What is iodine deficiency – in easy to understand language
Too little iodine in the body is also referred to as iodine deficiency. It is a major cause for concern with The World Health Organization(WHO), listing iodine deficiency as the most common reason for preventable brain damage (1).
What is iodine and what is its role in the body?
Iodine is a trace element which is quite rare in our soils, however, it is more readily found in oceans. This mineral plays a vital role in the healthy functioning of our body. Iodine is essential for the synthesis of the thyroid hormones triiodothyronine (T3) and thyroxine (T4).
• (T3) Thyroxine is the super thyroid hormone and is produced from T4 in your gut and liver.
• (T4) Triiodothyronine is made by the thyroid when it binds with iodine. It is mostly inactive but is converted to (T3)
What do thyroid hormones do?
Thyroid hormones are responsible for:
- the regulation of the metabolic pattern of most cells
- playing a critical role in the early development of most body organs including the brain
- playing a significant role in the development of the central nervous system, immune responses and bone and calcium metabolism
- energy production and oxygen consumption in cells required for reproductive function in adults
Approximately 70-80% of iodine is stored in the thyroid glands located at the neck (2) .
The remainder is found in the ovaries, muscles, salivary glands, breast tissues and other body parts.
What are the effects of iodine deficiency?
If you lack iodine in the body the thyroid will not be able to make thyroid hormones. This can lead to an enlarged thyroid (goitre) and hypothyroidism. Although numbers vary, it is reported that 10 million people in the USA have hypothyroidism and many may not be aware of this. It is estimated up to 10% of women may have hypothyroidism (3).
Iodine is essential in all stages of life (4). Because so many systems in the body rely on thyroid hormones (and therefore iodine) for healthy functioning, we cannot afford to be complacent.
The effects are well researched and listed for all stages of life.
- impaired brain development
- impaired learning
- lowered IQ
- delayed motor development growth
- speech and hearing problems
- delayed mental and physical growth, including delayed puberty
During adulthood and other ages:
- weakened mental function
- reduced work production
Maintaining iodine levels is most critical before birth, especially after the second trimester, and in the early stages of life. Low levels of iodine may not be the only cause of a low thyroid function but an insufficient supply of iodine can result in dire thyroid problems having devastating effects on your health, and especially the health of children.
What does iodine deficiency look like?
Iodine deficiency symptoms have been well researched and include:
- Gaining weight unexpectedly
- Hair loss
- Flaky, dry skin
- Lacking energy, feeling weak and tired
- Feeling cold, cold hands and feet
- Slowing heart rate
- Pregnancy complications
- Swollen neck
- Irregularities with the menstrual cycle
- Difficulties with memory and concentration, slow processing
- Joint stiffness
When iodine deficiency is left untreated, it may cause severe hypothyroidism. Another rare but critical life-threatening complication from hypothyroidism is myxedema, a condition that causes an intense intolerance to low temperatures and drowsiness that precedes extreme fatigue ultimately leading to unconsciousness. For people with hypothyroidism, myxedema can be triggered by certain infections, sedatives or stressors in the body. Should you experience the symptoms of myxedema, it is imperative to seek medical treatment immediately.
Why is iodine deficiency a health issue today?
Iodine deficiency disorders are considered one of the biggest preventable health problems today.
It effects about 25% of the world population. It is more common in developing countries where households and individuals lack access to enough iodine-rich foods. However, it can equally effect people in developed countries whose bodies cannot process iodine efficiently or do not have adequate iodine in their diet.
Due to the concerns that iodine deficiency could be the most prevalent yet preventable cause of brain damage in world populations, various health organizations have implemented measures that have greatly reduced this problem over time.
In response to the issue, the iodized salt program was established. Salt was chosen because it was readily available throughout the world and cheap to iodize. Because of the public health drive to curtail this under-publicized issue, there has been dramatic progress made over the last two decades. Most countries where iodine deficiency is a public health concern, have implemented this strategy . However, today there are concerns by those in the medical arena that salt intake should be monitored due to its negative effects on health. As a result, growing numbers of people are using natural salts such as Himalayan and use of iodized salt is diminishing.
Who is commonly affected by iodine deficiency?
Groups most at risk include:
- pregnant women
- those whose diets are vegan or vegetarian
- older people, especially women (7)
- those living in countries where there is little iodine in the soils.
Depending on circumstances and nutritional habits, the chances of being effected by iodine deficiency are higher in some individuals than others and can effect anyone.
Pregnant women, lactating women and infants are at a higher risk of developing iodine deficiency disorders
because their intake has to account for the developing fetus. Iodine plays a vital role in the growth of many organs including the central nervous system, the brain and many others. Small children have higher mortality levels and higher levels of degenerative brain problems. Irreversible mental retardation and brain damage are common disorders caused by severe iodine deficiency.
This alone makes it very important to supply the developing fetus with sufficient iodine.
Therefore, conscious choices need to be made regarding monitored levels of iodine. Women are encouraged by health workers to include iodine-rich foods and take, when necessary, supplements with iodine as preventative and corrective measures. It is also essential that this group avoid an excess of iodine (8). Prevention begins before conception, continues throughout the pregnancy and during the breastfeeding period. Baby formulas alone, do not provide enough iodine for babies.
Vegetarians and vegans may also be at risk because their diet may include more goitrogenic foods than a regular diet. (9) The vegetables in the brassica family are goitrogenic, meaning they can effect thyroid function by decreasing the production of thyroid hormones. Cooking these foods can neutralize these compounds. Included in this group of foods is brussel sprouts, soy, kohlrabi, turnips, radishes, cauliflower, cabbage and kale. (10) Monitoring of Iodine levels should be considered and supplementation in this group of people may be required in order to meet the daily intake requirement.
Research shows that older people commonly have hypothyroidism because of the increased occurrence of autoimmune thyroiditis. The thyroid becomes inflamed, the causes of this are not fully understood, yet it occurs as you age (11). Hypothyroidism also increases with age. The associated symptoms appear to be more severe in the elderly (12).
What causes iodine deficiency?
Iodine deficiency often occurs when the soil in which plants are grown, and livestock are reared, is deficient in iodine. Soils from mountain ranges and in areas that experience frequent flooding are particularly bound to be affected by iodine deficiency. This problem has been aggravated by soil erosion and deforestation. Food grown in iodine-deficient regions cannot provide the daily requirements of iodine. Unlike nutrients such as vitamins, calcium and iron, iodine does not naturally occur in specific foods. Rather it is present in soil and taken up through plants grown in that soil. Iodine deficiency usually occurs when there is a lack of iodine in the soil (13). The predicament, therefore, cannot be eliminated by eating specific foods that are grown in the same region.
Other than nutritional iodine deficiency, there are a variety of additional factors that aggravate the condition and related thyroid dysfunctions. They include ingestion of goitrogens, malnutrition, infected drinking water and high-residue bulky diets that interfere with the absorption of iodine.
There are also genetic and environmental factors that interfere with thyroxin synthesis. Goitrogens are an environmental cause of iodine deficiency. Another element is intensive inter-cropping which results in the removal of biomass in the soil. The widespread use of alkaline fertilizers rapidly depletes the iodine in the soil. Genetic factors are rare and they mainly effect the enzymes that are involved in the synthesis of thyroxin.
How to prevent iodine deficiency
Recommended daily intake.
Since the body does not produce its own iodine, the only way to introduce it into your system is through diet or supplementation. WHO and UNICEF recommend the following daily intake of iodine:
0 to 7 years 90 micrograms or millionths of a gram
7 to 12 years 120 micrograms
12 years plus 150 micrograms (for male and female)
Pregnant women 250 micrograms
Lactating women 290 micrograms
Iodine Rich Foods
The oceans of the world provide the best sources of iodine with only a small amount of iodine found in soil. Areas along coastlines are also more abundant in iodine than those further inland. Iodine can be found in various types of foods, however, it should be remembered that due to the different levels of iodine available in the soils and oceans the levels of iodine present will vary and is, therefore, approximate (15). The list below is an indicator of foods with iodine:
Dried kelp 1 sheet 19-2,000 mcg
Fish – Cod caught wild 3 oz 132 mcg
Organic yoghurt 1 cup 71 mcg
Baked potato medium 60 mcg
Milk – raw 1 cup 56 mcg
Navy beans ½ cup 32 mcg
Eggs 1 large 27 mcg
Tuna tin/3 oz 17 mcg
Cheese – raw 1oz 12 mcg
Banana 1 medium 3 mcg
In western diets, iodine often comes from unintended sources such as iodophors (a group of disinfectants containing iodine) in dairy foods, improvers in cereals, bread, and meat. If these were removed from the diet, iodine intake would fall below 100mg per day. Without marine foods and these unintended sources, iodine food intake would be below that which is recommended (150mg/day) (16).
Iodine deficiency is better corrected by maintaining a healthy diet. If your diet alone is unable to supply you with enough iodine, you may have to consider adding iodine supplements. Iodine supplements containing potassium are more easily absorbed by the body. Multivitamins may contain iodine, often in the form of sodium iodide or potassium iodide. A majority of people with iodine deficiency can correct the issue by adding supplementation and changing the diet. While supplementing, it is recommended you follow RDI as an excess may lead to an iodine overload (Hyperthyroidism) that is very harmful to the thyroid.
What does iodine excess look like?
The maximum tolerable iodine intake is 1100 micrograms for adults, for teens 14-18 years 900micrograms, teens 9-13 years 600 micrograms, 300 micrograms for children 4-8 years and for children 1-3 years 200 micrograms. These are intended as an average maximum limit.
The impact iodine has on the thyroid is complex. An imbalance in iodine can make your thyroid underactive (Hypothyroidism) or overactive (Hyperthyroidism). In turn, these lead to a variety of diseases collectively known as iodine deficiency disorders.
Excessive consumption of iodine can both worsen and cause hypothyroidism and hyperthyroidism (17). Too much iodine can result in thyroid papillary cancer and thyroiditis. At extremely high dosages, iodine poisoning is likely to cause a fever, burning in your mouth, throat and stomach, abdominal pain, vomiting or nausea and diarrhoea, a faint or weak pulse and coma. However, this only happens on rare occasions.
If iodine deficiency is attended to early, it can be reversed completely with few to no complications. However, if it is identified after complications arise, especially in children, the effects can be permanent. If complications have developed due to iodine deficiency, ensuring you get enough iodine can help prevent the complications from accelerating.
The key points to remember about iodine deficiency
Iodine deficiency is a common issue where soils and foods have low iodine levels and where chosen diets lack iodine.
Iodine is not made by the body.
The thyroid gland uses iodine to make hormones. Low levels of thyroid hormones are the principal influence responsible for a range of functional and developmental irregularities known as IDD (Iodine Deficiency Disorders).
Symptoms of iodine deficiency are well established.
You can complete an iodine loading test at home to measure your iodine levels.