I call iodine the forgotten nutrient as it doesn’t get talked about much!
Why is iodine important?
Iodine is crucial for the production of thyroid hormones involved in metabolism and proper development, but, it’s a fine balance. Too much or too little iodine can result in thyroid issues.
Iodine is particularly important for women who are pregnant as it is a critical nutrient for proper brain development of a baby in utero.
Traditional and well known sources of iodine include fish, seafood and dairy. But what about plant-based sources?
Although iodine deficiency is not common in North America, vegetarians and vegans in particular, are at a greater risk of developing a deficiency.
How much iodine do we need in a day?
What foods contain iodine?
- 1 sheet seaweed (nori or kelp), 16-2984 mcg
- Kombu (kelp)
- 1/4 tsp iodized salt, 85 mcg
- 1/4 cup soynuts, 60 mcg
- 1/2 cup cooked corn, 7 mcg
- 3/4 cup beans (navy, black-eyed), cooked, 46-53 mcg
- 3/4 cup beans (pinto, kidney), cooked, 19-28 mcg
The best naturally occurring source of iodine is saltwater seafood. As you can see above, sea vegetables like seaweed can be good sources of iodine as well, but the actual amount of iodine in them varies considerably.
For land grown foods, how much iodine is found in the food actually depends on how much iodine is in the soil that the food was grown in, or the food that the animals eat!
Today, for those following a 100% plant-based diet, iodized salt is the most reliable source of iodine.
All table salt in Canada is fortified with iodine, in fact 1 tsp of iodized salt contains about 380 mcg, 2.5x the recommended amount!
Sea salt or Himalayan salt does have some naturally occurring iodine, but not as much as iodized salt. Check the label of your salt to see if it is iodized or not.
What can interfere with iodine uptake?
You may have heard the term goitragen before, but what is it?
Goitrogens are substances that interfere with iodine uptake by the thyroid glands and can disrupt proper thyroid hormone production!
Goitrogens are found in cruciferous vegetables like cabbage, broccoli, cauliflower, kale, arugula, Brussels sprouts, watercress and radishes.
But not to worry, if you have adequate iodine intake and you eat a varied diet, eating foods that contain these goitrogens should not be a concern.
Should you take an iodine supplement?
In Canada and the United States, it is recommended that women who are pregnant or breastfeeding supplement with at least 150 mcg iodine every day. Most prenatal vitamin and mineral supplements in Canada do have iodine in them to cover your needs! Many of the prenatal supplements that I have looked at contain the recommended daily allowance (RDA) of 220mcg.
If you are not pregnant or breastfeeding and consuming a varied diet with iodized salt and/or using sea vegetables regularly, you likely don’t need to supplement.
I would recommend talking to your primary care provider or dietitian about supplementing with iodine if all of the following three points apply to you:
(1) You are 100% plant based and avoids processed foods
(2) You do not add salt to your diet
(3) You avoid consuming seaweed or seaweed based products.