Does Canned Salmon Have Iodine? A Guide to Getting Your Iodine Fill from Seafood

As a seafood lover and health-conscious home cook, I’m always trying to find ways to incorporate more fish and shellfish into my weekly meal planning. Not only are finfish and shellfish delicious, they are packed with important nutrients like protein, omega-3s, vitamin D, selenium and iodine.

Results and Discussion

We looked at 95 different kinds of seafood for this study and listed their iodine levels in descending order below. Iodine concentrations (mean ± SD) ranged from 2. 97 ± 1. 58 µg·100 g−1 flesh ww in common carp (Cyprinus carpio) to 427. 4 ± 316. 1 µg·100 g−1 flesh ww in Atlantic haddock (Melanogrammus aeglefinus). Overall, the samples that were looked at had mean and median iodine levels that were pretty close to each other. This means that there wasn’t much difference in the iodine levels (see Table S1 for values). However, large differences in iodine levels have been seen between individuals of the same species [1,38,40,51,52], and this study is no different. In particular, haddock (427. 4 and 323. 3 µg·100 g−1 flesh ww, mean and median, respectively), flathead grey mullet (Mugil cephalus, 52. 2 and 21. 9 µg·100 g−1), wild turbot (Psetta maxima, 52. 0 and 34. 6 µg·100 g−1), Atlantic mackerel (Scomber scombrus, 34. 4 and 23. 3 µg·100 g−1), Atlantic herring (Clupea harengus, 30. 4 and 16. 8 µg·100 g−1), Atlantic razor clam (Ensis ensis, 26. 9 and 15. 7 µg·100 g−1), lemon sole (Microstomus kitt, 26. 1 and 15. 5 µg·100 g−1), and sockeye salmon (Oncorhynchus nerka, 24. 9 and 13. 3 µg·100 g−1) all exhibited sizeable differences between their respective mean and median values. There are several factors that may account for differences between individuals of the same species. Location (fishing ground) may play a role in explaining any differences within the species, since the amount of iodine in seawater changes with depth and location [24,25]. Iodine can be found as iodate (IO3−), iodide (I−), or small amounts of dissolved organic iodine. Thus, identifying fishing grounds allows for direct comparisons between data to be made while minimising potential misinterpretation. For example, Nerhus et al. It was discovered that Atlantic cod (Gadus morhua) and pollack (Pollachius pollachius) from the North Sea had lower amounts of iodine than fish caught in the Norwegian and Barents seas and/or Norwegian fjords [40]. Based on the current findings, the 76. 1 ± 24. The 7 µg·100 g−1 value found in pollack that was caught in the North Sea (FAO Fishing Area 27, subarea IV) is within the normal range, though a little lower than the mean value reported for other North Sea pollack, which is 210 µg·100 g−1 [40]. If you compare the current value to the much higher mean value of 790 µg·100 g−1 reported for pollack from all North East Atlantic fishing areas (FAO27) [40], you might think that the difference is due to a mistake, like when the samples were being analyzed. Cod from this study, on the other hand, was said to have been caught in the Barents, Norwegian, and North Seas, as well as Iceland (FAO27 subareas I, II, IV, and V, in that order), but the iodine level (70%) was not clear. 7 ± 19. 0 µg·100 g−1) more closely resembled the value observed by Nerhus et al. [40] for cod caught in the North Sea (96 µg·100 g−1) than in the Barents or Norwegian seas (400 and 250 µg·100 g−1, respectively) or compared to the average value of all three fishing grounds (190 µg·100 g−1). Such differences in the amount of iodine in the same species’ bodies may also be caused by the food that is available [51]. The season has the most impact on a fish’s health and nutrition because it changes when food is available and how many fish can reproduce [53]. Delgado et al. [38] discovered that sardines (Sardina pilchardus) and mackerel bought from Portuguese markets had higher amounts of iodine in the summer and fall than in the winter and spring. Similarly, Nerhus et al. [40] found higher amounts of iodine in haddock that were caught later in the year. They thought this was because the elements were being replenished after the spawning season in April and May. Samples for this study were bought at different times of the year when it was possible to do so. However, some species are only sold when they are in season. Additionally, wild fish that is usually sold all year in the UK, like cod, mackerel, herring, and all species of Pacific salmon, will have been stored (deep freeze) for an unknown amount of time before being sold. Because of this, the iodine content will not necessarily reflect the time when the sample was bought and may even go down during the thawing process [54]. No matter if the differences are within or between species, this study shows the range of iodine levels found in seafood that UK consumers can buy.

All samples used in this study came from stores and fishmongers, the same places that people normally buy seafood. For many larger species, portions rather than whole fish or whole-side fillets are typically sold. It is known that the fillet of some fish species has different amounts of other nutrients, like lipids [55,56], which could make things more difficult. However, Karl et al. [52] looked at cod fillets from the left and right sides, the dorsal and ventral sides, and the head and tail sides and found no difference in the amount of iodine present. Instead, the same authors found that fish skin had up to 20 times more iodine than fish muscle, with iodine levels decreasing from the skin to the inner part of the fillet closest to the backbone. Because of this, the dark muscle, which is close to the skin, has been found to have more iodine than the white muscle [54]. All of the samples in this study were skinned before they were analyzed because not everyone eats the skin and many portions or fillets are sold without the skin. Nonetheless, muscle from the entire portion, including red muscle, was taken and blended to ensure a homogenous sample. As a result, samples may have less iodine than if the skin had been left on, but they are still comparable because all of them were prepared the same way.

Overall, marine species had higher iodine levels than freshwater species when it came to seafood groups. This supports what other studies [16,38,39,40,57,58] have found. After taking into account the fact that the data was not normally distributed across the different species in each seafood group, the geometric mean showed that the iodine levels were in the following order: shellfish (39 3 µg·100 g−1) > marine fish (19. 8 µg·100 g−1) > freshwater fish (6. 4 µg·100 g−1) ( ). Fish obtain iodine through gill and intestinal uptake [3]. Freshwater usually has a lot less iodine than saltwater, so the amount of iodine in fish is mostly the same as the amount in the water they live in [39,57]. Correspondingly, the two lowest ranking species, common carp and Nile tilapia (Oreochromis niloticus), were both freshwater fish. Of the marine fish, the top 8 species were all whitefish belonging to the Gadiformes (e. g. , haddock, cod). Only the two hake species, European hake (Merluccius merluccius) and Cape hake (M. capensis), failed to replicate the high iodine contents measured in the other Gadiformes (range 54. 9–427. 4 µg·100 g−1, ling (Molva molva) to haddock, respectively) containing levels of 13. 8 ± 8. 0 and 9. 7 ± 4. 9 µg·100 g−1, respectively, which were similar to values reported elsewhere [59,60]. It has been said that whitefish and other lean fish have higher iodine levels than oily fish [15,37,40,51,58]. It was found that lean fish had higher iodine levels than oily fish, but there was no overall link between lipid and iodine levels (r2 = 0). 0033, data not shown) in the present study. This might be because the current study looked at a lot of different types and amounts of samples. The data could be messed up because it included farmed, wild, freshwater, marine, and shellfish fish. But there was no correlation (r2 = 0) even when the data were split up to only look at wild marine fish species. 0019, data not shown). Aside from that, it’s not clear why iodine levels can be different in different fish species. It could be because of differences in the prey they eat and/or their own metabolism. Separating the shellfish into sub-groups revealed that crustaceans (60. 3 µg·100 g−1) contained the highest overall iodine contents of any group. Of the molluscs (31. 9 µg·100 g−1), bivalves (48. 3 µg·100 g−1) contributed more iodine than cephalopods (8. 9 µg·100 g−1). Most of the samples were tested while they were still raw, but many of the shellfish products were sold already cooked. Blue mussels (Mytilus edulis) were the only species whose raw and cooked products were both tested. The cooked product had more iodine than the raw (157). 6 ± 86. 6 µg·100 g−1) than raw (104. 8 ± 43. 9 µg·100 g−1). Although the origin of the mussels were different (i. e. There were differences between the types of fish (raw, farmed, and cooked), but the results were what we expected because cooking doesn’t have a big effect on the amount of iodine that is lost, but high moisture losses during cooking do make the iodine concentrations higher per weight [54].

When it came to where the seafood came from, wild seafood usually had more iodine than farmed seafood, but mussels and oysters that were not fed were an exception (and). Fish and prawns that are raised in farms are usually fed diets that are specially made to meet their nutritional needs [61]. But bivalves that are raised in farms get their nutrients from plankton, diatoms, and other small particles in the water. So, the makeup of bivalve species like oysters, mussels, and scallops depends a lot on the natural food that they can find, which changes depending on where they live [62]. Nonetheless, comparisons between wild and farmed seafood should be restricted to the same species or their closest counterparts.

Materials and Methods

A total of 95 different seafood samples comprising fresh and/or frozen fish and shellfish (crustaceans and molluscs)

The Untold Truth Of Canned Salmon