Adequate iodine intake is important for proper thyroid function. It can be easy to get from iodized salt and seaweed, but vegans still tend to be deficient. Given the importance of iodine during pregnancy and breastfeeding, it is recommended to supplement with 150 mcg per day.
What is iodine and why do I need it?
Iodine is a mineral that is critical in the production of thyroid hormones, which influence reproductive, metabolic, and nervous system functions – just to name a few. It is found naturally in some food, but the amount is highly variable depending on the location where it is sourced.
During pregnancy, thyroid hormones play a critical role in the brain and bone development of the baby. Iodine intake is also important for breastfeeding women. Even mild deficiencies in utero and in infancy can impair cognitive abilities of the baby .
How much iodine do I need?
The Recommended Dietary Allowance (RDA) from the National Academy of Medicine (NAM) is :
- Women over the age of 14: 150 mcg per day
- During pregnancy: 220 mcg per day
- While breastfeeding: 290 mcg per day
The Upper Intake Level (UL) for everyone over the age of 18 is 1,100 mcg per day.
Can I get enough iodine from food?
Iodine intakes vary drastically between individuals, depending on their food choices. On one hand, a diet high in processed foods is likely to be iodine deficient, since those foods typically do not use iodized salt . On the other hand, some healthy foods including cruciferous vegetables (such as broccoli, cabbage, and spinach), flax seeds, and soy contain goitrogenic compounds that can interfere with iodine absorption in the thyroid . To be clear, this does not release you from eating a healthy diet but emphasizes the fact that you should consume enough iodine.
Due to the risks of iodine deficiencies, many countries fortify salt with it . In the US, about a half of a teaspoon of iodized salt contains 150 mcg of iodine. Be aware that many other options such as sea salt and Himalayan salt do not have much iodine if any.
Seaweed is another great option, but the amount of iodine varies based on the type and location where it’s grown . For example, you can meet your daily iodine needs with just a few sheets of nori (37 mcg/g), the seaweed used for sushi . Wakame, often used in salads and miso soup, has about 140 mcg/g .
There are many healthful properties in seaweed, but a few types should be avoided altogether. Kelp, also known as kombu, contains an average of 2523 mcg of iodine per gram, which is far greater than the recommended limit . Another one to avoid is hijiki because of its high arsenic levels .
A plant-based diet can provide sufficient sources of iodine, however, studies show that vegans tend to be deficient in this critical nutrient . Oddly enough, this may be a result of the health-conscious diet that is low in salt and high in cruciferous vegetables.
Should I supplement with iodine?
Given how critical iodine is for baby’s development, the American Thyroid Association recommends that all pregnant and nursing women supplement with 150 mcg per day . Despite this, only about half of the prenatal supplements in the US contain iodine, so be sure to check the label.
Another study showing iodine deficiencies in vegans recommends that all vegan women who could become pregnancy supplement with 150 mcg per day .
Vegan Prenatal Supplements with Iodine
My top 2 prenatal supplement recommendations are Dr. Fuhrman’s Gentle Prenatal and Ritual’s Essential Prenatal. Both contain 150 mcg of iodine and in combination with iodine-containing foods, your daily needs should be met without exceeding the upper intake level.
- Women should consume 290 mcg of iodine per day if nursing, 220 mcg per day if pregnant, and 150 mcg otherwise.
- Iodized salt and seaweed such as nori and wakame are great sources of iodine, but kelp (kombu) and hijiki should be avoided.
- Vegans tend to be deficient in iodine and should supplement with 150 mcg per day, especially if pregnant or nursing.