We're going to start this review with a few visuals to get the ball rolling.
This is interesting on a few levels.
The obesity hockey stick is what we want to focus on. Right around the '70s-'80s period.
We can also see that sugar predates this explosion by decades. HFCS's (high fructose corn syrup) drop around 2000 but doesn't really dent the obesity rise.
We already covered the damage with glucose but there's another fascinating player.
Fats. The kind of fats specifically.
Take a look at this and see if it's a closer fit to the obesity epidemic:
See that gray line…vegetable oils. Sunflower. Soybean. Rapeseed. Etc. Look at the explosion in use around 2000.
Any connection with obesity?
Look at the green line. Up up and away.
What about diabetes prevalence?
Alright…roll up the sleeves…we're going deep to see if the massive switch to why seed oils is at the root of many ills.
Wait till you see the effects on appetite and dopamine (addiction) below! You're going to be hungry…for revenge!
We'll cover the following topics:
- A quick intro to seed oils
- Let's get to know fat
- The omega 3 and 6 balancing act
- Linoleic acid introduction
- Seed oils and steroidal hormones
- Seed oils and inflammation
- Seed oils and metabolism
- Seed oils and appetite
- Seed oils and brain function
- Seed oils and mortality
- Practical approach
Let's look at the biggest con game in food and health…maybe ever!
A quick intro to seed oils
One year ago, I had no idea how critical this was to health.
Like a good majority of the population.
We've been bashed over the head for decades now that fat is fat and it's all bad for you.
Our bodies have immediate uses for protein…and fat. Protein runs the machinery of the body while fat provides the architecture and scaffolding of our cells.
Sugar and carbs (just a more complicated version of sugar) are not directly needed as is evident from keto. Our body can convert protein into glucose to power its activity.
Fat, however, is essential. Steroidal hormones are derived solely from…LDL cholesterol. Yes…the so-called "bad" cholesterol.
The literal walls of your cells are made from fat. Your brain is approximately 75%...cholesterol!
But not all fat is equal!
A quick history.
As you can see from the chart above, our primary source of fat for…ever, was animal fat. Butter. Lard. Tallow. Etc. Sure…some coconut, etc depending on where in the world you were cooking.
Two brilliant marketers realized they could take industrial oil (cottonseed oil) and add flavor plus color. Voila! A ridiculously cheap form of cooking oil!
You're witnessing the explosion of Proctor and Gamble as an economic powerhouse.
There's a great run-down at this link but the takeaway:
"What was garbage in 1860 was fertilizer in 1870, cattle feed in 1880, and table food and many things else in 1890."
The processing of seed oil to cooking oil is a nasty process with solvents and chemical extractions.
It's factory food. Plain and simple.
As you can see above, it exploded in terms of share of fat calories around 1965 and the marketing prowess of Crisco sits front and center with this growth.
It never looked back.
Julia Childs once said she would never eat McDonald's french fries (she was a fan) again after replacing lard with vegetable oil.
The tide was never going to turn…cost of this factory oil was just ridiculously lower than animal based fats.
Take a look at almost any packaged/processed food. Seed oils are there.
Sunflower. Safflower. Rapeseed. Canola. Vegetable.
- Margarine was just a solidified form of this original sin
- Buttery spreads are vegetable oils in hard form factors
We'll ignore that most of the seed is raised with glyphosate, pesticides, GMO, and a brutal chemical extraction process.
Let's turn to the chemistry of the fat at the heart of this massive transition.
There's a great intro to the whole sordid history here:
The charts will start to make more sense.
Let's get to know fat
Fat actually has different forms and makeup with the basic categories being:
- Saturated fat - solid at room temperature; butter and lard as an example
- Unsaturated fats - liquid at room temperature; vegatable oils
- Trans fats - chemically processed - hydrogenated. Factory food essentially.
The unsaturated fats are broken into monounsaturated and polyunsaturated fats (PUFA)
Trans fats are cooked in the presence of hydrogen essentially to keep them from breaking down (spoiling).
The only thing everyone agrees on with fats is that trans fat is the Devil! (to quote Waterboy).
The other items are open for debate, unfortunately.
Saturated fats (animal fat essentially) have been the target of ire and derision for decades now but research is flipping on this.
The much supported PUFAs are actually not so great.
A pretty good explanation of the fats can be found here:
The whole keto movement has obliterated much of what you'll read there and it's clear that glucose, inflammation, and processed food is really where the focus should be.
There's so much confusion on fats and a great deal of this comes from cholesterol.
As we mentioned, cholesterol is the root ingredient for all steroidal hormones and they directly drive every pathway in the body including….cardiovascular health!
We learned that the hard way from a brutal perimenopause (see perimenopause cardiovascular when estrogen leaves the scene).
Let's take one example.
If you go by the basic guidelines, coconut oil should be a veritable poison. Loaded with saturated fats.
A study on people who exclusively use coconut oil (fruit oil along with avocado and olive) found they have higher cholesterol but NOT the cardiovascular risk.
Coconut oil consumption did not significantly affect markers of glycemia, inflammation, and adiposity as compared with nontropical vegetable oils.
So much more cholesterol but no impact on inflammation or obesity.
Clearly, fat is more complicated than we thought! Key differences are finally coming out.
Let's look at a big one.
The omega 3 and 6 balancing act
The simplest hierarchy is that of omega 3 and omega 6.
We'll leave the chemistry to other sources (basically where bonds occur in the chain) and focus on the health effects.
The general public is starting to recognize some of the big players:
- LA - Linoleic Acid (omega 6) must get from diet
- ALA - Alpha linoleic acid (omega 3) must get from diet
- DHA and EPA - Omega 3 fats that body can make from ALA
Let's focus on LA and ALA since these must be sourced from diet.
You hear about the ratio of omega 3 to 6 quite often. Why?
Because these both depend on the same shared pathway for metabolism:
In the human body, LA and ALA compete for metabolism by the enzyme delta-6-desaturase.
That's a great intro to the fats by the way!
The more omega 6 we take in, the less omega 3 we can process. So far so good.
So… let's take this back to our original charts. What changed?
Up until about 100 years ago, the omega-6/3 ratio has been around 4:1 or less. However, the typical Western diet now provides an omega-6/3 ratio of approximately 20:1 in favor of omega-6.
Well, that's not good.
Where is all this omega 6 coming from since animal products have a natural ratio more in line with our original intake.
The overconsumption of linoleic acid, mainly from industrial omega-6 seed oils, and the lack of long-chain omega-3s in the diet creates a pro-inflammatory, pro-allergic, pro-thrombotic state.
Goodness. We're slowly being poisoned…to cut costs.
Before we dive into the health effects, let's dive deeper into linoleic acid, the primary omega 6 intake.
Linoleic acid introduction
First, take a look at linoleic levels by type of oil (very insightful):
Look towards the bottom and you'll see the animal fats. There's coconut! Hmmm.
It's a fruit after all and olive and avocado also have similar profiles.
The interesting turn however involved soybean oil. Take a look at how big ag just fell in love with it!
See the timing on the inflection point? About 20 years before our health parameters went nuts.
A generation raised solely on seed oils.
What about soy's LA composition?
Commodity soybean oil is composed of five fatty acids: palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3). The percentage of these five fatty acids in soybean oil averages 10%, 4%, 18%, 55%, and 13%, respectively.
55% LA. Uh oh. Linolenic is also omega 6 so now we're 68%.
What's the problem with LA compared to other fats?
Oxidated Linoleic Acid metabolites.
The percentage of linoleic acid in the fat profile of any oil directly drives how stable it is:
Oxidative instability of soybean oil results from the relatively high percentage of the polyunsaturated fatty acids linoleic acid and linolenic acid.
We'll get into it more below (the inflammation section) but increased LA consumption results in increased oxidative stress..system-wide (yes…in the brain as well).
Increasing dietary LA significantly increased omega-6 fatty acids, decreased omega-3 fatty acids, and increased OXLAMs in the brain.
You're exhausting your primary detox pathway (glutathione) on a daily basis.
A high linoleic acid diet increases oxidative stress in vivo and affects nitric oxide metabolism in humans
That's not the only by-product of all this LA swirling around but it's a glaring example since oxidative stress is such a powerful force.
To show just how powerful this shift to Omega 6 is, let's look at just a few key systems knowing that every system is involved.
Seed oils and steroidal hormones
What on Earth is going on with testosterone?
The 1987-89 levels matches early century (1920-1934) levels. So…something really took a dip in the 80's. About 20 years after the big jump in seed oils!
This reflects a generation solely raised (birth, puberty, etc) with lots of linoleic acid.
It's only gotten worse from 2000-2020.
(yellow being latest and red being earliest)
Okay…obesity, smoking, and other attributes affect testosterone levels but even the researchers above admit they can't explain the drop.
Is there any data on omega 6 (like linoleic acid) excess and T loss?
Among healthy, young men:
The intake of omega-3 polyunsaturated fatty acids was positively related to testicular volume while the intake of omega-6 polyunsaturated fatty acids and trans fatty acids was inversely related to testicular volume.
The reason is many fold: inflammation, upstream hormone changes, oxidative stress, etc.
What about estrogen?
This may speak to the testosterone changes:
Linoleic acid supplementation indicated estrogenic activity of Linoleic acid which was in consistency with serum estradiol level
LA drives estrogen which antagonizes both testosterone and progesterone.
This excess estrogen activity shows in specific E-sensitive cancers:
diet rich in omega-6-polyunsaturated fatty acid like linoleic acid and endogenous estrogen may modulate BRCA1 gene expression thereby promoting breast cancer.
Since BRCA1 is an estrogen-sensitive pathway, it's logical to assume that omega-6 fats are estrogenic in nature.
Linoleic acid can actually bind to the estrogen receptor which allows more estrogen to be available!:
Liu et al.,40 reported the identification of linoleic acid as an estrogen receptor ligand capable of displacing estradiol from the ER and binding to the ligand binding domain
Does this hold for the seed oils directly?
The results showed an a significant effect of oils supplementation to ration on the estrogen hormone level and no effect on progesterone hormone level during the different stages of study.
So…estrogenic. We could spend all day on hormones but we have to move on!
Let's turn to probably the biggest difference between Omega 3 and 6.
Seed oils and inflammation
The linchpin for much of what see with seed oils comes down to inflammation.
Omega 6 and 3 fats have almost opposite effects on the immune system:
Omega-3 fatty acids help reduce inflammation, and some omega-6 fatty acids tend to promote inflammation. In fact, some studies suggest that elevated intakes of omega-6 fatty acids may play a role in complex regional pain syndrome.
What about linoleic acid specifically since it's all the rage on the food aisle?
Let's look at a few different tissues.
Let's start in the gut since it acts as a inflammation thermometer across the body (and brain):
The data support a role for dietary linoleic acid in the aetiology of ulcerative colitis. An estimated 30% of cases could be attributed to having dietary intakes higher than the lowest quartile of linoleic acid intake.
Um...30%?? How is this not front page (right below the fried chicken sandwich ad. Oh...forget it).
And the little inflammatory assassins called cytokines?:
The results revealed that a high linoleic acid diet increased the plasma and kidney interleukin 6 levels, whereas a low n-6/n-3 ratio diet ameliorated blood glucose homeostasis, reduced plasma tumour necrosis factor α levels, and inhibited systematic inflammation.
Goodness. Too much linoleic acid (omega 6) increased inflammation (IL6), blood sugar, and other important inflammatory agents (TNFa).
"Systemic inflammation" is the key there as this drives aging and ALL illness.
Let's look at Rheumatoid Arthritis:
The beneficial effect of unsaturated FA on the clinical parameters of RA was demonstrated in all 71 studies analysed. The content of omega-3 FAs in the diet and the consumption of fish, which are their main source, may contribute to a reduced incidence of RA.
Remember that Omega 3 and 6 compete for the same metabolic pathway.
A great deal of the inflammation comes down to Omega 3/6 ratio but we'll touch on more specifics as they apply to the areas below.
Let's turn now to metabolism.
Seed oils and metabolism
We started this whole review with obesity.
So…what's the connection?
A high omega-6 fatty acid intake and a high omega-6/omega-3 ratio are associated with weight gain in both animal and human studies, whereas a high omega-3 fatty acid intake decreases the risk for weight gain. Lowering the LA/ALA ratio in animals prevents overweight and obesity
Goodness. Lowering the ratio of linoleic acid to alpha-linolenic acid "prevents" obesity.
There's actually a type of fat that burns energy…called brown fat. Babies have lots of it. Cold exposure increases it. So does Omega 3!
Our theory? Fish are rich in Omega 3 as a protection from the cold! Omega 3 is thermogenic (creates heat). Brown fat in humans is also thermogenic.
Omega 6 intake directly affects this:
We noted significantly lower omega-6 fatty acids (p = 0.03) and MUFA (p = 0.02) intake in subjects with detected BAT activity after adjustment for age, daily average kcal intake, and DXA Lean mass
To translate...people with more brown fat (burns glucose) take in less omega-6.
What about the whole insulin energy complex?
Omega-6 fatty acids may increase the secretion of insulin, and/or reduce insulin catabolism, causing impaired insulin action and leading progressively to insulin resistance, which determines accelerated atherosclerosis.
Okay…just for shits and giggles…let's bring back up the diabetes levels over the same time frame we looked at in terms of the rise of seed oils.
Hmmm…notice the hockey stick around 2000 also:
This zoom out helps:
Sure, sugar is not great but sugar went up quite a bit before diabetes followed (1850).
The real jump was right around the same period that seed oils were substituted.
Look how the diabetes prevalence (grey triangle) explodes up right around 1960-1970 (remember the soybean use did the same thing).
We have a whole review on why glucose is so destructive in the body.
Remember that omega 6 increases the production of insulin and the eventual sensitivity to insulin (hello…diabetes!!).
Personally, looking at the research, the difference between our bodies in the 70's and now…is the addition of seed oils and omega 6 balances being way out of whack.
Don't take our word for it…
Rich in unsaturated fats, especially linoleic acid, soybean oil is assumed to be healthy, and yet it induces obesity, diabetes, insulin resistance, and fatty liver in mice.
One more stop…an insidious one at that. If you wanted to make your food product super addictive, what would you do?
Seed oils and appetite
Let's introduce you to ghrelin. Your hunger hormone.
Literally, if it's released, you want to eat…regardless of nutrient absorption, satiety (being full), caloric intake, etc.
The high-LA meal increased ghrelin levels (p < 0.05), a hormone which encourages food intake. This was coupled with a significant acute increase in resistin levels, which impairs insulin signaling.
When you eat food that boosts ghrelin, you want to eat more. Talk about improving your market share!
Maybe that's why seed oils are in every processed food you can find (in addition to it being so cheap). You literally want to eat more and more regardless of being full.
What about the hormones that tell your brain that you're full? Leptin?
Linoleic acid (1-200 microM) significantly decreased insulin-stimulated leptin secretion and expression
Almost by design. Food scientists. You've been fighting an uphill battle!
Look…willpower is no match for appetite hormones.
It gets worse.
The heart of addiction revolves around substances that spike dopamine, our primary reward circuit in the nucleus accumbens.
Well well well...
In another study, low concentration of non-esterified fatty acid (linoleic acid) increased the dopamine levels in the nucleus accumbens and amygdala in a manner equivalent to those resulting from corn oil in the brain’s reward system
Dopamine is there to reward food, water, sex, etc. Things that help us survive. Linoleic acid is tricking this system just like alcohol, benzos, opioids, cocaine, and more.
Just like high fructose corn syrup:
Ingesting linoleic acid also resulted in a significant increase in DA level during 0–20 min, reaching 125.9 +/- 9% after 10 minutes.
That's fast! Like…still eating the meal fast!
Let's put that in context so you understand what's happening TO you.
Chocolate can spike dopamine by 50% if you really love chocolate.
Sex can spike dopamine by 100%
Okay…so 125% with linoleic acid.
Methamphetamine is close to 1000% (hence the brutal addiction risk).
Still…on par with sex from consuming linoleic acid!
So…trick your brain into thinking you're hungry and make it think you need it for SURVIVAL.
Dopamine isn't a pleasure neurotransmitter. That's more opioids and anandamide (our bliss molecule).
Dopamine is the "do that again" pathway. For increasing survival odds.
So…just add linoleic acid in the form of seed oils to your product and it will be craved…on par with sex (actually higher).
Take a look at the ingredients now.
We got PLAYED.
Let's turn to the head…mental health.
Seed oils and brain function
We have big reviews on how brain inflammation is so important to mental health.
Better yet, early trauma, infection, or stress can ramp up the immune system in the brain and drive mental health risks later in life.
The immune system is the future of mental health tells the story.
Does the omega ratio figure into any of this equation since we know there's an inflammation piece?
cross-sectional studies suggest that patients with mood disorders have a higher ratio of omega-6 to omega-3 polyunsaturated fatty acids (PUFAs) and lower levels of omega-3 PUFAs
They dug deeper in a study and found the following:
A higher n-6/3 PUFA ratio at baseline predicted mood disorders in UHR individuals over a 7-year (median) follow-up (odds ratio=1.89, 95% CI=1.075–3.338, P=0.03).
There's a fascinating cascade from omega 6's versus omega 3's.
It comes back to the inflammation piece.
Omega 6 are made into prostaglandins, pain signallers first and inflammatory signals beyond:
Prostaglandins also set off the “fight or flight” response to stress by inducing the brain to send out corticotropin-releasing hormone, which leads to downstream release of cortisol, adrenaline, and other stress hormones.
Stress is key to our mental health response and addiction for that matter.
So…do we see results from this?
After adjustment for potential confounders, individuals in the top quartile of LA intake had 41% more likely to be depressed compared to those in the bottom quartile
Our favorite superstar for mental health and addiction is BDNF, the brain's fertilizer.
Omega 3 directly supports the repair/growth pathway:
A significantly greater increase in plasma BDNF levels was observed in the intervention compared to the placebo group (Cohen’s d = 1.54). Changes of BDNF levels inversely correlated with change in depressive symptoms assessed using the Calgary Depression Rating Scale in Schizophrenia
We know that omega 6 (like linoleic acid from seed oils) crowds out omega 3. They compete!
Brain inflammation is the future for mental health.
omega-6 unsaturated fatty acids (arachidonic acid, linoleic acid) cause inflammatory pathway activation in microglia that is observed through hike in pro-inflammatory cytokine expression (IL-1β, TNF-α) and activation of NF-κB pathway through TLR-4 signaling.
This is key for all mental health plus the neurodegenerative diseases like Alzheimer's, dementia, etc.
Let's zoom out to a 40,000 foot view.
Seed oils and mortality
Let's lead in with this:
The list of health problems related to omega-3 deficits with elevated proportions of omega-6 in the hormone precursors has grown to include atherosclerosis, thrombosis , arrhythmia, heart attacks, stroke, immune-inflammatory disorders, asthma, arthritis, cancer proliferation , obesity , psychiatric disorders, depression, suicide, homicide [21,22], oppositional behavior, unproductive workplace behaviors, length of stay in hospitals  and annual healthcare claim costs .
Okay…so we just listed off the major killers of people.
We also see signs of inflammatory imbalance (asthma, autoimmune, arthritis, etc).
Mental health is front and center there as well.
We like to look at double-blind, placebo studies since there's some questionable research out there.
A study looked at replacing animal fats (saturated) with seed oil fats high in linoleic acid:
The intervention group (n=221) had higher rates of death than controls (n=237) (all cause 17.6% v 11.8%, hazard ratio 1.62 (95% confidence interval 1.00 to 2.64), P=0.05; cardiovascular disease 17.2% v 11.0%, 1.70 (1.03 to 2.80), P=0.04; coronary heart disease 16.3% v 10.1%, 1.74 (1.04 to 2.92), P=0.04).
17.6% (seed oil) versus 11.8% (control) for ALL cause mortality!
A great deal of this was driven by cardiovascular risk.
There's a great review of the effects of linoleic acid (omega 6) and arteriosclerosis and cardiovascular function at this link but the net net:
evidence implicating omega-6-rich vegetable oils as a causative factor in atherosclerosis and coronary heart disease.
It's all about inflammation and oxidative stress!
Stroke operates on the same principles but in the brain.
We just had an eye exam and it's fascinating! It's an internal lens to see how your vascular health is.
Linoleic and oleic acid induce inflammatory mediators believed to be involved in the pathogenesis of diabetic retinopathy (DR).
Multiple signs of damage to vascular health!
What about cancer?
Understand that the immune system is tasked with detecting and removing faulty pre-cancerous cells.
Inflammation is the key weapon of the immune system and we know that omega3/omega6 directly affect this pathway.
several studies have shown that ω-3 PUFAs possess a therapeutic role against certain types of cancer.
In contrast, several studies have demonstrated that ω-6 PUFAs induce progression in certain types of cancer.
They go on to look at research on different kinds of cancer.
Part of the issue may be high heat and seed oils.
With the use of thermally oxidized oils overproduction of reactive oxygen species (ROS) with overwhelmed cellular antioxidants defense system results in oxidative stress, the known cause of cardiovascular diseases (CVDs), cancers and neurodegenerative disorders.
Oxidative stress is highly destructive (more on it here) and heat just ramps up levels in cooking oil.
Remember…it's the ratio between Omega 6 and 3 (as we need both of them in the body).
In fact, studies can pinpoint the effects of changing this ratio:
Through multiple linear regression test, the results found were the increase of 1 unit of omega-6/omega-3 intake ratio would increase MDA level of 0,023 nmol/mL (β = 0,023, 95% CI = 0,004 − 0,042, p = 0,017).
MDA is a great tool for viewing oxidative stress and damage in the body.
You can actually test your MDA levels.
It's a signal for fat oxidation. The worst type of actors in the body (the real culprit for arterioschlerosis). We have a massive review on cancer.
Okay…we have to wrap at some time (if you've made it this far).
There's just so much data out there, we could write 10 fold on this subject.
There's a great review of lots of research here:
Again, carbs and sugar have their role but the advent of cheap seed oils and their skew of omega 3 and 6 fats is front and center for many of the ills that have spiked over the last 60 years.
Be well. Take care of each other. Take care of yourself.
Read those labels!
Always work with a doctor or naturopath with any supplement!
The information provided here is not intended to treat an illness or substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.