worst kind of pro-inflammatory fats: MegaTrans.
Granola Up to half the calories in granola may come from vegetable oil.
Soft breads, buns, and most store-bought muffins
I saved these for last because, though the total
unnatural fat content tends to be low, most people eat a lot of these products in a typical week, and they constitute a major source of trans and especially harmful pro-inflammatory MegaTrans fats.
—to warn of the dangers of trans fat, present in hydrogenated oils.257 We can only presume that the politicians who learned of Dr. Mary Enig’s research had little personal experience with cheap butter substitutes or the convenience foods that contain them. But the rest of us were eating plenty of the stuff and we continued to do so decades after Enig’s warnings because we had never heard them. Only after European countries outlawed trans fat did we finally hear that it might be bad for our health.
Why did it take the United States so long to take trans fat seriously?
Earlier, I mentioned that scientific discoveries that are incompatible with commercial interests have a tough time making it to the papers. Trans is just one example. Cigarette smoking, another. Asbestos, another still.
And I’m guessing that if there’s something you and your family might be eating every day that scientists already know is deadly, you’d like to know about it now, not thirty years from now. That’s why I’d like to tell you the truth about vegetable oil.
Vegetable Oil Should Not Be Heated
Vegetable oils contain mostly heat-sensitive polyunsaturated fats.
When heated, these fragile fats turn into toxic compounds including trans fat.258 The heat sensitivity issue means that all processed vegetable oils, and all products that contain vegetable oil, necessarily contain trans fat. Canola oil degrades so rapidly that a testing company, needing to find the purest canola oil to use as a standard against which other oils could be compared, couldn’t locate any canola oil even from pharmaceutical-grade manufacturers with a trans fat content lower than 1.2 percent.259
This means that vegetable oil, and products made from vegetable oil, contain trans fat—even when the label seems to guarantee them trans free. But because heat so readily distorts their fatty acids, vegetable oil and products made from vegetable oil also contain something that is worse for us than trans. Before we get to that, I’d like to take a moment to compare and contrast the various fatty acids and their ability to
handle heat.
FAT VERSUS OIL: WHAT’S THE DIFFERENCE?
Lipid is a generic term for both fats and oils. If the lipid is solid at room temperature, it’s called fat. If it’s liquid, it’s oil. Butter is solid, so it’s called a fat. In general, lipids made of stiff, inflexible saturated fats are solid and those made of fluid, flexible unsaturated fats are liquid. However, to describe butter (and other animal fat) as
“saturated fat” is not strictly correct, because many fatty acids in butter are not saturated.
All storage fats (as opposed to fats in cell membranes and other actively functioning fats) exist in a chemical assemblage called a triglyceride. A triglyceride is made with three fatty acids that dangle like keys from a chain made out of glycerol, a short molecule to which each of the fatty acids is bound. The fatty acids can be any combination of saturated, monounsaturated, and polyunsaturated.
Butter carries more saturated fatty acids in its triglyceride chains than vegetable oil, but not all are saturated fat. If they were, butter would be as stiff and solid as wax. Vegetable oil actually contains saturated fatty acids, but nowhere near as many as butter. The different blends of saturated and unsaturated combine to generate the final melting point of the fat.
WHY VEGETABLE OILS ARE PRONE TO OXIDATION
Polyunsaturated fats (PUFAs) have two or more double bonds, hence the “poly.” The two molecules shown here are the two most common PUFAs found in canola and other vegetable oils, linoleic and linolenic acid. If a fatty acid has two double bonds near one another, the molecule becomes highly susceptible to attack by oxygen, particularly when heated as in processing and cooking. If it has three double bonds near one another, as does linolenic acid, it’s even more vulnerable to an attack by oxygen. The products of these oxidation reactions are the damaged, distorted molecules that make vegetable oils so toxic.
Who Can Take the Heat? Cooking-Fat Basics
For the purposes of cooking, we want to pick the kinds of fats that can take heat. On that count, saturated fats (present in butter, coconut oil, lard, and traditional fats) win hands down. Why? Because they can resist a kind of heat-related damage called oxidation. Thanks to their shape, saturated fats have no room for oxygen to squeeze in, and even high heat can’t force these tough molecules to be more accommodating.
Monounsaturated fats have room for just one oxygen molecule to sneak in. But it’s not easy, so monounsaturated fat-rich olive oil resists the harmful oxygen-induced molecular rearrangements and is still okay to cook with. Polyunsaturated fat—now that’s another story.
Polyunsaturated fat has two places where oxygen can chemically react, which makes oxygen not twice as likely to bind with the fat molecule, but billions of times more likely. This exponential increase in reactivity with oxygen is true of molecules generally, not just fats. TNT (trinitrotoluene) has six places where oxygen can react, making it so reactive it’s literally explosive! But we’re not cooking with explosives in our frying pans, are we? Actually, in a sense, we are, though on a slightly less dramatic scale. And it is those explosive oxidative reactions that we need to avoid.
The oils extracted from seeds that get processed into vegetable oils are composed primarily of polyunsaturated fatty acids, or PUFAs. If you want to remember which type of fatty acid most readily reacts with oxygen, just remember this: “PUFAs go Poof!”
Biology makes use of this reactivity. Enzymes in plants and animals fuse oxygen to polyunsaturated fats on purpose to change them from one shape to another. For example, fish oil isn’t anti-inflammatory per se.
Enzymes in the human body oxidize the PUFAs in fish oil to convert them into specific compounds that turn off pro-inflammatory enzymes.
But this mutability also means polyunsaturated fats are more capable of being accidentally altered, and thus heat is a threat to their utility.
Where Does Vegetable Oil Come From?
Vegetable oil is the lipid extracted from corn, canola, soy, sunflower, cottonseed, safflower, rice bran, and grapeseed. Vegetable oil doesn’t come from broccoli, and it doesn’t equate to a serving of greens. It is found in almost all ready-made foods, from granola and squishy-soft baked goods, to rice milk and soy milk, to vegetarian cheese and meat substitutes, to frozen meals and side dishes, even salad dressings that say olive oil on the front label. I once purchased a package of dried cranberries only to discover, after I brought it home and read the label, that they were coated with vegetable oil.
There’s a reason these oils are particularly temperature sensitive.
Seeds stay dormant over the cold winter. But come spring thaw, the
heat-sensitive PUFAs wake up in response to warming, facilitating germination.260 To protect the PUFAs from damage as the ground warms and the sun’s rays beat down on them, the plant has loaded its seeds with antioxidants. Unfortunately, refining these oils ultimately destroys both healthy PUFAs and their complementary antioxidants, converting them into distorted, unhealthy molecules. So what was once healthy in the seed isn’t healthy in the bottle.
Canola Oil: Just Another Vegetable Oil
When I advise my patients to avoid vegetable oils, they often tell me that they only use canola oil, as if it were somehow exempt. I can’t blame them for thinking this; the canola industry goes to great lengths to present their product as heart healthy, and the American Heart Association plays right along. They claim that canola oil is rich in anti-inflammatory omega-3 essential fats. And there’s a grain—I should say seed—of truth to that claim. There’s just one problem: omega-3 is a PUFA, which means it is easily distorted when exposed to heat. And since the omega-3 in canola seeds has three places for oxygen to react, it’s really, really reactive. Canola oil still in the seed may indeed be full of omega-3, but factory-processed canola oil, even organic-expeller-pressed, contains mutated, oxidized, heat-damaged versions of once-healthy fats.261 Canola consumption has been shown to cause the same health problems as the rest of the vegetable oils.262, 263 If we could somehow get canola oil out of the seed without exposing it to heat, it would be good for us. But nobody can.
Well, that’s not entirely true. In the old days, flax and rapeseed (a relative of canola) were gently extracted in the home using a small wedge press. Over the course of a day, the wedge would be tapped into the press a little further until, ever so slowly, the golden oil would start to drip, fresh and full of natural antioxidants and vitamins. These oils were not used to fry food, and therefore never exposed to damaging heat. If you aren’t up for installing a wedge press in your kitchen, a few small enterprises can provide flax, hemp, and other healthy omega-3
rich oils—none of which should ever be used for cooking.
“Stop the Presses!” Oil Seeds Plead, “You’re Squeezing Me Too Hard!”
If we took a stethoscope and placed it to the side of a giant factory press as it applied more and more intense heat and pressure to a batch of tiny oil seeds, we might very well hear muffled cries indicating that, rather than being treated like little ambassadors of a heart-healthy diet, the seeds were being processed and refined like so much machine oil. In fact, one of the initial steps in making vegetable oil involves the use of hexane, a component of gasoline. If you were to get up close and catch the stench of the initial extract, you might never imagine it could be cleaned up. Making these stinky oils palatable requires a degree in chemical engineering; it takes twenty or so additional stages to bleach and deodorize the dark, gunky muck. And don’t be fooled by so-called health products containing “expeller-pressed” oil; that only means the manufacturer didn’t use solvents to maximize extraction. Organic, expeller-pressed oil has gone through all the usual hazardous steps in the process of being “refined.”
Olive oil, palm oil, and other oils that are good for us (see here) have mostly saturated and monounsaturated fatty acids, which are not so fragile. They are also easily extracted at low temperatures. Vegetable oils come out less readily, and are more prone to side reactions that polymerize and mutate the fat molecules. So getting them out creates a witch’s brew of toxic lipids, only some of which will be removed. The rest, you eat.
Chemical analysis shows that even bottles of organic, expeller-pressed canola oil contain as much as 5 percent trans fats, plus cyclic hydrocarbons (carcinogens) and oxyphytosterols (highly damaging to arteries).264 Of course, natural fats are all okay before they’re processed and refined, so there’s no harm in eating corn, soybeans, sunflower, and other tasty seeds.
Inflammation and Free Radicals
Maybe 5 percent trans (and other mutant fats) doesn’t sound that scary. The real trouble is not so much that there’s bad fat in the bottles (and other products). The real trouble has to do with the fact that after you eat these distorted, mutated fatty acids, they can reproduce inside you.Imagine a zombie movie, filmed at the molecular level, except the mutant fatties don’t stumble through your bloodstream in slow motion.
Using free radicals (defined in the next section), mutated PUFAs convert normal fatty acids into fellow ghouls at the rate of billions per second.265 I call this conversion-on-contact the zombie effect because, as every horror-movie connoisseur knows, when a zombie bites you, you become one of them. When a throng of molecular miscreants starts hacking away at your cells, things can really get scary. Their ability to damage normal PUFAs makes this class of oxidized PUFAs more dangerous than the trans fat we’ve all heard about on the news. Since they’re a lot like trans, only worse, I call them MegaTrans.
There are many technical names for MegaTrans, including peroxidized fats, lipoxygenases, oxidized fat, lipid peroxides, lipid hydroperoxides, and a few others. Think of them all as different gangs of bad fats. While some of these toxic fats are in the trans configuration and others aren’t, that’s not the point. The point is these toxic fats are all gangsters with one thing in common: they’re really bad for you. They contaminate all foods with trans fat and, in fact, all foods made from vegetable oils. They’re bad because they lead to the formation of free radicals, which not only turn normal polyunsaturated fatty acids into mutants, but can also damage almost any part of your body: cell membranes, chromosomes, other fats—you name it.
The Reason Vegetable Oil Inflames Your Arteries
Free radicals are high-energy electrons that are involved in every known disease. They cause disease by restructuring nearly every molecule they come into contact with, converting biologically functional molecules into dysfunctional or even toxic molecules. Why would they
do this? After all, the human body sometimes employs free radicals in order to perform basic physiologic functions like killing bacteria. It all boils down to a kind of loneliness—at the atomic level.
Imagine a set of neighboring molecules in your cell membranes as a village of polyamorous communes in the middle of a forest in Upstate New York. The electrons who are the members of these communes agree on one rule: we must always maintain an even number of members so that no one electron will ever feel left out; everyone should have a partner. Now imagine a circumstance where one electron decides to pursue an acting career and clears out one night without notice.
Immediately, the unpaired electron it left behind goes berserk, racing through the halls of the commune, busting down doors, breaking walls, and completely disturbing the commune’s essential structure as it desperately seeks out a new lover. The unpaired electron has been (free) radicalized—turned into a free radical. This commune now has two serious problems. One, it’s no longer the commune that it once was; it’s been beaten up and rendered entirely unrecognizable. And two, because it’s breaking the cardinal even-number rule it has to do something about it. It chooses to solve the problem by passing the abandoned lover electron to another commune, and letting them deal with the consequences.
FRENCH-FRIED HEART
This dissected artery shows some fatty deposits, but of far greater concern is the effect MegaTrans has had on the arterial wall as free radical cascades have literally fried the arterial tissue. The artery and surrounding heart muscle are greasy and fragile, much like crispy fried food. When that fragile tissue tears and bleeds into the artery, it creates a clot. That’s a heart attack.
HOW FREE RADICALS DAMAGE MEMBRANES
This is a closeup view of a cell membrane under attack. This particular section of membrane is composed of PUFAs. (The insert in the upper right is a cross-section of the same membrane.) Once the radical strips an electron from one of the PUFAs, it initiates a cascade reaction across the membrane, releasing more damaging unpaired electrons. In addition to mangling and distortion membrane PUFAs, the cascade reaction can damage hormone receptors, nutrient channels, and other proteins in the membrane, disrupting membrane function and putting the entire cell at risk.
Those consequences are predictable. Whether the newly introduced electron ousts another lover from his bed or fails to find anyone willing to partner with him, in no time commune number two will have to deal with a lonely electron knocking down walls and wreaking havoc and forcing the commune members to hold an emergency meeting. Until such time that a patchouli-wearing therapist antioxident, such as the totally groovy vitamin E, shows up to say, “Whoa, dudes. I’ll take your extra lover … it’s all good … I’ve got another therapist friend I work with called vitamin C and, like, the whole even-number lovers thing will be, like, totally restored,” this chaotic process will continue, leaving each and every affected commune permanently changed—and not for the better.
Chemists call this series of reactions a free radical cascade. Free radical cascades damage normal PUFAs, turning them into ugly molecular ghouls (the zombie effect). Just a little MegaTrans in the bottle of canola oil can become a lot of MegaTrans after you—or the cereal/donut/frozen dinner manufacturers—cook with it. On the plus side, free radical cascades make your food extremely crispy. (Free radical cascades also happen to play a role in the polymerization reactions that make plastic solid. This is probably the origin of the well-intentioned, but not strictly scientific, assertion that “margarine is one molecule away from plastic.”) On the minus side, free radical cascades make your arteries extremely crispy. They will also damage other bodily