Not surprisingly, in the past few days, I’m getting numerous questions about which foods are a good source of iodine. With recent unfortunate events in Japan, many are concerned about the effects of radiation on their health and are interested in knowing how iodine might help protect against thyroid cancer. Whether we are in any real danger or risk of radiation exposure in the United States today, the truth is, the American diet is lacking iodine anyway.
Why is Iodine so important? Iodine is a mineral that is essential for proper thyroid function. Iodine, when combined with the amino acid tyrosine, produces vital thyroid hormones that control our metabolism, enzyme and protein synthesis, and are essential in the development of the skeletal and central nervous systems of developing fetuses.
Iodine deficiency Fortification of salt with iodine occurred in 1924 when we were experiencing an epidemic of “goiters” or enlarged thyroid glands. Thyroids become enlarged in an effort to absorb more iodine from the bloodstream. Besides hypothyroidism and goiters, iodine deficiencies have been linked to mental retardation and neurodevelopmental disorders in children, mental and physical impairment in adults, increased risk of thyroid cancer, and some research suggests that there may be a link between iodine deficiency and fibrocystic breast disease.
Food sources Iodized salt, for the most part, is the main source of iodine in our diet. Table salt usage is decreasing and with our new dietary guidelines encouraging less table salt consumption, we are at risk of inadequate iodine intake. So, where else can we get iodine in the diet?
The present Dietary Reference Intake for most adults is 150 mcg and below is a chart showing the richest food sources to meet that need. Besides iodized salt, you will see that sea vegetables are an amazing source of iodine yet are under utilized as a dietary staple in the United States. The good news is, unlike potassium iodine supplements, it is unlikely that there will be a shortage of sea vegetables anytime in the near future as there is virtually an endless supply in the sea.
So why aren’t more people eating sea vegetables? Truth be told, they taste terrible by themselves. However, made properly, you would be surprised at how good they taste!
|Seaweed, whole or sheet, 1 g||16 to 2,984||11% to 1,989%|
|Cod, baked, 3 ounces||99||66%|
|Yogurt, plain, low-fat, 1 cup||75||50%|
|Iodized salt, 1.5 g (approx. 1/4 teaspoon)||71||47%|
|Milk, reduced fat, 1 cup||56||37%|
|Fish sticks, 3 ounces||54||36%|
|Bread, white, enriched, 2 slices||45||30%|
|Fruit cocktail in heavy syrup, canned, 1/2 cup||42||28%|
|Shrimp, 3 ounces||35||23%|
|Ice cream, chocolate, 1/2 cup||30||20%|
|Macaroni, enriched, boiled, 1 cup||27||18%|
|Egg, 1 large||24||16%|
|Tuna, canned in oil, drained, 3 ounces||17||11%|
|Corn, cream style, canned, 1/2 cup||14||9%|
|Prunes, dried, 5 prunes||13||9%|
|Cheese, cheddar, 1 ounce||12||8%|
|Raisin bran cereal, 1 cup||11||7%|
|Lima beans, mature, boiled, 1/2 cup||8||5%|
|Apple juice, 1 cup||7||5%|
|Green peas, frozen, boiled, 1/2 cup||3||2%|
|Banana, 1 medium||3||2%|
*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for iodine is 150 mcg for adults and children aged 4 and older. However, the FDA does not require food labels to list iodine content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
Photo generously provided by Kok Robin (my sincere apologies for previously omitting this credit)
Kombu is known as the “king of seaweeds” and is one of the richest sources of iodine out of all of the sea vegetables. It is an essential staple in the Japanese diet and is used to make Dashi (stock) and has a wonderful Unami taste. It can also be rehydrated and chopped up and added to stews, soups and casseroles. A strip of it added to a pot of beans, while cooking, reduces gas-producing raffinose.
Here is a traditional Japanese recipe that features kombu called Tsukudani. It is basically a kombu side dish that can be added to rice or eaten by itself. Enjoy!
- 1 oz. kombu, hydrated
- 1 tbsp sake
- 1 tsp rice vinegar
- 1 tbsp sugar
- 1 tbsp lite soy sauce
- 1/2 tsp. toasted sesame oil
- 1 tsp black or white sesame seeds