Iodine: the essential nutrient you never knew you needed
Dr Malcolm Sandler, an endocrinologist at Mediclinic Panorama, explains what iodine is, how deficiency occurs, how this impacts the body, and how iodine deficiency is prevented.
What is iodine and why is it essential?
Although iodine is not produced in the human body, this mineral is essential because the thyroid gland uses it to make thyroid hormones, which regulate growth and development and the metabolism of every cell. These hormones control your breathing, heart rate, temperature, cholesterol, muscle strength, menstrual cycle, and weight – to name just a few functions.
“Pregnant women are routinely monitored for thyroid deficiencies,” says Dr Sandler.
Where do you get iodine from?
The source of most iodine is the sea. When seawater evaporates and falls as rain, some iodine is present, and it enters the soil this way. If the soil is deficient in iodine, the plants and animals produced there – and the people who eat them – will be too. Many regions lack iodine. Flooding, deforestation, intensive farming, use of alkaline fertilisers and irrigation all contribute to deficiency.
What happens if we don’t get enough iodine?
According to the World Health Organization, iodine deficiency is the most common cause of impaired brain development in the world. The good news is that this is preventable and has almost been eliminated.
If pregnant women don’t get enough:
- They could experience spontaneous abortion or stillbirth.
- Their babies are at risk of mental retardation.
If children don’t get enough:
- Even a relatively low degree of iodine deficiency can cause stunted neurological development in babies and children, reflected in below-normal IQ.
- Physical development is delayed.
If adults don’t get enough:
- Low iodine can result in low thyroid hormone levels and, in turn, hypothyroidism, which is characterised by a slow metabolism, with wide-ranging symptoms from fatigue, apathy, memory loss, reduced productivity, irritability and depression to weight gain, weakness and muscle aches.
The most obvious sign of iodine deficiency is swelling at the base of the throat, which is called a goitre. The thyroid gland enlarges as it attempts to take in more iodine, and this may make breathing and swallowing difficult, and cause coughing or hoarseness.
What is the solution?
It’s simple, cheap and effective: many countries have implemented a programme of salt iodisation, which has led to lower incidences of iodine deficiencies.
As salt is such a widely used household staple, the simplest way to avoid iodine deficiency is for salt producers to add a form of iodine.
Just don’t overdo the salt, though – the WHO notes that elevated salt intake results in elevated blood pressure and is associated with cardiovascular disease. They also add that most of us consume far more salt than we need.
How are we doing in SA?
Since 1995, salt iodisation has been legislated. However, iodisation was variable in the salt industry, but this has improved. And some of the salt bought by poorer households, particularly in Limpopo, Mpumalanga and North West provinces, is not iodised. By 1998, we had reached optimal iodine nutrition, with 86,4% of our households using iodised salt.
So there’s no need to worry about getting enough iodine?
Generally, iodine deficiency disorders no longer seem to be an issue in South Africa, unless you are very poor, and buy your salt from unconventional sources.
“I have never seen a patient with iodine deficiency disorder in my practice,” says Sandler, who has decades of experience in his field.
2.2 billion = the number of people living in iodine-deficient areas
+70 = the number of countries that have implemented salt iodisation programmes
54 = countries that are still iodine deficient
70% = percentage of households worldwide that use iodised salt
1995 = the year mandatory salt iodisation was introduced in South Africa
5 = cost in US cents of iodising salt per person per year
10–15 = possible loss in IQ points as a result of iodine deficiency
10% = estimated proportion of women in the US who may have thyroid hormone deficiency