by Nikki Machin

The World Health Organisation (WHO) recommends that adults get 150 µg of iodine daily, but how can you make sure you’re getting enough? And why do we even need it at all?

Iodine is the key ingredient to thyroid hormones. If your iodine levels are depleted, or too high, you’ll run into issues with your thyroid.

Your thyroid affects your metabolism, thermoregulation, heart rate and energy use. If you aren’t getting adequate amounts of iodine, your energy slows down, you gain weight despite eating healthily, and you can even start losing your hair.

If it gets really bad, your thyroid gland will grow, causing pressure on your chest and lungs. This can look like an enlarged throat (goitre), bulging eyes, and shortness of breath.

Iodine deficiency used to be much more widespread. Public health interventions practically eliminated iodine deficiency for a while, and yet now, so many struggle with these problems. With changing dietary trends, we’re actually beginning to see an increase in iodine deficiency.

So, let’s take a minute to sort this out.

First, you need to know where it comes from.

Dietary sources of iodine

Iodine comes from the ocean; specifically, seaweed. You can find it in some other sources as well, like fish and other seafood, or vegetables grown in iodine-rich soil (coastal regions). Dairy and salt are also frequently enriched with iodine.

And if you’re lucky enough to live near a thriving kelp forest, you might even be able to reach your recommended intake simply by breathing in the fresh sea air [https://link.springer.com/article/10.1007/s10653-011-9384-4]!

Seaweed

But what’s the best source? Well, the best source is whichever one you’ll actually eat. But if you’re willing, it’s best to go straight to the source: seaweed [https://pmc.ncbi.nlm.nih.gov/articles/PMC8077470/ ].

Now, the most important thing to note is that iodine levels vary WIDELY across seaweeds. If you just snack on some nori every once in a while, you’re not going to get enough. You would need to have at least two whole sheets of nori every day to get enough.

By contrast, kombu, which is a brown kelp, contains hundreds of times more iodine than nori. A little goes a long way. Toss a few chunks into your soups and stews to add a wonderful umami dimension of flavour while also loading up on your iodine.

Fish and Crustaceans

Getting your iodine from fish requires eating fish about twice per week, but only if the fish are saltwater fish. Freshwater fish will not have the same levels of iodine. We also see higher levels of iodine in wild vs farmed fish.

Shellfish, particularly crustaceans, are the highest source of iodine in fish, but even with that, you’d have to eat about 20 shrimp to reach your iodine intake for one day.

But what if you don’t like seafood or umami flavour?

Dairy

In many countries around the world, iodine is also found in dairy products. This comes from a combination of factors, including variations in feed and sanitation procedures, like using iodine as a disinfectant for teat dipping. But it varies quite a bit from country to country and can even vary according to season. [https://www.sciencedirect.com/science/article/pii/S0308814624020387 ]

Those who used to get their iodine intake from dairy will need to find other sources if they have replaced traditional dairy with plant-based alternatives. Some plant-based dairy is fortified with iodine, but not many.

Salt

The easiest way to ensure you’re getting enough iodine every day is to use iodised salt in your home cooking. All you need is about half a teaspoon (or a little more) of iodised salt each day. That’s it. Easy.

Iodised salt was once the most successful nutritional intervention in the world. Many populations suffered from goitre, and this innovation solved it. Over time, speciality salts became trendy, and many stepped away from iodised salt. As a result, we are now seeing a rise in iodine deficiency.

Salt in processed foods rarely, if ever, is iodised. Whole food living means you get less salt from processed foods, and have more room for adding iodised salt and controlling your intake of both salt and iodine. Ourdaily intake of salt is about a teaspoon per day. If you make sure that half of that intake is iodised salt in your home-cooked meals, you’re good to go!

Extra factors

What if you’re eating enough iodine, but you’re still noticing signs of deficiency? Well, there are actually a few key reasons this might happen.

Iodine receptors will also bond to other elements in the halogen group. While there are several sources of these elements in our environment, the biggest source is our drinking water.

Fluoride in toothpaste is fantastic for maintaining dental hygiene, but it’s not necessary to add it to drinking water. Some places started adding it as a precaution for dental hygiene, but the benefits aren’t really as robust as anticipated.

Chlorine is an essential additive to clean away contaminants from our water. Too much of it in our bodies, though, can impact your iodine absorption. Simply allowing your water to sit and off-gas for 12-24 hours will reduce the levels of chlorine entirely. A more permanent solution is to invest in a water softener. Try it out and see if it helps.

Just right

Remember: you don’t want too much, either! Don’t go out and consume an entire package of kombu in one sitting. A small 50g bag of kombu can contain up to 1000 doses! That’s enough to last you years.

Take stock of how you feel and how you look. Notice the state of your neck and your ability to regulate your temperature and weight. If you think something is off, talk to your doctor and get your thyroid examined.

And maybe have a little iodised salt on hand, just in case.

FOOTNOTE: Mandatory fortification of iodine in commercial bread began in New Zealand and Australia in 2009.