Tag Archives: PUFA

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.

 

Conclusion

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.

 

References

[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).

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