Problems with Salt (and Iodine)

Nine out of ten Americans eat more than the recommended daily limit of salt, which puts them at increased risk of raised blood pressure, which in turn increases their risk for stroke, coronary heart disease, heart failure, and kidney disease.  A report published in the New England Journal of Medicine quantified the benefits of cutting salt in the diet, and public health officials are planning to push companies to use less salt in processed foods.  (I wrote a blog on this subject in January this year.)

The Journal article produced a response from a trio of thyroid gland experts, who submitted a letter about a possible risk of cutting salt in the diet.  Since 1920 most salt used for human consumption in the USA has contained iodine, in order to help avoid iodine deficiency disorders.  The three members of the American Thyroid Association Guidelines Task Force point out that iodine blood levels in the US population have decreased by 50% in the last thirty years, and reducing salt intake may reduce iodine intake still further.  Pregnant women and infants are the populations most at risk – the unborn child or infant can develop mental retardation.  A deficiency of iodine can cause swelling of the thyroid gland, called goiter; if thyroid gland secretions are affected, this may influence heart rate, nerve response to stimuli, the rate of body growth, and overall metabolism.

It’s clearly important that any public health action to reduce salt intake must be done in a way that maintains iodine intake; a first step would be to require all salt used in processed foods to be iodized.  And pregnant women should have prenatal vitamin supplementation that includes some iodine.