Industrial Seed Oils

Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness. (Isaiah 55:2)

Of all the toxins in this book, the industrial seed oils hide most in plain sight. They do not lurk; they pose.

They sit on the grocery shelf in tall clear bottles, labeled “heart-healthy.” They are in the salad dressing, the mayonnaise, the crackers, the granola bars, the plant-based spreads and the bag of roasted nuts. They are in nearly every restaurant fryer in the country. And yet corn, soybean, canola, cottonseed, sunflower and safflower oils barely existed in the human diet a hundred years ago. For newcomers, they have made themselves very much at home.

In the last chapter I introduced Dr. Joseph Mercola and his case against the modern American diet. The second of the three chemical changes he names is the replacement of traditional fats with industrial seed oils. Of the three, it is the change that has been least visible to the average shopper, and it may be the most consequential. Nobody notices the oil; it just quietly comes along with everything else.

In this chapter I want to teach you how these oils are made, why their fats spoil so easily, how fast they took over our food and our bodies, what the research debate is really about, and which traditional fats replace them in your kitchen.

The Fats Humans Always Ate

Start with history, because history is the clearest teacher here, and it does not have a product to sell.

For the entire history of our species, until about 1900, the fats people ate were animal fats: butter, lard, tallow, schmaltz, and the fats of fish and poultry. In some places people also had the plant fats that are easy to get from fruit: coconut oil, palm oil and olive oil.

These fats share certain characteristics. They are stable at high temperatures. They do not oxidize easily during cooking. And they have been part of human life long enough that the body is well adapted to them. They are old friends, not new acquaintances.

The industrial seed oils are different. They come from seeds that, until industrial chemistry made the extraction possible, could not have been turned into large amounts of oil by any traditional method. You cannot squeeze a cup of oil out of a handful of corn kernels or cottonseeds in your kitchen, however strong your grip. It takes a factory.

The shift from traditional fats to seed oils began in the early twentieth century, accelerated dramatically after World War II, and reached near-total dominance of the American fat supply by the 1980s. It was driven partly by the campaign against saturated fat and cholesterol, rooted in the work of Ancel Keys and his Seven Countries Study, which, despite its methodological problems, became the foundation of mainstream dietary advice for half a century. (In Chapter 8 you will read how the sugar industry helped steer that same advice away from sugar and onto fat.) It was also driven by the commercial interests of the seed oil producers, who had a cheap product to sell and a large advertising budget to sell it with. Cheap to make and loud to advertise is a hard combination to beat.

What They Are and Where They Hide

The industrial seed oils are the usual suspects:

• corn oil
• soybean oil
• canola (rapeseed) oil
• cottonseed oil
• sunflower oil
• safflower oil
• grapeseed oil
• rice bran oil

They are often sold together, or blended, simply as “vegetable oil.” The name conjures up a basket of carrots and delivers a soybean. Butter, tallow and extra-virgin olive oil are not seed oils. Soybean oil is.

They are in nearly every restaurant fryer, salad dressing, mayonnaise, chip bag, cracker, granola bar, plant-based spread and roasted nut. And most of them come from genetically engineered crops sprayed with glyphosate, which you learned about in Chapter 5. Corn, soy, canola and cotton are four of the most engineered crops in America, so a bottle of “vegetable oil” carries the problems of Chapter 5 inside the problems of this one. Two chapters for the price of one bottle.

My teachers agree. It is striking how teachers from very different fields arrive at the same warning, and they did not compare notes.

Dr. Russell Blaylock, the neurosurgeon whose work on excitotoxins you will meet in Chapter 7, was blunt when he wrote about protecting the brain:

“avoid corn, safflower, sunflower, soybean and canola oils, all of which are Omega-6 fats.” (Russell L. Blaylock, M.D., “Why Fluoride Is Toxic,” The Blaylock Wellness Report, 2004)

The Ultimate Guide to GMOs on Mercola.com lists “Processed vegetable oils like canola oil, rapeseed oil, and cottonseed oil” among the GMO-derived ingredients to avoid.

And Dr. Richard Schulze, the herbalist, with his usual humor, described what happens to these oils in the fryer:

“French fries (another name for rancid trans-fat grease sticks) are the most eaten vegetable in America.” (Dr. Richard Schulze)

A neurosurgeon, a physician and an herbalist, each coming from a different direction, all point at the same bottle. When that happens, I pay attention. When three compasses point the same way, I stop arguing with north.

How Seed Oils Are Made

No traditional fat was ever made this way.

Compare the old fats first. Butter is churned from cream. Tallow is rendered, slowly, from beef fat. Lard is rendered from pork fat. Olive oil is pressed from the fruit. A grandmother could make any of them in her own kitchen, with nothing more exotic than a pot, a press or a churn.

Now the seed oils. The seeds are crushed and heated, and the oil is extracted with a chemical solvent such as hexane, a petroleum byproduct. The oil is then degummed, bleached, and deodorized at high heat. The deodorizing is there to hide the rancid smell the process itself creates. In other words, the factory makes a mess and then sprays air freshener on it. What comes out at the end is the clear, pale, neutral-tasting oil that fills the supermarket shelf, and that no one before the twentieth century had ever eaten.

The difference matters. A simple press, a churn or a slow rendering keeps a fat close to what nature made. Heat and a chemical solvent such as hexane do not. One is a kitchen; the other is a refinery.

Hydrogenation and trans fats. For much of the twentieth century, seed oils went through one more step. They were hydrogenated to make solid fats, such as shortening and margarine, and that process created trans fats. Margarine was promoted for decades as healthier than butter, with all the confidence a jingle can buy. Then the evidence against trans fats became impossible to ignore. The FDA removed partially hydrogenated oils from its “generally recognized as safe” list in 2015, and they were phased out of U.S. foods starting in 2018.

Think about that. A generation of mothers was told to throw out the butter and buy margarine for the sake of their families’ hearts. Decades later, the government quietly took the margarine’s key ingredient off the safe list. No apology came in the mail. I tell this story not to frighten anyone but to remind us that “approved” and “recommended” are not the same as “true.”

Fragile Fats and Oxidation

Here is the heart of the problem, and I want to explain it simply, no chemistry degree required.

Seed oils are rich in linoleic acid, an omega-6 polyunsaturated fat. Polyunsaturated fats have several weak spots in their structure, called double bonds. Those weak spots are where heat, light and air attack, like rust finding the scratches in a car’s paint. That makes the polyunsaturated fats the fats most easily oxidized of all.

When they oxidize, in the bottle, in the fryer, or in the body, they break down into reactive compounds, such as aldehydes, that damage cells. The bottle may look clean; the chemistry is not.

It helps to picture a ladder of stability:

Kind of fat	Examples	Weak spots (double bonds)	Stability
Saturated	butter, ghee, tallow, coconut oil	none	stable; the best for high heat
Monounsaturated	olive oil, avocado oil	one	fairly stable
Polyunsaturated	corn, soybean, canola, sunflower, safflower oils	two or more	fragile

This is why tallow is among the most stable fats you can cook with, and corn, sunflower and canola oils are among the least. It is also why a fragile oil can be damaged before it ever reaches your mouth: by the heat of its own manufacture, by the light falling on a clear bottle, by the air in a half-empty one, and above all by the fryer, where the same oil is heated again and again, and again. The clear bottle, it turns out, is a showcase for its own undoing.

Why this matters to the body. Remember the simple idea from Chapter 1: a toxin is anything that adds to the oxidative load the body must clear. Dr. Thomas Levy puts it even more simply: oxidation is the common thread under the chronic illnesses we fear. Fragile seed oils fit that idea exactly, like a key in a lock. Every bit of oxidized fat adds to the body’s load.

And here is the part that most people never hear. The fats we eat become part of us. The body builds the fats we eat into its cell membranes, the thin walls that hold every cell together. When people replace butter and tallow with seed oils, they replace stable fats with fragile ones, right in the cell membranes that hold their bodies together. It is like rebuilding a brick house with cardboard, one brick at a time. An oxidized oil delivers oxidized fat directly into those membranes, and a fragile fat built into a membrane can keep oxidizing there, from inside the cell.

So when you hear “seed oils are high in polyunsaturated linoleic acid,” hear this: they are made of the fat that spoils most easily, and we have been building our bodies out of it. “You are what you eat” was never meant quite this literally.

Omega-6 and Omega-3: A Balance Lost

There is a second problem with the seed oils, separate from oxidation. As if one were not enough.

Omega-6 and omega-3 fats are both needed by the body, but they compete with each other. The body turns omega-6 fats into signaling molecules that drive inflammation. In small amounts this is normal and necessary; inflammation is a useful response when we are injured or fighting an infection. It is the body’s fire alarm. The trouble comes when the omega-6 side of the scale is loaded far beyond the omega-3 side, and the alarm never quite stops ringing.

Traditional diets supplied omega-6 and omega-3 fats in a ratio of about 1:1 to 4:1. The modern diet, heavy in seed oils, supplies 15:1 or more. That is not a scale; that is a seesaw with one end on the ground. Many researchers link that imbalance to chronic, body-wide inflammation, the kind that sits underneath so much of the chronic illness of our time.

The answer is not to swallow fish oil while still eating soybean oil at every meal; that is bailing water while leaving the tap running. The answer is to bring down the omega-6 side by removing the seed oils, and to bring up the omega-3 side with real food from the sea and the pasture, which I describe at the end of this chapter.

A Dramatic Change in One Century

Researchers have documented how fast the seed oils took over, and the numbers are startling.

• Soybean oil rose more than 1,000-fold. A 2011 analysis in the American Journal of Clinical Nutrition (Blasbalg and colleagues) found that U.S. consumption of soybean oil rose more than 1,000-fold during the twentieth century, and that linoleic acid rose from under 3% to over 7% of calories. Not a trend; a takeover.
• Our body fat changed. A 2015 review in Advances in Nutrition (Guyenet and Carlson) found that the linoleic acid content of Americans’ body fat rose by about 136% over half a century. We did not only eat more of it. We became more of it.
• A third of our calories. Dr. Chris Knobbe, an ophthalmologist and former associate clinical professor at UT Southwestern, estimates that seed oils now supply roughly a third of all the calories in the average American diet. One bite in three, give or take, from a factory bottle.

Why the change takes time to undo. Body fat turns over slowly. The linoleic acid stored in your body fat today was laid down over years, and it leaves just as slowly, on its own schedule. That is why, when a person stops eating seed oils, the change in her stored fats takes a year or more. I tell my students this at the beginning, so that no one gives up after a month.

Dr. Knobbe’s case. In his widely watched lecture “Diseases of Civilization: Are Seed Oil Excesses the Unifying Mechanism?”, Dr. Knobbe traces the rise of seed oils alongside the rise of heart disease, cancer, diabetes, obesity and macular degeneration, the eye condition at the center of his own practice. He names the “foods of modern commerce” and the dates each one entered the diet, and he builds on the work of Dr. Weston A. Price. His case rests on two things: the history, and what happens to fragile fats inside the body.

A rise in two things at the same time does not by itself prove that one caused the other. Ice cream sales and sunburns rise together too. I want you to hold Dr. Knobbe’s history together with the clinical trials I describe below. Together, they make a case worth taking seriously.

What Dr. Price Found

You met Dr. Weston A. Price in Chapter 1, and you will meet him fully in Chapter 13. In the 1930s this Cleveland dentist traveled the world to study the healthiest peoples he could find, people still eating the traditional foods of their ancestors, with broad jaws, straight teeth and almost no decay, and not an orthodontist in sight. Here I want to tell you only what he found about fat.

Every healthy traditional people Dr. Price studied ate animal fats: butter, cream, lard, tallow, fish oils and the fat of organ meats. Some, in the tropics, used coconut and palm. None used industrial seed oils. Those diets differed enormously, from the Swiss villagers’ butter and cheese to the islanders’ fish and coconut, but on this point they agreed, without ever having met.

And when these same peoples took up what Dr. Price called the “foods of modern commerce” (white flour, sugar, canned goods and vegetable oils), decay and illness followed within a generation. Vegetable oils were on that list from the start; they were not latecomers to the problem.

The Weston A. Price Foundation sums up his findings in its Wise Traditions principles. One of them speaks directly to this chapter: the fats of traditional diets were mostly saturated and monounsaturated, with omega-6 and omega-3 fats in balance. Those are exactly the stable fats at the top of the ladder above, in exactly the balance the modern diet has lost. The traditional animal fats also carry the fat-soluble vitamins A, D and K2 that Dr. Price prized; a bottle of corn oil carries none of them. It brings calories to the party and leaves the gifts at home.

Notice, too, that Dr. Price’s peoples ate the fat of animals that lived as their ancestors lived, on grass and pasture and in the sea. That matters today. The fat of grass-fed and pasture-raised animals is dramatically different in its fatty acid composition from the fat of animals raised in confinement on corn and soy, and the butter and milk of grass-fed cows differ in their vitamin content as well. A cow is what it eats, too. When I say “traditional fats,” I mean the fats of healthy animals.

The Foundation was co-founded by the lipid biochemist Dr. Mary G. Enig, a scientist who studied fats for her whole career. It has taught for decades that the traditional fats are the safe fats, long before it was fashionable to say so.

The Research Debate

You will meet the other side of this question in almost every conversation, often before the soup is served, so I want you to understand it well.

The conventional view. Most medical associations, including the American Heart Association, still recommend replacing saturated fat with vegetable oils, because doing so lowers LDL cholesterol. Your client’s cardiologist probably believes this, and believes it sincerely. Be ready for that conversation, and be respectful in it.

The other side. Two large trials from the 1960s and 70s tested exactly that advice. Their full data were analyzed only decades later. Some answers take their time.

• The Sydney Diet Heart Study replaced saturated fat with safflower oil margarine in men who had had a heart attack. A 2013 reanalysis in the BMJ (Ramsden and colleagues) found that the men on safflower oil were more likely to die, of heart disease and of all causes.
• The Minnesota Coronary Experiment replaced saturated fat with corn oil. Cholesterol fell, just as the theory predicted. But a 2016 reanalysis in the BMJ (Ramsden and colleagues) found no reduction in deaths. In older participants, the greater the drop in cholesterol, the higher the risk of death.

These trials do not settle every question. But they show why “lowers cholesterol” and “saves lives” are not the same thing. A number on a lab report is not the same as a life. The Minnesota experiment lowered cholesterol with corn oil and did not reduce deaths. The Sydney study, done in exactly the kind of man who is told today to switch to “heart-healthy” oils, found more deaths, not fewer.

How I have the conversation. When someone asks me whether she should throw out her canola oil, I ask what her great-grandparents cooked with. It is a gentle question, and a disarming one. I invite her to read the studies for herself. And I encourage her to see how she feels when she changes.

For anyone with heart disease, high cholesterol or diabetes, I am careful. I share the research, including the Sydney Diet Heart Study, which tested this exact advice in men who had had heart attacks. I suggest extra-virgin olive oil, which both sides agree is healthy, as the easy first step, and grilled rather than deep-fried food. Bigger changes, such as eating more saturated fat, are made alongside their cardiologist, who can track their labs. And no one stops a heart or cholesterol medication on their own. Our role is to inform and encourage, not to tell anyone that seed oils are perfectly safe or that all fat is dangerous, and never to tell anyone to stop a medicine.

Cooking, Shopping and Eating Out Without Seed Oils

Now the practical work. This is the work of one kitchen cupboard, and it is some of the most rewarding work in this book.

• Cook with traditional fats. Butter or ghee from grass-fed cows. Tallow from grass-fed beef. Schmaltz from pasture-raised poultry. Coconut oil. These stable fats suit higher heat and do not fall apart when the pan gets hot.
• Use extra-virgin olive oil for dressings and gentle cooking. Dr. Schulze used cold-pressed olive oil in his liver flush and his salad dressings. Avocado oil is another good choice; it is one of the few non-traditional plant oils that is reasonably stable and not extracted with industrial chemistry. No solvents, no deodorizer, no cover-up.
• Clear the cupboard. Remove, as you can, the bottles of soybean, corn, canola, cottonseed, safflower and sunflower oil, and anything labeled simply “vegetable oil.” It is the most satisfying kind of spring cleaning.
• Read labels. Seed oils hide in mayonnaise, dressings, crackers, chips, “healthy” snack bars, plant-based spreads, roasted nuts, baby food and even “natural” products. The phrase “may contain one or more of the following” usually means seed oils; it is the label’s way of shrugging. Mayonnaise and dressing are easy to make at home with olive oil or avocado oil, and the jar you make yourself is the one you can trust.
• Eat out wisely. Restaurant fryers almost always use seed oils that are reheated for days, which is exactly what Dr. Schulze meant by “rancid trans-fat grease sticks.” Ask what the kitchen cooks with; a good kitchen will be happy to tell you. Choose grilled or roasted dishes. Ask for olive oil and vinegar instead of dressing.
• Balance with omega-3s from wild fish, fish roe, cod liver oil and pastured egg yolks.
• Be patient. Because body fat turns over slowly, the change in your stored fats takes a year or more. You will likely feel better long before then, but the full change is a slow one. Think of it as a slow cooker, not a microwave.

A good exercise for any household: list every fat and oil in your kitchen, including the ones inside bottled dressings and spreads, and mark which ones Dr. Price’s traditional peoples would have recognized. Butter, yes. Tallow, yes. Olive oil, yes. The tall clear bottle of “vegetable oil,” no. They would not have known what to do with it, and neither, it turns out, does the body.

The reader who can replace the seed oils in her kitchen with traditional fats, and who can make her own dressings and sauces from scratch, will remove one of the largest single sources of oxidative damage in the modern diet. Let your soul delight itself in fatness, the good kind, the kind your great-grandmother would have known.

The candle is in your hand. The cupboard is being cleared. In the next chapter we turn to the flavor enhancers made in factories, and to the neurosurgeon who warned us about them, long before most of us were listening.

Footnotes and sources for this chapter

Sources and Further Reading

• Mercola, J. Fat for Fuel. Hay House, 2017.
• Mercola, J. The Ultimate Guide to GMOs. Special report, Mercola.com.
• Blaylock, R. L. “Why Fluoride Is Toxic.” The Blaylock Wellness Report, 2004.
• Knobbe, C. “Diseases of Civilization: Are Seed Oil Excesses the Unifying Mechanism?” (lecture).
• Blasbalg, T. L., et al. Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the twentieth century. American Journal of Clinical Nutrition, 2011.
• Guyenet, S. J., and Carlson, S. E. Increase in adipose tissue linoleic acid of US adults in the last half century. Advances in Nutrition, 2015.
• Ramsden, C. E., et al. Reanalysis of the Sydney Diet Heart Study. BMJ, 2013.
• Ramsden, C. E., et al. Reanalysis of the Minnesota Coronary Experiment. BMJ, 2016.
• Simopoulos, A. P. “The Importance of the Ratio of Omega-6/Omega-3 Essential Fatty Acids.” Biomedicine & Pharmacotherapy 56, no. 8 (2002): 365–379.
• DiNicolantonio, J. J., and O’Keefe, J. H. “Omega-6 Vegetable Oils as a Driver of Coronary Heart Disease: The Oxidized Linoleic Acid Hypothesis.” Open Heart 5, no. 2 (2018): e000898.
• Price, W. A. Nutrition and Physical Degeneration. Price-Pottenger Nutrition Foundation, eighth edition 2009.
• Fallon Morell, S. Nourishing Traditions. NewTrends Publishing, revised edition 2001.
• Weston A. Price Foundation, the Wise Traditions principles.
• Shanahan, C. Deep Nutrition: Why Your Genes Need Traditional Food. Flatiron Books, 2017.
• Teicholz, N. The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet. Simon and Schuster, 2014.
• See Chapter 1 for the idea that a toxin is anything that adds to the body’s oxidative load, Chapter 5 for the GMO crops most seed oils come from, and Chapter 13 for Dr. Price’s traditional diets in full.