Ashley Armstrong
Story at-a-glance
- The diet of animals we consume directly affects the nutritional quality of meat, dairy, and eggs, which impacts human health
- Modern farming practices have increased PUFA (polyunsaturated fat) levels in chicken and pork, contributing to the overconsumption of omega-6 fats. High PUFA intake can lead to health issues, including liver problems, inflammation, and metabolic disruption
- Conventional chicken is now the highest source of linoleic acid (LA), a problematic omega-6 fat, in the American diet. Pigs fed a high-PUFA diet can have fat concentrations similar to canola oil
- Ruminant animals like cows have a unique digestive system that helps convert PUFAs into more stable saturated fats
- You can reduce PUFA intake by choosing grass fed meat, pasture-raised animal products, and avoiding seed oils
In our modern quest for optimal health, we often focus intensely on what we put on our plates. However, there’s a crucial aspect of nutrition that often goes overlooked: the diet of the animals we consume. (What we eat, eats) This oversight can have significant consequences for our health, particularly when it comes to our intake of polyunsaturated fatty acids (PUFAs).
Consider this startling fact: conventional chicken is now the highest source of linoleic acid, an omega-6 PUFA, in the American diet. This means that a food many consider to be a healthy, lean protein source is actually contributing significantly to our overconsumption of PUFAs.
Figure 1. Top source of linoleic acid consumption in the U.S.1But it’s not just chicken we need to be concerned about. Pork, another staple in many diets, can be equally problematic. When pigs are fed a high-PUFA diet, their fat can have the same PUFA concentration as canola oil — a fact that might make you think twice about having several pieces of conventional bacon every single day for breakfast.
These surprising revelations beg the question: how did we get here, and what does it mean for our health? The answer lies in the intricate relationship between animal feed and the nutritional quality of meat, eggs, and dairy products that end up on our tables. As the saying goes, “You are what you eat.” But perhaps more accurately, we are what our food eats.
[…]
What Are PUFAs?
Fats are composed of fatty acids, which can be categorized into three main types:
1. Saturated fatty acids (SFAs) — These have no double bonds between carbon atoms.
2. Monounsaturated fatty acids (MUFAs) — These contain one double bond.
3. Polyunsaturated fatty acids (PUFAs) — These contain two or more double bonds.
The number of double bonds in a fatty acid is crucial because it affects the fat’s stability and how it behaves in our bodies. PUFAs, with their multiple double bonds, are the least stable and most prone to oxidation.
Over the past century, there has been a dramatic increase in PUFA consumption, particularly linoleic acid. This shift is largely due to the widespread use of seed oils (often called vegetable oils) in food production and as a component of animal feed. Common sources of these oils include:
| Vegetable oil (which is some combination of the items below) | Soybean oil |
| Corn oil | Sunflower oil |
| Safflower oil | Canola oil |
These oils are high in omega-6 PUFAs, particularly linoleic acid. While omega-6 fatty acids are essential in small amounts, the modern diet often contains an excessive and potentially harmful level of these fats.
“Prior to the 20th century, the average intake of LA was under 2% of the total daily caloric intake. The biological optimal range is approximately 1% to 2%, but current LA consumption is over 25% of the total calorie intake for the average person.”2
Why PUFAs Are Problematic
1. Instability and oxidation — PUFAs are highly unstable due to their chemical structure. Each double bond in the fatty acid makes it more susceptible to oxidation.3 This instability means that PUFAs can easily form harmful compounds when exposed to heat, light, or oxygen — a process that can occur during cooking or even inside our bodies.
2. Tissue incorporation — The fat we consume is used as a fuel source, but it is also used to make up structures inside of us. So dietary fats have energy, structural and signaling roles — impacting metabolism, gut health, cellular repair, and more. A higher PUFA environment inside of you will lead to different cellular signaling relative to an environment that is low/moderate PUFA and higher in SFA.
When a lot of PUFAs get incorporated into cellular structures, they make cells very fluid, leaky and unstable. Being too fluid impairs proper cellular function4 and can increase permeability and leakiness, letting things we do not want to get inside the cell5 — like water leaking from a bucket with holes. We of course want some permeability, but too much can allow electron leakage and large sized particles, like calcium, to get inside cells.
The half-life of fats is approximately 2 years, meaning these fats stick around for a while and it can take up to 2 years to improve the fatty acid profile inside of you!
3. Oxidative damage — When PUFAs oxidize, they form lipid peroxides and other breakdown products that can cause significant cellular damage.6,7,8 These oxidized fats can harm proteins, DNA, and other crucial cellular components, potentially leading to inflammation and various health issues.
4. Disrupt liver function — The liver plays a crucial role in processing fats and detoxifying harmful substances in our bodies. High PUFA intake, especially linoleic acid, has been linked to liver problems. PUFAs can promote liver fibrosis.9,10 Plus, experimental and epidemiological studies have shown that dietary linoleic acid is required for the development of alcoholic liver damage.11
Even small amounts of linoleic acid (0.7% or 2.5% of diet) combined with alcohol consumption caused fatty liver, necrosis, and inflammation in animal studies. These findings suggest that the high levels of linoleic acid in modern diets, partly from high-PUFA animal products, may be contributing to the rise in liver diseases.
5. Metabolic disruption — High PUFA intake can interfere with thyroid function and metabolism.12,13,14,15 PUFAs have been shown to block thyroid hormone production, transport, and receptor binding, leading to a slower metabolism and associated health problems. Studies have shown that reducing PUFA consumption can increase metabolic rate (measured by basal respiration).16
A lower metabolic rate means down regulated systemic function (you won’t function at your best) AND weight gain even with a lower calorie intake — something no one wants or needs.
6. Impaired carbohydrate utilization — PUFAs can inhibit the body’s ability to properly use carbohydrates.17,18,19 They interfere with key enzymes involved in glucose metabolism, potentially contributing to insulin resistance and metabolic syndrome.20,21
More specifically, studies document that PUFAs Inhibit Cytochrome C Oxidase activity22 and inhibit the function of the PDH enzyme.23,24 PDH is the rate-limiting complex responsible for the decarboxylation of pyruvate to acetyl-CoA and thus serves as a pivotal role in fuel selection and regulation of carb oxidation.
PUFAs have a reductive effect, pushing the pyruvate towards the lactate, glycolytic pathway instead of the acetyl-CoA and thus full oxidative phosphorylation pathway.
One study noted that “enrichment of the diet with polyunsaturated fatty acids causes changes in adipose tissue metabolism that favour fat deposition.”25 Another study demonstrated that consuming a meal high in PUFAs, as opposed to saturated fats, led to lower rates of carbohydrate oxidation after the meal.26
These findings suggest that the high PUFA content in modern diets, including from animal products, may be contributing to the rising rates of Type 2 diabetes and obesity.
7. Damage hut health and increase inflammation — The health of our gut is intrinsically linked to our overall well-being, and high PUFA intake may be compromising gut integrity:
• PUFAs can increase the permeability of tight junctions in the gut,27 potentially leading to “leaky gut” syndrome.
• A diet rich in omega-6 PUFAs resulted in increased host inflammation, oxidative stress, and gut barrier dysfunction in one study.28
• High dietary intake of linoleic acid was associated with a significant increase in ulcerative colitis, an inflammatory bowel disease.29
These effects on gut health can have wide-ranging consequences, as gut health is linked to immune function, mental health, and various other aspects of overall well-being.
Diets high in omega-6 PUFAs have been associated with increased inflammation and gut permeability. This can contribute to various inflammatory conditions and potentially compromise gut health.
8. Cholesterol synthesis inhibition — While often vilified, cholesterol plays crucial roles in our bodies, including hormone production and cell membrane integrity. PUFAs can inhibit the body’s natural cholesterol production, which may have unintended negative consequences.
We of course do not want super high levels of cholesterol (that is a sign of hypothyroid), but we also don’t want super low cholesterol since cholesterol is protective.30,31
Moreover, anything that suppresses your cholesterol synthesis increases the risk of cancer.32 Statins are major carcinogens and are linked to diseases like ALS and other muscular dystrophies.
9. Immune suppression — High PUFA intake can suppress immune function.33,34,35 This immunosuppressive effect is so well-established that there are several established products on the medical market based on a combo of linoleic and linolenic acid that are given to organ transplant patients.36
[…]
The immunosuppressive effects of vegetable oils are not limited to intravenous administration. Consuming vegetable oils in foods has been found to have similar harmful effects on the immune system. This is particularly concerning given the widespread use of vegetable oils (and high linoleic acid levels) in modern diets.
Now that we understand the potential issues with high PUFA intake, let’s explore how the feed given to livestock impacts the nutritional composition of the animal products we consume.
The Feed-Food Connection: How Animal Diets Affect Our Health
Ruminants, thanks to their unique digestive system, have a natural mechanism that helps protect against high levels of PUFAs in their tissues. The bacteria in their rumen can convert some of the PUFAs they consume into saturated fats through a process called biohydrogenation.
This means that the fat in beef and milk will still tend to be more saturated. However, it’s important to note that modern farming practices can still influence the fat composition of ruminant products. (Scientists are now researching how to bypass this process and have been able to significantly increase PUFA concentration — yuck!) A conversation for another day!
The situation is quite different for monogastric animals like pigs and chickens. These animals do not have the biohydrogenation process that occurs in ruminants. As a result, the fats they consume are more directly reflected in their body fat and other products. Several studies have demonstrated this direct relationship.
In pigs, increasing dietary PUFA led to a significant decrease in saturated fatty acid levels in adipose tissue. The concentration of linoleic acid increased significantly with an increase in dietary PUFA.37 In chickens, the PUFA content of thigh meat increased exponentially as the inclusion of dietary PUFA increased.38
The push to decrease saturated fat content in animal products has led to an increase in PUFA content in our food system, based on the misguided belief that this improves the nutritional quality of the meat.
“Overall, decreasing the content of SFA and increasing the content of UFA have become the trend of improving the nutritional quality of pork.”39 The conventional system is trying to manipulate food to fit a false health narrative!
And they contradict themselves all the time in the literature — “It’s well known that although dietary PUFA improves meat nutritional qualities, such meats are more susceptible to lipid oxidation during processing.”40 It is well documented how unstable these fats are!
This direct relationship between livestock feed and fat composition in monogastric animals means that conventional chicken and pork can be significant sources of PUFAs in the modern diet. And as we discussed earlier, the higher PUFA content of modern can have far-reaching effects on human health. High-PUFA diets will negatively impact:
| Metabolic health | Thyroid health |
| Gut health | Liver health |
| Inflammation | Insulin sensitivity and glucose metabolism |
| Cholesterol synthesis | DNA and cellular structures |
While some papers were presented above, there are more papers outlined in Dr. Mercola’s review article.41
The Most Revolutionary Act 
Are you saving glyphosate residue for another post? You probably know the Codex Alimentarius allows one hundred times more residues on animal fodder than on human food . . . and that will be stored in the tissues humans consume. Organics are Essential to our survival. Cheers, ZD
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Ashley Armstrong, the author of the article, specializes in cellular and mitochondrial health. That’s what her book is about, and I think she prefers to limit what she presents to areas in which she has expertise.
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