extreme cases, this could lead to loss of consciousness. [14].

8. Learning and memory problems

Iodine deficiency can affect the ability to learn and remember.

A study of over 1,000 adults found that those with higher thyroid hormone levels performed better on learning and memory tests than those with lower thyroid hormone levels [15].

Thyroid hormones help the brain to grow and develop. This is why a deficiency in iodine, which is necessary for thyroid hormone production, can reduce brain development.

In fact, studies have shown that the hippocampus, the part of the brain that controls long-term memory, appears to be smaller in people with low thyroid hormone levels [16].

9. Problems during pregnancy

problem-of-pregnancy-another-symptom-of-iodine-deficiencyPregnant women are at high risk of iodine deficiency.

During pregnancy, the mother must consume enough iodine to meet her own needs and those of her baby. These needs must also be met during the breast-feeding period.

Not consuming enough iodine during pregnancy and breastfeeding can cause side effects in both mother and baby.

Mothers may experience symptoms of an underactive thyroid, such as goiter, weakness, fatigue and a feeling of cold.

Iodine deficiency in infants can stunt physical growth and brain development. In addition, severe iodine deficiency can increase the risk of stillbirth.

10. Iodine deficiency can also disrupt menstrual periods

Heavy, irregular menstrual bleeding can occur as a result of iodine deficiency.

Like most symptoms of iodine deficiency, this is also linked to low thyroid hormone levels, as iodine is needed to make thyroid hormones.

In one study, 68% of women with low thyroid hormone levels had irregular menstrual cycles, compared with only 12% of healthy women [17].

Research has also shown that women with low thyroid hormone levels experience more frequent menstrual cycles with heavy bleeding. This is because thyroid hormones disrupt the signals of hormones involved in the menstrual cycle.

Natural solutions to iodine deficiency

There are very few good sources of iodine in the diet. This is one of the reasons why iodine deficiency is common throughout the world.

The recommended daily allowance (RDA) is 150 mcg per day. This daily intake should meet the needs of 97-98% of all healthy adults.

However, pregnant and breast-feeding women need more. Pregnant women need 220 mcg per day, while breastfeeding women need 290 mcg per day.

The following foods are excellent sources of iodine:

  • Seaweed, dried whole leaf – 11-1,989% of RDI
  • Cod (85 g) – 66% of RDI
  • 1 plain yoghurt – 50% of RDI
  • Iodized salt, 1/4 teaspoon (1.5 g) – 47% of RDA
  • Shrimps (85 g) – 23% of RDI
  • 1 large egg – 16% of RDI
  • Canned tuna (85 g) – 11% of RDA
  • 5 Dried prunes – 9% of RDA

Seaweed is generally an excellent source of iodine, but this depends on where it comes from. Seaweed from certain countries, such as Japan, is rich in iodine.


Smaller amounts of this mineral are also found in various foods such as fish, shellfish, beef, chicken, lima and pinto beans, milk and other dairy products.

The best way to get enough iodine is to add iodized salt to your meals. Half a teaspoon (3 g) throughout the day is enough to avoid a deficiency.

If you suspect iodine deficiency, it’s best to consult your doctor, who will check for signs of swelling (a goiter) or take a urine sample to check your iodine levels.

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