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Why Oysters Don't Get Hypertension

January 5, 2012 by Joanna Drake, Registered Dietitian

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Why Oysters Don't Get Hypertension

I have an admission to make: I don't know everything. This includes the physiology of oysters, other bivalves, or basically anything that lives in the ocean. This came out rather comically in a recent blog meeting:

Kenton: "Are there foods high in sodium that might be a surprise for people?"

Joanna: "What about seafood?"

Kenton: "Seafood isn't high in sodium."

Joanna: "Even though it lives in salt water?"

Kenton: "So, you're wondering if the salt water acts as some sort of permanent brine?"

We all start laughing.

Andrea: [Coming to my defence…] "Some seafood is high in sodium. I think that's all she's saying."

Dean: [Smirking] "I don't think that's what she was trying to say."

Joanna: "OK Mr. Smarty Pants. How do they get rid of it?"

Kenton: "They have systems." ("Systems" was said with air quotes because Kenton didn't know the details and was trying to be elusive).

Joanna: "Systems?" (I repeat the air quotes).

Kenton: "Yes, systems." (More air quotes. Air quotes are the best).

Joanna: "Oh. Ok. Well – new slant – what if I write about the fact that seafood isn't high in sodium because many people probably think it is?"

So before I wrote this blog I searched Canadian Nutrient File for the actual sodium content of seafood. Perhaps Kenton was right. All the seafood products with the highest sodium levels were those that had been salted, brined or smoked. That's when I found these little nuggets of bragging gold (naturally higher sodium seafood choices):

Food Sodium Content (per 75 gram portion)
Crab, Alaska king, boiled or steamed 804mg
Mollusks, cuttlefish, mixed species, boiled or steamed 558mg
Crab, Atlantic snow crab (spider, queen), boiled or steamed 518mg

Unfortunately for my ego, most seafood is quite low in sodium:

Food Sodium Content (per 75 gram portion)
Mollusks, octopus, common, boiled or steamed 345mg
Lobster, american (northern), boiled or steamed 285mg
Mollusks, mussel, blue, boiled or steamed 277mg
Mollusks, scallop (bay and sea), cooked, steamed 199mg
Shrimp, mixed species, boiled or steamed 168mg
Mollusks, oyster, pacific, boiled or steamed 159mg
Halibut, Atlantic or Pacific, baked or broiled 52mg
Salmon, sockeye (red), baked or broiled 50mg
Tuna, light, canned in water, drained, unsalted 38mg

From a nutrition perspective, this is fantastic. Seafood is a great source of protein, is low in saturated fat and contains varying amounts of omega-3 fats which have a number of positive health functions. Even crab and cuttlefish, which are higher in sodium, can be great choices when you consider the overall context of the meal and pair them with lower sodium options.

So Kenton, I guess most seafood does actually have a "system" for dealing with all that salt in sea water. This is probably why oysters, which have an incredibly stressful job creating pearls, don't get hypertension. I assume we can agree that we were both right on this one?!

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Comments (6)


Posted on Thursday January 5, 2012 a 6:26pm

I've never really thought of this. Great article. I will still eat Alaska King Crab though!!!


Posted on Thursday February 2, 2012 a 9:39am

But I like to dip my seafood in butter. Is butter low sodium? Can I get low sodium butter?

cpetelski's picture

HealthyFamilies BC

Posted on Monday February 6, 2012 a 3:07pm

Thank you for your question. You can get unsalted butter which has only about 2mg of sodium per tablespoon compared to regular, or salted, butter which has about 83mg of sodium per tablespoon. Butter is not only a source of sodium; it's also high in saturated fat, which has been linked with heart disease. For an everyday spreadable fat, the better choice would be a non-hydrogenated margarine which is low in saturated fat and contains no trans fat.

Overall, I recommend that your decisions be informed by the bigger picture of healthy eating. Using regular butter to dip seafood can be part of a healthy diet as long as you keep in mind moderation and frequency - keep your portions small and enjoy this occasionally. Remember that it's what we do most of the time that counts.



Posted on Friday January 6, 2012 a 8:25am

I know your article talks about salt, but can you go more indepth on the other nutrients seafood can provide their benefits, for example omega-3 fats? Also how much seafood should a child eat? I have heard conflicting messages. Thanks.

cpetelski's picture

HealthyFamilies BC

Posted on Monday January 9, 2012 a 10:15am

Thanks Rockstar and rose77. Good question rose77. The benefits of eating fish and other seafood do extend well beyond them being low in sodium. They're good sources of iron and vitamin B12 and excellent sources of protein. As you point out, seafood is often a good source of omega-3 fat and low in saturated fat. The amount of omega-3 fat in seafood varies and is related to the amount of total fat - the more total fat there is, generally the more omega-3 than a leaner piece of fish like halibut or sole.

Canada's Food Guide recommends that we eat at least two servings of fish each week for overall health. There is no specific recommendation for other seafood. Health Canada recommends limiting or avoiding some types of fishes because they are high in mercury. For information about the amount and type of fish to eat to limit mercury intake for both adults and children, please refer to the HealthLink BC File Healthy Eating: Choose Fish Low in Mercury. Joanna


Posted on Saturday January 7, 2012 a 5:43pm

rid of sodium use squeezing the lemon any seafood meal


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