Why Vegetable Oils Are Unhealthy


To their credit, (non-hydrogenated) vegetable oils have improved on the health side, but they can still increase risk of epidemic-level problems like heart disease.

There’s something disarming about seeing the word “corn,” “safflower,” or “vegetable” sandwiched between fifteen-letter-long preservatives on food labels, which is one reason why unhealthy vegetable oils have evaded serious criticism for so long.

Still, these seemingly benign animal fat alternatives have recently been exposed for what they really are: industrially processed, omega-6-rich oils that jack up major disease rates like Gamestop stock.

How harmful are these oils exactly, and why are we still using them?

It all started with an early-1900s soapmaking operation.

How Vegetable Oil Rose to Prominence

Like many discoveries and inventions, hydrogenated vegetable oils were originally used for a different purpose.

We’ll keep the history lesson brief, but once you appreciate how deep the vegetable oil industry’s roots run, it’s easier to appreciate how hard these products are to avoid.

At the turn of the twentieth century, two enterprising brothers-in-law began pioneering new and cheaper ways to manufacture soap for their business.

Proctor and Gamble weren’t initially interested in usurping lard as a cooking ingredient, but after they learned how to hydrogenate cottonseed oil for their soap (around 1910), American restaurants and retailers quickly became their best customers.

This is because the hydrogenated cottonseed oil they produced strongly resembled lard, the presiding fat of the day, and could be produced at a fraction of the cost.

And so, Crisco was born.

Stupefyingly high in trans fat (fifty percent by weight), Crisco swept the nation in a matter of months.

Proctor and Gamble marketed this lard alternative as much healthier than animal fats, and because food labeling and testing regulations in 1912 were a joke, they got away with it.

Almost a century passed before Crisco finally got the shaming it deserved (though people still use it), but from its greasy ashes have risen a series of slightly less harmful, but still problematic products, such as:

  • Soybean oil
  • Corn oil
  • Cottonseed oil
  • Sunflower oil
  • Peanut oil
  • Canola oil
  • Safflower oil

These products are extremely prevalent today, as food producers stuff them into margarine, chips/cookies/snacks, pastries, fried food, and much more. 

Why Vegetable Oil Is Unhealthy

Many nutrition experts still cling to the belief that these oils are healthy, but we have two very important reasons why they definitely are not:

  • Hydrogenation and/or heat treatments that these oils are subjected to create trans fats and oxidized lipoproteins that wreak havoc in the body.
  • Even without the issue of processing, these oils are very high in the polyunsaturated fatty acid (PUFA) known as omega-6, which is the last thing the American diet needs at this point in time. 

Worsening the Omega-6/Omega-3 Ratio

Yes, omega-6 acids are healthy in their own right, and our bodies do need them to promote heart health, but when the ratio of omega-6 to omega-3 (the two PUFAs) is too high, a litany of serious problems can result. 

The American diet is already far too high in omega-6 acids, thanks to these oils, and far too deficient in omega-3 acids, which are found in salmon, flaxseed, nuts, and other quietly neglected foods you’ll never see in a super bowl commercial.

As pre-agricultural nomads and cave dwellers, humans got plenty of omega-3s from wild game, nuts, and seeds, but we are now severely deficient.

According to best-selling author and family physician Dr. Mark Hyman, “Omega-6 fats not only fuel your body’s inflammatory pathways, but also reduce availability of anti-inflammatory omega-3 fats in your tissues, resulting in more inflammation.”

This is because omega-6 fats prevent the conversion of omega-3s into EPA and DHA, two very important fatty acids in the prevention of serious diseases.

Aided very much by the prevalence of vegetable oil, this skewed ratio has resulted in increased incidences of the following diseases:

  • Type 2 diabetes
  • Obesity
  • Heart disease
  • Inflammatory bowel syndrome
  • Rheumatoid arthritis 
  • Cancers
  • Autoimmune diseases

Oxidative Stress

As the term “oxidative stress” slowly works its way into the layman’s lexicon, it is subjected to plenty of misinterpretations.

Put simply, this refers to an increase in the ratio of free radicals, which aren’t always bad, to antioxidants.

Free radicals are unstable, highly reactive molecules that cause chain reactions in the body’s cells, often referred to as oxidation. 

When there aren’t enough antioxidants (molecules that donate electrons to free radicals, rendering them stable) around, the body is said to be in a state of oxidative stress.

According to a study from Laval University in Quebec, heated vegetable oils contain “cyclic fatty acid monomers,” which “increased the levels of markers of oxidative stress” on Wistar rats that were fed canola or soybean oil over a 28-day period.

Similar to a high omega-6/omega-3 ratio, oxidative stress can contribute to the development of many serious diseases, including Alzheimer’s, Parkinson’s, cancer, asthma, and much more. 

Coronary Heart Disease Risk

The type of omega-6 acid most commonly found in the Western diet, i.e., in vegetable oils, is called linoleic acid.

A systematic review from Saint Luke’s Mid-America Heart Institute in Kansas City, MO, found that the amount of linoleic acid in adipose (fat) tissue is “positively associated with coronary artery disease,” also noting that “omega-3 acids are inversely related.” 

This supports our earlier mention of the role of omega-6 in inhibiting the effects of omega-3s, but it’s not so simple as a 1:1 conflict.

According to the review, it is the metabolites of linoleic acid that promote atherosclerosis, not the acid in its original form.

Still, less of the precursor means less of the metabolite. 

Swap Out Refined Oils for These Alternatives

Vegetable oils are extremely commonplace, and avoiding them altogether is unrealistic, but you can significantly cut down your intake with these alternatives.

Enough of the bad news—there’s hope yet for conscientious objectors to the refined oil establishment. 

While it’s virtually impossible to avoid industrial vegetable oils in even progressive (gluten-sensitive, vegan, etc.) restaurants, you can seriously reduce or eliminate your intake with a careful overhaul of your grocery list.

We used the following criteria when selecting the best alternatives to commonly used vegetable oils:

  • High omega-3 and low omega-6 content
  • Processing and pesticides (organic, cold-pressed oil > refined/processed)
  • Overall nutritional value

These oils and foods made the cut:

  • Extra-virgin olive oil: cold-pressed, preferably organic
  • Extra-virgin coconut oil: cold-pressed, preferably organic
  • Nuts
  • Fatty fish
  • Avocados
  • Wild-caught/grass-fed game, grass-fed butter

Final Pointers

It’s easy enough to swap out vegetable oils for EVOO at home, but be wary of restaurants and pre-packaged snacks/pastries.

Even if you don’t think a grocery store item contains vegetable oil, always check the label.

Finally, it’s important not to get into an anti-omega-6 mindset; it’s much better to increase omega-3 intake to reach a 1:1 ratio.

In the case of processed vegetable oils, however, one drop is too many.

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