Dietary fat part 2: Polyunsaturated fatty acids

 

In my last post, I provided a short history of the history and politics of saturated fat: the dietary villain of the past 40 years. Big sugar corporations had a big role to play in this vilification, financially supporting researchers who could prove fat and not sugar, was the contributing problem in the heart disease epidemic and disempowering scientists who have claimed the opposite.

Research is pointing towards elevated sugar and carbohydrate intake as the contributing factor to heart disease and total mortality, as well as to obesity and diabetes. Saturated fat does not appear to be the main causative factor we once thought, and some studies are even pointing to the fact that saturated fat intake might actually be protective (1).

However, in the prime of the saturated fat debate years ago, scientists believed that replacing saturated fat with vegetable oils and margarine, would reduce cholesterol deposits in blood vessel walls, and thereby reducing chances of developing heart disease.

Industrial seed and vegetable oils such as sunflower, corn, soy, canola, and vegetable oil, contain primarily omega-6 polyunsaturated fatty acids (PUFA), otherwise called linoleic acid. It was believed that swapping out saturated fats for PUFA would reduce heart disease risk because Ancel Keys said that saturated fat is the cause of all of our problems. Despite the “compelling relations”, no study had outright shown that replacement of saturated fat with vegetable oils would reduce heart disease or death (2).

As a matter of fact, more and more evidence is pointing towards omega-6 PUFA being detrimental to health in high quantities.

[ctt template=”7″ link=”865Pa” via=”yes” ]More and more evidence is pointing towards omega-6 Polyunsaturated fatty acids being detrimental to health in high quantities.[/ctt]

 

Wait, what? How can that be?

Here’s the deal: Historically, before the advent of refined and processed food, omega-6 PUFA naturally occurred in foods such as nuts and seeds, but the consumption of this linoleic acid averaged 2-3% of calories eaten. This percentage equated to an average of a 1:1 to 4:1 ratio compared with the intake of omega-3 linolenic acid, which is an essential fatty acid most commonly found in fish, and small amounts in grass-fed meats.

When the ratio of omega-6 to omega-3 consumed is between 1:1 to 4:1, all is well. Intake of both of these fatty acids is necessary, as we cannot produce them on our own (2,4).

The problem arises when this ratio becomes skewed. With the rise of heavily refined seed oils from soy, corn, sunflower, canola, etc, our intake has risen 1000-fold in the past 100 years. Instead of 2-3% of calories eaten, omega-6 PUFA (linoleic acid) now represents 7-8% of calories eaten, which equates to a ratio of about 16:1 to 30:1 depending on the individual’s diet (2,3).

When linoleic acid intake exceeds the optimal 1:1 to 4:1 ratio with linolenic acid, the excess linoleic acid starts to cause problems. Excess omega-6 contributes to inflammation in the body through various pathways. This pro-inflammatory effect contributes to the development of heart disease, weight gain, obesity, diabetes, and even cancer (4-12, 21, 22).

Consuming excess levels of omega-6 fatty acids may not only affect you directly but also your children. Mouse studies show that the offspring of mothers who consume excess omega-6 fatty acids during pregnancy demonstrate higher levels of excess weight and obesity (4). It is also theorized that high levels of omega-6 fatty acids in a father’s diet can cause enough oxidative damage to his sperm to potentially increase the risk of the development of childhood cancers in his offspring (12).

Studies show that this inflammatory effect not only affects body systems and tissues but also the brain. Canola oil is shown to cause memory problems, and influence the development of Alzheimer’s disease, and possibly dementia. Medical News Today states that “Based on these results, the researchers speculate that long-term consumption of canola oil is unlikely to offer any benefits for brain health, and it may actually be harmful.” (13-15, 21).

It is not only the excess levels of omega-6 fatty acids from polyunsaturated industrial seed and vegetable oils that can cause problems in the body. When these oils are heated, chemicals called aldehydes are released. Aldehydes are linked to the development of cancer, heart disease, and dementia, as well as malformations during pregnancy.

Frying food in vegetable oil can produce aldehyde levels 100 to 200 times more toxic than the safe daily limit set by the World Health Organization. Saturated fatty acids like lard, coconut oil, and butter do not produce aldehydes to this elevated degree. (14,16,17)

Wow! That’s a lot of information! I haven’t even gotten into discussing olive oil yet!

I have only scratched the surface of information on this topic, but it is a good amount to start with so that you can begin to make better-informed decisions for yourself.

So what have we learned so far?

It seems that the “evil saturated fats” aren’t actually as evil as we once believed, and in moderate amounts might actually be protective, when consumed as part of whole foods with naturally-occurring saturated fatty acids, such as coconut oil, duck fat, tallow, butter, and eggs.

Financial backing from the sugar industry appears to have been a giant impetus to fuel this belief that saturated fats must be avoided.

As a result, the industrial processed seed and vegetable oil industry began to flourish. This food industry as it turns out, is a financial supporter of the American Heart Association (AHA), which adamantly sticks by the outdated belief that we need to replace all saturated fats with polyunsaturated fats like seed and vegetable oils. Various other food companies pay thousands of dollars every year per product to get a “heart-check mark” from the AHA to demonstrate that their processed food product is low in fat, in particular, saturated fat, regardless of the sugar content (18,19,20).

More and more evidence is starting to point to these refined omega-6 containing seed and vegetable oils as major contributors to many of the epidemic diseases of modern society, like obesity and diabetes.

Is this new news for you? Will this information change the way you look at your food choices?

Next week, I will discuss omega-9 fatty acids, and then put it all together. Be sure to check it out!

References:

1. Dehghan, MahshidDiaz,  R et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. The Lancet. 2017;390(10107): 2050-2062. http://dx.doi.org/10.1016/S0140-6736(17)32252-3
2. Ramsden, Zamora D et al. Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). BMJ. 2016;353:i1246. https://doi.org/10.1136/bmj.i1246
3. Blasbalg TL, Hibbeln JR, Ramsden CE, Majchrzak SF, Rawlings RR. Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century. The American Journal of Clinical Nutrition. 2011;93(5):950-962. http://doi.org/10.3945/ajcn.110.006643.
4. Simopoulos AP. An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients. 2016;8(3):128. http://doi.org/10.3390/nu8030128
5. Yam D, Eliraz A, Berry EM. Diet and disease–the Israeli paradox: possible dangers of a high omega-6 polyunsaturated fatty acid diet. Isr J Med Sci. 1996 Nov;32(11):1134-43. https://www.ncbi.nlm.nih.gov/pubmed
6. Goodrich, T. Omega-6 fatty acids: the alternative hypothesis for diseases of civilization. Aug 2017. http://breaknutrition.com/omega-6-fats-alternative-hypothesis-diseases-civilization/
7. Deol P, Evans JR, Dhahbi J, Chellappa K, Han DS, et al. (2015) Soybean Oil Is More Obesogenic and Diabetogenic than Coconut Oil and Fructose in Mouse: Potential Role for the Liver. PLOS ONE 10(7): e0132672. https://doi.org/10.1371/journal.pone.0132672
8. Deol P, Fahrmann J et al. Omega-6 and omega-3 oxylipins are implicated in soybean oil-induced obesity in mice. Scientific Reports. 2017; 7(12488). http://doi.org10.1038/s41598-017-12624-9
9. University of California – Riverside. “GM soybean oil causes less obesity and insulin resistance but is harmful to liver function: Mouse study compares Plenish to conventional soybean, coconut, and olive oils.” ScienceDaily. 2 October 2017. <www.sciencedaily.com/releases/2017/10/171002084828.htm>
10. Mangan P. Vegetable oils cause insulin resistance. Oct 2017. http://roguehealthandfitness.com/vegetable-oils-cause-insulin-resistance/
11. Whiteman H. Canola oil may worsen memory. Dec 2017. https://www.medicalnewstoday.com/articles/320294.php
12. Gellespie D. How fathers avoiding vegetable oil can prevent childhood cancer. Mar 2017. http://davidgillespie.org/how-avoiding-vegetable-oil-can-prevent-childhood-cancer/
13. Hinde, N. Vegetable oil linked to cancer and dementia, experts recommend butter, lard and olive oil instead. Sep 2015. http://www.huffingtonpost.co.uk/2015/11/09/cooking-with-vegetable-oil-associated-with-cancer_n_8509382.html?utm_sq=fjg64yy01j
14. Thistlethwaite, F. Dementia update: Vegetable oil putting millions at risk of degenerative brain disease. Feb 2017. https://www.express.co.uk/life-style/health/762144/Vegetable-oil-dementia-link?utm_sq=fjg62sp245
15. Lauretti E, Pratico D. Effect of canola oil consumption on memory, synapse and neuropathology in the triple transgenic mouse model of Alzheimer’s disease. Scientific Reports. 2017; 7(17134). http://doi.org/10.1038/s41598-017-17373-3
16. Mendick R. Cooking with vegetable oils releases toxic cancer-causing chemicals, say experts. Nov 2015. http://www.telegraph.co.uk/news/health/news/11981884/Cooking-with-vegetable-oils-releases-toxic-cancer-causing-chemicals-say-experts.html?utm_sq=fjg63mes1g
17. Holland L. Don’t use vegetable oil, says experts: Butter, lard and olive oil are better. Nov 2015. https://www.express.co.uk/life-style/health/618023/health-vegetable-oil-coconut-lard-butter
18. Rosenberg M. The American Heart Association – Protecting industry not patients. Feb 2014. https://www.huffingtonpost.com/martha-rosenberg/health-news_b_4398304.html
19. Mercola. American Heart Association renders itself obsolete with 1960s dietary advice on coconut oil. July 2017. http://www.prohealth.com/library/showarticle.cfm?libid=30507
20. Hari V. Is coconut oil healthy? The controversy explained. July 2017. https://foodbabe.com/2017/07/11/coconut-oil-healthy-controversy-explained/
21. Patterson E, Wall R, Fitzgerald GF et al. Health implications of high dietary Omega—6 polyunsaturated fatty acids. J Nutr Metab. 2012; 2012:539426. https://dx.doi.org/10.1155%2F2012%2F539426
22. Joseph M. 8 harmful effects of soybean oil: what it really does to you. Apr 2017. http://nutritionadvance.com/harmful-effects-of-soybean-oil/