Iodine quick facts
- Iodine is mainly used to make thyroid hormones.
- The thyroid helps to regulate the rate at which your body uses energy. It also plays a role in growth and
- The thyroid helps to regulate the rate at which your body uses energy. It also plays a role in growth and
- You only need very small amounts of iodine for good health. Without iodine your health can be affected over
the long term.
- Iodine is also needed for good mental health, without adequate amounts, mood can be affected.
- Your body does not make iodine so it needs to come from the foods you eat. Most people can meet their
mineral needs by eating a variety of healthy foods.
- The iodine content in foods can vary. The mineral content of foods depends on the mineral content of the soil
where the food was grown or where the animals were raised.
Getting enough iodine is key to achieving and maintaining good, overall health. Below is a list of some of the best food sources of iodine to help you prevent both a clinical deficiency and a functional deficiency. See which ones appeal to you and include more of them in your diet.
9 best foods with iodine
- The best natural occurring source of iodine is saltwater seafood.
- Freshwater seafood also contains iodine.
- Iodine is added to all table salt in Canada. 1 teaspoon of table salt contains 380 mcg of iodine.
- However, iodine is volatile. It’s lost from salt very easily by evapouration.
- If you’ve had your table salt for a while, the iodine content wouldn’t be as high.
- Even if in a sealed container and low humidity, almost 60% is lost after 3 years (1).
- Kosher salt, pickling salt and sea salt are a source of natural iodine but do not contain as much as iodized table salt.
- These salts are not reliable sources of iodine.
1. Seaweed (sea vegetables)
Seaweed is an untapped food source for sure. Seaweed nutrition isn’t talked about much in nutrition and health circles. The oceans are full of them and they are rich in nutrients, not unlike their land-dwelling plant food cousins. Naturally low in calories, seaweed benefits are plentiful. It’s packed with the usual suspects of phytonutrients and antioxidants..
- Nori: nori is the greenish, blackish sheets that sushi is wrapped in. It’s a type of red seaweed and is much lower in iodine than other types. This is a good thing given how much nori is used to make sushi – it would be possible to over do it on the iodine front if you ate a lot of sushi! Nori contains about 16-43 mcg per gram. If you’ve ever watched sushi being made, you’ll have a sense of what a sheet of nori looks like. A typical sheet has about 16 mcg of iodine (1, 2, 3).
- Kombu kelp: this species of seaweed by far has the highest amount of iodine by weight. One, 1 g sheet can have up to 3000 mcg of iodine, an amount that could be a problem for anyone with thyroid issues (4). It can be sold as a dried condiment, or a powder used to make the Japanese stock dashi.
- Wakame: this is typically a staple of miso soup. Wakame is a type of brown seaweed that is slightly sweet. The iodine content depends on where it’s grown; high in Asian countries compared to Australia. On average, 1 g of wakame provides about 66 mcg of iodine. Not too shabby (5).
So, is seaweed good for you and, are seaweed health benefits worth it? In a word YES. The next time you’re an an Asian restaurant, considering ordering a seaweed salad as an appetizer!
Dairy has always been one of the better sources of iodine in the North American diet (6).
The amount of iodine in milk and dairy products can vary depending on what cows eat (7, 8).
There isn’t a mandatory level of fortification for iodine or other nutrients in feed, so the iodine content does differ from brand to brand. Organic milk, or milk from grass-fed cows tends to have less iodine. This is because organic farmers typically don’t use fortified feed and the iodine content of soil is highly variable so the amount of iodine in grass will as well.
One study found that conventional milk had 74% more iodine than the organic counterpart (9).
Another important source of iodine in milk is the use of iodine-containing disinfectants on teats during during the milking process (10, 11).
According to the Canadian Nutrient File, on average, 250 ml (1 cup) of milk has between 52-62 mcg of iodine. Similar findings are found in the USDA Nutrient Database, 1 cup of milk provides about 80 mcg.
Since yogurt is made from milk, yogurt is another decent source of iodine. One cup (250 ml) of plain, low-fat yogurt offers about 75 mcg of iodine per serving.
I bet many of you might not be thinking ‘eggs’ when it comes to iodine but they are a reliable source. Eggs of course offer stellar nutrition including high quality protein, vitamins A, B5 & B12, D, folate, and choline.
Egg yolks are where most of the nutrition is, the white is just protein; half the total amount of protein in an egg. The yolk has the nutrients. Iodine is added to chicken feed and whatever a chicken eats, she’ll concentrate in her egg.
It’s true, the amount of nutrients in chicken feed varies, but in the end, one large egg provides about 50 mcg of iodine (12, 13). If you eat at least 2 eggs at a time like I do, then you’ll etc an impressive 100 mcg of metabolism-boosting iodine.
Prunes!!? Yup, prunes make the list. Why they’re good is because they’re a good source of iodine for those who don’t like seaweed and/or don’t eat a lot of, or any animal foods. Five prunes provides about 13 mcg of iodine (12). You’ll get some iodine while supporting your gut health as well.
6. Cod and haddock
All saltwater fish are good sources of iodine. One country that relied on cod as a staple food source is Iceland. Food analysis from that country indicates that cod is an excellent source of iodine (14).
One, 85 g (3 oz) serving of cod has about 87 mcg of iodine on average or between 63-99 mcg (14). Like the omega 3 content of fish, the amount of iodine in cod can vary depending on whether the fish was farm-raised or wild-caught (12, 14).
Haddock is another white fish that is an excellent source of iodine, like cod, it has 87 mcg of iodine per 85 g serving .
7. Iodized salt
This should be no surprise to anyone. Table salt was iodized in the early part of the twentieth century as a public health measure to prevent overt iodine deficiency called goiter. In Canada at least, even though iodine was recognized as the essential mineral to prevent goiter, mandatory fortification of table salt with iodine didn’t happen until 1949.
Different countries have different standards when it comes to the use of salt in food processing. In Canada, only table salt needs to be iodized, the salt used in food manufacturing, e.g. pasta sauces, breads, cereal bars etc is not required to be iodized. This isn’t the case in Australia for example where they use iodized salt in processed foods.
Iodized salt contains about 71-95 mcg per 1/4 teaspoon which is about half the recommended daily intake of iodine. Because table salt has sodium, many however have been eliminating an important source of iodine from their diets when they avoid salting their foods. Thing is, the pinch or two of table salt isn’t the issue. Excessive sodium comes from canned, instant and packaged foods, condiments etc.
The best thing to do is to include iodized salt in your diet and cut back on your sodium intake in other ways. It’s important to note though, iodine isn’t very stable and the iodine content of table salt diminishes over time (1). It’s better to buy smaller amounts of salt and replenish it more frequently.
8. Salmon (canned)
As a fattier fish rich in omega 3 fats including the forgotten DPA omega 3, canned salmon with bones is rich in nutrients. These include selenium, zinc, iron, vitamins B12, D, magnesium, calcium, choline and phosphorus.
One small, 105 g can (3.7 oz) of salmon has 60 mcg of iodine. If you eat a larger can like I do when I make one of my really large salads, you’ll get a whopping 120 mcg of iodine.
Another great seafood option. Like all seafood, shrimp is a decent source of iodine because of the iodine that is naturally present in seawater (15). Three ounces of shrimp contains 35 mcg of iodine, or 23% of the recommended daily intake (12).
Impact of processing, storage and cooking
For the most part, iodine is stable to storage and many types of processing. Dried seaweeds for example can be stored for a very long time and maintain a relatively stable iodine content.
As rule of thumb, there isn’t any consideration to store iodine rich foods in any special way. It’s stable in canned and frozen foods. If you’re boiling a dried food like cod or seaweed, the iodine will leach into the water which is find if you’re making a stock, soup or stew.
As mentioned, the one exception is table salt. Iodine is a very volatile molecule and it will evapourate. Keeping salt about the store where it can be humid, exposed to the air, will result in a lot of lost iodine. It’s best to keep iodized salt in a sealed, dried container and better still to buy smaller amounts of it more often.
How much iodine do you need?
Age in years
|Aim for a minimum intake* of micrograms (mcg) per day||Upper Level considered safe* mcg per day|
Birth to 6 months
Men & women 19+ years
Pregnant women 19 and older
Breastfeeding women 19 and older
*This includes sources of iodine from food and supplements.
Risk of iodine deficiency
Clinical iodine deficiency is rare in most Western countries. This is not the case for a lot of the world (1). To make matter worse, Rates of iodine deficiency have increased fourfold over the past 40 years according to the World Health Organization.
Interestingly, given how much iodine was used in food processing in the past, some estimates are that North Americans used to get about 800 mcg of iodine per day. This is much less than we do today, making for a potential public health problem.
Those at the highest risk include (16, 17, 18):
- People living in regions with iodine-poor soils. This includes South Asia, Southeast Asia, New Zealand and European countries.
- People with marginal iodine status who eat foods with goitrogens
- Those who don’t use iodized salt (this includes sea salt, Himalayan salt)
- Pregnant women
- Breast-fed and weaning infants
- Breast-feeding women
- People on special diets
- Those with poor quality diets (a.k.a. highly processed)
- People who follow a vegetarian or vegan diet.
On the other hand, clinical iodine deficiencies are rare in North America. This is because there are sufficient levels of the mineral in the food supply (5). Having said that, many still don’t get an optimal amount of iodine and don’t reap all of its benefits. Are you aware the signs and symptoms of iodine deficiency?
Getting more foods with iodine is easier than you think. Where most of us miss the mark is consistently choosing nutrient-dense foods. Unfortunately, we are surrounded by highly-processed foods so foods rich in iodine can take a back seat in the name of convenience.
With a few easy and simple tweaks, you can up your game and give your body, brain and thyroid the iodine they need for long term health and well-being.
Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, mental health. Follow me on Facebook, Instagram and Twitter.