This story originally appeared on Everyday Health’s network site Diabetes Daily.
There’s a new bogeyman in the nutrition world: vegetable oil, especially so-called “industrial seed oils” like canola, corn, and soybean oils. Nutrition influencers on Twitter, TikTok, and elsewhere are telling their followers that these oils are sneakily unhealthy, downright dangerous, or even “the worst food in human history,” according to DoctorKiltz.com.
The most prominent voices are advocates for low-carbohydrate and keto diets, eating patterns that have helped many people with diabetes improve their blood sugar management. So, should people with diabetes be avoiding industrial seed oils?
Mainstream nutrition experts sure don’t think so. These very same oils have long been touted as safe by authorities such as the American Heart Association (AHA) and American Diabetes Association, and are commonly listed as among the healthiest fats available.
This article will dive into the claims of anti–veggie oil advocates and find out what all the fuss is about.
What’s an Industrial Seed Oil?
The buzzy phrase that these nutrition influencers prefer is “industrial seed oil.” Here, we are talking about vegetable oils that are extracted from seeds, mostly using modern technology.
Here are the oils most commonly singled out for criticism:
- Canola
- Soybean
- Corn
- Safflower
- Sunflower
- Cottonseed
- Grapeseed
- Rice bran
Sometimes these oils are called RBD oils, per Harvard T.H. Chan School of Public Health, which stands for refined, bleached, and deodorized, another reference to the industrial extraction processes required to make them edible.
These oils make up a huge amount of the calories that Americans consume. Soybean, canola, and corn oil combine for something like 75 percent of all of the added fats that we eat, according to U.S. Department of Agriculture (USDA) data.
Not all plant-based oils are attacked as industrial seed oils. Cold-pressed olive oil, for example, is one fat that practically everyone agrees is good for you. And anti–seed oil advocates generally approve of coconut oil and avocado oil — though they tend to prefer butter, lard, and tallow.
How Industrial Seed Oil Is Manufactured
Part of the skepticism over industrial seed oils stems from how they’re made. These oils are often subjected to modern chemical processes that just sound highly unnatural.
Take canola oil, widely considered one of the healthiest added fats available. Canola oil is extracted from the rapeseed plant. According to The Guardian, until the 1970s, rapeseed oil was almost entirely limited to industrial uses — rapeseed oil lubricated steam engines, for example — because a high erucic acid content made the oil both toxic and unpleasant to eat. Scientists in the 1960s and ’70s bred a low-acid variety; the oil was not recognized as a safe food ingredient in the United States until 1985.
Today, most canola oil is made from genetically modified (GMO) varieties of rapeseed, per the Non-GMO Project. The oil is extracted using a chemical named hexane, which is, believe it or not, a byproduct of crude oil production. According to the Canola Council, many other manufacturing steps result in a product that is clean, clear, and odorless.
“Don’t eat anything your great-grandmother wouldn’t recognize as food,” advises the writer Michael Pollan, author of The Omnivore’s Dilemma. Clearly, our great-grandmothers weren’t eating anything quite like modern canola oil, which was unheard of as recently as the early 1980s. Between 1997 and 2017, Americans increased their intake of canola oil by nearly 500 percent.
It’s easy to understand why anyone concerned with eating natural, whole foods would look askance at oils that need to undergo so many refining processes. Nevertheless, all of this industrial science does not necessarily mean that canola oil is actually unhealthy.
Are Industrial Seed Oils Making Us Fat?
Industrial seed oils have exploded in popularity in recent decades, and their growth has occurred in concert with the growing twin epidemics of diabetes and obesity.
The use of “salad and cooking oils” has climbed steadily since the USDA began tracking the category, from 12.7 pounds per capita in 1966 to 53.6 pounds in 2010. A small percentage of the growth is attributable to olive oil, but the vast majority is from the increased prominence of other vegetable oils.
Meanwhile, the use of animal fats has cratered. Lard and tallow are rarely used in American households anymore, and Americans only eat about one-third as much butter as they did a century ago.
All told, Americans are eating more added fat than ever, and an ever-increasing proportion of it comes from oils like canola, corn, and soybean. It’s a massive nationwide dietary change. (An analysis by the Pew Research Center shows that consumption of grains has also increased, while meat, dairy, fruit, and other categories have stayed fairly steady.)
Anti–seed oil agitators find all of this highly suspicious. But correlation does not imply causation — we don’t actually know if the explosion of vegetable oil consumption is a cause (or the cause) of America’s growing waistbands.
Is Industrial Seed Oil Unhealthy?
Let’s be clear up front: Most nutrition authorities, like The American Heart Association and Harvard Health Publishing, believe that vegetable oils, even highly processed and refined veggie oils, are healthy.
Such claims are disputed by many sources, both expert and amateur alike. Some of the strongest voices arguing that industrial seed oils are unhealthy are (to be frank) vague, anecdotal, and conspiratorial. But some are doctors and nutritionists with citations to many academic studies and trials.
The data favoring veggie oils as heart-healthy is by no means unambiguous. Studies with contrary evidence have prompted even mainstream outlets like Time magazine to declare that “vegetable oil isn’t as healthy as you think.” And veggie oil advocates have had to grapple with the fact that the rise of vegetable oil has so neatly coincided with the rise of obesity.
In 2017, the AHA released a major statement on cooking fats and heart health. This guidance, which relied on dozens of studies and clinical trials, argued the following:
- Saturated fats raise LDL cholesterol and triglycerides. Unsaturated fats lower LDL cholesterol and triglycerides.
- Vegetable oils, especially polyunsaturated fats, are healthier than saturated fats from meat and dairy.
- However, when people replace fats with carbohydrates, they don’t get healthier.
This last point is intended to help explain why the explosion of low-fat dieting and low-fat snack foods around the 1980s did not actually stem the tide of the obesity crisis.
Why the Debate Might Not Even Matter
This article cannot determine whether or not industrial seed oils are bad for your health, in and of themselves. But one possible takeaway is that the debate doesn’t really matter.
Everyone, on both sides of the debate, agrees on a few important points:
- Most of us are eating too many calories.
- Vegetable oils constitute a huge percentage of those excess calories.
- Vegetable oils are ubiquitous in highly-processed and fried foods.
- Most of us should be eating fewer highly-processed and fried foods.
Likewise, almost everyone agrees that a healthy diabetes diet relies on principles such as the following:
- Eat more nonstarchy vegetables.
- Eat less sugar and refined grains.
- Choose whole foods over highly-processed foods.
So, to put it simply, most nutrition authorities and influencers agree that we should be eating less vegetable oil — and doing so by reducing our intake of fried and processed foods.
If you make healthy changes to your diet, you’ll undoubtedly find yourself consuming much less “industrial seed oil,” and be doing it in a way that everyone can agree is beneficial.