Salt restriction could increase risk of iodine deficiency

By Caroline Scott-Thomas

- Last updated on GMT

Related tags: Iodine deficiency, Iodine

Restricting salt intake could increase risk of iodine deficiency, particularly among women, according to a new study published in the American Journal of Hypertension.

Nearly a third of Americans have hypertension, a risk factor for heart disease and stroke, according to the Centers for Disease Control and Prevention (CDC). Excessive sodium consumption has repeatedly been linked to high blood pressure, and Americans consume on average about 4,000mg a day – far more than the 2,300mg recommended in the 2005 Dietary Guidelines for Americans.

In addition, the CDC recommends that 69 percent of the population – including blacks, those aged 40 or older, and those with high blood pressure – should limit their sodium intake to 1,500mg a day, as these groups are at particular risk of health problems arising from consuming too much sodium.

However, the United States’ salt supply is fortified with iodine, deficiency of which can lead to hypothyroidism, infertility, thyroid cancer, goiter, poor cognition, lethargy, and decreased labor productivity in adults.

“Restriction of dietary salt consumption as a treatment option for hypertension could mean a significant curtailing of iodine intake and hence risk of iodine deficiency,” ​the study’s authors wrote.

Iodine deficiency prevalence

The researchers examined data from the 2001–2004 National Health and Nutrition Examination Surveys (NHANES) for associations between hypertension, salt restriction and iodine deficiency in a sample of 996 men and 960 women.

They found that hypertensive women were more successful than men in restricting their salt intake – with 41.8 percent of women in the study sample who were trying to restrict salt consuming a moderate amount of sodium (2,400mg a day or less), compared to 26.1 percent of men who aimed to restrict salt. More men than women reported restricting salt intake – 13.6 percent compared to 12.8 percent.

Across the study sample, 25 percent of men and 40.4 percent of women were found to be iodine deficient.

“Dietary salt restriction associated with iodine deficiency among women but not among men. Alternative sources of iodine should be suggested to those who need to cut dietary salt for hypertension and for other health reasons,”​ the researchers concluded.

Salt fortification

Iodization of salt was introduced in the United States in 1924 in order to curb iodine deficiency disorders, and was voluntarily taken up shortly afterwards. Today, the Food and Drug Administration (FDA) mandates fortification of salt with iodine in the form of potassium iodide or copper iodide at a level of 0.01 percent.

“Taking cognizance of intake levels, food processing effects, and cooking losses, this level of fortification could contribute about 50 μg iodine to the average person’s daily iodine need of 150 μg,”​ the authors wrote.

Food manufacturers have taken strides to slash sodium from their products in recent years, as they have come under pressure to do so from public health and governmental bodies. An estimated 70 to 80 percent of American sodium consumption comes from packaged foods.

Source: American Journal of Hypertension

October 2010, Vol. 23, No. 10, pp. 1095-1102

“Hypertension, Dietary Salt Restriction, and Iodine Deficiency Among Adults”

Authors: Francis A.K. Tayie and Katie Jourdan

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Food manufactures need law to label iodine content

Posted by Pam_L,


Food manufactures may or may not use iodized salt, the problem is they are not required to tell us. Look at any label and you will see sodium, never iodine. It's a hidden peril for those of us sensitive to iodine. We need just enough, and not too much.

I am a long term Graves' disease patient in a long remission after years of medication and diet modifications. Most peoples bodies store iodine and use it as needed. So fish on Friday and they're good for the week. Keep in mind all foods we eat have varying iodine levels, partly determined by where it is grown ( the iodine content of the soil) and partly by the ability of the individual plant to uptake iodine. Asparagus in the champ in this regard. Iodine content of animals, poultry, and dairy products vary by the diet of the animal and how the product is processed.

As a Graves' patient my body does not store iodine well. If I am accidentally fed a product with hidden iodine my body seems to utilize it right away.... Flushing and heart palpitations . Uncomfortable, but a much bigger problem for those with an iodine allergy, though they tend to need larger amounts to react.

Graves' and Hashimoto's ( hypo thyroid) are autoimmune diseases. Higher the needed iodine intake increases the antibodies and can worsen the condition. Lots of studies over at PubMed to confirm this.

In my experience I can not trust any manufactures to be consistent in the type of salt they use. A product may not cause problems for years.. then a batch appears with hidden iodized salt, then later the same product is safe for me again.

Obviously home cooking only is my answer, but if they were required by law to properly control the type of salt used, and to have accurate labels...we wouldn't be flying blind here. And I would be able to purchase a few of their products once in awhile.

I don't expect this to happen to protect a minatory of people,due to their initial costs , but maybe if the average consumer became more aware of the importance of iodine they could be made to comply with what I view as a basic right to know.

Given the health problems suffered due to lack of such information being available, I'll never understand why at the very least our health care professionals don't seem to care. They certainly have the organizations and money to back up such a request to the FDA.

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Posted by Kenneth Tremble,

There is enough salt in foods we eat without adding salt to it. I am 75 years old and my blood pressure has been below normal all my life which doctor said was normal for me. When I turned 70 it became true normal. When Governments put Sodium Fluoride Pesticide Poison in drinking water, for the first time I had serious medical problems.

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Please confirm or deny

Posted by Maggie Conklin,

I was once told that processed food makers are exempt from using iodized salt, thus leading to the huge number of people with thyroid related diseases today. Since most modern world consumers pass on table salt and get massive amounts of salt from processed foods, they are no longer getting the iodine needed for a healthy thyroid, etc. Can anyone please confirm or deny this please?

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