I want to preface this with acknowledging the fact that I have written previous blogs on the subject of seed oils and those were painted in a negative light. I'm going to leave those up for reference to the fact that we can all change our minds sometimes, its good for people to see how I've come full circle in my thought processes and perhaps it will help people be aware that we can change our minds at any time on any topic.
I also want to say I am not a Physician, Nutritionist, or Toxicologist. I am simply a gal who is a hobby researcher and looking at the total body of evidence. I don't claim to know enough to even be close to qualified on the science of seed oils. What I am doing is simply presenting my findings and sharing what I understand the evidence to show in a digestible light.
Welcome back, I couldn't resist doing another deep dive on this topic mostly for my own curiosity. This time I'd like to take the conversation farther. I'd like to look at some the claims about seed oils in today's natural living cliques and groups. Let's go over of these claims and look at them closely while we also search for anything to give weight to these claims. Is there any weight to them, and are they true? Seed oils are deemed as the "worst of the worst" when it comes to oils you can consume, with its opponents claiming they will cause major inflammation and countless other health issues. As someone who has been on the anti-seed oil bandwagon for the last 4 years, I want to dive headfirst into this topic and dig up every study available and see what they show.
You may be wondering why? Why am I even opening this door to the topic of seed oils? I am a pretty "natural" and "holistically" focused person and if I had to pick a diet or lifestyle that I most align with it would be the carnivore diet. I eat very high protein, high saturated fats, natural sugars in fruits and lots of honey every day with some veggies in there too and complex carbs. I eat that way mainly because I feel my best with that kind of lifestyle. I lift weights 4-5 times a week I need high protein to maintain my muscle. Due to living that way that I've been aware of the belief that seed oils are toxic for years now and being in that circle I hear it constantly. I read about it constantly, my fellow peers in carnivore/crunchi/natural skincare communities push it constantly. I must admit I only started to have my doubts fairly recently. When specific things are so demonized to the point of someone being crucified if they say the opposite that gets my attention. You could almost say it's become cult like in the Carnivore/crunchi/natural community.
Logic and reasoning are the way I have looked at things around me for a long time, so I ask again are seed oils the culprits? They've been so targeted to the point of ad nauseum that I think its worth looking into.
Its important to remember that data changes, new tests are performed, new information is always being released, so these studies are pertinent to right now in late 2023. In another five years there could be new information released that would change my mind again. It truly depends on how much more we learn about seed oils and the effect on our health.
WHEN DID SEED OILS BECOME THE ENEMY?
Many health and wellness influencers and natural skincare businesses push the idea that seed oils, Linoleic Acid or Omega 6s are oxidizing in your body and causing a number of health ailments such as more severe sunburns, heart disease, diabetes, thyroid issues, hormonal issues, progressed aging, major inflammation, and even cancer. This seems like a fair evaluation considering we didn't start eating seed oils more widely until the 1960s and since then our health issues as a species have skyrocketed. Our weight issues have skyrocketed. We need to look at things as a whole and look at the bigger picture when evaluating if something is to blame. It seems at first glance this could be a result of quite a few factors, but are seed oils alone specifically to blame? It seems sometime in the last ten years the focus has shifted to seed oils as being one of the main reasons for all of our health issues, and within the last five years it has been a full blown war on them in Western America throughout the natural/carnivore/crunchi/naturopathic communities.
TESTING TYPES AND LINGO
There are three types of lab tests that are done, Invitro which are done in a lab in a test tube with human tissue or human cellular matter. Animal studies which are typically done on animals like rats or rabbits, and Randomized Control Trials which are the ones we will be focusing on which are used on actual human subjects.. Those are the best ones to evaluate due to being tested with real human subjects it gives us an accurate meta-analysis on participants inflammation levels, and cholesterol levels. Randomized control trials are the best way to understand data and how something effects humans with long term and short-term in regards to an ingredient or chemical.
*An important point to note is variability in trials and Meta analysis. Scientists and researchers can perform the same tests ten times and it could produce slightly different results for one of those tests dependent on different variables. The main takeaway to remember is that we need to evaluate the sum results as a whole. Taking away information from all the different tests performed and pooling them together to draw a conclusion. Anyone can take one test that was performed out ten that showed slightly differing results and only present that to the viewer which in turn presents it in a way that doesn't correlate with all the evidence together as one sum. So, it could not be an accurate reflection of all the data.
WHO IS IN THE BACKROUND?
Let’s talk about Ray Peat, who is Ray Peat? Ray Peat is a biologist who has researched the interaction between nutrition, hormones, and health. He is well known for the Ray Peat diet. Ray Peat is the main person I am aware of to start really pushing that seed oils were completely and totally toxic. (Folllowing him was Mark Sisson with the rise of the Paleo diet and the Primal diet that he pioneered to the forefront in the early 2010s). Ray Peat is the first that I am aware of to really bring the seed oils into spotlight of people's minds.
Here is what Ray Peat has to say about seed oils-
"Vegetable oil is recognized as a drug for knocking out the immune system. Vegetable oil emulsions were used to nourish cancer patients, but it was discovered that the unsaturated oils were suppressing their immune systems. The same products, in which vegetable oil is emulsified with water for intravenous injection, are now marketed specifically for the purpose of suppressing immunity in patients who have had organ transplants. Using the oils in foods has the same harmful effect on the immune system. Unsaturated oils get rancid when exposed to air; that is called oxidation, and it is the same process that occurs when oil paint "dries." Free radicals are produced in the process. This process is accelerated at higher temperatures. The free radicals produced in this process react with parts of cells, such as molecules of DNA and protein and may become attached to those molecules, causing abnormalities of structure and function."
According to Ray Peat the reason seed oils are so toxic is because of their double bond carbon chains. When heated they are unstable and oxidize quickly and easily. Ray Peat says its the polyunsaturated fats themselves which are toxic.
Ray Peat references two studies in the article one is: C. J. Meade and J. Martin, Adv. Lipid Res., 127, 1978, and E. A. Mascioli, et al., Lipids 22(6) 421, 1987. I could not find any actual excerpts of these two studies which I suspect is because they are very old and from a Science Journal titled the Role of Lipids in the regulation of the immune system.
The Carnivore MD Paul Saladino references a study from the 1960s called the Minnesota Coronary Experiment which we will talk about in the next section.
ALL THE STUDIES
Before we jump into all the studies, it's important to to mention that not all studies are created equal. There are certain variables that can affect outcome and validity of studies. One is the type of studies. Two is who is funding the studies, three is can they be reproduced. If a trial or study was done at one time and can never be replicated with similar results, then the validity of that study is questionable. It doesn't mean the study or trial wasnt valid just that there were probably certain factors influencing the results so that that specific study can never be reproduced with the same results. That would take away credibility to that. These are things we need to keep in the back of our mind when reading through these.
Lets go over the Minnesota Coronary Experiment the one the Carnivore Md mentions a lot. which is an unpublished study that was performed in 1968-1973. Here is a link for it.
Test of effect of lipid lowering by diet on cardiovascular risk. The Minnesota Coronary Survey. (ahajournals.org) This study is a difficult read so I've linked and article with a good eplanation.
A Decades-Old Study, Rediscovered, Challenges Advice on Saturated Fat - The New York Times (nytimes.com) *Note this is a New York Times Article evaluating the Minnesota Coronary Experiment*
The purpose of this study was to see if in a control group which consisted of 9,000 mental institution patients were fed a diet low in saturated fats that their mortality rates would drop significantly due to less risk for heart disease the control group was fed a diet with higher saturated fats. This trial only lasted 15 months. The study concluded without a definitive conclusion, they ultimately found that the cholesterol did drop in the trial group. But they found the mortality rate was higher in the control group fed unsaturated fat. The study was never published and we don't know why exactly. When the study was analyzed by Frank Hu a top Nutritionist here's what he had to say, " I don’t think the authors’ strong conclusions are supported by the data." The other science researchers that reviewed the study concluded that it wasnt long enough to give a definitive conclusion but that it also doesnt line up with the longer control trials that have been done in regards to taking vegetable oils instead of saturated fats.
Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73) - PubMed (nih.gov) * This is a re-evaluation of the experiment*
This is a study I would label a rogue study that was incomplete. There are other studies that are longer and were published that show definitive results, but this is a good one to examine when trying to understand why certain people have pushed anti seed oil rhetoric, since this study is referenced by many in the health and wellness space. The issue with this study is that it only stated that subjects in the control group didnt show less mortality than the ones in the saturated fat group. It also showed that consuming unsaturated fats did infact decrease LDL cholesterol.
My issue with this study is that it only lasted 15 months-thats not long enough to make a determination that the control group died because for one year of their lives they swapped out saturated fats with unsaturated fats, and when comparing the rate of death in both groups they are very similiar. The numbers of mortalities are very close to one another. The data also showed an improvement on LDL cholesterol which is a positive. What the main takeaway is, is that having lower cholesterol didn't reduce the rate of mortality.
This article below states the opposite of the older study that Ray Peat was referencing. This article states that the use of PUFA and Omega 6s show greater benefits to patients
I think this article is worth reading. Its from 2014, and it was an article done by several molecular biologists in Malaysia, and several people who were on the Malaysian Palm Oil Board. The object of this study was to determine the inflammatory markers present in obese people who consumed higher saturated fat diets. ------> Modulation of obesity-induced inflammation by dietary fats: mechanisms and clinical evidence | Nutrition Journal | Full Text (biomedcentral.com)
the author concluded that obese persons consuming higher amounts of Polyunsaturated fats instead of saturated fats have less inflammatory responses. They actually say that higher saturated fat intakes in invitro studies have a pro inflammatory response in the body. Keep in mind this isn’t an actual study but more an opinion piece with study references.
Let's look briefly at different cultures and geographical locations that consume higher levels of polyunsaturated fats in the form of oil.
China consumes 13.4% of the worlds vegetable oils, they are the top consumers.
Followed by India, USA, and Brazil. This is based off a 2013 study but I would imagine it is close to the same today. Not surprising since China has a higher population. Palm, Soybean, and Canola were the top most consumed oils.
This study belows measures the lipid oxidation values when using vegetable oils for high heat cooking repeatedly. This study was from 2019.
This second study is similar to the previous one as it is looking at the effects of cooking with vegetable oils repeatedly at high heat using the same oil over and over again. They are looking at the peroxidation markers for inflammation. Both of these studies were performed on rabbits. Here is an exerpt:
"Methods: In this study, healthy adult male rabbits of local strain were divided into 4 groups (n = 12). First, two sets of rabbits were treated with 1 and 2 ml/kg/day of repeatedly heated mix vegetable oils (RHMVO) respectively. The third set of rabbits was given 1 ml/kg/day of single time heated mix vegetable oils (STHMVO) and the fourth set of rabbits served as controls and fed with normal rabbit diet to for 16 weeks. Serum liver function markers including total-protein, albumin, serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT) and alkaline phosphatase (ALP) along with the activity of hepatic antioxidant-enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) for lipid peroxidation were compared among different groups of rabbits. Histopathological examination was performed for all four groups.
Results: Significantly (p < 0.05) elevated hepatic enzymes and MDA levels, with lower total protein, serum albumin, GPx, SOD and CAT levels were found in high and low doses RHMVO treated groups, in comparison to control. In the STHMVO group, all mentioned markers were insignificantly changed. Accumulation of liver fat in low and high dose oil-treated groups was further confirmed under the microscopic examination of liver tissues, presented significant fat accumulation in liver tissues, in addition, 40-60% increased oxidative stress compared to control, in a dose-dependent manner.
Conclusions: These results conclude that consumption of thermally oxidized mix vegetable oils for longer duration can impair the liver function and destroy its histological structure significantly through fat accumulation and oxidative stress both in high as well as low doses."
From this fairly recent study we can definitely conclude that cooking with the same vegetable oil repeatedly at high temperatures can raise oxidative stress and inflammation-IN RABBITS. It's interesting that with the group of rabbits that were served a vegetable oil that was heated to high heat only once there were no significant changes in inflammatory markers or oxidative stress. That no markers of stress or inflammation were significant in the consuming of vegetable oils that were heated only once. The markers of stress and inflammation were only present when the oil was heated repeatedly.
*Now this study I wasn't going to include in this blog because its not on humans but rabbits, and rabbit anatomy is extremely different then human anatomy. Rabbits are very sensitive to many things, and their bodies are going to show a pretty extreme reaction to things that our bodies might not. Keep that in mind. I left this up for informational purposes only, because it does show a different angle.
Where do we run the risk of eating vegetable oils that are heated to high temperature repeatedly? Restaurant's. When we cook at home we are not reheating the same oil over and over again.
I am going to link several more studies. This study below is examining the relations of seed oils and inflammation.
Results- "In addition, Pischon and colleagues20 observed that the lowest levels of inflammation were found in subjects who had the highest consumption of both omega-3 and omega-6 PUFA among 405 healthy men and 454 healthy women from the Health Professionals Follow-Up Study and the Nurses’ Health Study, respectively...Based on the current evidence from RCT and observational studies there appears to be virtually no data available to support the hypothesis that LA in the diet increases markers of inflammation among healthy, non-infant humans. However, in light of the limitations of the evidence available, one cannot fully reject the “diet LA drives inflammation hypothesis” at this time. To do so, will require additional data from larger and longer studies with meticulous dietary control that include subjects from differing genetic endowments. Nevertheless, the outcome of this recent systematic review should provide the dietetic and medical community with a measure of reassurance regarding current dietary recommendations that emphasize optimal intake of both omega-3 and omega-6 PUFA."
This is a compiled list of studies that will you give a better understanding of seed oils and how they affect our health. There are many more I didnt include. If you dont want to read them then to sum them all up, none of them show any issues with consumption of vegetable oils with varying higher levels of linoleic acids, and there are no adverse health effects. Many of these studies were done over long periods with a large number of participants.
The postprandial inflammatory response after ingestion of heated oils in obese persons is reduced by the presence of phenol compounds - Perez‐Herrera - 2012 - Molecular Nutrition & Food Research - Wiley Online Library
CLA Does Not Impair Endothelial Function and Decreases Body Weight as Compared with Safflower Oil in Overweight and Obese Male Subjects: Journal of the American College of Nutrition: Vol 30, No 1 (tandfonline.com)
Effects of plant oils with different fatty acid composition on cardiovascular risk factors in moderately hypercholesteremic Chinese adults: a randomized, double-blinded, parallel-designed trial - Food & Function (RSC Publishing)
I wanted to go through more studies but perhaps in another blog.
SUMMARY & TAKEAWAYS
The studies I linked above show that consumption of seed oils dont show overall any of adverse health effects that they are associated in the crunchi/natural groups. No Inflammation, atherosclerosis, cancer, or raised LDL. They infact show the opposite. So what does that mean?
Im going to let you decide what you want to believe. You can read all of these studies and not be moved. You can continue to avoid eating seed oils, and thats your perogative.
I must admit after reading all these studies my viewpoint has completely changed. It should be obvious to most people that a diet high in processed food, high in carbohydrates, sugar, fat, and just overconsumption in general will lead to many health problems such as inflammation. So why do seed oils get the heat? Perhaps because they are an affordable byproduct that can easily be used in place of expensive oils and fats and that is what makes them appealing to food manufacturers. Also the fact that many industrial seed oils go through an intense manufacturing process. Producers are using something that would otherwise go to waste to make their goods. Consequently, we need something to blame. Could it be that the health and wellness industry created a fear, and made seed oils a problem just so they could provide a solution? Who knows.
I think in our search for what is making our society unhealthy in general has led many of us to conclude that its polyunsaturated oils that are the culprint when really it is likely many different factors. I'm sure factors like drinking alcohol, smoking cigarettes, eating highly processed fast food every day, lack of exercise, lack of mobility, and staying indoors more frequently have had a hand in all of our health woes as a society. We have become an overconsumption sedentary society.
I am not going to demonize them anymore when the overwhelming body of evidence doesn't support it. Infact, it supports the opposite that seed oils eaten in a healthy balanced diet in normal amounts can greatly improve overall health and have no impact. Sure highly processed oils are more processed but a lot of the studies showed the same results even with highly processed oils.
We are in the age of the social media influencer's, and health and wellness influencer's where they will say whatever they want online. Anyone can sound convincing, but many of us fail to look deeper and research on our own. Which leads to a continual problem and we end up going along with what ever is next on the list to cancel. It’s misplaced fear.
After writing my first blog on seed oils in skincare I have shifted my perspective and am willing to look constructively over the data not from an emotionally charged view. These control trials and studies are really all we have to base our judement's on. They are the evidence that is currently available at the moment.
Now are all of these studies bought and paid for by a lobbyist/corporation with something to gain. Thats hard to believe. Thats like saying all of them are lying and in cahoots with each other so they can put their poison in all of our food. Many of these studies were just funded by our tax dollars or independent researchers. Not Canola oil companies. When examining the total body of evidence, logic and rationalization are our friend. We need to put the emotions down and take a look from a clear perspective.
Our bodies are amazing and when we do take care of them they usually take care of us. Instead of demonizing the seed oils we probably should be encouraging people to eat more whole foods, less fast highly processed food, get outside, move their bodies more, and live a lifestyle of moderation and balance. In the event a seed oil is eaten rest assured you’re going to be ok.