Tag Archives: omega-6

In Part I of this series, we looked at the longstanding recommendations of many governmental health organizations to reduce dietary saturated fat and replace it with omega-6 fats. Doing so supposedly, these organizations claim, reduces cardiovascular disease (CVD) risk. As we saw in Part I, however, there is considerable controversy within the nutrition science community concerning this claim. There’s a case to be made for decreased saturated fat, but there’s also a case for decreased omega-6. Since the current science is far less black-and-white than the recommendations would lead you to believe, with Part II of this series, we’ll be looking at the debate from a paleolithic perspective, with the hope of gaining a broader and more balanced perspective on optimal consumption levels of both saturated and polyunsaturated fats.


Paleo PUFA Consumption

Although conclusive scientific studies are lacking, we can gain valuable insight by examining the diets of our Paleolithic ancestors. How much of these nutrients did they consume? How do current PUFA recommendations compare to PUFA consumption by our Paleolithic ancestors?

To know how much saturated fat and PUFAs they ate, we first must estimate how much total fat they ate. As always, Paleolithic diets varied based on geography and access to certain foods, but in general, our ancestors ate relatively more fat, more protein, and less carbohydrate, compared to contemporary diets. In 2000, Dr. Cordain and his colleagues estimated the following macronutrient ratios for Paleolithic diets:[1]

  • Fat: 28-58% of calories
  • Protein: 19-35% of calories
  • Carbohydrates: 22-40% of calories

They arrived at these estimates, in part, by analyzing the diets of 229 hunter-gather societies, assessing their specific foods, and measuring their ratios of plant to animal food consumption. The vast majority (73%) of these societies derived more than 50% of their calories from animal foods [2].

Next, we need to estimate how macronutrients are distributed within the specific foods our ancestors ate. Figures 1 and 2 below compare the meat of wild animals with the meat of commercially raised animals. Figure 1 shows the percentage of calories from protein, fat, and carbohydrate (note that carbs are negligible in animal meat) whereas Figure 2 shows each type of fat as a percentage of total fat. We can assume, with a reasonable degree of certainty, that wild animals today are similar to those hunted and consumed by our ancestors, with respect to body composition.

Macronutrient Calories in Animal Foods

Figure 1. Percent of calories from macronutrients (protein, fat and carbohydrate) in wild and commercial animal foods.

Proportion of Fatty Acids in Animal Foods

Figure 2. Proportions of fatty acids in wild and commercial animal foods.


Examining these figures, two dominant trends emerge:

1. Wild meat is proportionally higher in protein and lower in fat compared to commercially raised meat.
2. The fat portion of wild meat is proportionally higher in PUFAs – both omega-6 and omega-3 – compared to commercial meat.

Additionally, we can say that grass-fed beef is closer to wild meat than grain-fed beef, but both grass-fed beef and grain-fed beef poorly approximate wild meat.

The above observations are based on data from the USDA Nutrient Database and are substantiated by numerous studies comparing wild and domesticated animals [3], [4], [5], [6], [7].

Additionally, scientists have recently extracted frozen, Paleolithic-era animal carcasses from the Siberian tundra. Tissue analyses of these carcasses further highlight the similarities between Paleolithic meat and modern wild meat, particularly with respect to n-6/n-3 ratios [8], [9].


The Ever-Important Omega Ratio

As we saw in part I, many RCTs, observational studies, and meta-analyses addressing omega-6 consumption fail to properly account for omega-3 consumption (and the n-6/n-3 ratio). For our Paleolithic ancestors, this ratio was approximately 1/1 (and probably no higher than 3/1) [10]. Today, however, the ratio approaches 20/1 for people consuming typical Western diets [11].

This disparity is critical to the entire debate about saturated fat and its replacement with omega-6. Recent studies show saturated fat isn’t a health menace, as previously believed [12][13][14][15]. On the other hand, our reliance on commercially raised meat has probably skewed our fat consumption by over-representing saturated fat and under-representing PUFAs. We’ve compensated by consuming large quantities of vegetable oils, which are rich in omega-6, but omega-3 consumption has fallen by the wayside.

The consequences of our dramatically elevated n-6/n-3 ratios include the following:[16]

  • Increased inflammation
  • Increased leptin and insulin resistance
  • Increased risk for diabetes
  • Increased weight gain and risk for obesity


Keeping it Real

Just as previous generations shunned saturated fat, we would be foolish to shun omega-6 completely. After all, omega-6 is an essential fatty acid (EFA), meaning our body requires it and can only obtain it from food. That being said, some sources of are better than others.

It’s easy to get good quality omega-6 from olive oil, avocados, nuts, and from certain animal foods. By following the Paleo Diet template, you’ll get a good balance of omega-6 and omega-3, plus a good distribution of SFAs, MUFAs, and PUFAs.

With respect to omega-6, our best advice would be to eliminate all vegetable and seed oils from your diet. These include, among others:

  • Soybean oil
  • Corn oil
  • Safflower oil
  • Sunflower oil
  • Canola oil
  • Grapeseed oil

The problem with these oils is they contain very high amounts of omega-6. Consuming them increases your n-6/n-3 ratio, while also introduces potentially dangerous free radicals.


Unstable Seed Oils

The industrial processing of vegetable seed oils involves high-heat and the use of various chemical solvents – a guaranteed recipe for free radical oxidation and lipid peroxidation [17].

Cooking with PUFA-rich oils creates lipid oxidation products known as alkenals, some of which are toxic [18].

Olive oil, which contains some PUFAs, but is mostly comprised of MUFAs, has been shown to be more heat-stable and better for cooking compared to vegetable oils [19],[20]. It’s best to avoid high-heat cooking with any oils, but those containing higher amounts of SFAs and MUFAs are more stable than those with higher amounts of PUFAs.



Saturated fat isn’t unhealthy, but it needn’t be over represented in our diets. Many health authorities recommend replacing saturated fat with omega-6, and although some studies support this recommendation, most fail to differentiate between omega-6 and omega-3. Replacing some saturated fat with PUFAs could be beneficial, particularly if doing so lowered the n-6/n-3 ratio. For most people, this would mean eliminating all vegetable seed oils, while increasing oily fish (omega-3) consumption.

It’s also important to recognize that meat from game animals is better than commercially raised meat, but since obtaining wild meat is impractical for most people, pasture-raised meat (grass-fed, etc.) should always be favored.

Don’t over complicate things too much. You don’t need to meticulously track your fat consumption. By following The Paleo Diet template and listening to your body, you’ll get a healthy mix.



[1] Cordain L, et al. (2000). Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition, 71(3). Retrieved from (link).

[2] Cordain L, et al. (2000). Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition, 71(3). Retrieved from (link).

[3] Davidson B, et al. (Mar-Apr 2011). Meat lipid profiles: a comparison of meat from domesticated and wild Southern African animals. In Vivo, 25(2). Retrieved from (link).

[4] Rule DC, et al. (2002). Comparison of muscle fatty acid profiles and cholesterol concentrations of bison, beef cattle, elk, and chicken. J Anim Sci., 80(5). Retreived from (link).

[5] Cordain, et al. (Mar 2002). Fatty acid analysis of wild ruminant tissues: evolutionary implications for reducing diet-related chronic disease. Nature, 56(3). Retrieved from (link).

[6] Cordain, et al. (2001). Fatty acid composition and energy density of foods available to African hominids. Evolutionary implications for human brain development. World Rev Nutr Diet., 90. Retrieved from (link).

[7] Fine LB, et al. (2008). Comparison of lipid and fatty acid profiles of commercially raised pigs with laboratory pigs and wild-ranging warthogs. South African Journal of Science, 104. Retrieved from (link).

[8] Guil-Guerrero JL, et al. (2014). The Fat from Frozen Mammals Reveals Sources of Essential Fatty Acids Suitable for Palaeolithic and Neolithic Humans. PLoS One., 9(1). Retrieved from (link).

[9] Guil-Guerrero JL, et al. (2015). The PUFA-Enriched Fatty Acid Profiles of some Frozen Bison from the Early Holocene found in the Siberian Permafrost. Scientific Reports, 5. Retrieved from (link).

[10] Eaton SB, et al. (1998). Dietary intake of long-chain polyunsaturated fatty acids during the paleolithic. World Rev Nutr Diet., 83. Retrieved from (link).

[11] Simopoulos AP. (2016). An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients, 8(3). Retrieved from (link).

[12] Ruiz-Nunez, B., D.A.J. Dijck-Brouwer, and F.A.J. Muskiet, The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease. Journal of Nutritional Biochemistry, 2016. 36: p. 1-20.

[13] Chowdhury, R., et al., Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk A Systematic Review and Meta-analysis. Annals of Internal Medicine, 2014. 160(6): p. 398-+.

[14] Astrup, A., et al., The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010? American Journal of Clinical Nutrition, 2011. 93(4): p. 684-688.

[15] Hoenselaar, R., Saturated fat and cardiovascular disease: The discrepancy between the scientific literature and dietary advice. Nutrition, 2012. 28(2): p. 118-123.

[16] Simopoulos AP. (2016). An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients, 8(3). Retrieved from (link).

[17] Kanner J, et al. (2007). Dietary advanced lipid oxidation endproducts are risk factors to human health. Mol Nutr Food Res., 51(9). Retrieved from (link).

[18] Halvorsen BL, et al. (2011). Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements. Food Nutr Res., 55. Retrieved from (link).

[19] Halvorsen BL, et al. (2011). Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements. Food Nutr Res., 55. Retrieved from (link).

[20] Silva L, et al. (2010). Oxidative stability of olive oil after food processing and comparison with other vegetable oils. Food Chemistry, 121(4). Retrieved from (link).

FOOD-official-meatFor over a decade now, a debate has been raging within the nutrition science community. One side views saturated fat as generally unhealthy; they recommend replacing these fats, at least to some degree, with omega-6 polyunsaturated fats. The other side views saturated fat as health-supportive, or at least health-neutral; likewise, they regard omega-6 as somewhat unhealthy and typically recommend decreasing its consumption. So, who has it right? The truth seems to be grey and somewhere in between.


The Modern Diet

Americans have largely followed the US government’s dietary advice for the past 40 years. For example, following official dietary advice in the 80s to reduce fat in our diets, we decreased our fat consumption from 45 to 34% of calories, on average, while increasing our carbohydrate consumption from 39 to 51% of calories [i].

We made these changes because doing so – or so we were told – would decrease cardiovascular disease (CVD), which was and still remains the number one cause of death in the western world.

However, there are also different types of fats (see Figure 1) and both international and US government guidelines have made recommendations about the types of fats we should consume. Current recommendations suggest reducing saturated fat to a maximum of 10% of total calories while increasing omega-6 to somewhere between five and 10% of total calories  [ii], [iii].

Figure 1. The basic types of fat.

Different Types of Fats


As a population, we’re pretty much within these recommended zones. We get 11% of our calories from saturated fat and 8% from polyunsaturated fat (primarily the omega-6 variety)[iv], [v].

CVD mortality has declined since its peak in the 1950s, but CVD prevalence remains very high. For example, the total number of inpatient cardiovascular operations and procedures increased 28% between 2000 and 2010 (from 5.9 million to 7.6 million procedures) [vi]. Moreover, prevalence of metabolic syndrome, a precursor to CVD, has reached a staggering 34% of the population [vii].

If the advice to replace saturated fat with omega-6 was designed to reduce CVD, then what went wrong? Was the advice misguided? Let’s look at the evidence.


The Pro-PUFA Studies

Numerous recently published meta-analyses support the conclusion that replacing saturated fat with polyunsaturated fat (though not necessarily omega-6) leads to modest CVD risk reductions. For example:


  • Mozaffarian D, et al. (2010) pooled data from 8 randomized controlled trials (RCTs) encompassing 13,614 participants and 1,042 coronary heart disease (CHD) events. They determined that for every 5% caloric increase in polyunsaturated (PUFA) fat there is a corresponding 10% decrease in CHD risk [viii].

Study Limitations: PUFA consumption for this study included both omega-6 and omega-3. Therefore, it’s possible the positive results may have been primarily from omega-3; negative effects from omega-6 could have been masked.


  • Hooper L, et al. (2015) pooled data from 13 long-term RCTs encompassing 53,300 participants. They found “a small but potentially important reduction in cardiovascular risk when saturated fat intake was lowered,” particularly by replacing saturated fat with PUFAs, but not by replacing it with carbohydrates [ix]. However, the study found no clear effect of reducing saturated fat on total mortality.

Study Limitations: Among these RCTs, omega-6 and omega-3 PUFAs were grouped together. Therefore, analyzing the individual impact of either PUFA was not possible.


  • Farvid MS, et al. (2014) conducted a meta-analysis of 11 studies pertaining to omega-6 (LA) intake and CHD. They concluded “a 5% of energy increment in LA intake replacing energy from saturated fat intake was associated with a 9% lower risk of CHD events and a 13% lower risk of CHD deaths”.

Study Limitations: (1) Whereas this study did specifically measure omega-6, it didn’t account for the ratio of omega-6 to omega-3 (referred to as “n-6/n-3” hereafter), (2) the meta-analysis only included observational studies, not RCTs, and (3) the meta-analysis measured cardiovascular disease mortality, but not all-cause mortality.


  • Yanping Li, et al. (2015) conducted a meta-analysis of two observational studies, the first of which followed 85,000 women for 24 years and the second of which followed 43,000 men for 30 years. In total, 7,667 cases of CHD were documented. The authors concluded that replacing 5% of the energy intake from saturated fats with equal energy from PUFAs was associated with a 25% reduced risk of CHD [xi].

Study Limitations: (1) The study was observational (no RCTs were included), (2) the study didn’t account for the n-6/n-3 ratio, and (3) the data was derived from food frequency questionnaires.


  • Wu JH, et al. (2015) conducted a cohort study of 2,792 older US adults (mean age, 74). To avoid the problems associated with food frequency questionnaires, they analyzed circulating omega-6 (LA only) blood levels, an objective biomarker of LA consumption[xii]. Those within the highest quintile of circulating LA had 13% lower all-cause mortality than those in the lowest quintile. Interestingly, when the authors stratified subjects based on combined LA and omega-3 PUFA concentrations, those in the highest quintile had a 54% lower all-cause mortality risk compared to those in the lowest quintile.

Study Limitations: This study was designed better than most, but didn’t completely demonstrate how changes to the n-6/n-3 ratio affect mortality.


The Anti-PUFA Studies

Christopher Ramsden, MD is a clinical investigator for the National Institutes of Health. During the past decade, Ramsden has been among the most prominent scientists challenging the mainstream narrative that omega-6 should replace saturated fat. Through a series of studies, most of which were published by the British Medical Journal, Ramsden and his colleagues have put forth an important antithesis [xiii], [xiv], [xv]. Some of their conclusions include:

  • Increasing omega-3 relative to omega-6 significantly reduces the risk of heart disease.
  • Diets rich in omega-6 increase risks of all CHD endpoints, while increasing all-cause mortality risk.
  • Substituting dietary omega-6 LA in place of SFA increases all-cause mortality risk, as well as risks from coronary heart disease.
  • Benefits previously attributed to greater intake of total PUFAs may be specifically attributable to omega-3 and not to omega-6 LA.

Some of the problems with the studies used to justify increased omega-6 consumption, according to Ramsden and his colleagues, include:

  • Failure to distinguish between trials that selectively increased omega-6 and those that substantially increased omega-3
  • Failure to acknowledge that omega-6 and omega-3 replaced not only SFAs, but large amounts of trans-fats in many trials used in the pro-PUFA meta-analyses
  • Failure to provide the specific compositions of the diets (particularly with respect to omega-6 and trans-fat) used in the pro-PUFA meta-analyses
  • Failure to analyze the impact of n-6/n-3 ratios

The Middle Ground

As you can see, the consumption of saturated fat and omega-6 are controversial, partly because we lack rigorous studies specifically designed to test the optimal balance between saturated fat, omega-6, and omega-3. This was precisely the conclusion of a 2015 Cochran review by Al-Khudairy L, et. al. [xvi].

The authors sought RCT data demonstrating the effectiveness of increasing or decreasing omega-6 for the prevention of cardiovascular disease. Additionally, they wanted to assess the impact of total omega-3 consumption and the n-6/n-3 ratio.

Unfortunately, “very few trials were identified with a relatively small number of participants randomized.” They concluded, (1) there is currently insufficient evidence to recommend either increased or decreased omega-6 consumption, and (2) larger, better RCTs on this topic are needed.



In Part 1 of this article series, we’ve seen that many critical questions about optimal saturated- and polyunsaturated fat consumption levels haven’t yet been answered by science. While we wait for better RCTs to be conducted, we can gain deeper insights and a better understanding of this issue by examining the fat consumption patterns of our Paleo ancestors. Be sure to check out Part II of this series, where we’ll do just that.



[i] Cohen E, et al. (2015). Statistical review of US macronutrient consumption data,

1965–2011: Americans have been following dietary guidelines, coincident with the rise in obesity. Nutrition, 31. Retrieved from (link).

[ii] US Department of Health and Human Services and U.S. Department of Agriculture. (Dec 2015). 2015–2020 Dietary Guidelines for Americans. 8th Edition. Retrieved from (link).

[iii] FAO. (2010). Fats and fatty acids in human nutrition: Report of an expert consultation. Rome: Food and Agriculture Organization of the United Nations. Retrieved from (link).

[iv] Ervin RB, et al. Centers for Disease Control. (Nov 2004). Advanced Data from Vital Health Statistics. Retrieved from (link).

[v] Wright JD, et al. Centers for Disease Control. (Nov 2010). Trends in Intake of Energy and Macronutrients in Adults. From 1999–2000 Through 2007–2008. NCHS Data Brief, 49. Retrieved from (link).

[vi] Mozaffarian D, et al. (2015). Heart Disease and Stroke Statistics—2015 Update. Circulation, 131. Retrieved from (link).

[vii] Aguilar M, et al. (2015). Prevalence of the Metabolic Syndrome in the United States, 2003-2012. JAMA, 313(19). Retrieved from (link).

[viii] Mozaffarian D, et al. (2010) Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS Med, 7(3). Retrieved from (link).

[ix] Hooper L, et al. (Jun 2015). Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev., 10(6). Retrieved from (link).

Farvid MS, et al. (Oct 2014). Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies. Circulation, 130(18). Retrieved from (link).

[xi] Yanping Li, et al. (Oct 2015). Saturated Fats Compared With Unsaturated Fats and Sources of Carbohydrates in Relation to Risk of Coronary Heart Disease. Journal of the American College of Cardiology, 66(14). Retrieved from (link).

[xii] Wu JH, et al. (Oct 2015). Circulating Omega-6 Polyunsaturated Fatty Acids and Total and Cause-Specific Mortality: The Cardiovascular Health Study. Circulation, 130(15). Retrieved from (link).

[xiii] Ramsden CE, et al. (2010). n-6 Fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials. British Medical Journal, 104(11). Retrieved from (link).

[xiv] Ramsden CE, et al. (2013). Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. British Medical Journal, 346. Retrieved from (link)

[xv] Ramsden CE, et al. (Apr 2016). Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). British Medical Journal, 353. Retrieved from (link).

[xvi] Al-Khudairy L, et al. (2015). Omega 6 fatty acids for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev., 16(11). Retrieved from (link).

Seafood Mercury Concerns Subside Amid New Research | The Paleo Diet

Fish and other marine life have been integral to human diets since the Paleolithic era. Some researchers even speculate that these foods “made us human” by enabling the rapid expansion of grey matter in the cerebral cortex. For three million years of evolution during the time of Australopithecus, brain capacity remained constant, but then curiously doubled during a one-million-year period between Homo erectus and Homo sapiens.1 The reasons for this great expansion are not entirely known, but increased dietary omega-3 from fish and shellfish was likely involved.

Fish consumption remains critically important today, but comes with complications unimaginable to our distant ancestors. Industrial pollution has greatly increased environmental mercury, much of which ends up in oceans and lakes, and finally, in small amounts, in the bodies of fish. In higher amounts, mercury is toxic and is especially problematic for developing babies. For years, the FDA was advising pregnant women to limit their fish consumption during pregnancy, but last year, they issued a draft revision encouraging prenatal fish consumption.2 This draft, which will eventually replace their previous recommendations, reflects a growing awareness, seen in the scientific literature, that fish is essential for developing babies and contains nutrients that limit, or even counter, the potentially harmful effects of mercury.

Recently published in the American Journal of Clinical Nutrition, a new study, representing 30 years of research in the Seychelles, is one of the longest and largest population studies regarding seafood and mercury.3 The Seychelles is a nation of islands clustered together in the Indian Ocean, where residents consume 10 times as much seafood as do Europeans and Americans, making it an ideal place to study the long-term impact of mercury exposure via seafood. The researchers concluded that high fish consumption by pregnant mothers, as much as 12 meals per week (the FDA recommends three), does not cause developmental problems in children.

To the contrary, fish is extremely beneficial for development, and contains special nutrients that protect against mercury. Lead author Dr. Sean Strain explained, “This research provided us the opportunity to study the role of polyunsaturated fatty acids [PUFAs] on development and their potential to augment or counteract the toxic properties of mercury.”4 Mercury is thought to damage the brain through oxidation and corresponding inflammation. Fish are rich in omega-3 PUFAs, which prevent inflammation, as opposed to omega-6 PUFAs, which promote inflammation. This was reflected in the study whereby children of mothers who had higher omega-6 blood levels performed worse on tests designed to measure motor skills.

This study builds upon an impressive body of research conducted by Dr. Nicholas Ralston and colleagues at the University of North Dakota. Ralston has demonstrated that selenium also protects against mercury toxicity and that foods with relatively higher amounts of selenium with respect to mercury, pose neither developmental nor neurological risks based on mercury toxicity.5 “This may explain,” Ralston says, “why studies of maternal populations exposed to foods that contain Hg [mercury] in molar excess of Se [selenium], such as shark or pilot whale meats, have found adverse child outcomes, but studies of populations exposed to MeHg [methylmercury] by eating Se-rich ocean fish observe improved child IQs instead of harm.”6

The vast majority of commonly consumed fish and shellfish contain far more selenium relative to mercury and many have significant amounts of omega-3 PUFAs. This means that fish and shellfish, two important components of the Paleo diet, should not be limited nor discontinued based on mercury concerns. Whether for pregnant women, babies, children, or adults, we encourage you to keep seafood on the menu.

Christopher James Clark, B.B.A.

Nutritional Grail

Christopher James Clark | The Paleo Diet TeamChristopher James Clark, B.B.A. is an award-winning writer, consultant, and chef with specialized knowledge in nutritional science and healing cuisine. He has a Business Administration degree from the University of Michigan and formerly worked as a revenue management analyst for a Fortune 100 company. For the past decade-plus, he has been designing menus, recipes, and food concepts for restaurants and spas, coaching private clients, teaching cooking workshops worldwide, and managing the kitchen for a renowned Greek yoga resort. Clark is the author of the critically acclaimed, award-winning book, Nutritional Grail.


[1] Bradbury, J. (May 2011). Docosahexaenoic Acid (DHA): An Ancient Nutrient for the Modern Human Brain. Nutrients, 3(5). Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257695/

[2] U.S. Food and Drug Administration. (June 2014). Fish: What Pregnant Women and Parents Should Know. Draft Updated Advice by FDA and EPA. Retrieved from http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm393070.htm

[3] Strain, JJ, et al. (January 2015). Prenatal exposure to methyl mercury from fish consumption and polyunsaturated fatty acids: associations with child development at 20 mo of age in an observational study in the Republic of Seychelles. American Journal of Clinical Nutrition, 101(1). Retrieved from http://ajcn.nutrition.org/content/early/2015/01/21/ajcn.114.100503

[4] University of Rochester Medical Center. (January 21, 2015). Fatty acids in fish may shield brain from mercury damage. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2015/01/150121144835.htm

[5] Ralston, NV and Raymond, NJ. (November 2010). Dietary selenium’s protective effects against methylmercury toxicity. Toxicology, 278(1). Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/20561558

[6] Ibid, Ralston.

Selecting Seafood for Health and Sustainability | The Paleo Diet

There’s no question that seafood is a great source of protein and omega-3 fatty acids, and that it should form an integral part of the Paleo Diet. But seafood doesn’t thrive in polluted waters, overfished waters, or in habitats damaged by fishing gear. So to get the good without the bad—and to ensure we have it for years to come—we need to know which species have the holy trinity of seafood: sustainable, safe, and nutritious.


Sustainably caught fish may seem like a nice-to-have, but it should really be on par with nutrition for importance when selecting seafood. Not only do we want our food to be harvested or caught in its highest nutritive state, we want that to continue indefinitely. It hasn’t always been that way, but more and more fisheries are making sustainability a reality by considering the health of ecosystems and fish populations as well as their profits. Seafood Watch® makes science-based recommendationsfor sustainable seafood.1,2,3 Here’s their current list of best choices, good alternatives, and choices to avoid.

Selecting Seafood for Health and Sustainability

The seafood recommendations in this guide are credited to the Monterey Bay Aquarium Foundation ©2014. All rights reserved.

Download the PDF


In the seafood world, mercury, dioxins, and PCBs are the usual suspects when it comes to contamination. They’re not normally features of a “healthy and abundant stock” which is a fundamental criterion for sustainability1—so if you’re choosing sustainable, you’re likely choosing safe too. In addition, SeafoodWatch® posts health alerts if there are specific concerns for human health from a fishery.

Mercury, however, is a changing story. Mercury accumulates in fat tissues of large, long-lived predatory fish or shellfish, ultimately ending up on our dinner plates. We’ve been cautioned to limit these species in our diets, but surprisingly, that’s not the whole story. Mercury readily and irreversibly binds to selenium,4 which means that as long as the fish you’re eating has more selenium than mercury, your body won’t actually be retaining the mercury you ingest. And since the oceans are full of selenium, most ocean fish are perfectly safe to eat.5,6 Simply avoid shark and limit swordfish, tilefish, and king mackerel or use this infographic to moderate your consumption . Also keep in mind that in freshwater, mercury and selenium levels vary greatly with the composition of the surrounding soil. Check with your local authorities for health alerts.


Fish are great sources of vitamins and minerals as well as protein, but the biggest benefit from eating fish is the omega-3 fatty acids EPA and DHA.7 Anyone who’s had king salmon and a haddock fillet can tell you, however, that all fish are not created equal when it comes to fat—and they’re not all created equal when it comes to omega-3 to omega-6 ratios either—and that matters! Here’s some nutritional data from the USDA for some popular fish and shellfish.6

Sustainable Choices in SeafoodSustainable Choices in Seafood

Highlighted numbers in the first four columns are amounts greater than 1 g/100 g; highlighted numbers in the last column are the fish with ratios greater than 5. A few things jump out.

  • Total fat isn’t everything: the number of fish hitting 1 g/100 g decreases as we move from total fat to polyunsaturated fat to omega-3s.
  • Atlantic mackerel, chinook salmon, herring, swordfish, and Bluefin tuna have high total fat and great omega-3/omega-6 ratios.
  • Only farmed Atlantic salmon has more than 1 g/100 g of omega-6s.
  • All but tilapia have an omega-3/omega-6 ratio greater than 1.
  • There doesn’t seem to be a relationship between total fat and the omega-3/omega-6 ratio. There are high fat options with low ratios (Atlantic salmon) and high ratio options with lower fat (squid).

Sustainable + Safe + Nutritious

So can we have our fish and eat it too? Yes! There is an impressively wide array of sustainable options to choose from, and we can assume that they’re safe choices, not only because they’re sustainable, but because they’re high in selenium. Many of those sustainable options are also fatty fish with great omega-3/omega-6 ratios (anything above 1 is great). SeafoodWatch® compiled their “Super Green List” based on these criteria, but let’s look at the poor performers to compare.

  • Atlantic salmon: not sustainably caught, high omega-6s, ratio close to 1
  • Bluefin tuna: great fat profile, great ratio, but not sustainable
  • Tilapia: sustainably farmed, but lower in fat, ratio less than 1
  • Sharks: more mercury than selenium, not sustainably caught

The bottom line: while some seafood looks good in the nutritional breakdown, from a sustainability standpoint, some species may be better than others. So, eat your recommended portion of omega-3s, but choose options that tick all the boxes for your health as well as the ocean’s.

Andrea MooreAndrea Moore has dipped her toes in a lot of ponds, lakes, and oceans over the years. She has adventured around the world doing odd jobs and studying biology, languages, and sailing.

Now surprisingly settled in Halifax, Nova Scotia, Andrea’s still up to a bit of everything as a marine biologist, a writer, and an editor, living the Paleo lifestyle.

fix-logoFix.com is a lifestyle blog devoted to bringing you expert content to make your life easier. From products, to food, to fishing, to projects, we’ll be providing you with a daily fix of content from our experienced and knowledgeable team of writers.



1. Monterey Bay Aquarium. Developing Seafood Watch® Recommendations. Version: January 23, 2014.

2. Monterey Bay Aquarium. Seafood Watch® Criteria for Aquaculture. Accessed: September 5, 2014.

3. Monterey Bay Aquarium. Seafood Watch ® Criteria for Fisheries. Version: March 31, 2014.

4. Ralston NVC, Ralston CR, Blackwell 3rd JL, Raymond LJ. Dietary and tissue selenium in relation to methylmercury toxicity. NeuroToxicology 2008;29(5):802-11.

5. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th Edition, Washington, DC: U.S. Government Printing Office, December 2010.

6. US Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory. USDA National Nutrient Database for Standard Reference, Release 27. Version Current: August 2014.

7. Kidd PM. Omega-3 DHA and EPA for cognition, behavior, and mood: clinical findings and structural-functional synergies with cell membrane phospholipids. Altern Med Rev 2007;12(3):207-27.

Omega-3 vs. Omega-6: Rethinking the Hypothesis

When you’re eating a meal, you’re probably not thinking about macronutrients, like carbohydrates, fats and proteins. The vast majority of individuals following a Western diet aren’t consciously thinking is this food essential to the human body? It is important to note, however, that while there is no such thing as an “essential carbohydrate,”1 there are “essential fats.”2 Essential in the sense that the human body cannot make these fats endogenously,3 and therefore, must be obtained via diet or supplementation.4 Within the class of essential fats, we have omega-3, which has different forms such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (E’PA).5 However, omega-3 is more commonly known to the general populace as “fish oil.”

Omega 3 fatty acids are long chain in structure and found in a variety of foods.6 The action of these long chain fatty acids is commonly called “anti-inflammatory,” though this is a misnomer.7 They are simply less inflammatory than omega-6 fatty acids. Omega-3 FAs and omega-6 FAs compete for the same enzyme to eventually be converted into anti-inflammatory prostaglandins (PGE3) and less inflammatory leukotrienes and into pro-inflammatory prostaglandins (PGE2) and more inflammatory leukotrienes, respectively.8 This paper then goes on to declare, it is the ratio of omega-6 to omega-3 that is vital to reduce or promote the overall inflammatory state of the body.9,10,11 When we look to the habits of hunter-gatherers, the ratio of omega-6 to omega-3 has been estimated at 2:1 or 3:1.12 This is in contrast to the modern diet, which has been estimated at 10:1, or even 25:1.13

With this evidence, it is assumed that emulating the ratio of hunter-gatherers is correct, if we want to improve bio-markers of health.14 Certainly the theory that an inflammatory diet, full of omega-6 rich vegetable oils and very little omega-3 would likely lead to health problems, makes basic sense.15 However, newer research suggests both omega-6 and omega-3 FAs reduce the risk of heart disease, and the ratio of these fatty acids is “not useful and can be misleading.”16 One study reported that omega-6 FAs do not inhibit the beneficial effects of omega-3 FAs, and the combination of both fatty acids leads to the greatest reduction in levels of inflammation.17

However, the real issue here is that omega-3 FAs bind to G coupled-protein receptors, and cause broad anti-inflammatory effects.18 If you remove the omega-3 FAs from your diet, inflammation returns. This means that adequate omega-3 intake alone, regardless of omega-6 intake, is enough to stop inflammation in the body. The same is apparent when you look at the biochemical pathway of omega-6 and omega-3 FAs. They compete for the same enzyme19 through a process known as competitive inhibition.20

The best method of action to pursue, is to simply follow a Paleo Diet and eat plenty of fish rich in omega-3. If you want to avoid dietary intake of omega-3, and obtain the requirements solely from a supplement, DHA is preferable to all other forms of omega-3, since it can be retro converted into EPA.21 Only in the context of a very inflammatory diet (like the standard Western diet) does the ratio of omega-3 to 6 matter. Another case where the ratio would be of utmost importance, is if you aren’t getting any omega-3 FAs at all. This isn’t to say that the omega-3 to omega-6 ratio is completely irrelevant, but if you’re consuming a Paleo Diet, you will likely be getting the right amounts of these essential fatty acids for optimal health.


1. Westman EC. Is dietary carbohydrate essential for human nutrition?. Am J Clin Nutr. 2002;75(5):951-3.

2. Insel, Paul. Nutrition: Custom Edition. 4th Edition. Jones & Bartlett Learning, 2010; 182.

3. Chang CY, Ke DS, Chen JY. Essential fatty acids and human brain. Acta Neurol Taiwan. 2009;18(4):231-41.

4. Singh M. Essential fatty acids, DHA and human brain. Indian J Pediatr. 2005;72(3):239-42.

5. Wainwright PE. Dietary essential fatty acids and brain function: a developmental perspective on mechanisms. Proc Nutr Soc. 2002;61(1):61-9.

6. Meyer BJ, Mann NJ, Lewis JL, Milligan GC, Sinclair AJ, Howe PR. Dietary intakes and food sources of omega-6 and omega-3 polyunsaturated fatty acids. Lipids. 2003;38(4):391-8.

7. Foitzik T, Eibl G, Schneider P, Wenger FA, Jacobi CA, Buhr HJ. Omega-3 fatty acid supplementation increases anti-inflammatory cytokines and attenuates systemic disease sequelae in experimental pancreatitis. JPEN J Parenter Enteral Nutr. 2002;26(6):351-6.

8. Macsai MS. The role of omega-3 dietary supplementation in blepharitis and meibomian gland dysfunction (an AOS thesis). Trans Am Ophthalmol Soc. 2008;106:336-56.

9. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002;56(8):365-79.

10. Gómez candela C, Bermejo lópez LM, Loria kohen V. Importance of a balanced omega 6/omega 3 ratio for the maintenance of health: nutritional recommendations. Nutr Hosp. 2011;26(2):323-9.

11. Simopoulos AP. The omega-6/omega-3 fatty acid ratio, genetic variation, and cardiovascular disease. Asia Pac J Clin Nutr. 2008;17 Suppl 1:131-4.

12. Cordain L, Eaton SB, Sebastian A, et al. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr. 2005;81(2):341-54.

13. Yan L, Bai XL, Fang ZF, Che LQ, Xu SY, Wu D. Effect of different dietary omega-3/omega-6 fatty acid ratios on reproduction in male rats. Lipids Health Dis. 2013;12:33.

14. Apte SA, Cavazos DA, Whelan KA, Degraffenried LA. A low dietary ratio of omega-6 to omega-3 Fatty acids may delay progression of prostate cancer. Nutr Cancer. 2013;65(4):556-62.

15. Kang JX, Liu A. The role of the tissue omega-6/omega-3 fatty acid ratio in regulating tumor angiogenesis. Cancer Metastasis Rev. 2013;32(1-2):201-10.

16. Anton SD, Heekin K, Simkins C, Acosta A. Differential effects of adulterated versus unadulterated forms of linoleic acid on cardiovascular health. J Integr Med. 2013;11(1):2-10.

17. Pischon T, Hankinson SE, Hotamisligil GS, Rifai N, Willett WC, Rimm EB. Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women. Circulation. 2003; 108(2): 155-160.

18. Oh DY, Talukdar S, Bae EJ, et al. GPR120 is an omega-3 fatty acid receptor mediating potent anti-inflammatory and insulin-sensitizing effects. Cell. 2010;142(5):687-98.

19. Babcock TA, Novak T, Ong E, Jho DH, Helton WS, Espat NJ. Modulation of lipopolysaccharide-stimulated macrophage tumor necrosis factor-alpha production by omega-3 fatty acid is associated with differential cyclooxygenase-2 protein expression and is independent of interleukin-10. J Surg Res. 2002;107(1):135-9.

20. Oleñik A, Mahillo-fernández I, Alejandre-alba N, et al. Benefits of omega-3 fatty acid dietary supplementation on health-related quality of life in patients with meibomian gland dysfunction. Clin Ophthalmol. 2014;8:831-6.

21. Conquer JA, Holub BJ. Dietary docosahexaenoic acid as a source of eicosapentaenoic acid in vegetarians and omnivores. Lipids. 1997;32(3):341-5.

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