The Definitive Guide to Fish
The Definitive Guide To Fish: Why and How To Eat It
By Mark Sisson
In nutrition, there are very few universal consensuses. Conventional wisdom says that fat makes you fat and whole grains are essential, and millions of people agree, but the ancestral health and keto communities (and reality) disagree. Primal and keto folks don’t worry much about saturated fat and limit polyunsaturated fat; conventional health advocates do the opposite. The opinion on meat intake varies wildly, with some people suggesting we eat nothing but red meat, others recommending “palm-sized” pieces of strictly white meat, and still others cautioning against any meat at all. Pick a food and you can find a sizable group that hates it and a sizable one that loves it. You can find researchers who spend their lives making the case against it and researchers who spend their lives making the case for it.
But not fish. Fish is about as close to a universal as any food. Barring the vegans and vegetarians (some of whom, however, are sneaking wild salmon when their followers aren’t watching), everyone appreciates and extols the virtues of eating seafood. Including me.
Sea Food = Sea Change: The Evolutionary Story
Remember: I always view things through an evolutionary prism. It’s where I begin. If something doesn’t make sense in the light of evolution, it probably doesn’t make sense at all. And seafood has been one of the most important dietary factors in human brain development. Without the selenium, iodine, zinc, iron, copper, and DHA found abundantly in fish and shellfish, human brain encephalization—the massive increase in relative size and complexity of the brain representing a shift toward higher order thought—wouldn’t have been easy to pull off. Maybe impossible.
If the human brain came to rely on the nutrients found in seafood for its evolution, it stands to reason that they remain important. The studies bear this out. Fish offers unique and important benefits to humans living today.
- More omega-3s in your red blood cell membranes, less heart disease.
- More omega-3s in your diet, lower expression of inflammatory genes and less airway inflammation if you have asthma.
- More EPA in your diet, improved depression.
- More EPA and DHA in your diet, less progression from inflammation into full-blown arthritis and improved rheumatoid arthritis symptoms.
- More omega-3s in your diet, stronger anabolic response to strength training.
Not to mention the imbalanced, inflammatory omega-3:omega-6 ratios most of us have, or had. Even if you’ve been Primal for ten years, you spent a good portion of your life eating the standard Western diet full of industrial seed oils high in omega-6 fatty acids. Omega-3s from seafood help correct that balance.
The Modern Picture: Calm the Alarm
But there’s a problem, isn’t there? If you listen to the alarmists, our seas are overfished and full of toxins, and the fish that remain are dripping with mercury, cadmium, and other heavy metals. Farmed fish are even worse, some say; they swim in tepid baths of antibiotics, soybean oil, and glyphosate. Besides, oceanic acidification is killing all the delicious fish and shellfish and crustaceans. Pretty soon the only thing served at Red Lobster will be fried jellyfish.
Though there are glimmers of truth to all those claims, they’re certainly exaggerated:
- There are still plenty of excellent and sustainable seafood choices to make, according to Seafood Watch, which takes environmental impacts, overfishing, and other ecological and safety concerns into account.
- While some species are indeed overburdened with heavy metal contamination, plenty aren’t. Eat salmon, sardines, mackerel, younger, smaller tuna. Besides, most seafood—in one study, this included shrimp, crabs, squid, and tropical fish in the Atlantic Ocean—is high enough in selenium that it binds to and prevents absorption of mercury.
- Jellies may be taking over, or they may be following the natural 20-year boom and bust cycle observed throughout history.
- Even farmed salmon isn’t as bad as we might assume. And farmed mollusks—oysters, clams, mussels—are as good as wild, since they live no differently from their wild cousins.
Even if all those claims were totally on the level, we’re faced with a grand overarching truth: You have to eat something. What, are you gonna eat vegan meat patties instead of cod, salmon, sardines, and oysters? Drink Soylent? Go vegan? Go Breatharian?
Of course not. You need to eat seafood. You know you should.
But isn’t it too expensive?
For one thing, I already mentioned that safe farmed fish exists. Farmed salmon probably isn’t as bad as we’ve been led to believe (or assume), as long as you watch out for the egregious ones. U.S.-farmed trout, barramundi, and catfish show up with very low toxin levels and good nutrient profiles. And farmed bivalves like oysters, clams, and mussels are raised like they’re wild. There’s basically no difference between a farmed oyster and a wild oyster. They both live out in the ocean attached to rocks, munching on what the sea provides.
Two, wild seafood isn’t always expensive.
Restaurant supply shops, Walmart, and other large stores often have frozen wild salmon, cod, and other wild fish for cheap, about $5-6 per pound.
At Costco, you can get wild caught salmon (at least on the West coast) in season for $5-6 pound. You might have to buy it whole, though (recipe down below). They also have other types of wild fish for good prices.
Canned seafood is a viable option.
Fish and Seafood: How To Optimize the Benefits
Why We Need Seafood
First, evolutionary precedent, which I already discussed. It’s folly to ignore the long history of humans eating seafood. It’s higher folly to ignore the importance of seafood in human brain evolution. Wherever they have access, people eat seafood.
Second, the benefits are well-established. Even if the links to better health are purely correlational (and they’re not, since we have controlled trials listed above), seafood looks great on paper: bioavailable protein, high levels of essential nutrients, the best source of long chained omega-3 fatty acids.
Third, seafood is a reliable source of important micronutrients that may be lacking on a terrestrial Primal, keto, or carnivore diet. Selenium, magnesium, folate, astaxanthin, and vitamin E can be tough to get if you’re just eating steaks and ground beef.
A recent study on the ketogenic Mediterranean diet had great results feeding its participants over two pounds of fish per day. Two. Pounds. Mostly salmon, sardines, and mackerel, which are fatty omega-3 rich fish very low in contaminants.
But what about those who say they’re meat eaters, turf people who claim grass-fed beef and pastured pork is enough for them? Fish is meat. Fish are animals. You’re seriously limiting your options—and selling your ancestors short—by willfully avoiding seafood. And you’re probably missing out on some important nutrients. Like iodine, for example, which doesn’t show up in the standard nutritional databases but is incredibly important for brain and thyroid health and almost certainly appears most abundantly in seafood.
What Exactly Should I Eat?
Okay, so should I just throw in some salmon and be on my way?
Salmon is a great start, but there’s way more fish (and bivalves, crustaceans, and cephalopods) in the sea.
Can’t I just take fish oil? As a fish oil purveyor, I wish I could say that fish oil is enough. It offers incredible benefits not to be dismissed, but it’s not equivalent to food either. The fact is, I do both. Seafood contains a ton more than just the omega-3s. Just check it out….
- Salmon: Vitamin D3, B-vitamins, magnesium, iron, selenium.
- Cod: B-vitamins, magnesium, selenium, potassium
- Halibut: B-vitamins, vitamin D3, magnesium, selenium, potassium
- Sardines (canned): B-vitamins, vitamin D3, selenium, calcium (if bone-in), iron, copper
- Scallops: Vitamin B12, magnesium, folate, selenium, zinc.
- Oysters: B-vitamins, magnesium, selenium, zinc, copper, iron, omega-3s, manganese
- Mussels: B-vitamins, selenium, zinc, manganese, folate, omega-3s
- Clams: Vitamin B12, iron, magnesium, vitamin A
- Shrimp: B-vitamins, magnesium, selenium, zinc, astaxanthin (a potent carotenoid, great for ocular and mental health)
- Crab: B-vitamins, vitamin E, magnesium, folate, selenium, zinc, copper
- Lobster: B-vitamins, vitamin E, selenium
- Squid: B-vitamins, magnesium, iron, copper, zinc, selenium, vitamin E
- Octopus: B-vitamins, magnesium, iron, copper, zinc, selenium
Although I didn’t mention it, every single sea creature you can eat is a very good source of highly bioavailable protein and, usually, creatine.
And some studies even suggest that fish proteins themselves offer unique benefits.
- In one study, rats with injured muscles saw faster recovery when fed cod protein as opposed to casein or peanut protein.
- In people with insulin resistance, cod protein reduces the inflammatory marker CRP and increases insulin sensitivity.
- Fish protein may even enhance fat loss and muscle gain compared to other protein sources.
Most of the research is in animals, but it’s compelling and another good—if speculative—reason to include fish in your diet.
I’m Sold. How Much Should I Eat?
Keeping in mind the contamination in certain varieties, eat much as you can afford/tolerate. It’s hard to eat too much seafood. In my experience, there seems to be a built-in regulatory mechanism that reduces the palatability of seafood at a certain level of consumption. A big slab of wild sockeye salmon is fantastic, but I can’t eat pounds of it like I can with a grass-fed ribeye.
You can also use omega-3:omega-6 ratio as an indicator. Run the numbers on the seafood you’re eating and aim for a 1:1 or 1:2 ratio and you should be golden.
In my opinion, leaner fish has no upper limit. Eat as you desire.
Keep in mind that the keto Mediterranean diet study I recently discussed gave over 2 pounds of fish to participants every day, and they had great results. Two. Pounds. Mostly salmon, sardines, and mackerel, which are fatty omega-3 rich fish very low in contaminants. After 12 weeks of that:
- They lost 30+ pounds.
- Their BMIs dropped from almost 37 to 31.5, from the middle of class 2 obesity to the bottom of class 1 obesity.
- They lost 16 centimeters, or 6 inches, from their waist.
- Fasting blood sugar dropped from 118 (pre-diabetic) to 91 (ideal).
- Triglycerides dropped from 224 to 109.
- HDL increased from 44 to 58.
- They went from prehypertensive to normotensive.
- Their liver enzymes and liver fat reduced and in some cases completely resolved.
- All 22 subjects started the study with metabolic syndrome and ended it without metabolic syndrome.
As always, pay attention to how you feel. Eat and observe. Make it an official N=1 experiment and look for the feedback it provides.
How I Do Seafood
Okay, but how do you eat it? How do you prepare it?
Admittedly, there’s a lot less room for error with seafood. It goes bad more quickly, cooks faster, and simply isn’t as forgiving. We’ve all had the experience of buying some salmon fresh from the butcher, keeping it in your fridge a half day too long because we weren’t sure how to prepare it, and having to throw it out. That’s the worst.
I’m not a big “recipe” guy (I have people who help me parse out my creations into legible formats for blog posts and cookbooks). I like to improvise. A dish here, a dash there. So, I’m just going to give a freeform account of how I eat fish, shellfish, and other seafood. If you need clarification on something, feel free to ask in the comment board.
I like doing a kind of pseudo-ceviche using any high quality lean fish—halibut’s great—marinated in Primal Kitchen® Greek Dressing & Marinade with a few splashes of tamari or soy sauce and some diced fresno chile. Let it sit for 5-10 minutes, then plow into it. Really good, even though if you tried to serve this in Peru they’d probably arrest you.
I always have canned sardines from Wild Planet in my pantry. A favorite quick (and keto-friendly) meal is to do a can or two of sardines mashed up with an avocado and a tablespoon or two of Greek Goddess dressing.
If I’m doing salmon, I’ll sometimes marinate the fish in the Primal Kitchen No-Soy Teriyaki.
Another great way to cook fish is in a curry. Sear the fish, making sure to get crispy skin if it’s on. Set aside. In the same pan without washing or draining, heat up some garlic, ginger, chili peppers (if you like it hot), and onions (or shallots), adding more fat if you need it. Salt. When they’ve softened, add the curry powder or paste. Cook for a minute or so. Then add some bone broth and coconut milk. Reduce until you’ve reached the texture you desire. I’ll keep gelatin powder on hand to whisk in if it doesn’t have enough body. At the last moment, add the fish back in and toss to coat.
Scallops? Either raw at a good sushi joint, preferably separated by thinly sliced lemon, or seared in butter followed by a pan reduction with white wine and butter. By the way, for those who are interested, Butcher Box has some killer scallops now (it’s literally the last day to grab the deal—apologies to anyone reading this tomorrow.) And full disclosure—I’ve always been a proud affiliate. They do things right there.
Clam chowder is still the best way to eat clams, roasted on an open fire on the beach with a little sand still in there. Maybe it’s just the New England in me.
Anytime I’m out at a decent restaurant I trust with oysters on the menu, I order them. At least a half dozen, raw. I also like the canned smoked oysters from Crown Prince.
Mussels I like the classic way: cooked in butter, white wine, and garlic. Only modification I make is after the mussels have cooked, I remove them from the pan, sprinkle in some gelatin powder, and reduce down to make a viscous sauce.
Cod or other similar lean white fishes are best in lots of butter and garlic, followed by a squeeze of lemon.
Whole salmon? Clean, gut, and scale. If you can, keep the liver. It’s delicious. Salt and pepper the interior and exterior of the salmon. Cut some deep vertical slashes in the outside, on both sides. Stuff shallots, garlic, and lemon slices into the interior and inside the slashes. Coat with avocado oil, then grill over indirect heat with the cover on until skin is crispy and flesh is lightly pink and flaky, or bake at 375 for 30-40 minutes.
If I’m ever cooking a cephalopod, it’s all about the Instant Pot. Throw some bone broth, lemon juice, and olive oil in the pot with the squid or octopus and cook on manual for 15-20 minutes. If you like, you can take it out, allow it to cool, then grill it over coals or open flame. Save the broth.
Whenever I cook fish, I use either monounsaturated fats (as found in avocado oil and olive oil) or saturated fats (as found in butter and coconut oil). Both types of fats enhance absorption of omega-3 fatty acids, whereas omega-6 fats inhibit it. Both omega-3 and omega-6 compete for the same absorption pathway.
When applicable (as in curry), I also use turmeric to cook my fish. Turmeric and its curcumin enhances absorption of omega-3s, specifically increasing DHA levels in the brain.
I know seafood is intimidating for some people. They don’t like the “fishiness.” They don’t know how to cook it. It’s “too expensive.” It goes bad too quickly. Hopefully, after today you feel a bit better about cooking and eating seafood. Hopefully, you feel equipped and empowered to incorporate some salmon, cod, trout, oysters, and other marine animals into your diet.
Take care, everyone, and please leave your favorite ways to eat seafood down below. How much seafood do you eat? What’s your go-to recipe? What underrated sea animal do you covet but others do not?
Thanks for reading!