The World Health Organization’s (WHO) Guidelines on Salt Iodisation

A lack of iodine can lead to a range of health issues known as Iodine Deficiency Disorders (IDDs). IDDs affect close to 1.9 billion people worldwide, and are a major public health concern in many countries, including South-East Asia, the Western Pacific, Africa, the Eastern Mediterranean, as well as Eastern/Western Europe.

To combat this, the WHO and United Nations Children’s Fund (UNICEF) recommended universal salt iodisation in 1993, as the main strategy to eliminate iodine deficiency disorders. Today, iodisation is a standard implementation in more than 120 countries around the world.

Although the recommended dosages and guidelines differ per country, in line with the population requirements, there are general guidelines to ensure that each country’s needs are met and not exceeded.

What is iodine and why is it important?

Iodine is a necessary micronutrient that aids in thyroid hormone synthesis. This plays an important role in the body’s growth and development. Adequate iodine intake from foetal development through adolescence is essential for lifelong health.

The thyroid requires iodine to synthesise thyroid hormones, while the kidneys excrete excess iodine in urine. The principal thyroid hormone that’s secreted by the thyroid gland is thyroxine. This is taken up by cells and converted into triiodothyronine – a vital element in developmental and metabolic processes.

Both the insufficient and excess intake of iodine can have negative effects on thyroid function, leading to IDDs. Common IDDs include impaired mental functioning, hypothyroidism, cretinism, abnormal physical development, and goitre, which is recognised by the swelling of an ill-functioning thyroid gland. Pregnant women, lactating women, women of reproductive age, and children under 3 are at the highest risk of iodine deficiency.

Further health issues include decreased fertility, miscarriages, stillbirths, and congenital abnormalities.

The WHO on salt iodisation

According to the WHO, most people today need an additional source of iodine as it is found only in small amounts in modern diets.

The recommended daily intake for iodine is:

• 90 mg for preschool children (0 to 59 months)
• 120 mg for children aged six to 12 years
• 150 mg for adolescents (above 12 years) and adults
• 250 mg for pregnant and lactating women

To promote sufficient iodine intake around the world, all food-grade salt, i.e., the WHO stipulates that all salt used in household and food processing should be fortified with iodine as a safe and efficient strategy for the prevention and control of iodine deficiency and related disorders.

Salt iodisation is the process of fortifying salt by adding iodine. The recommended levels of iodine to be added to salt is between 40 mg/kg and 20 mg/kg. This is based on an estimated average salt consumption in adults, which is between 5 and 10 grams daily. These iodine levels are considered safe with salt intakes of around 25 gram per day when iodine from dietary sources is low – as it typically is across the world.

Iodisation in South Africa

To comply with the WHO’s goal of iodising salt globally, South Africa introduced the compulsory iodisation of all table salt on 1 December 1995. Its formulation is regulated to ensure that it doesn’t cause a large increase in cost and is suitable for coarse, unrefined salt as well.

For some, salt iodisation contradicts health concerns connected to consuming too much sodium, but the public health goals of reducing salt and increasing iodine intake through salt iodisation are compatible, according to the WHO. However, control is important and the levels of iodine in salt and the iodine status of the population should be monitored and adjusted continuously.

South Africa is a forerunner in advocating for salt reduction and was the first country to mandate maximum salt limits, especially in processed foods. The National Department of Health’s (NDoH) aim is to reduce the general population’s salt intake to less than 5 gram per day. This amounts to one teaspoon of salt, and includes the salt already found in foods as well as the raw salt that’s added. This means that even with the added iodine, salt should be consumed in moderation.

Further regulations

• Salt iodisation should be regulated by governments, in harmony with local programmes, to ensure that fortified salt is delivered safely within the acceptable dosage range. Attention should be given to eliminate barriers preventing access for all population groups that require iodine-fortified salt.
• Clear legislation should also be established and implemented for food producers and distributors, especially where the main source of dietary salt is processed foods and meals consumed outside of households. This legislation should cover the proper iodisation of salt, along with the salt content of industrialised food products.
• Salt and iodine intake should be monitored closely at country level to adjust salt iodisation as and when necessary. This is dependent on the observed intake in the population, to ensure that individuals consume sufficient iodine.
• Concentrations of iodine may need to be adjusted by national authorities responsible for the implementation and monitoring of universal salt iodisation, in light of their country’s own data regarding dietary salt intake.
• National distributors must provide guidance for the concentration of iodine in salt. Sufficient iodine should be supplied to the majority of the population, even those with a lower salt intake.
• Ideally, iodised salt should reach, and be used by, the entire population after the age of 1. Infants are assumed to be covered via breast milk or iodine-enriched infant formula. The addition of salt to products consumed by young children may need regulation, to avoid the inadequate or excessive consumption of both sodium and iodine.

For additional guidelines and recommendations, read the WHO’s complete guide on the Fortification of food-grade salt with iodine for the prevention and control of iodine deficiency disorders.

FAQs

• What is iodine and why is it important?

  Iodine is a vital micronutrient that aids in thyroid hormone synthesis, which plays an important role in the body’s growth and development. Adequate iodine intake from foetal development through adolescence is essential for lifelong health.

• What is salt iodisation?

  Salt iodisation is the process of fortifying salt for human consumption by adding iodine.

• Why does the WHO recommend global salt iodisation?

  According to the WHO, most people today need an additional source of iodine as it is found only in small amounts in modern diets. The iodisation of salt is, therefore, recommended on a global scale to control and prevent Iodine Deficiency Disorders (IDDs.

• Is the fortification process regulated?

  Yes, it’s controlled by the WHO and local authorities. There are specific guidelines to ensure that each country’s needs are met and not exceeded.