Tag Archives: canned fish


From 2006 to 2017 a dramatic collapse occurred in the Northern Pacific Sardine population (extending from Baja California to British Columbia, Canada), amounting to a 95 % decline in the entire sardine population (Figure 1, Info graphic 1) (1-3).

Figure 1.   The Pacific sardine population (biomass in millions of tons) has declined 95 percent since 2006 and it is now below the minimum level required to support a commercial fishery (called the “cutoff”) (1, 3).

This fishery collapse caused biologists at the West Coast Region of the National Oceanic and Atmospheric Administration (NOAA) Fisheries to impose a moratorium on all commercial sardine fishing in the Northern Pacific Sardine population (including California, Oregon and Washington) for 2015, 2016, 2017 and then on through to June 30, 2018 (1-3) – a 4-year moratorium, which will likely be extended (2).

Accordingly, fresh Pacific sardines have disappeared entirely from U.S. supermarkets and fish dealers and elsewhere worldwide.  For any U.S. consumer wanting to purchase fresh sardines, you are now limited to a single high volume fish vendor in New York City (The Lobster Place: https://lobsterplace.com/) which imports “fresh” sardines seasonally from Spain.   

Only a single on-line U.S. merchant (https://wholey.com/sardines/) sells frozen sardines – also caught in Spanish waters.   These flash frozen fish retail at $64 for an 8-pound bag of sardines.  This cost is difficult to justify for frozen sardines when fresh salmon, mackerel or herring with comparable or superior omega 3 fatty acid concentrations are regularly available throughout the U.S.   

Infographic 1.


The current cost to import either “fresh” or flash frozen sardines from Spain or other Mediterranean countries to a select few U.S. markets represents an exorbitant expense when compared to other U.S. fresh, fatty fish such as salmon, mackerel and herring.  Hence, U.S. consumers now infrequently or never can purchase fresh or even flash frozen sardines at a reasonable cost.  The net result is that almost all U.S. consumers of sardines now have no choice but to eat canned sardines.


Canned Sardines

As The New York Times reported, the last sardine cannery in the U.S. closed its doors on April 18, 2010 in Prospect Harbor, Maine (4).  This action brought a final closure to our once thriving national, sardine packing industry which peaked during WWII and served as the backdrop of John Steinbeck’s gritty novel, “Cannery Row”.   

U.S. sardine canneries have been declining for 60 years and have now completely fallen victim to foreign competition because of: (1) less restrictive foreign fishing policies, (2) foreign disregard for U.S. consumer health and safety regulations, (3) foreign obliviousness to global environmental laws, and (4) low-cost foreign labor to process and can sardines.  The net result of these actions has been to produce an un-sustainable global sardine industry of unrestrained catches along with no international health or safety regulations for canned sardines and human health.

Excessive sardine catches during the same period in which natural environmental factors wax and wane to normally reduce sardine populations, creates an unsustainable situation which can eventually deplete or eliminate sardine populations (1-3).   Most marine biologists studying Pacific sardine populations understand the multitude of factors which operate synergistically to deplete sardine populations.  Unfortunately, my blog may be the first that you (most sardine consumers) have heard of this dismal situation for Pacific sardines.  

Marine biologists studying the collapse of Pacific sardine populations are well aware of this ecologic disaster, but unfortunately are generally unaware of the nutritional and health consequences of our reliance upon canned sardines in lieu of fresh sardines.


The Nutritional and Health Consequences of Eating Canned Sardines

Although the nutritional and health consequences of eating canned sardines versus eating fresh sardines may initially seem inconsequential, this viewpoint is flawed. For U.S. consumers who can’t purchase fresh sardines, this is a moot point.  Let’s examine the data.


Canned vs. Fresh Sardines
The canned sardines we consume in the U.S. actually are not a single fish species, but may represent one of 21 small marine fish species within the family (Clupeidae), that fall into the following four genera’s: Sardina, Sardinops, Sardinella, Dussumieria (5).  Frequently, lack of quality control in the global sardine canning industry results in numerous small fish being packed and labeled as “sardines” when in fact they are not sardines, but other species (5).

In order to understand why canned sardines may represent a nutritional and health risk for human consumption, it is necessary to follow the steps involved in catching wild sardines as they are processed and packed into the tinned cans we purchase at the supermarket.

After sardines are caught at sea, usually via encircling nets called purse seines, a number of processing steps may occur when the fish are intended for human consumption via canning.  Depending upon boat size, time at sea and distance to the cannery the sardines are put into brine tanks, which are either cooled or uncooled, or placed on ice.  If there is a local market for these seined fish, they can be sold as “fresh” sardines, as long as refrigerated conditions are maintained for a few days to a week.  Sometimes, sardines are flash frozen at sea and can then be marketed worldwide as “frozen”.

At the cannery, the sardines are normally washed, eviscerated and their heads removed.  The fish then are cooked, typically by deep-frying in soybean or olive oil or by steam-cooking, after which they are dried.  The sardines are then packed by hand into cans containing salt (brine), or (olive, sunflower or soybean oil with salt), or salt containing tomato, chili or mustard sauces.  The cans are sealed and then heated above the boiling point via pressure cooking (called retort cooking) for 2 to 4 hours. This process is employed to kill all bacteria including those that cause botulism.


Deleterious Nutritional and Health Effects from Consuming Canned Sardines

High Salt and Low Potassium Content in Canned Sardines
Table 1 below demonstrate how salt is nearly universally added to commercially canned sardines.  Fresh sardines like virtually all other unadulterated marine and fresh water fish contain  more potassium than sodium (8).  Notice that fresh sardines contain 4.04 times more potassium than sodium on a milligram by milligram basis compared to average processed sardines.  Conversely, canned sardines contain exceptionally higher sodium concentrations and lower potassium concentrations than fresh sardines.

Table 1.   Comparison of the sodium (Na+) and potassium (K+) concentrations between fresh and canned sardines (from citation 7) .

I have previously written about how a high salt (sodium) diet contributes to osteoporosis, hypertension, cardiovascular disease and exercise induced asthma (9-11).  More recently, high salt/sodium diets have been implicated in chronic inflammation (13-20) autoimmune disease (21-31), immune dysfunction (20, 21, 32-35) and cardiovascular disease from endothelial damage via glycocalyx dysfunction (36-39).  Given this information, it is irresponsible by the international fish canning industry to include added salt in canned sardines or any other canned fish product, particularly when these products can easily be manufactured without the addition of salt.

Decline in Vitamin and Mineral Content in Canned Sardines
In addition to their high salt content, canned sardines (because they are cooked twice at high temperatures during the canning process) maintain drastically reduced vitamin and mineral contents compared to their fresh counterparts. Table 2 below shows how B vitamins and  minerals decline with the canning process.  On average the canning of fresh sardines reduces vitamin B1 by 75 %, vitamin B2 by 51 %, vitamin B3 by 34 %, vitamin B6 by 50 % and vitamin B12 by 38 %.  Magnesium on average in canned sardines compared to fresh sardines is reduced by 44 %, zinc by 36 % and copper by 19 %.

Table 2.  The decline in nutrients between fresh and canned sardines.


The Formation of Oxidized Cholesterol by Products in Canned Sardines
Perhaps the least appreciated, but most important change in the nutritional quality of canned sardines (or any canned fish product) compared to their fresh counterpart is the formation of oxidized cholesterol by-products (40, 41).  Oxidized cholesterol by products are known to scientists as “oxysterols” and maintain multiple deleterious effects upon human health (42-46).  Oxysterols occur universally with the canning and processing of fish and seafood (40) and are associated with a multiplicity of chronic diseases including atherosclerosis (coronary heart disease), neurodegenerative diseases, inflammatory bowel diseases, and age related macular degeneration (40-46).

Canned fish and seafood products such as sardines (canned tuna, salmon, herring, shrimp, oysters etc.) are particularly susceptible to the formation of cholesterol oxides (oxysterols).  These fish and seafood products also contain high concentrations of long chain omega 3 fatty acids (docosahexaenoic acid [DHA], eicosapentaenoic acid [EPA] which have multiple beneficial health effects when they are consumed fresh.  Nevertheless, the long chain omega 3 fatty acids (DHA and EPA) found in canned fish and seafood are highly susceptible to thermal (heat) processing, and together with their endogenous cholesterol, yield highly toxic cholesterol oxide products (oxysterols) (40-46) that directly result from the retort cooking necessary to eliminate bacteria and botulism.  The very same process (retort cooking) which frees humanity from developing fatal botulism in canned foods, directly promotes chronic systemic inflammation via the synthesis of oxysterols that underlie heart disease, cancer, neurodegenerative diseases and inflammatory bowel diseases (40-46).     

Something as simple as eating canned sardines or canned tuna had never been considered to be a health risk, but the current evidence is undeniable, irrefutable and damning (40-46) particularly when canned sardines, fish and seafood are consumed on a regular basis.  Do yourself a favor, eat fresh fish, the way nature has always intended, and avoid the salt and cholesterol oxides found in the tainted products we call canned fish.




2.Hill, K.T., P.R. Crone, J.P. Zwolinski. 2017. Assessment of the Pacific sardine resource in 2017 for U.S. management in 2017-18. Pacific Fishery Management Council, April 2017 Briefing Book, Agenda Item G.5.a, Portland, Oregon. 146 p. Available at: //www.pcouncil.org/wpcontent/uploads/2017/03/G5a_Stock_Assessment_Rpt_Full_ElectricOnly_Apr2017BB.pdf




6.FC Lago, B Herrero, JM Vieites, M Espiñeira. FINS methodology to identification of sardines and related species in canned products and detection of mixture by means of SNP analysis systems. Eur Food Res Technol, 232 (6), 2011: 1077-1086.

7.Nutritionist Pro, nutritional software. //www.nutritionistpro.com/


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10.Carrera-Bastos P, Fontes Villalba M, O’Keefe JH, Lindeberg S, Cordain L. The western diet and lifestyle and diseases of civilization. Res Rep Clin Cardiol 2011; 2: 215-235.

11.Gotshall RW, Mickleborough TD, Cordain L. Dietary salt restriction alters pulmonary function in exercise-induced asthmatics. Medicine and Science in Sports and Exercise, 2000;32:1815-19.

12.Jantsch J, Schatz V, Friedrich D et al. Cutaneous Na+ storage strengthens the antimicrobial barrier function of the skin and boosts macrophage-driven host defense. Cell Metab. 2015 Mar 3;21(3):493-501.  

13.Jantsch J, Schatz V, Friedrich D et al. Cutaneous Na+ storage strengthens the antimicrobial barrier function of the skin and boosts macrophage-driven host defense. Cell Metab. 2015 Mar 3;21(3):493-501.

14.Dmitrieva NI, Burg MB. Elevated sodium and dehydration stimulate inflammatory signaling in endothelial cells and promote atherosclerosis. PLoS One. 2015 Jun 4;10(6): e0128870. doi: 10.1371/journal.pone.0128870

15.Yi B, Titze J,  et al.  Effects of dietary salt levels on monocytic cells and immune responses in healthy human subjects: a longitudinal study. Transl Res. 2015 Jul;166(1):103-10.  

16.Zhou X,  et al.  Variation in dietary salt intake induces coordinated dynamics of monocyte subsets and monocyte-platelet aggregates in humans: implications in end organ inflammation. PLoS One. 2013 Apr 4;8(4):e60332.

17.Ip WK, Medzhitov R. Macrophages monitor tissue osmolarity and induce inflammatory response through NLRP3 and NLRC4 inflammasome activation. Nat Commun. 2015 May 11;6:6931.

18.Foss JD, Kirabo A, Harrison DG. Do high-salt microenvironments drive hypertensive inflammation? Am J Physiol Regul Integr Comp Physiol. 2017 Jan 1;312(1):R1-R4

19.Min B, Fairchild RL. Over-salting ruins the balance of the immune menu.  J Clin Invest. 2015 Nov 2;125(11):4002-4.

20.Amara S, Tiriveedhi V. Inflammatory role of high salt level in tumor microenvironment (Review).  Int J Oncol. 2017 May;50(5):1477-1481

21.Kleinewietfeld M, et al.  Sodium chloride drives autoimmune disease by the induction of pathogenic TH17 cells. Nature. 2013 Apr 25;496(7446):518-22

22.Schatz V, et al.  Elementary immunology: Na+ as a regulator of immunity. Pediatr Nephrol. 2017 Feb;32(2):201-210.  

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24.Wu C, et al. Induction of pathogenic TH17 cells by inducible salt-sensing kinase SGK1. Nature. 2013 Apr 25;496(7446):513-7.

25.Hucke S, et al.. Sodium chloride promotes pro-inflammatory macrophage polarization thereby aggravating CNS autoimmunity. J Autoimmun. 2016 Feb;67:90-101.  

26.Zostawa J, et al. The influence of sodium on pathophysiology of multiple sclerosis. Neurol Sci. 2017 M

27.Khalili H et al. Identification and characterization of a novel association between dietary potassium and risk of crohn’s disease and ulcerative colitis. Front Immunol. 2016 Dec 7;7:554. doi: 10.3389/fimmu.2016.00554. eCollection 2016.

27.Sigaux J, et al. Salt, inflammatory joint disease, and autoimmunity. Joint Bone Spine. 2017 Jun 23. pii: S1297-319X(17)30129-X. doi: 10.1016/j.jbspin.2017.06.003.

28.Sundstrom B et al.  Interaction between dietary sodium and smoking increases the risk for rheumatoid arthritis: results from a nested case-control study. Rheumatology 2015;54:487-493

29.Yang X et al.  Exacerbation of lupus nephritis by high sodium chloride related to activation of SGK1 pathway. Int Immunopharm 2015;29:568-573.

30.Krementsov DN et al.  Exacerbation of autoimmune neuroinflammation by dietary sodium is genetically controlled and sex specific. FASEB J 2017;29(8):3446-3457.

31.Jorg S et al.  High salt drives Th17 responses in experimental autoimmune encephalomyelitis without impacting myeloid dendritic cells. Exp Neurol 2016;279:212-222

32.Schatz V, et al.  Elementary immunology: Na+ as a regulator of immunity. Pediatr Nephrol. 2017 Feb;32(2):201-210.  

33.Grivennikov SI, Wang K, Mucida D et al. Adenoma-linked barrier defects and microbial products drive IL-23/IL-17-mediated tumour growth. Nature. 2012 Nov 8;491(7423):254-8.

34.Safa K, et al.  Salt accelerates allograft rejection through serum- and glucocorticoid-regulated kinase-1-dependent inhibition of regulatory t cells. J Am Soc Nephrol. 2015 Oct;26(10):2341-7

35.Hernandez AL,  et al.  Sodium chloride inhibits the suppressive function of FOXP3+ regulatory T cells. J Clin Invest. 2015 Nov 2;125(11):4212-22

36.Oberleithner H, et al.  Plasma sodium stiffens vascular endothelium and reduces nitric oxide release. Proc Natl Acad Sci U S A. 2007 Oct 9;104(41):16281-16286.

37.Kusche-Vihrog K, Schmitz B, Brand E. Salt controls endothelial and vascular phenotype. Pflugers Arch. 2015 Mar;467(3):499-512

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Contradictions in The Paleo Diet for Athletes | The Paleo Diet

Hi Dr. Cordain,

I recently read your book The Paleo Diet for Athletes (I lift weights about 5-8hr/week). I really enjoyed the book. I noted on page 110 you say “Our experience, supported by the scientific evidence, leads us to believe that, as an athlete, you will benefit from C and E supplements as well.”

Yet in this interview (//sportsnutritioninsider.insidefitnessmag.com/2442/sni-interviews-dr-loren-cordain-author-of-the-paleo-diet)
you say “If fatty fish (salmon, mackerel, herring, sardines etc.) arent consumed regularly (3-5 times per week), then I recommend taking fish oil. I also recommend taking at least 2,000 I.U. of vitamin D per day if regular sunlight exposure is not possible. All other supplements are unnecessary because the Paleo Diet is so nutrient dense. In fact, large meta analyses (multiple population studies) show that antioxidant supplements can be harmful and actually increase overall mortality.”

(1) So I’m a little confused. I’m assuming it’s the increased free radicals/oxidative stress from regular intense exercise that give people who partake in regular intense exercise an increased demand, but the statement from the interview seems all encompassing. I noticed the interview is dated 2011, but your book was out in 2005. Has your opinion on the use of antioxidant supplements changed in recent years?

(2) In table 9.2 of your book you list canned fish, even sardines and salmon as a food to avoid, but in the interview you specifically mention sardines. Fresh sardines are not commonly available, I’m wondering what it is specifically about canned salmon and sardines that makes it worth avoiding? I just find them to be a highly convenient source of protein and good fats and make compliance for the diet easier.

(3) Also if you don’t mind, I’d really appreciate your take on oxidative stress caused by omega-3/fish oil supplementation and countering with taking Vit. E with your fish oil dose.

Fish oil supplements increase requirements for Vitamin E
LONDON, ENGLAND. A recent experiment carried out at King’s College in London showed that daily intake of fish oil supplement reduces the plasma concentration of vitamin E to below normal range. Nine healthy male subjects were given a daily fish oil supplement containing 2.1 g docosahexaenoic acid (DHA) and 0.8 g eicosapentaenoic acid (EPA) for a six week period. The proportion of DHA and EPA in the blood increased during the trial while the concentration of very-low-density-lipoprotein-cholesterol and triacylglycerol decreased. Blood pressure fell slightly during treatment, but rose again once the fish oil supplementation was discontinued. Of particular interest was the finding that alpha-tocopherol (vitamin E) concentration in the blood fell from 20 micromol/l to about 10 micromol/l during the experiment. This raises the question whether fish oil supplementation increases the need for antioxidant supplementation.
Sanders, T.A.B. and Hinds, Allison. The influence of a fish oil high in docosahexaenoic acid on plasma lipoprotein and vitamin E concentrations and haemostatic function in healthy male volunteers. British Journal of Nutrition, Vol. 68, July 1992, pp. 163-73

I know you’re busy. So I really appreciate any time you take to respond to this e-mail.


E. Ryan

Dr. Cordain’s Response:

Hi Ryan,

Good to hear from you.  Joe Friel (my co-author of the Paleo Diet for Athletes) have recently revised our book and the revision will hit the bookstores in the Fall.  We have modified some important points in the book and can no longer support the use of any antioxidants by athletes.  If you want to find out why before the release of our revised book, I have touched upon this topic as well in my new book, The Paleo Answer.  So, indeed, I have changed my perspective in this area based upon new comprehensive meta analyses that weren’t available in 2005.

All canned fish and meat contain high concentrations of oxidized cholesterol which in animal models accelerate the atherosclerotic (artery clogging) process.  Additionally, as I have pointed out in my first book, the vitamin content of canned meats and fish is significantly lower than either fresh meat or fish. Hence, it is always preferable to eat fresh meat and fish whenever possible.

Not consuming long chain omega 3 fatty acids (EPA and DHA) from either fatty fish or fish oil represents a much greater risk to overall heath than the slight reductions produced in vitamin E status.  Most meta analyses of either fish or fish oil consumption shows that long chain omega 3 fatty acid reduce overall mortality (death) from all causes and morbidity (disease incidence) from a wide variety of diseases that impact most of the western world.


Loren Cordain, Ph.D., Professor Emeritus

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