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May 2, 2023 | Max Jenkinson

Seed Oils - Our Greatest Dietary Mistake

Have you ever felt like a conspiracy theorist?


While trying to answer a question your research points you in the complete opposite direction of what the mainstream says.


You feel slightly insane but sense that your reasoning at least isn’t as bad as flat earthers.


You start to question how the mainstream came to those conclusions.

You dive deeper and become terrified at what you find.


This is where I ended up while diving into the topic of this blog series, the infamous vegetable oils.

Important to note is that the terminology here is a bit off.

Vegetables are not a biological category. For example, olives are a fruit, and so are avocados and coconuts.

The vegetable oils we are talking about are not derived from fruits but instead from seeds. 

Thus I will now refer to them as seed oils but they are usually synonymous.

My interest in seed oils


Five years ago as I was getting into health, I started hearing a lot about seed oils.


Everyone I was listening to was telling me how bad they were.


How they were driving obesity, diabetes, inflammation, mitochondrial dysfunction and the like.


If you’ve spent any time on the health side of social media you have likely come across someone telling you about the dangers of seed oils.


Even though everyone in the health space seemed to agree, the mainstream view was, and still is, that they are healthy for us.


How could there be a completely opposite stance between the smartest people I knew and the large scientific government bodies that allegedly have our best interests at heart?


I went on a journey to try to figure this out.


I read about the history of seed oils, the biology, chemistry, and the studies made.


I even wrote my bachelor’s thesis on it.


Edible vegetable oils were not a part of history until the early 1900s.


Since then the intake of seed oils has increased alongside the rise in chronic disease.


But as we all know, correlation does not infer causation.


I will argue that the consumption of seed oils is the most costly dietary mistake humans have ever made.


I’ll explore how seed oils became a part of our diet, what they are chemically, and what the studies say.


There is a lot to go through and so I’ve divided this up into five parts.


  1. The history of seed oils. This will help us understand why governments still recommend them as healthy.
  2. The epidemiological link between diet & disease (over the past 100 years).
  3. What fats are.
  4. The best nutritional studies ever conducted (& what they tell us about seed oils).
  5. A simplified version of my bachelor’s thesis. All about the link between obesity, mammalian hibernation and seed oils.

Hope you enjoy.

Why eating fat from seed matter

As you will now know if you have read any of my previous posts, I like to look at health through an evolutionary lens.

Animals adapt to a specific environment and diet over millions of years.

This is why we do not feed lions’ leaves and giraffes’ meat at the zoo.

We feed animals at the zoo a diet as close to their natural diet as possible.

Animals in unfamiliar environments struggle to regulate trillions of internal processes. 

These processes are all trying to maintain the animal’s health.

Over time, this dysregulation leads to chronic disease. 

Animals in the wild do not suffer from these. Humans living in the wild do not either.

The difference between the animal’s natural environment and the one it now lives in is what we call mismatches.

The greater the mismatch the greater its impact on the capacity to regulate internal processes and thus the greater the impact on health.

Look at diet as a part of the environment, which it is.

Now, consider the greatest dietary changes from our natural diet.

Fixing these mismatches should have profound impacts on health.

Thus, we should identify them to improve our health.

We have two questions that need answers:

  • What is the species-appropriate diet for humans?
  • What are the biggest differences between that diet and our current one?

To answer them we need to look at our past, our physiology and how it compares to other animals. More specifically, other mammals.

Humans evolved to eat what was edible, and what had the highest reward-to-risk ratio in the form of calories.

As long as we have been humans, and way before, we have hunted.

It seems as if we mainly hunted large ruminants because of their high energy return. But, we also gathered plants like fruits and tubers.

We all know the three macronutrients, fats, carbs and protein.

Animal tissue is almost entirely fat and protein. Plant tissue is mainly carbohydrates.

The fat and protein we evolved on came from animals, while the carbohydrates came from plants.

Fat from seeds was almost non-existent until the early 1900s when chemical processes were developed to extract the fat from seeds.

Why is this important you may ask. What if the fat comes from animals or from seeds? Fat is fat am I right?

Well, dietary fat mainly comes in three forms, saturated, monounsaturated, and polyunsaturated.

The difference between them has profound effects on our physiology.

Fats from animals are generally:

  • High in saturated fatty acids (SFAs)
  • Low in monounsaturated fatty acids (MUFAs)
  • Extremely low in polyunsaturated fatty acids (PUFAs)

Fats from seeds are generally:

  • High in PUFAs
  • Lower in MUFAs
  • Extremely low in SFAs

Hunter-gatherer populations have around 1-4% PUFAs in their fat. We can assume this is similar to what we evolved with.

Today that number is somewhere between 15-20% in the West.

This is a large mismatch.

And again, large mismatches have large negative health outcomes.

How Seed Oils Snuck Their Way Into Our Diet


It all started with the industrial revolution.


Mass production machinery needed oils as lubricants to extend their lifespan. 

During the early 1800s, the oil of choice was whale blubber.


As the industry grew so did the killing of whales. They had a sustainability issue.


During the late 1800s, they figured out they could use waste products from the cotton industry instead.


The waste was used to make chemically extracted seed oil. It was easily mass-produced and cheap.


The whale blubber got replaced.


During the early 1900s, scientists developed a complicated process to stabilize seed oils. Turning them from liquid form (oil) into solid (fat) through something called hydrogenation.


These hardened oils started out selling as soap, as a replacement for soaps made from animal fats. 


Again, because they were cheaper to produce.


Procter & Gamble, the company that did this, found a hole in the market.


They realised that they could sell hydrogenated oils as a replacement for cooking fat. 


At the time they were almost exclusively, butter, tallow and all which are animal fats.


In 1911 Procter & Gamble came out with the first commercial product to replace dietary animal fats, named Crisco.


They launched a massive marketing campaign. Its goal was to replace the common cooking fats that were used for thousands of years.


13 years later in 1924 heart disease was on the rise. In response, an organisation was started named the American Heart Association (AHA).


Still, Crisco wasn’t as big as Procter & Gamble would have liked. 


They wanted to entirely replace the animal fats in the American diet.

The slow and steady replacement was not enough for them. 


In 1948 Procter & Gamble made a huge investment into the then small organisation AHA.


According to the AHAs own company history, the money from Procter & Gamble was the real jumping-off point.


“Overnight millions flew into our coffers”.


In a matter of days, a small organisation became one that could influence the world.


During the middle of the last century, these vegetable fats were now common. 


The yellow vegetable fat margarine had also been created as a cheaper replacement for butter.


Up until this point, nobody had been able to sell these fats as oils.

They quickly oxidise and become rancid, start smelling bad and taste even worse. 


During the 1940s they found a chemical solution to this problem.


The second world war left economic hardship in its wake. People became more frugal with their spending.


During this time a lot of people made the switch from animal fats to the cheaper vegetable fat alternatives.


Still, health was not a big selling point for the companies behind them.


In 1955 experts gathered at a World Health Organisation (WHO) summit. Where, the now infamous scientist, Ancel Keys presented his famous Diet-Lipid-Heart Hypothesis.


It laid out the hypothesis that saturated fat and cholesterol cause heart disease. He did this with “his usual confidence and bluntness”.


The same year President Eisenhower had his first heart attack.


Ancel Keys was then hired to figure out why heart disease had risen dramatically.


Heart disease was an uncommon cause of death in the US at the beginning of the 20th century. By mid-century it had become the commonest cause. […] It is very likely that the 20th century was the only century in which heart disease was the most common cause of death in America.
– Delen et al. 2014

The AHA wanted to make recommendations to the American public on how to avoid heart disease. The issue was there was no data.


1960 rolls around and Keys becomes a part of the AHA nutrition committee.


One year later, in 1961, the AHA comes out with its first dietary recommendation.


It told us to replace animal fats with vegetable fats, specifically Crisco.


This was the first time in history that humans were recommended to replace animal fats.


The demonization of animal fats had begun and soon spread to the rest of the West.


Ancel Keys is most known for the Seven Countries Study which started in 1958.


It was based on questionnaires, measurements of cholesterol and the frequency of heart disease in different countries.


The seven countries Keys chose supported his hypothesis slightly.


The study is epidemiological which can only show correlation and not prove causation.


The study was published 20 years later in 1978.


Keys was not against fat in general but more specifically saturated fat.


Our understanding of diet at the time was very limited. In the 70s the AHA recommended limiting all fats.


The idea was that they contained more than double the calories of both carbs and protein.


This was the start of fat as the dietary scapegoat.


After the recommendation was put out, studies were done to make sure they were sound.


These are the studies that were done (Howard et al. 2006; Walden et al. 2000; Knopp et al. 1997).


The recommendation came before the proof. Read that again.


The recommendation came before the proof.


The studies done could not show any positive effects of the limitation of dietary fat.


In 2015 the recommendation to limit fat was dropped by the AHA.


The majority of the literature did not support the claim that it had positive effects on health.


The recommendation, which was not supported by data, lived on for 50 years.

Evolutionarily the majority of fat humans ate came from animal tissue. Animal tissue is high in saturated fats.

This changed in the early 1900s when methods to extract oil from seeds were developed.

The seed oils are very high in polyunsaturated fats which evolutionarily would have been rare.

Alongside the increased intake of PUFAs, we have seen an almost exponential rise in chronic diseases. 

These include obesity, type-2 diabetes, heart disease, neurodegenerative disease and many more.

Despite this, we smoke less, exercise more, and eat more vegetables than during the 70s.

If this is the case something else must be the cause.

In the next post, we’ll go over the statistics and correlation between diet and disease to try to figure it out.

Using correlation, which dietary aspect is the most likely candidate for the increase in disease?

Is it carbohydrates or sugar? Is it salt? Is it meat? Is it seed oils? Or is there something else we are missing?

Now, let’s move on to an investigation of the link between diet and disease.

Thank you for reading. And until next time, do what makes your future self proud.

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