One of the staple proteins of a sensible low carb diet has always been fish. One of the best food sources for important nutrients, such as omega fats, is fish. But all the bad news about PCBs, heavy metals, and other toxins found in fish makes you pause to reconsider the wisdom of enjoying them very often, whatever the weight loss, brain health, or cardiovascular benefits might be. After all, you can get protein from other less toxic sources–pasture-fed beef and lamb, natural chicken and pork, cage free eggs. And you can get purified omegas from both marine and farmed algae sources and not have to worry about the contaminants.

But, doggone it, if you like fish (and I do) how can you reconcile feasting on them in good conscience?

With these thoughts in my head, I happened to be sorting through the big bags of literature that Mike and I lugged home from the big Natural Foods Expo West that we attended in March, when I stumbled onto a handy little wallet sized card I’d picked up at the Nordic Naturals booth. (Nordic Naturals is a company that makes a really high quality line of fresh, pure omega-3 supplement products for adults and kids–free of heavy metals, dioxins, and PCBs.) The card they were handing out contains a quick reference to the mercury levels found in all the fish we typically consume as food. It avers that its data came from the Natural Resources Defense Council or NRDC, so I clicked onto their website, which indeed contains the same helpful groupings of fish by ‘Highest” “High” “Lower” and Lowest” mercury content and a whole lot more fish and shellfish info. Their data, so they say, comes from tests conducted by the FDA.

I was gratified to see that some of my favorites are in the lowest category: Anchovies, calamari, caviar, spiny lobster, oysters, and sardines. I admit that I was secretly pleased to see mackerel in the “Highest – Avoid Eating” category, since I don’t especially like mackerel and now I have a good reason to eliminate it from my sashimi combo in the future. Sadly, other of my favorites–Maine Lobster and Tuna–were in the “High” category.

I suppose I can take some small measure of solace that my beloved lobsters weren’t in the very highest category. That’s not to say I won’t eat them now and again, because my love of eating a big, hot, Maine lobster with the butter dripping down my chin and onto my lobster bib is legend; I enjoy one every time we visit Maine and intend to continue to do so. Fortunately, we don’t travel to Maine as often as we once did, so my heavy metal exposure will have a limit. If I lived on the coast of Maine, I fear I would probably have destroyed my brain with mercury long go.

In the meantime, thanks to this info, I can order up a plate of oysters on the half shell and pile extra anchovies on my Caesar salad with a clear conscience.


  1. I live in Maine and have done for many years now. I seldom (as in almost never) eat lobster. Isn’t that a sad state of affairs???

    COMMENT from MD Eades: But perhaps at least a more prudent state of affairs, at least from a mercury avoidance perspective. Still…there’s not much tastier than a piping hot whole Maine lobster with lemon and drawn butter.

  2. I feel a bit awkward about these supplements with fishoil.

    Maybe it?s not just about how much heavy metals there in the oil.

    What happens to the fragile omega-3 acids when they
    manufactor it. Mayby it?s not so healthy after all.

    If they heat it up part of it could change into transacid fat (If thats what it?s called in English Im Swedish by the way)

    I tend to eat a lot of salmon from Norway. The fish is not freecatched but very tasty. The manufactors say its very low in metals..but that ofcourse depends of what they feed them and thats not so easy to check..

    COMMENT from MD EADES: You bring up a good point, that fish oil, to be healthy, has to be of really good quality. Reputable manufacturers (Nordic Naturals, for instance) tests their oil to be sure it is free of oxidized or peroxidized fats and toxins. It’s important to check with the manufacturer to find out the quality control methods used to insure a pure and healthy product.

    As to what determines the heavy metal contamination in the fish themselves, in farmed salmon, it’s not only a matter of the food they are fed, but what might already be in or seep into the ground water in their ponds. Toxic chemicals, heavy metals, dioxins, pesticides all can find their way into the ponds, so this too is an important fact to find out.

  3. I’m confident that if the omega 3 oils are damaged, it will be obvious. Nordic Naturals was the brand of cod liver oil I used this past winter to help curb my SAD. The first bottle I bought was perfectly clean-tasting, then the second tasted distinctly fishy. I took it back and exchanged it.

    A similar phenomenon is noted if you overcook omega-3 eggs. They go fishy very easily.

    Thanks for your blog, Dr Eades. I enjoy reading both yours and Dr Mike’s.

    COMMENT from MD EADES: Glad you enjoy the blogs and you’re absolutely correct that oxidized marine fat smells and tastes fishy and is pretty easy to pick up in liquid formulations you take by the spoon. It’s a bit tougher in capsules, which is why we recommend biting and chewing up the occasional capsule of anybody’s product.

    As to omega-3 eggs, I much prefer to get my cholesterol from eggs and my omegas from fish or supplements for the very reason you describe–there’s bound to be some damage from the cooking, even though I like my yolks runny and my scrambles very soft.

  4. There have been studies done on PCB/Flame retardant(PBDE)/etc contamination. The Physicians for Social Responsibility’s web site has specific information. The least contaminated farmed salmon was from Chile and Washington state in the US. The most contaminated were from Scotland and some other European countries (I don’t remember which other ones were tested)

    COMMENT from MDEADES: That may be true, but one always has to bear in mind that whatever is in the local ground water can seep into farmed ponds, unless they’re tanks lined with stainless steel, I suppose. And, again, I think at least at this point, wild trump farmed.

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