Linoleic acid
As our diets have evolved with the advent of industrialization and the proliferation of convenience foods, the balance of fatty acids in our diets has shifted dramatically.
Found abundantly in vegetable oils, processed foods, and factory-farmed animals, linoleic acid (LA), an omega-6 fatty acid, has become a large part of modern diets. The influence of this omega-6 fatty acid on our health is complex and multifaceted. This article covers the health implications with the LA component of modern diets.
As a quick refresher, polyunsaturated fatty acids, or PUFAs, are involved in the structure and operation of cell membranes. They contribute to several biological functions such as cell signaling, gene expression regulation, they act as metabolic precursors in innate immune responses of Eicosanoids, and so much more.
PUFAs can be subdivided into our omega-3 fatty acids and omega-6 fatty acids.
In modern diets, our PUFAs are derived from vegetable and seed oils rich in LA, which is an omega-6 fatty acid. LA is classified as an essential fatty acid, because we do not produce it endogenously, and it makes up a significant portion of human tissue composition.
The issues lie when our intake of LA is drastically increased and levels of LA in the bloodstream surpass our little need for them in what I just described.
How much LA is essential – if at all?
In traditional diets before the 1900s, our diet’s omega 6 to omega 3 ratio was approximately 1:1. But over the last 100-150 years, western diets have moved to around 20:1. We moved away from animal fats as cheap products like Crisco from Procter & Gamble.
The currently established recommended requirement of 2% of our total daily calories coming from omega-6 fat is based on two studies showing physiological symptoms of omega-6 deficiency in human infants showing scaling of the skin. Come to realize, the control diets were deficient in omega 3s, which delegitimizes this 2%. Reviews have mentioned this and brought it down to about a 75% reduction in even that, to as little as 0.5%.
So to put into perspective how much LA we need, the established requirement for total daily caloric needs of omega 6’s from studies shows that adequate omega-3 fatty acid alpha-linolenic acid (ALA) diminishes symptoms of LA deficiency.
This calls into question if LA is even essential – especially knowing how difficult it would be to attempt a deficiency with our modern food. Even if you are avoiding seed oils (the primary source), if you consume conventional chicken fat or pork, you are surpassing that initial 2%.
The effect of LA on breast milk
To look into a more biological and developmental requirement for LA, I’d suggest we look into breast milk. This is one of the many reasons we know and can say that cholesterol is vital for our health. If LA were to be naturally high in this perfect food – I’d suggest it be important.
LA found in breast milk is dependent on the amount of LA in the mother’s diet. In a study where lactating women went on a high LA diet of about 15–30% of total calories approximating the LA content of the standard American diet. And within 2–3 days of changing from their usual diet, the amounts of LA in their breast milk increased from around 9% to 42%.
As you’d imagine, the LA content of breast milk has drastically increased as our diets have, taking the nature of breast milk from less than 5% of total fatty acids in the 50s to more than 15–25% today being LA. I only see this number increasing as new lab products come out, replacing traditional foods with far inferior “alternatives” marketed as healthier options.
Studies show an adverse effect of increased LA in breast milk on a babie’s neurodevelopment. In one study, breastmilk LA percent composition (>9.7%) was associated with reduced motor and cognitive scores in 2-3 years of age. In the same cohort, LA composition was associated with reduced verbal IQ at 5-6 years of age. They also found a correlation between breast milk LA% composition and cognitive scores in 15-year-olds, suggesting a long-lasting impact of breastmilk LA on cognitive skills. Children breastfed with the highest levels of LA had cognitive scores comparable to children who were never breastfed!
That said, there are so many reasons to opt for high-quality animal fats. The DHA and EPA are essential for brain development.
Wrapping back to the omega 3 to 6 ratio
Omega 3s include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). EPA and DHA come strictly from animal foods. ALA is from plants but ALA must be converted to EPA and DHA to be utilized. The conversion rate is less than 10%.
On top of the low conversion rate, when we’re consuming LA alongside ALA, ALA competes for the same elongase and desaturase enzymes that turns linoleic acid into arachidonic acid (AA). This reduces this elongation of ALA into EPA and DHA even further.
Note the shared enzymes (FADS2, Elongase, FADS1). This increased LA intake creates greater competition that lowers the conversion rate of ALA to EPA and DHA.
On another important mention – membrane lipids made up of these PUFAs, and higher in LA, will be more susceptible to lipid peroxidation due to the weak carbon-hydrogen bonds between adjacent carbon double bonds. Each and every cell in our bodies is surrounded by a cell membrane being a phospholipid bilayer, composed of fat. So you can see why this is an issue if linoleic acid were to be degenerating. If someone were to have unnaturally elevated tissue levels of LA, as someone would consuming an excess of LA, this can accelerate metabolic damage.
Maintaining a low omega 6:3 ratio by minimizing omega 6 and maximizing omega 3s is well-established as being the way to go about this. We can’t simply keep the omega 6s high, and supplement omega-3s to support an ideal ratio. An excessive circulation of linoleic acid in the bloodstream, regardless of omega-3 fatty acid intake, will contribute to metabolic damage and disease.
What is this LA doing at the cellular level?
LA is a polyunsaturated fatty acid made up of highly fragile double bonds that are susceptible to oxidative damage. Due to how easily altered through oxidation they are, they lead to systemic effects of cellular tissue damage – as all metabolic processes will leave these double bonds vulnerable to damage by oxygen, heat, and pressure. That said, LA also contributes to the formation of free radicals that go on to wreak havoc on healthy cells and cause oxidative stress.
But that’s not the end of it. LA is a precursor for the production of oxidized linoleic acid metabolites or OXLAMs. Through the LA conversion into AA (mentioned above), we contribute to the formation of a major precursor to oxidized arachidonic acid metabolites or (OXAAMs). These products are in no way health-promoting but they are rather degenerating. The increased circulation of oxidized metabolites and free radicals has been linked to a range of diseases accelerating metabolic damage. These metabolites can damage lots of different structures down to our DNA, mitochondria, cell membranes, proteins, and stem cells. (here, here, here)
Takeaways
When it comes to this new “fad diet” of avoiding seed oils, it’s safe to say that seed oils being so new are the real fad. There are real metabolic changes made from this unnaturally high level of this omega-6 in the diet. I find it strange that avoiding such a nutrient-void food is often seen as “disordered” or “restrictive”. This “food” is no food at all. There is no reason to support their production when I know of something many times better for me, the environment, and the support of local farms. While I don’t go into panic when consuming them on occasion (the body is resilient), it is not something I feel I struggle to restrict due to cravings.
I will say, there are choices we have to make. For example, when I go over to Grandma’s house and she has made some baked goods – I personally feel healthier making her happy knowing that I enjoy and appreciate what she made rather than saying no. Health is multifaceted in so many ways. Relationships are one of them. I’d feel worse leaving knowing that she prepared food with me in mind to have it turned down. Truly the thought of that makes me sick. But you know I bring up the topic of butter and how wonderful it is every chance I get. ;)
When eating out, I try to avoid them because it is not difficult. I use the Seed Oil Scout App to find restaurants that use local ingredients which is generally my number one goal. Ordering a steak cooked in nothing but itself (or real butter) is easy just about anywhere. Any proteins can easily be found when eating out. I steer away from sauces and stick to what I know is made traditionally. Don’t be afraid to speak up but also don’t be afraid to consume traces of seed oils. We’ve lived up to the point that most of us used to consume them daily. Before my family knew better, we used organic grapeseed oil as our cooking oil of choice. I’m sure it’s still making up parts of my cell membranes but I’m alive and well.
Appreciatively, Mia
