Are seed oils bad? An Associated Registered Nutritionist challenged my assertion in a monthly Health and Nutrition column that seed oils (vegetable oils) are bad for you. They included a link to an article by an Otago University Professor headed to “clear up the misleading information and confusing messages about what healthy eating looks like”. If you would like to read this, the link is here:-
You may have noticed that mainstream dietary advice is failing. Many of the recommendations made about diet such as less salt, low fat, 60% carbs and healthy whole grains are being challenged because of the growing epidemic of sickness, including Type-2 diabetes, heart disease, Alzheimer’s and cancer. The advice I provide is often very different to the standard rhetoric. If you have been educated in conventional nutrition and achieved a registration of some sort, finding that the education was flawed would be very hard to accept. The whole reason I write these articles is to offer improved information about nutrition and health, often at odds to the mainstream rhetoric.
I have come to understand that many of the “experts” in the field of nutrition are adamant about their knowledge of the subject but may have not kept up to date with the latest research or may have discounted research which does not support the view that they were educated on. This could be the case here. As an example of this, Michelle Hurn, Registered Dietitian, and author of the book “The Dietitians Dilemma”, leads us through a progression of ill health which she personally suffered and which was not resolved until she began to do her own research, implementing a dietary approach almost the opposite of her nutrition education which then solved her health problems. I recommend her book.
Another factor which can cause confusion about nutrition is the dominance of research funded by organization's looking to support their profits through the presentation of favorable nutrition research. I provide here some typical examples of this:
- Recent research that determined red meat caused diabetes, when there is no biological mechanism for red meat which has almost zero glucose to cause a disease that is the result of excess glucose.
- The Food Compass from Tufts University in USA, which amongst many other ridiculous claims, claimed that Fruit Loops, a sugar coated breakfast cereal, was healthier than a hen’s egg cooked in butter.
- This from the New York Times: 'The Associated Press reported that candy makers were funding studies that claimed children who eat candy tend to weigh less than those who do not'.
- There are thousands of examples of this type of corruption in nutrition research.
Nutrition research is the modern Wild West and care must be taken when reading claims.
My response to the challenge raised are summarized here:
1. There does appear to be a correlation between rising seed oil consumption and rising levels of CVD (Cardio Vascular Disease) which I show below.
2. The Otago article ignores the proven release of toxins within polyunsaturated seed oils from manufacture and storage which enter your body with the oil.
3. The Otago article referenced, quotes research that agrees seed oils will damage cellular membranes but finds that okay because vitamin E, that slows or minimizes the damage, can come from seed oils amongst other things.
4. The Otago article claims that the Sydney Diet Health Study, where mortality was higher when saturated fats were replaced by seed oils, is unreliable but you will see from the comments below that their claim is not backed up by the information reported from the study.
5. The meta-analysis “Marklund et al”., quoted to claim a reduction in CVD with seed oil consumption is healthy, comes from the same team at Tufts University which claim in their ‘Food Compass’ that for our health, we should be encouraging the consumption of Frosted Mini-Wheats plus other cereals and avoiding the consumption of real eggs, cheese and beef.
6. In 1900, seed oils did not exist because the technology did not exist until 1910 to produce them and the majority of fats people ate were animal based. In 1900 heart attacks were extremely rare in the USA. Today heart attacks are the number one killer and seed oils represent approximate 30% of the calories in standard diets. They are in 80% of the foods with a nutrition label.
This from Dr. Cate Shanahan’s book titled: ‘Dark Calories, How vegetable oils destroy our health and how we can get it back’ where she explains the toxicity of seed oils and the danger they pose to our health. To paraphrase a diagram from her book, I quote “In 2000, Americans consumed 340 calories a day from seed oils and obesity was 20%. In 2020 Americans consumed 730 calories per day from seed oils and obesity was 42%.”
You can follow mainstream advice and eat seed oils if you want. Some arguments suggest that they are okay. Why would you eat them? There are much better alternatives which are less profitable to business and have been eaten without harm for thousands and thousands of years. Seed oils have only been part of our diet for about 100 years. I include here references to research and books by trained doctors. Each of which includes hundreds of references.
The evidence from the Sydney Diet Heart Study
The Otago article claims that the Sydney Diet Heart Study, where the group that replaced animal fats with seed oils had a higher mortality rate, is an unreliable source of evidence against seed oils. Their reasoning: the PUFA used was margarine and was hydrogenated which we know to be toxic. Maybe they didn’t actually read the study report. Below is the ‘Diet Intervention Statement’ from the study describing the PUFA sources:
“To achieve these targets, intervention participants were provided with liquid safflower oil and safflower oil polyunsaturated margarine (“Miracle” brand, Marrickville Margarine). Liquid safflower oil was substituted for animal fats, common margarines and shortenings in cooking oils, salad dressings, baked goods, and other products, and was also taken as a supplement. Safflower oil polyunsaturated margarine was used in place of butter and common margarines.”
It is clear from the above that margarine was used. However, it does not stipulate that this was the primary source but infers that liquid safflower oil was used extensively, with safflower based margarines used instead of butter and common margarines. This would suggest in fact that the liquid safflower oil was the primary source of PUFA’s. It also infers, that the control group were consuming butter and ‘common’ margarines during the study, possibly also hydrogenated. This suggests to me that claims that this study was unreliable are not valid.
Oxidation of lipids
Polyunsaturated fats have multiple double bonds and are very prone to oxidation. This is well known and is the reason these oils are supplied in dark bottles. The most common extraction processes require significant pressure and heat, both of which will accelerate oxidation of these fragile oils.
Oxidation is what happens when wood is burnt producing smoke. It is also the process by which energy is released from petrol in your car engine, producing toxic by-products. Oxidation of seed oils also produces toxic by-products:
- in the manufacturing process,
- in the bottle as it is stored,
- In your frypan
- in the deep fryer as it is heated and cooled for cooking and,
- in your body.
Light, heat and air exposure over time rapidly oxidizes seed oils making them rancid and generates toxic chemicals unknown to your body. Everyone of these toxic chemicals has the opportunity to enter your body and create havoc leading to whole body inflammation.
For the very reason that we avoid charred food, rancid food, smoke inhalation and car exhaust, we should also avoid these toxic by products. While seed oil manufacturers seek to process out the toxic elements, they cannot be sure to eliminate them all. Avoiding seed oils is the only way to be sure you have not ingested toxic elements that can damage you.
Should you be interested to pursue the science further I suggest you read this report from Europe:
Their conclusion stated:
“In conclusion, the heating of PUFAs (Polyunsaturated Fatty acids) (seed oils) and, to a much lesser extent, MUFAs (Monounsaturated Fatty Acids) present in EU-available seed and other CFO (culinary frying oils) products according to high temperature standard frying practices, which predominantly represents the prime purpose for which they are used by consumers, substantially promotes their peroxidation, a process giving rise to the generation of very high levels of cytotoxic and genotoxic aldehydes. The 1H NMR analysis of these samples, - - - confirmed the thermally promoted, time-dependent production of a range of aldehydic LOPs (Lipid Oxidation Products) in all oils investigated, the highest levels being observed in PUFA-rich sunflower or corn oils. Lower quantities of these LOPs were formed in monounsaturated fatty acid (MUFA)-rich canola and extra-virgin olive oils, and their generation was preceded by one or more significant lag phases. As expected, only low levels of selected aldehydes were formed in SFA-laden (saturated fat) coconut oil during these laboratory-simulated shallow frying episodes.”
The oxidizing oil becomes rancid, releasing free radicals which are molecules with an unpaired electron, making then highly reactive. These free radicals are very toxic to the body and damage everything around them. The Otago study asserts that the vitamin E in the seed oil will act as an antioxidant and mop up the excess toxic oxygen, thereby mitigating oxidation in the body and preventing damage to fragile membranes.
To claim that eating these is okay because vitamin E will minimize cellular damage is the same as suggesting it is okay to eat poison if you also eat the antidote. My point is PUFA’s can be damaging, even the Otago provided study agrees with this and vitamin E may minimize the damage but it can only minimize the damage from the oxidation occurring in your body. Toxic by-products produced from earlier oxidation will already be present. Why eat these in the first place.
The only way your body can get rid of seed oils is to burn them up in the mitochondria for energy. A concern from that, is that we also know that the generation of energy in our mitochondria from PUFA creates more free radicals (oxidation) than other energy sources. We know that anti-oxidants like vitamin E can help. However, if we are using up all the antioxidants dealing with seed oils, will we have sufficient leftover to maintain a low oxidative environment for everything else?
Links between seed oil consumption and CVD
The Otago report then makes this statement: “A valid criticism of modern diets is the excessive use of seed oils in processed foods like deep fried items and baked goods. Consuming seed oils in this context likely has different health consequences compared to using them to stir fry our vegetables.”
The report seems to be agreeing with me that seed oils are bad and should be avoided. Does your body know if the seed oil came from baked goods, a deep fryer or used to stir-fry your vegetables? I doubt it. Their suggestion that using them to stir-fry your vegetables is okay is directly contradicted by the study I referenced previously.
In reviewing the article presented by the Associate Registered Nutritionist I was flummoxed to find a statement that claimed “if seed oil consumption was linked to an increased risk of CVD (Cardio Vascular Disease) we would see a positive correlation in population”.
Below is a graph of CVD deaths from 1990 to 2020 vs vegetable oil consumption and saturated fat consumption in the USA as compiled by Dr. Chris Knobbe, a researcher into the diseases caused by Vegetable Oil consumption. You will note that there is rise in vegetable/seed oil consumption that does not have a strong correlation with the rise in CVD deaths, however both are rising in-step since 1910. As seed oil consumption has risen, so has CVD risen.
Dr. Chris A. Knobbe’s book: Is titled - ‘The Ancestral Diet Revolution: How Vegetable Oils and Processed Foods Destroy Our Health - and How to Recover!’
A fascinating element of this graph is that while it provides minimum correlation for seed oils with CVD it shows zero correlation for CVD with saturated fat consumption. This then challenges the statement made later in the report which says “substituting saturated fat with polyunsaturated fat (PUFA) which includes seed oils has shown the most significant benefit in reducing CVD risk.” The graph shows that seed oil use and CVD have been rising dramatically but Saturated fat consumption has remained relatively steady.
Cardio Vascular Disease (CVD) has started to decline and researchers have linked this to more effective intervention following heart attacks and reduced smoking in the population, rather than to seed oil consumption.
Poor quality research claims
A research paper quoted in the Otago sourced article, “Marklund et al”., is produced by the same group at Tufts University that created the previously mentioned Food Compass. I would caution the reader in regard to this study, to be aware that this group strongly promotes plant based foods and ultra-processed food in preference to any food that is animal based. Their Food Compass scores foods out of 100, for which higher is better. The following are some of their claims :
- Kale scores 100, (why? it has minimal nutrition)
- Kellogg’s Frosted Mini-wheats is 87
- Kellogg’s Nutri-grain cereal bar is rated at 52
- Kellogg’s Cinnabon is rated at 42
- Special K chocolate delight is rated 41
- Ground beef is rated at 26
- Egg fried in butter is rated at 29
- Cheddar cheese is rated 28
I am concerned, looking at the above examples, that the motivation behind the research is to maintain relationships with food manufacturers rather than any interest in our health. As a result of this concern, I recommend discounting any research from this group.
Finally, take a look at this video from Dr Chris Knobbe where he outlines the problems with seed oils. https://youtu.be/MuYvGyNXvPk?si=pss6FiMxdW8FlkwP
Based on my detailed review, I will continue to believe that seed oils are bad for you. They are the number one element I choose to avoid for my health. I firmly believe that ancestral oils and animal fats such as olive oil, tallow, butter, suet, lard and coconut oil are far healthier.
For more free reading like this, see my blogs at www.takebackyrhealth.com where you will also find links to the 4th edition of my book on Amazon. Seek professional medical advice before making dietary changes, particularly if you are on medication. Contact me if you have questions or for diet consultation.
Good health, George Elder, MBA, Diet Research Reviewer, Dip. Nutrition.
“The greatest thing you can do for your health, is eat better.”
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