11 April 12 Are You Getting Enough Iodine in Your Diet?

Public health messages about not using the salt shaker have worked. In the United States, the salt shaker no longer accounts for the majority of sodium added to foods at the table. Unfortunately, sodium from iodized table salt has been replaced with sodium from non-iodized salt in processed foods. Too bad – we still have the problem of very high sodium intake yet now we have to consider the possibility of not getting enough iodine.

Why is Dietary Iodine Important?

Iodine deficiency is the most common cause of preventable mental retardation and brain damage in the world. We need to ingest iodine to sustain normal thyroid functioning for growth and development. It is particularly important that children, as well as for women who are pregnant or breastfeeding, get enough iodine to support normal growth and development, especially for the brain. Iodine deficiency in adults can cause hypothyroidism and goiter.

Given the importance of iodine for normal fetal brain growth, I was troubled to read that the Centers for Disease Control (CDC) recently reported that in the United States, iodine intake (as measured by urinary iodine excretion) was lowest among women of childbearing age – that is, women aged 20-39 years. Their intake was just "slightly above insufficient intake." For more information, please see the CDC's recently released executive summary, "Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 2012."

Dietary Sources of Iodine

Although iodine is a mineral that is abundant in the sea, foods from the sea contain varying amounts of iodine. Certain types of seaweed (e.g. kelp), marine fish, and seafood tend to be good sources of iodine. Milk products from animals grazing upon grass from iodine-rich soil will be good sources of iodine but not if the soil is iodine-poor. Same goes for meat. Soil may or may not be iodine-rich – there are "goiter belts" worldwide where the soil is particularly low in iodine - mountainous areas far from the sea are notorious for being poor in iodine.

One of the most simple and cost-effective ways to ensure adequate iodine intake in those without regular intake to marine-based foods is to fortify salt. In the U.S., fortifying salt with iodine is voluntary, not mandatory. Most iodized salt products contain about 60 – 70 mcg of iodine per serving – this provides 40 - 45% of the RDA for adults who are not pregnant or breastfeeding.

Ironically, sea salt is NOT a good source of iodine! However, sea salt fortified with iodine is a good source.

Iodine Requirements

The Recommended Dietary Allowance (RDA) for iodine is 150 mcg for both men and women. Pregnant women need 220 mcg whereas breastfeeding women need 290 mcg.

Before jumping into taking iodine supplements, be aware that too much iodine can be harmful. The Tolerable Upper Limit (UL) for iodine is 1100 mcg for all adult men and women. For teenage girls who are pregnant or breastfeeding, the UL is 900 mcg.

What Should I Do With This Information?

Although the U.S. does not report high numbers of iodine deficiency compared to other nations where access to iodized salt and natural sources of iodine are extremely limited, it is still something to be aware of, especially given the CDC's report of lower iodine intake in women of childbearing age.

If you include a variety of seafood and fish in your diet, consume dairy products and meat from iodine-rich soils, consume seaweed sources known to be high, and use iodized salt or iodized reduced sodium salt, then you are not likely to be likely to be deficient in iodine. However, if you are a woman of childbearing age, then be sure to ask your doctor or nurse regarding adequate iodine status or intake if you are pregnant or planning to become pregnant.

Looking for iodine as a nutrient to track in MyNetDiary? Since there is so much missing data for this nutrient in foods, it is not included as one of the nutrients to track. However, we might be including iodine in future updates – let us know what you think about that.
Katherine Isacks, MPS, RD
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Disclaimer: The information provided here does not constitute medical advice. If you are seeking medical advice, please visit your healthcare provider or medical professional.

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Foods & Recipes/Fish & Seafood Nutrients/Other Vitamins & Minerals Nutrients/Salt/Sodium

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