Are You Getting Enough Iodine in Your Vegan Diet?

There is no such thing as a perfect diet. For vegans—and for many omnivores in the US and UK—iodine is one nutrient to watch. If you’re relying on plant-based milk for your iodine requirements, it might be time to consider adding a supplement or iodine-fortified food to your diet.

A recent UK study looked at the iodine in plant milk and found that vegan milks contain far less iodine than cow’s milk. That’s important, because milk is where a lot of people get their daily iodine, but it doesn’t mean that we need dairy to meet our iodine requirements.

Ginny Messina, R.D. explained in an article about the findings that iodine is important because chronic iodine deficiency may impact brain function, and it could raise our thyroid cancer risk. It’s also important for children and pregnant women to get adequate iodine, since deficiency can cause children to have learning and developmental issues.

Cow’s milk is a good source of iodine for two reasons: 

• Farmers supplement cow’s diets with iodine.
• Iodine is an ingredient in cleaners used during the milking process. The iodine from the cleaners leaches into the milk.

In the study, researchers tested 47 different vegan milks and found that only the handful that were fortified with iodine rivaled cow’s milk for iodine.

Cow’s milk is a significant source of iodine in an omnivore diet, so when you go vegan, you can’t just replace cow’s milk with vegan milk and expect to still meet your needs.

Does this study mean that a vegan diet is unhealthy? No. All Americans can benefit from supplements. In fact, omnivores are also often deficient in iodine. Americans have a long history of iodine deficiency, which is why iodized salt is a thing.

HOW MUCH IODINE DO WE NEED?

This chart from the Linus Pauling Institute at Oregon State University shows the recommended daily allowances for iodine, based on age and life stage:

VEGAN SOURCES OF IODINE

There are vegan foods that contain iodine. Like cow’s milk, many of them are fortified:

• sea vegetables (Though this isn’t a reliable source of iodine – you don’t want to rely on sea veggies alone for your daily iodine intake.)
• packaged breads
• iodized salt

Jack Norris, R.D. recommends that vegans take 75-150 µg of iodine every few days. He says that you can take kelp tablets or replace 1/4 teaspoon of your daily salt intake with iodized salt.

According to the American Thyroid Association, it is possible to get too much iodine, though iodine toxicity is pretty rare. The Upper Daily Limit for iodine is 1,100mcg per day. They advise that children should not take iodine supplements containing more than 500mcg per day.