Salmon Contains Iodine, But Some Fish Pack A Lot More

Salmon may not be the best dietary source of iodine, but it can still make a valuable contribution to the average person's iodine intake. Not least because it's so common in the American diet. But how much iodine does this dinnertime favorite actually contain, and how does it compare with other fish? HealWithFood.org investigates.

Iodine in salmon

Unprocessed foods, whether plant- or an animal-based, rarely contain consistent levels of iodine. Salmon is no exception, with amounts varying considerably from one fillet to another.

One of the main factors influencing the iodine content of salmon is the diet of the fish [1]. In the wild, salmon love to eat krill and other tiny crustaceans like shrimp, which happen to be excellent sources of iodine. Larger salmon also eat smaller fish, many of which are naturally rich in iodine. On the other hand, salmon also feed on insects and other foods that may not provide much iodine.

How much iodine the fillet in front you contains is directly linked to what was on the salmon's menu before it landed on your plate.

Like wild salmon, farmed salmon can have varying levels of iodine depending on the iodine content of their diet. However, in the case of farmed salmon, the fish aren't feeding freely but instead, their diet it controlled by the farmer. Farmers can boost the iodine content of their fish by adding iodine-rich ingredients like marine algae to the feed [2–4].

The problem is, from a consumer's perspective, that the ingredients in salmon feed aren't consistent across farms, so the iodine levels can vary, too. Usually, salmon feeds contain some marine-based ingredients such as fishmeal or fish oil, but they may also contain varying amounts of plant-based ingredients like soy, corn, or legumes, which are low in iodine. As a shopper, you never know exactly what the farmed salmon on your plate was fed.

The good news is that, on average, wild and farmed salmon don't seem to differ dramatically in their iodine levels. In one study, wild Atlantic salmon averaged 17 micrograms of iodine per 100 grams, while farmed Atlantic salmon provided 13 micrograms [5].

What stood out, however, is the much greater variation between the farmed fish samples than the wild ones, with values ranging from 5 to 34 micrograms for farmed salmon and from 12 to 23 micrograms for wild salmon [5]. Though the authors didn't speculate on the reasons behind the wider range of values in the farmed salmon, it probably comes down to differences in feed: some farmers use more marine-based feeds which supply ample iodine, while others rely more on plant-based feeds.

Now that we have an idea of how much iodine salmon contains, let's put it in perspective. The Recommended Dietary Allowance (RDA) for iodine is 150 micrograms per day for most adults, while pregnant and lactating women typically need more—about 220–290 micrograms per day [6]. With an average fillet of Atlantic salmon containing around 15 micrograms of iodine per 100 grams (a weighted average combining wild and farmed salmon), you'll get a decent dose of iodine from a regular serving of salmon—but it won't cover the full requirement on its own. Including other iodine-rich foods such as dairy, eggs, seaweed or other fish can help you meet your daily requirement.

It's also interesting to see how salmon stacks up against other types of fish in terms of iodine content. While salmon provides a moderate amount, some fish—like haddock and cod—contain many times more iodine. In fact, by eating just one serving of haddock, you'll likely exceed your daily iodine needs. On the other hand, freshwater fish tend to be low in iodine and often contain much less of this vital nutrient than your average fillet of salmon.

To help you visualize how different fish compare, we've created a chart showing the iodine content of salmon versus other commonly eaten fish species:

Chart comparing iodine content of salmon vs other fish

The values are averages based on multiple samples consisting of the raw, edible flesh portion of the fish. The chart was created by healwithfood.org by compiling and adapting data from M. Sprague et al. and Public Health England [5, 7].

If you're more of a numbers person, here are the average iodine content of salmon vs other selected species in mcg per 100 grams:

  1. Haddock: 427
  2. Sardines: 79
  3. Cod: 71
  4. Pollock: 57
  5. Salmon: 15
  6. Rainbow trout: 12
  7. Tuna: 10
  8. Pangasius: 3

The value for salmon listed above is the weighted average calculated from multiple samples of different types of wild salmon (Sockeye, Atlantic, Keta, and Pink salmon) and farmed Atlantic salmon. If you're curious about how the different species stack up, here's an overview of the average iodine contents of different types of salmon:

Chart showing iodine contents of different types of salmon

The chart above was created by healwithfood.org from data adapted from M. Sprague et al. [5].

To sum up, salmon may not be the iodine champion at the fish counter, but it still contributes to your intake. And if you also include other iodine-containing foods in your diet, you can easily meet your daily needs naturally.

Plus, the fact that salmon doesn't contain excessive amounts can actually be a good thing because iodine is one of those nutrients you can get too much of. A high consumption of iodine-packed seaweeds, for example, has been associated with thyroid problems [8, 9].

Iodine aside, salmon provides plenty of other nutrients such as high-quality protein, carotenoids and, of course, those much-needed omega-3 fatty acids. In fact, it belongs to the special group of fish that are rich omega-3s but low in mercury. So, whether you're looking for a natural way to nudge your iodine intake up, or just want to eat more nutritious seafood, salmon stands out as an accessible, affordable, and versatile food choice that can be enjoyed in countless ways.

References

  1. K. Julshamn et al (2006). A preliminary study on tailoring of fillet iodine concentrations in adult Atlantic salmon (Salmo salar L.) through dietary supplementation. Aqualculture Nutrition.
  2. L. Valente et al (2015). Iodine enrichment of rainbow trout flesh by dietary supplementation with the red seaweed Gracilaria vermiculophylla. Aquaculture / ScienceDirect.
  3. R. Ribeiro et al (2015). Dietary macroalgae is a natural and effective tool to fortify gilthead seabream fillets with iodine: Effects on growth, sensory quality and nutritional value. Aquaculture / ScienceDirect.
  4. S. Schmid et al (2003). Marine algae as natural source of iodine in the feeding of freshwater fish: A new possibility to improve iodine supply of man. Revue de Médecine Vétérinaire / CABI Digital Library.
  5. M. Sprague et al (2022). Iodine Content of Wild and Farmed Seafood and Its Estimated Contribution to UK Dietary Iodine Intake—Supplement. Nutrients, 14(1), 195.
  6. National Institutes of Health (2025). Iodine. Fact Sheet for Health Professionals. U.S. Department of Health & Human Services.
  7. Public Health England (2021). Composition of foods integrated dataset (CoFID).
  8. Crawford et al (2010). Iodine toxicity from soy milk and seaweed ingestion is associated with serious thyroid dysfunction. The Medical Journal of Australia, 193(7):413-5.
  9. Blikra et el (2024). Consequences of acute and long-term excessive iodine intake: A literature review focusing on seaweed as a potential dietary iodine source. Comprehensive Reviews in Food Science and Food Safety.