The Importance of Fish in Our Diets

August 14, 2012 in Categories: , , by

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In my previous post, I discussed why the mercury content of fish is not worthy of concern for most fish species (see this post).  My point isn’t just that we don’t need to worry about eating too much fish; we should really be eating way more of it!

It completely frustrates me that it is generally recommended for pregnant women to limit seafood consumption to two 6oz servings per week in order to avoid excess mercury exposure.  Many women take this a step further and avoid all seafood while pregnant.  Some even avoid seafood while lactating.  Not only is the mercury exposure from seafood a complete non-issue (with the exceptions of the few fish that are higher in mercury than selenium), but by limiting seafood during pregnancy, women are missing out on the best food source of DHA, an extremely essential nutrient for their health and the health of their growing baby.  In fact, a maternal diet rich in DHA has been shown to improve a baby’s IQ by 10 points.  The recommendation should probably be for a minimum of three 6oz servings of oily cold-water fish per week for these women, if not a diet that is heavily based on fish as a protein source (although, there still is a legitimate rationale for avoiding sushi).  I personally wonder how different my two pregnancies would have been if I had known this back then.

Fish and other seafood should be a major part of everyone’s diet.  What are the health benefits of fish and other seafood?

Fish and shellfish are rish in long chain omega-3 fatty acids DHA and EPA.  These are the anti-inflammatory omega-3 fats that are readily used by our body.  The shorter chain omega-3 ALA, which is in flax, chia and walnuts, is actually not easily used by our body because it must first be converted into DHA or EPA, which is a very inefficient process.  A 3.5oz serving of wild-caught salmon (fresh or canned; any species), sardines, albacore tuna, trout or mackerel has over 500mg of DHA + EPA.  Fish which have moderate amounts of DHA+EPA (150mg-500mg per 3.5oz serving) include haddock, cod, hake, halibut, shrimp, sole, flounder, perch, bass, oysters, crab and farmed salmon).1  Why not just get your DHA and EPA from fish oil supplements?  These polyunsaturated fats are very easily oxidized in response to heat or light and are not very shelf stable, especially once isolated.  Consuming oxidized omega-3 fats is not helpful to your health (contributes to inflammation as opposed to reducing it).  Eating fresh, frozen or canned whole fish protects the omega-3 fats from oxidation plus provides all the necessary cofactors for optimal absorption and use by the body. 

The protein in fish and shellfish is very easy to digest and research shows that the amino acids in fish are more bioavailable (your body can absorb and use them more readily) than beef, pork or chicken 2,3.  Fish and shellfish also have a balanced quantity of all of the essential amino acids, giving them very high Amino Acid Scores (see http://nutritiondata.self.com). 

Fish is also rich in two very important minerals which can be challenging to get in sufficient quantities from other foods:  iodine and selenium.  Iodine (which is also rich in algae and seaweed) is vital for normal thyroid function but is also extremely important for proper immune system function, wound healing, and fertility.  Table salt is enriched with iodine due to rampant dietary iodine deficiency (goiters were very common before the advent iodized salt).  Since paleo diets tend to be lower in salt (and many people switch to sea salt, which is not iodized), it is very important to include food sources of this essential mineral.  Selenium is required for a class of enzymes called selenoenzymes which are part of the body’s natural protection against oxidants.  Selenoenzymes are particularly important for protecting the brain against oxidative damage, but selenium deficiencies are also linked to thyroid disease, cardiovascular disease and cancer.

Fish is also a food source of Vitamin D (which can also be found in organ meats).  Vitamin D is a steroid hormone that controls expression of more than 200 genes and the proteins those genes regulate.  Vitamin D is essential for mineral metabolism (it regulates absorption and transport of calcium, phosphorous and magnesium) and for bone mineralization and growth.  Vitamin D is also crucial for regulating several key components of your immune system, including formation of important anti-oxidants.  Very importantly, Vitamin D has recently been shown to decrease inflammation and may be critical in controlling auto-immune and inflammatory diseases.  Vitamin D is also involved in the biosynthesis of neurotrophic factors, regulating release of such important hormones as serotonin (required not only for mental health but also for healthy digestion!).  Vitamin D helps control cell growth, so it is essential for healing.  Vitamin D also activates areas of the brain responsible for biorhythms.  Scientists continue to discover new ways in which Vitamin D is essential for human health; for example, Vitamin D may prevent cancer.  As we spend less and less time outdoors (our bodies synthesize Vitamin D in response to sun exposure), dietary vitamin D becomes more and more important.

Which fish are best to include in your diet?  Oily cold water, wild-caught fish will have the highest omega-3 and Vitamin D content.  However, even fresh water white fish are an excellent source of protein.  The only fish that are worth limiting in your diet are farmed tilapia and farmed catfish as these fish tend to have higher omega-6 content 1 (they still have that great easily digested protein though!).  Yes, fish can be expensive.  Canned fish (especially sardines and salmon) are great inexpensive options.  Pickled herring and smoked kipper are often less expensive as well.  I can usually find frozen wild-caught pink salmon fillets on sale for $4 per pound at my local grocery store (which means it’s cheaper than ground beef!).  The take home message here is that fish is good for you, so eat it as often as you want.

1 Gene Smart “Guide to Omega-3 Levels of Fish”

2 Faber, TA et al. “Protein digestibility evaluations of meat and fish substrates using laboratory, avian,and ileally cannulated dog assays” J ANIM SCI 2010, 88:1421-1432.

3 Sheeshka J and Murkin E “Nutritional Aspects of Fish Compared with Other Protein Sources” Comments on Toxicology 2002. 8(4-6):375-397

4 Protein Efficiency Ratio Table 6-13

Comments

I always felt that the benefits outweighed the risk in my pregnancy with my daughter, plus salmon was all I craved so I ate it all the time. This time around my craving is sardines with mustard and lemon. I’m so glad I tolerate seafood well while pregnant! Plus, aren’t sardines one of the lowest in mercury since they’re caught while so small?

Thank you for all the source referencing in your posts. That will really help when I discuss my eating plan with my nutritionist and my naturopath. Their guidance for my health is in line with your research. Thanks for making the science of eating right accessible and digestible!

I have totally boring taste in fish and prefer salmon and canned tuna among the oily fishes, but while I was pregnant I only ate small amounts of canned tuna (worried about the BPA and mercury) and almost no salmon, because I live in Denmark and the Baltic salmon has high levels of dioxins. You can get Norwegian salmon, but those were subject to the same mercury warnings as you all have over in the US. But if I understand correctly I don’t need to worry about the mercury next time, so it would be okay to look for the Norwegian salmon?

Where should the fish originate if you live in California? Is the Wild Alaskan still a great choice or should I be concerned because it’s not too far from where the Japan Tsunami took place with radiation etc? I heard things but not sure what to believe.

Can you share your fish buying strategies? It’s a rare day that I’m both grocery shopping and ready to prepare fish, so I usually get it frozen, but only end up eating it about twice a month, partly because I have to have protein leftovers for my son who won’t eat fish. Where do you buy fish?

I mostly buy frozen and canned fish. We eat alot of frozen pink salmon, since it’s so inexpensive (I buy at my local grocery store). I typically thaw at room temp for about an hour (two in the winter when my kitchen is colder) and then either bake or poach (nice thing is that if it’s not completely thawed, it still cooks nicely). I’m switching from buying frozen tilapia to either frozen hake or frozen cod (which I buy at costco) and typically bake or pan fry. I eat sardines straight out of the can. Canned tuna and salmon, I usually mix with onion, chives and/or celery and some homemade mayo and eat with cucumber, lettuce or celery. Occasionally, I buy fresh fish, typically sockeye or coho salmon when it’s in season (and usually when I want to barbecue it) and try and cook it within 2 days of buying.

This hopefully isn’t too off topic, but I was wondering about your thoughts regarding supplementation in general, esp. for those trying to heal from autoimmune/leaky gut issues. Obviously, food is the best source of vitamins, minerals, etc. but for those of us who have not been absorbing them well and now also have a VERY limited diet (personally, I’m just eating boiled meat and fats at the moment & am finally getting some relief, hoping to one by one begin adding in things from the autoimmune protocol soon with attention to both FODMAPS & SIBO). Additionally, do you have any insight into the whole magnesium stearate issue? Apologies if you address this elsewhere and I’ve missed it.

This is such a great site, really can’t say it strongly enough. I know this takes much of your time, I will be making a donation to your new show to throw a little support back your way!

THANK YOU!!! In general, I think it’s better if we can get the nutrients our bodies need from food. That being said, a leaky gut and inflammation can stop you from absorbing what you need. I even read that if you have inflammation, your body can’t make vitamin D from the sun efficiently! I think taking some carefully chosen supplement to help heal (with the idea that once you are healed you can stop taking them) makes sense.

I’m not sure whether or not the magnesium stearate issue is relevant to the amount that’s actually used in capsules (there might be a large variability in how people respond to it too; and there are very likely other reasons why some people aren’t absorbing vitamins). It’s very hard to find vitamins without it. I guess I don’t really know enough right now to have a strong opinion on it at the moment.

I completely agree with your post! Fish is my most-often consumed meat, mostly in the form of sardines. I LOVE them, in fact just posted to my recipe blog about them yesterday. They are just as nutritious as salmon but way more inexpensive and sustainable to boot! :)

Mickey

Sarah, sorry to bother you but just one more question…
I know FCLO is very beneficial but since I’m eating lots of oily fish, palm margarine (has vitamin E) and supplementing with D and K2 (Thorne Research, Vitamin D/K2, 1 fl oz (30 ml)) do you think I’m missing something (in terms of bioavailability for example)? It’s just because it’s quite expensive to ship Green Pasture FCLO to Portugal (and I would also avoid the vitamin A problem in terms of food sensitivity)

It sounds like you have your supplements and nutritional needs covered. I like FCLO but I like getting complete nutrition from food sources even better. I think making sure you eat liver, kidney and heart meat from time to time in addition to what you are already doing will cover your bases very well!

Great read. I have a question. Many (but not quite all) the frozen fish at my grocery store contains Tetrasodium pyrophosphate or something similar. I avoid foods with additives, but due to this I am eating almost no fish. My family will only tolerate tilapia (which does not have this ingredient) and I love salmon (which also doesn’t have it) but I would love to branch out especially since the tilapia is Chinese farmed.
Suggestions?

My Go To frozen fish are salmon and hake,which don’t have any additives (hake is a whitefish similar to tilapia, but is wild and has more omega-3 and is even cheaper!). Other types of fish, I usually buy fresh and they end up being special treats because they tend to be much more expensive. I do try and stock up on whole wild red snapper when Costco has it, which is the other one we like a lot that isn’t too expensive.

Hello – I am SO grateful I found your website. Especially this post!

Long story short – I have had severe food allergies my entire life. Eggs, tree nuts, peanuts, legumes, shellfish, fish and sulfites all trigger anaphylaxis, with dairy and wheat causing a slight discomfort. In the past year the dairy and wheat have become such a problem that I have tried to take them out of my diet as much as possible. In the last two weeks it seems like almost anything I eat that I have deemed ‘Sarah Safe’ in the past is making me feel sick. I am going Paleo as of today, but I see that fish are such a big part of the auto immune diet and I can’t go near them. What would you recommend as a substitution? If you could please help me with this I would be SO grateful.

And I can’t wait for your book. Thank you!! :)

Good question! I guess stick with meat for your protein. It might be worthwhile finding an algae-based DHA supplement. You will probably get enough selenium if you are eating locally-grown vegetables from a small scale farm, but if not a selenium supplement might be useful as well (there’s an episode of Chris Kresser podcast all about fish and selenium and he has recommendations for specific forms of selenium and dose in that).

I appreciate you quick response – thank you! I will definitely check that out that podcast. And will be signing up for my local organic CSA. Lots of veggies in my future! :)

Another good source of fish may be the livers of white fish, like cod liver. Because the white fish have the bulk of their oils concentrated in their livers, it means that you can get some pretty solid nutrients in their livers. That and being liver means that it has the benefits of eating liver, like high vitamin A.

Canned cod liver (not the supplement, but the actual liver) is fairly cheap here in Canada. Make sure to buy the liver that is in it’s own oil though.

At the moment, I use a widely available brand called “S&F”. They retail for about $2-$3 CAD per 120g can, so it’s a pretty good deal for what you get. You get 7g of Omega 3 per 120g can.

The only drawback is that a lot of people simply loathe the taste of cod liver. Let me put it this way, if you cannot stand unflavored cod liver oil, you will probably not find the taste of cod liver agreeable.

Also, when cooking seafood, you may want to lower the temperature as PUFAs are pretty easy to oxidize (besides overcooked salmon does not taste good – it’s dry and often you see white stuff, albumin oozing at higher temperatures). Use Rosemary spice to reduce the Omega 3 decay and perhaps cooking oils rich in Vitamin E (palm oil is the best choice, although it does imprint the “palm oil flavor” into the fish kind of like coconut oil makes food taste a bit like coconut).

Hi Sara! Before I start I just have to say I love your blog (and it’s such a relief to see information cited!). I do have one specific question for you, and please forgive me if you’ve already addressed this, but if I’m taking Fermented Cod Liver Oil, should I be concerned about eating fish every day as well (in the forms of canned tuna, canned salmon, or canned sardines)? Also, do you think that if I, and my family, will soon be implementing a lower oxalate diet to aid in a mercury detox (due to my mother’s mercury fillings that leeched into our systems while we’re were in the womb), that we need to completely cut fish out? According to one gentleman they spoke with he said gradually go low oxalate and absolutely NO fish for the entirety of the up to two year detox. Anything you can speak to these things? Thank you!

First, the argument still holds that more seafood is better for heavy metal toxicity because you need the selenium plus all the other incredibly important vitamins, minerals, and essential fatty acids. Second, oxalic acid might help plants take up mercury from the soil (much more weakly than other organic acids such as citric acid), but there’s absolutely no evidence in humans that oxalate has any effect on mercury uptake or detox. In fact, high oxalates may protect against mercury toxicity. Have you actually done heavy metal testing?

I’m so sorry for the late reply! I didn’t know that you’d actually respond to this and I didn’t get a notification :) . My younger sister (17 years old) and my mom will be going in soon to get the tests done and I will be getting tested before I make any drastic changes. I had no idea they had no effect on uptake or detox! The doctor they are seeing is the one who made the recommendations— This is exactly why I wanted to talk to you! What do you think they should do to get rid of the mercury (assuming they are toxic)? Or what questions should they ask the doctor? My sister was the first to have her consultation and he ( a rheumatologist ) supposedly is really good and has told her that he can probably get rid of /or alleviate many of her problems. She’s struggling with tons of health issues. She’s been recently diagnosed with rheumatoid arthritis, fibromyalgia, and a host of other problems. She’s always had asthma and severe (anaphylaxis) allergies to several foods. She (and another sister, my mom, and uncle) have been diagnosed with Celiac disease. All of my sisters and mom are gluten free (and have been gluten free for over 7 years), I am the only one who began eating Paleo this summer after first being hurled through the low-calorie chronic cardio nearly raw/vegan mess (good thing that didn’t last long… I was NOT healthy), and my dad eats whatever he wants. He has always had autoimmune blood disorders… My mom wanted me to ask you if mercury toxicity affects liver function. She has major health issues as well; A couple years ago she had her gallbladder removed (which promptly sent her into pancreatitis) only to find that there was nothing wrong with her gallbladder at all. Since then she has had to go in again because they said her valve wasn’t flushing properly (so naturally they cut and that sent her into pancreatitis again). Now, scar tissue has built up again and she is always experiencing abdominal pain.. and they’ve scheduled another surgery to deal with that next month. Her body has slowly been making it so she cannot eat breakfast or dinner (she only can get away with drinking her shakes she makes) and eating lunch without being in crippling pain. Her liver counts are really bad and she doesn’t drink or eat meat (because it hurts her stomach too much.. she loves meat) she cannot eat crucifers without pain.. As you can see my family is riddled with health problems. I wish I could better summarize… I cannot express how deeply I want their pain to go away. The only problems I have to speak of are lactose intolerance, peanut intolerance, (for some reason..) in the last four years I have stopped being able to eat turkey (let’s just say “liquid stomach”- egh) and in the last few months my body has rejected chicken in the same fashion, and my body does NOT like it when I eat chocolate (racy heart, harder to breathe ,Etc.). I also have pretty bad acne.. that didn’t really show up fully in all its glory until I started mountain biking my senior year of high school. Thank you again for getting back to me!

Well, my two biggest recommendations for you and your family are the autoimmune protocol and digestive support supplements (these are discussed on the autoimmune protocol page with links to brands I recommend). I see far more signs of hindered digestion and malnutrition in what you describe than anything that would point to heavy metal poisoning. I think a focus on nutrient dense foods (which will give your bodies what they need to naturally detox) and digestive support supplements to help you get the nutrition out of your food will make the biggest difference. Mercury is neurotoxic, but very high levels of heavy metals do tax the liver. I don’t think that’s what’s going on, but a legitimate heavy metal test will answer that for you. Your mother without a gallbladder should be taking ox bile supplements with every meal, which will make a big difference with her ability to digest meat (probably in addition to pancreatic enzymes due to pancreatitis).

Thank you Sarah! Do you think that we should seek out a probiotic supplement as well? If so, do you still think the NOW foods probiotic you linked to on one of your pages would be a good one?

This isn’t a new idea within the paleo community. Polyunsaturated fats are very fragile, especially one isolated, so a proportion of the fats will be oxidized (and depending on the quality of the fish oil, how it has been stored, it could be a very high proportion). Consuming oxidized fats can then cause more damage than the benefits you get from consuming long-chain omega-3 fats. What you tend to see with studies is benefits from fish oil supplementation in the short term (say 4-6 weeks) and detriment over the long term (probably because of the initial benefit of improving omega-3 to 6 ratio in cell membranes and then the build-up of damage over time from oxidized fats from fish oil). This is why it’s actually very important to get your omega-3s from whole food sources, predominantly seafood. The fats are much more stable as part of the whole foods so they are protected from oxidation.

So, does that mean that canned fish are potentially more harmful in the long term? Do the fats oxidize to the same extent in whole canned fish as in fish oil? Also, I love canned mackerel and it’s more affordable than many other protein sources, but one 15-ounce can could contain one daily supply of sodium (i.e., here: http://www.bumblebee.com/products/sardines-mackerel/bumble-bee-jack-mackerel/). What is your feeling on sodium in canned fish? I read that one could soak the fish for 24 hours, but it seems like insanity in action, especially considering that many beneficial nutrients will probably be leeched away along with the salt.

One thing I love and keep on hand for quick snacks/meals is smoked wild caught salmon (like Lox style). We live in FL so get plenty of good fresh seafood options, but something about smoked salmon (and trout when we are in NC) are just yummy to me. Can you tell me if the smoked is ok? I check for bad ingredients like additives and sugars but have found some pretty good options at places like Earth Fare and Whole Foods. We even have a local place that smokes it in house. I’m sure fresh is better but does the smoked (hot or cold smoked) still have the Omega 3 and other good minerals? Thanks!

I used to eat more fish but recently have read eating anything farmed is a bad idea. I did find some wild caught salmon the other day at Target and purchased it. I used to love catfish and tilapia wasn’t bad either but have now stay completely away from them. I have heard some people say that shrimp and other shellfish isn’t that good for you but I still love shrimp, crab, lobster, mussels, and scallops. I like oyster’s as long as they are steamed but I can see these definately being bottom feeders and maybe not as good for you? What are your thoughts. I don’t think I have ever seen catfish that isn’t farmed. Have you ever seen it. I used to love it. Are there some farmed fish that are safe?

Hi Sarah!

I’ve completely cut out eating fish this past month because I’m convinced it gives me a worse histamine reaction than anything. (I’ve cut out everything that could be causing histamine problems)
What’s more important, getting my omega-3s / iodine or feeling super fuzzy from the histamine?

Thanks and can’t wait for the book to get here in the mail!
James

So it’s OK to eat fish daily, even a couple times a day every week?

The only tilapia I can find it farmed…. Is this ok or should it be avoided?

Dear Sarah
Have you ever heard of Pemphigus Vulgaris? Wondering if this Auto Immune disease has crossed your radar

are there any chances of getting an omega 3 overdose, if i eat sardines everyday. sardines and tilapia are my cheapest sources of protien. what is the upper limit on omega 3 consumption from eating fish?

What if you have developed what seems to be an allergy to fish (and fish oil)? :( It can’t be good for me to keep eating (or taking) something that makes me have to run to the bathroom every time I consume it and sometimes makes me stuffy or sneeze or makes my lips tingle. I’m bummed because the fish oil really helps my pain and salmon is one of my most favorite foods but I am not reacting well to it now.

I’m curious if the use of sodium tripolyphosphates in seafood, especially scallops, is a concern for autoimmune reaction. I’m following a very strict AIP with happy, energetic results. But a recent severe digestive and autoimmune flare leaves me afraid to include fish that may be sprayed with STPP, as they call it. Interested to hear if anyone has similar experience or expertise on effects of this chemical.

I have a question. I am into the AIP by month because of general inflammation and joint pain. The problem is I am too much underweight so I introduced lard coconut oil and olive oil to have calories. Obviously I eat almon trout etc and offal tripe and liver. I think that with lard coconut and olive oil I get too much omega 6 and this is a problem for inflammation, but if I don’t eat this fats how can I gain weight? thank you fron Italy, you are great

Excuse me I was saying I eat salmon, trout and cod but I fear omega 6 it’s too much with lard coconut and olive oil. remember in Italy there’s no grass fed meat or lard!

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