Taking worldwide health with a grain of salt

Opinion

Hey there, time traveller!
This article was published 30/12/2016 (3201 days ago), so information in it may no longer be current.

In A Tramp Abroad, Mark Twain in 1880 related the remarks of a fellow traveller: “Well, I am satisfied, I have seen the principal features of Swiss scenery — Mont Blanc and the goiter — now for home!”

Goiter was then, and is still now, common across much of the world, including parts of Europe. A swollen thyroid gland — goiter — is a symptom of thyroid disease and is caused most often by iodine deficiency. Today, one in three people across the globe is iodine-deficient: as recently as 1970 that figure was two in three.

Iodine is vital to our health from womb to tomb. It is used to build thyroid hormone that is effectively our metabolic thermostat: too little and we run slow and cool — chronic fatigue is a frequent byproduct. Too much and we run hot and irritable: insomnia, sweating and heat intolerance are common symptoms.

Most importantly though, iodine and thyroid hormone is vital to fetal and neonatal growth and brain development. Pregnant and nursing women and their babies have the greatest iodine demands and are at greatest risk of iodine deficiency.

Iodine deficiency is the single most important preventable cause of cognitive impairment across the globe today. The World Health Organization estimates 50 million people suffer from brain damage induced by iodine deficiency.

Extreme iodine deficiency results in cretinism: cretins have short stature, small brains, suffer extreme cognitive impairment and are often deaf and mute. Less severe iodine deficiency impairs neuromotor function with major impacts on brain and cognitive development. In iodine-deficient regions of rural Asia, for example, deficits of 11 to 15 IQ points are well-documented.

The array of health problems associated with iodine deficiency is easily addressed in the diet. Many foods contain plentiful iodine: seafood, dairy, eggs, meat and kelp are all good sources, as are certain processed foods, most notably iodized salt. Multivitamin supplements can help, but only if they contain iodine; many do not.

Ironically, iodine deficiency is often associated with “healthy” diets. Vegetarians and vegans have an elevated risk of iodine deficiency because most plants are poor sources of iodine and some plants are goitrogenic.

Goitrogens are chemicals such as thiocyanate and perchlorate that are antinutrients. They impair iodine uptake and thyroid function. Cabbage, sweet potato, soy, broccoli, Brussels sprouts, turnips, cassava, corn and kale are all goitrogenic to varying degrees.

Most of us consume goitrogenic plants routinely and, with adequate dietary iodine, these foods are safe and healthy. But with marginal or deficient dietary iodine, goitrogens can be harmful and worsen thyroid disease.

So if you are a raw food vegan who eschews table salt, processed flour and downs a kale smoothie every morning, you might find yourself feeling listless, tired, constipated, sensitive to cold, with coarse hair and dry skin. Perhaps add a little kelp to the diet, as these are all symptoms of hypothyroidism.

In the 1960s, the WHO identified iodine deficiency as a global public health threat and it is still a major problem today. In 2012, the Copenhagen Consensus named micronutrient deficiency the top global challenge to be solved today.

Much progress has been made. The WHO focused on universal salt iodization as an effective tool to address iodine deficiency. The program has been overwhelmingly successful, halving the proportion of the globe’s population suffering from iodine deficiency. At a cost of five cents per person per year, it is the most cost-effective public health initiative ever.

We need not go far to see dramatic effects. Until the 1920s, iodine deficiency was common in America’s goiter belt — around the Great Lakes, in Appalachia and the Pacific Northwest. Salt iodization was introduced in 1924 and, within a decade, mean IQ rose 15 points in the goiter-belt states.

Unfortunately, iodine deficiency is making a comeback in many previously iodine-sufficient areas. In the United States, for example, mean iodine intake fell 50 per cent from 1971 to 2001. Australia, New Zealand and parts of Europe have lapsed back into mild iodine deficiency in recent years.

The reasons are two-fold. First, our growing fear of salt. This has greatly reduced the intake of iodized salt. In combatting iodine deficiency, natural salt is not better. Give me the artificial stuff fortified with iodine any day. Second, historically we obtained some of our dietary iodine from dairy products where iodine-based cleaners added iodine inadvertently. These have largely been removed from use, reducing the iodine content of dairy products.

Across the globe, a network of agencies is working hard to address micronutrient deficiencies — including iodine — that are major health problems especially in the developing world. The improved health and nutrition that result make an enormous difference in the lives of quite literally billions of people.

During the festive season, much of it inspired by religious celebration, one might in a quiet moment wonder whether angels are real. I’m not wise enough to know the answer to that, but I do know that UNICEF, the WHO, the Global Alliance for Improved Nutrition, Oxfam, Project Healthy Children and others are doing the work of the angels by ensuring the food we eat can help prevent disease.

Scott Forbes is an ecologist at the University of Winnipeg.

Twitter: @lsf58