We’re often told certain nutrition “truths” as one-line headlines, without ever being encouraged to ask why.
One examples is: “Linoleic acid is an essential fatty acid.”
But what does essential actually mean?
How much do we truly need?
And have we taken this concept far beyond what the science supports?
Are we now eating too much?
What was the study that showed Linoleic Acid was essential?
Let’s slow down, zoom out, and examine the data.
Key Bullet Points
-
> “Essential fats” are naturally present in whole foods
-
> The amount required to prevent deficiency is very small
-
> Higher intakes are not required, and more is not merrier
-
> We do not need to go out of our way to add more omega-6 fats
-
> Most people would benefit from eating less linoleic acid, not more
-
> The classic rat experiment used to define “essential fatty acids” has never been replicated in humans
What Are “Essential Fats,” Really?
Dietary fats fall into three main categories:
-
Saturated fats
-
Monounsaturated fats (MUFAs)
-
Polyunsaturated fats (PUFAs)
These fats differ in carbon chain length and number of double bonds, giving them very different chemical structures, and very different biological effects.
PUFAs are labeled as “essential fatty acids.”
This is because humans cannot synthesize them internally, whereas we technically can synthesize some saturated and monounsaturated fats through de novo lipogenesis (the process of creating fat from non-fat sources like carbs.
PUFAs include both Omega-6 fats (like linoleic acid, abundant in seed oils) and Omega-3 fats.
“The term essential fatty acids (EFA) refers to those polyunsaturated fatty acids that must be provided by foods because these cannot be synthesized in the body yet are necessary for health.”
So far, so good.
But necessary does not mean needed in large amounts.
Note: In this article, the focus is on omega-6 polyunsaturated fats, which are predominantly plant-based. While omega-3 fats are also polyunsaturated, this discussion centers on plant-derived PUFAs, as both plant-based omega-6 fats and plant-based omega-3 fats (such as ALA) appear in the literature to carry the most significant metabolic consequences. Animal-derived fats naturally contain small amounts of omega-3s and are not the focus here.
What Do Current Guidelines Recommend
Current dietary guidelines recommend about 12–17 grams of linoleic acid per day, which equals 5–10% of daily calories on a 2,000-calorie diet.
Here’s the problem:
👉 There is no historical precedent for humans consuming this much linoleic acid.
So... is the current dietary guideline too high?
How do these numbers compare to the 'essential' amount? Are we eating more than what is 'essential'?
When you examine the literature carefully, it becomes clear that overconsumption of omega-6 fats leads to metabolic and inflammatory consequences over time.
How Much Are Americans Actually Eating?
Most analyses estimate that the average American consumes 12–17 g of linoleic acid per day (ref), already at the upper end of recommendations.
Other estimates even report some people eating a lot of processed foods, conventional pork/chicken and seed oils, intake may reach 20–30 g/day.
Our biology was never designed for this level of exposure. And remember, the fat we consume gets stored inside of us, for years.
At the same time as our Linoleic Acid consumption has gone up, metabolic health is declining, obesity rates are rising, and chronic disease is accelerating.
And now, many people think 'vegetable oils' (aka seed oils, high in Linoleic Acid) are good for us!
(Listed positively in many American Heart Association graphics, and included on the Harvard Food Pyramid as a healthy fat).
So it's important to remember where much of the push for higher PUFA intake came from:
- - Fear of cholesterol, and Omega 6 PUFAs lower serum cholesterol
- - The belief that lowering LDL at all costs improves health
This framework is outdated, and lowering cholesterol indiscriminately is not a health goal. (I discuss this in depth in another blog post, here).
There is enormous financial incentive for Big Ag and Big Pharma to promote the idea that we need more essential fats.
- - Big Ag is designed to sell expensive seeds, inputs and chemicals to grow more corn and soy which are high in Omega 6 fats
- - Big Pharma makes billions on statins, which are designed to lower your cholesterol at all cost
The lipid-lowering effects of PUFAs produced by Big Ag conveniently support the statin model produced by Big Pharma.
This approach clearly isn’t working.
So… Is Linoleic Acid Essential?
Yes... technically.
But only in very small amounts.
And most people are eating way more of this.
For context:
- - 1 tablespoon of soybean oil = ~7–8 g of linoleic acid
- - That’s 3–8× an entire day’s requirement
Humans require roughly 0.5–1% of calories from linoleic acid, about 1–2 g/day, to prevent deficiency.
That amount is effortlessly met by eating whole foods.
And anything beyond this baseline has negative metabolic consequences, which I've discussed extensively in other posts, like this one.
Where Did the “Essential Fatty Acid” Idea Come From?
What is the quality of the data that supports essentiality?
Before the 1930s, fats were not considered essential nutrients.(ref)
Researchers knew we could synthesize fat from carbohydrates and believed fats mainly served as energy storage and vitamin carriers.
That changed with the work of George and Mildred Burr in the 1920s–1930s.(ref, ref)
They fed rats a completely fat-free, lab-engineered diet (not possible outside a laboratory).The animals developed:
- - Poor growth
- - Scaly skin and dermatitis
- - Hair loss
- - Increased mortality
When very small amounts of linoleic acid were added back in to the diets, these symptoms resolved.
From this, linoleic acid was deemed “essential.”
But here is the important context that often gets ignored:
- - This deficiency occurred on an artificial, fat-free diet
- - Only a small amount of PUFAs were required to reverse symptoms (0.4% of calories as PUFA when provided by lard, and 0.1% of total calories when provided by liver (ref))
- - These studies do not justify modern high-PUFA intake
- - Linoleic acid was deemed essential because it prevented deficiency when all fats were removed, not because higher intakes were shown to improve long-term metabolic health.
A Different Way to Look at “Essentiality”
From a bioenergetic perspective, some researchers argue that PUFAs may not be truly essential (at least at the amounts recommended today!)
When the original deficiency studies are viewed through this lens, a different interpretation emerges: adding PUFAs back into the diet lowered metabolic rate.
A lower metabolic rate reduces the body’s demand for nutrients, because fewer vitamins and minerals are needed when less energy is being produced. (Higher metabolism = more energy production = higher nutrient demand.)
In this context, slowing metabolism with PUFAs can mask nutrient deficiencies.
In other words, adding PUFAs may not actually cure a deficiency... it may simply lower energy demand enough that the deficiency no longer shows up.
This distinction matters, and it’s an important question to ask!
What the Burrs Also Observed (But Few Mention)
Burr himself noted that fat-deficient rats had:
- - Higher basal metabolic rates
- - Higher respiration
- - Higher energy expenditure
" The most marked differences shown by the fat-deficient rats are higher basal rate, higher specific dynamic action of food, and higher respiratory quotients” (ref).
At the time, many B vitamins and trace minerals had not yet been discovered.
Later research showed that the “EFA deficiency skin condition” was actually caused by vitamin B5 and B6 deficiencies (ref, ref, ref, ref), not lack of linoleic acid.
The "skin condition" was produced by deficiencies of nutrients that were not yet discovered!
Numerous studies since then confirm that "Essential Fat deficient" animals have higher metabolic rates, because PUFAs suppress metabolism.
- - “In EFA deficient rats,…[r]esting metabolism in relation to body surface area was 25% increased.’ (ref)
- - “After 10 wk of consuming a diet low in EFA at 5 degrees C, the body weight of rats was 75% of that of controls (87% at 29 degrees C); the food intake was 135% of controls at 5 degrees C (120% at 29 degrees C). The resting respiration in deficient rats was 125% of controls at 5 degrees C (110% at 29 degrees C).” (ref)
- - “Compared to controls, in EFA-deficient rats… [r]esting metabolism expressed per surface unit was 15% increased.” (ref)
- - “Basal respiration in relation to the body weight is significantly increased by EFA deficiency;…Oxidative phosphorylation in isolated liver mitochondria is unaffected by EFA deficiency… Respiratory chain enzyme activities in mitochondria from heart and skeletal muscle and specific amounts of mitochondria in these tissues are unchanged by EFA deficiency.” (ref)
What Happens in Humans?
Crucially, this experiment was never replicated in humans.
Biochemist William Brown volunteered to eat a very low-fat diet for six months to test the "EFA Deficiency" in humans. (ref, ref)
Results after 6 months
- - No skin abnormalities
- - Weight loss despite adequate calories
- - Improved metabolic rate
- - Reduced fatigue
- - Normalized blood pressure
- - Resolution of lifelong migraines (since less PUFAs oxidizing!)
“Inducing an essential fatty acid deficiency in an adult human proved much more difficult than curing one…Each day, he consumed three quarts of defatted milk, a quart of cottage cheese made from it, sucrose, potato starch, orange juice and some vitamin and mineral supplements. His blood lipids became more saturated and their concentrations of linoleic and arachidonic acids were cut in half. He experienced a marked absence of fatigue, his high blood pressure returned to normal, and the migraines he had suffered from since childhood completely disappeared.” – Dr. Chris Masterjohn (ref)
This suggests that what was labeled “essential” may have been compensating for other deficiencies by slowing metabolism.
So What’s the Takeaway?
You can:
- - Correct nutrient deficiencies by eating nutrient-dense whole foods
- - Or mask them by slowing metabolism with excess PUFAs
An organism with a lower metabolic rate has a decreased need for nutrients so one can “cure” a vitamin deficiency by taking something (like more PUFAs) that slows the metabolism.
The symptoms the mice experienced may have just been a nutrient deficiency!
Now, this does NOT mean:
- - Zero fat diets are good (they aren’t)
-
- Or that PUFA intake should be zero (that’s impossible)
It means we don’t need to overdo it.
Key Takeaways:
> Even if these fatty acids are “essential”, they are only needed in very small amounts (ref) and are IMPOSSIBLE to avoid if you are eating real food.
> So we do NOT need to stress about increasing our consumption of essential fats in foods, and especially not supplements. For example: there is some in milk fat, cheese, butter, meat, eggs, and fish.
> Plus, modern food (seed oils, vegetable oils, dressings, bread, conventional eggs/chicken/pork) contain way more PUFAs than we have ever been exposed to.
> If you eat real food, you are likely not going to be deficient.
What We Know Now
These ‘essential fatty acid’ tests were performed in the early 1900s, which predates modern understanding of oxidative stress, lipid peroxidation, mitochondrial dysfunction, and endocannabinoid signaling
We now understand that eating more than the small baseline requirement has negative health consequences: lowers metabolic rate, steals valuable oxygen, hinders proper carb oxidation, damages gut health, increases cellular damage due to lipid oxidation, and more.
- - Humans efficiently recycle linoleic acid
- - LA is stored in body fat with a half-life of years
- - Some PUFA intake is inevitable
- - Whole foods easily meet essential requirements
- -High PUFA intake ≠ essential
- - More is not better
Excess linoleic acid
- - Lowers metabolic rate
- - Steals oxygen from energy production
- - Negatively impairs carbohydrate oxidation
- - Damages gut integrity
- - Increases lipid peroxidation and cellular stress
Thriving doesn’t require more “essential fats.”
It requires the right amount, from the right foods.
Why This Matters for Our Eggs
The Industrial Agriculture Food System and Government Subsidies has changed the food livestock eat, drastically increasing their PUFA exposure, too. So conventional eggs and chicken can contain a lot of PUFAs.
Four of our Angel Acres eggs provide only ~1.2 g of linoleic acid, right in line with daily essential needs. (And significantly lower than most eggs out there).
By comparison:
- - Four Organic Vital Farms Pasture-Raised eggs provide ~4× more
- - Four standard organic cage-free eggs provide even more
In fact, only two Organic Vital Farms eggs contain roughly the same linoleic acid as one tablespoon of canola oil.
Learning about this “big fat swap” in our food system is what inspired us to create a custom, corn- and soy-free Low PUFA feed, changing the fatty acid profile of our eggs.
