The optimal balance between salt reduction and the elimination of iodine deficiency disorders
Last month, the Medical Journal of Australia (MJA) reported on a study of more than 16,000 people, which found that the salt intake of Australian adults exceeds the World Health Organisation’s (WHO) recommendation of a maximum of 5 g per day. The report showed that Australian men are ingesting 10.1 g daily, twice the recommended amount, with women not far behind at 7.34 g.
Earlier this month, during a radio interview on 5 AA, Talking Adelaide, Pete Evans, the MKR presenter and TV chef warned listeners of the dangers of the use of common table salt, describing it as a “poison”.
“If you are using table salt that you would get in a supermarket that is iodised… I would suggest you throw it in the bin right now.”… “Seriously, if you’ve got the old school table salt that a lot of people have, I would call that a poison. I would never put that anywhere on my plate or on my children’s plates…”
Evans added, “There are really good quality salts that have trace minerals that are essential for us. It depends on the quality of the salt that you use. You have to dig a little bit deeper,”
Professor Creswell J Eastman from Sydney Medical School, Chair of the Australian Centre for Control of Iodine Deficiency Disorders (ACCIDD), says,
“Opinions such as those expressed by Pete Evans, undermine the several decades of work by public health advocates who are seeking an optimal balance between salt reduction and the elimination of iodine deficiency disorders through salt iodisation. These types of claims can cause serious harm to our population by providing inaccurate and dangerous information. In addition, encouraging the use of non-iodised ‘Himalayan salt’ is not recommended as it is not regulated and contains other minerals, some of which could be injurious to our health when taken in excess quantities.”
“Of course, excessive intakes of ordinary salt (sodium chloride) can be a contributor to the development of cardiovascular disease. High salt intakes are a primary cause of high blood pressure, one of the main risk factors for heart attack, kidney disease and stroke – the leading causes of death and disease worldwide1. The WHO promotes the implementation of programs to lower population salt intake as a cost effective strategy to reduce the burden of non-communicable diseases2; however, it also recommends universal salt iodisation (USI) to prevent and control iodine deficiency disorders (IDD).
Nutritional iodine deficiency causes a variety of mental and physical disorders collectively known as IDD. USI is the process by which all salt for human consumption is iodised, and is the preferred approach of the WHO, UNICEF and International Council for Control of Iodine Deficiency Disorders (ICCIDD) to prevent or correct iodine deficiency in a population.
IDD’s are a major global health problem causing impaired cognitive development, reduced IQ, congenital anomalies, cretinism, endemic goitre and other thyroid disorders3. It is estimated that 1.9 billion people worldwide remain at risk of insufficient iodine consumption4. The WHO, United Nations Children’s Fund (UNICEF) and the International Council for the Control of Iodine Deficiency Disorders - Global Network (ICCIDD-GN) recommend an intake of 150 µg iodine/day for non-pregnant, non-lactating adults and children and 250 µg/day for pregnant and lactating women.
Food grade salt is the primary vehicle for dietary iodine fortification5 and is preferred because the technology is simple, iodine levels in salt can be easily monitored, salt consumption is mostly stable throughout the year and salt is affordable. The estimated annual cost attributable to IDD’s in the developing world is $36 billion, compared with just $0.5 billion required to deliver effective salt iodisation programs6.
“The important message to the community is that the first 1,000 days of life are critical to brain development and maturation. Any deficits during this time are likely irreversible. A public health education campaign is long overdue to correct this sinister threat to the intelligence of current and future generations of Australian children.”
Iodine deficiency (ID) in utero and in early childhood damages the developing brain and, according to the WHO, is “the leading global cause of preventable loss of intellectual performance”7. Moderate to severe iodine deficiency, occurring during pregnancy and early childhood, can result in an irreversible loss of 10 to 15 IQ points8. Lesser degrees of dietary iodine deficiency have lesser impacts.
ID reemerged in Australia in the 1990s as a serious public health problem9,10 and could have contributed to the problem of declining educational performance. Remedial action, by way of mandatory iodisation of all salt used in the manufacture of bread, was implemented in late 2009 and has made a difference to the population’s iodine nutritional status as a whole, but iodine intake in pregnant and lactating women remains suboptimal, thus putting their offspring at risk of loss of IQ unless women correct the deficiency by taking a supplement11.
This is well illustrated by a study from the Menzies Institute in Hobart which found that NAPLAN scores of nine-year-old children born to mildly iodine deficient mothers were around 10 per cent lower than a control group of mothers who had sufficient iodine intake during pregnancy12. Similar studies have been reported elsewhere in the developed world13.
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This article appeared in the February 2018 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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