Vegetable oils may be killing us

The war against processed seed oils—euphemistically called “vegetable oils”—is often treated skeptically by the media and American population alike. And I can see why. Many people’s initial exposure to these ideas usually comes from some overly-muscular influencer ranting about “seed oils” and trying to red-pill you on health benefits of eating red meat, lifting weights in the sun, and perineum sunning.

I was skeptical too at first and never really took any of these ideas seriously. I’d usually just laugh. There are few things more ironic than thinking other people are “sheep”, while tanning your butthole because an Instagram influencer told you to.

However, I recently stumbled upon this article in The Atlantic that describes how processed oils entered the American diet in the early 1900s as a cheaper alternative to animal fats.

I found it bizarre that these oils—which only came into existence after the invention of a chemical process called hydrogenation—now comprise more than 20% of calories Americans consume. This process of hydrogenation is used to extend food shelf life, but it has been shown to have harmful side effects. A large body of research in the 1990s sounded the alarm on the deleterious health effects of these oils (e.g. cardiovascular disease, cancer, diabetes, obesity, etc.), and they were officially banned by the FDA in 2018.

Yet, you’ve probably noticed that vegetable oils are still on grocery shelves across the US and listed in the ingredient labels of almost all processed foods. That’s because the FDA only banned “partially hydrogenated” oils and food manufacturers have simply switched to “fully hydrogenated” oils, which are permitted because full hydrogenation returns the oil to a “zero trans-fat” level.

I don’t really have the time nor expertise to prove any sort of causation with respect to skyrocketing chronic illness and obesity in the US. But I decided to write an essay that explains what they are, how they became such a pervasive part of our diets, why they may be killing us, and the fact that almost every food manufacturer in the US would face negative financial consequences if vegetable oils were actually banned.

My hope is that this essay can help spark a productive conversation around the health consequence of these oils and the various conflicts of interest in the organizations that shape American dietary guidelines.

If there’s something you think I should change, you can submit a pull request here.

What are industrial seed oils and why are they in everything?

Industrial seed oils are highly-processed oils extracted from soybeans, corn, rapeseed (the source of canola oil), cottonseed, and safflower seeds, that were introduced into the American diet in the early 1900s.

Their origins can be traced back to the 1870s when two brothers-in-law, William Proctor and James Gamble, formed a soap- and candle-manufacturing operation in Cincinnati, Ohio. At the time, soap was sold in huge wheels that were sliced into custom-sized portions at general stores, but Proctor and Gamble wanted to mass-produce individually wrapped bars of soap. To pull this off, they needed to drastically reduce the price of their raw ingredients, which meant finding a replacement for expensive animal fats. They settled on cottonseed oil—a waste product of cotton farming—and in short order this soap was sold to Americans across the country.

Thanks to Proctor & Gamble, the United States boosted the production of cottonseed oil. And to ensure a steady, cheap supply for soap production, the company formed a subsidiary in 1902 called Buckeye Cotton Oil Co.

Up until this point though, cottonseed oil was still consigned to the status of “toxic waste” and nowhere close to entering our food supply. Before processing, cottonseed oil is cloudy red and bitter to the taste because of a natural phytochemical called gossypol (it’s used today in China as male birth control) and is toxic to most animals, causing dangerous spikes in the body’s potassium levels, organ damage, and paralysis.

However, this all changed on October 18, 1907, when a German chemist by the name of Edwin Kayser wrote to Proctor & Gamble about a new chemical process called hydrogenation that could create a solid from a liquid. The company’s researchers had been interested in producing a solid form of cottonseed oil for years, purchased US rights to the patents, and created a lab to experiment with the new technology. Soon the company’s scientist produced a new creamy, pearly white substance out of cottonseed oil that looked a lot like the most popular cooking fat of the day: lard. Proctor & Gamble then decided it would be good business to sell this new substance (known today as hydrogenated vegetable oil) to home cooks as a replacement for animal fats.

Proctor & Gamble filed a patent application in 1910, describing it as “a food product consisting of a vegetable oil, preferably cottonseed oil, partially hydrogenated, and hardened to a homogeneous white or yellowish semi-solid closely resembling lard. The special object of the invention is to provide a new food product for a shortening in cooking.” They came up with the name Crisco, which they thought conjured up crispness, freshness, and cleanliness.

Convincing homemakers to swap butter and lard for a new fat created in a factory would be a tall task though, so they hired the J. Walter Thompson Agency to devise a marketing strategy. Samples of Crisco were mailed to grocers, restaurants, nutritionists, and home economists. Doughnuts were fried in Crisco and handed out in the streets. Women who purchased the new industrial fat got a free cookbook of Crisco recipes. Recipes for asparagus soup, baked salmon with Colbert sauce, stuffed beets, curried cauliflower, and tomato sandwiches all called for three to four tablespoons of Crisco.

Health claims on food packaging were then unregulated, and the copywriters claimed that cottonseed oil was healthier than animal fats for digestion. Advertisements in the Ladies’ Home Journal encouraged homemakers to try the new fat and “realize why its discovery will affect every family in America.” The unprecedented product rollout resulted in the sales of 2.6 million pounds of Crisco in 1912 and 60 million pounds just four years later.

Soon, other vegetable oils followed. Soybeans were introduced to the United States in the 1930s, and by the 1950s, it had become the most popular vegetable oil in the country. Canola, corn, and safflower oils followed shortly after that. The low cost of these cooking oils, combined with strategic marketing on the part of the oil manufacturers, made them wildly popular in American kitchens even though their use was unprecedented in human history.

However, the most significant shift in industrial seed oil consumption followed Proctor & Gamble’s $1.5 million gift to a small group of cardiologists who were members of the still somewhat new American Heart Association (AHA) in the late 1940s. Thanks to this gift from the makers of Crisco, the AHA now had sufficient funding to grow its national profile as a physicians organization dedicated to heart health. And they were quick to endorse industrial seed oils (more kindly referred to as “vegetable oils”) as a healthier alternative to traditional animal fats. Below is an excerpt from an article in The American Journal of Clinical Nutrition:

“The historical event immediately preceding the largest increase in apparent consumption of soy oil in the United States was the 1961 American Heart Association (AHA) Central Committee Advisory Statement that advised Americans to replace their saturated fat intake with polyunsaturated fats. Vegetable oils and, to a lesser extent, shortening and margarine were recommended as replacements for animal fats such as butter, cream, and cheese.”

Seed oil consumption

This led to the sweeping replacement of natural dietary fats such as lard and butter with industrial seed oils, indelibly altering the American (and eventually, the global) food landscape.

Unfortunately, it wasn’t until the 1990s that the health risks of these substances (which are 50% trans fat) started to be understood. Yet, today these oils comprise as much as one-fifth of the calories we eat. Go to your fridge, your snack drawer or a fast food restaurant and you’ll find vegetable oils everywhere.

The health effects

Today, antibiotics and modern medicine have prevented most infectious disease-related deaths in developed countries, but chronic diseases—like cancer, heart disease, and diabetes—have taken their place. Chronic disease is by far the leading cause of death in the US, accounting for 70% of lives lost and 90% of healthcare dollars spent. Some 60% of Americans have a chronic disease, and obesity rates skyrocketed from less than 10% in the early 1900s to more than 40% today.

To make matters even more pressing, the epidemics of worldwide obesity and diabetes are being exported to other countries whenever their populations pass through a nutrition transition from a traditional diet and lifestyle to a western one.

Life expectancy vs health expenditure over time

Even childhood obesity is surging

Trends in obesity among children and adolescents

So what’s causing this?

According to the Center for Disease Control (CDC), the primary causes of chronic disease are poor nutrition, lack of physical activity, excessive alcohol, and tobacco use. Yet we are, in aggregate, smoking less, drinking less, and exercising more. So it’s probably our diet.

We all know Americans have awful diets and eat tons of terrible stuff. But how do we know it’s vegetable oils that are causing these issues and not something like sugar? For example, Americans consume 25% more sugar per capita than any country in the world. And some people like Gary Taubes have put forth the idea that sugar might be the root of these chronic illnesses and obesity.

However, others like Stephan Guyenet have suggested that sugar intake isn’t all that predictive independent of the increase in calorie intake and body fatness. In the chart below he shows how between 1999 and 2013, intake of added sugar declined by 18%, taking us back to our 1987 level of intake. Total carbohydrate intake declined as well. Over that same period of time, the prevalence of adult obesity surged from 31% to 38%, and the prevalence of Diabetes also increased:

Trends in obesity among children and adolescents

Americans have been reining in our sugar intake for more than 14 years, and not only has it failed to slim us down, it hasn’t even stopped us from gaining additional weight. This suggests that sugar is highly unlikely to be the primary cause of obesity and society’s laser-like focus on sugar is a distraction from the true nature of the problem.

To put it bluntly, people have no idea what the root cause of this obesity epidemic is. But I do find it shocking that highly processed oils that only came into existence roughly 100 years ago now account for more than 20% of calories in Americans diets. And if you look at the data, obesity really starts to accelerate in the mid-1900s, almost in lock-step with the consumption of industrial seed oils. It’s hard to find great data on this, but the charts below from articles in the American Journal of Clinical Nutrition and the Journal of Paediatrics and Child Health show the alignment relatively well:

Trends in obesity among children and adolescents

I’m well aware that correlation does not necessarily imply causation. So what does “the science” say?

Well, hydrogenation is a good place to start. The excerpt below is from an article in the Harvard School of Public health:

Trans fatty acids, more commonly called trans fats, are made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, a process called hydrogenation… Partially hydrogenated oil is not the only source of trans fats in our diets. Trans fats are also naturally found in beef fat and dairy fat in small amounts… Trans fats are the worst type of fat for the heart, blood vessels, and rest of the body because they: [1] Raise bad LDL and lower good HDL [2] Create inflammation—a reaction related to immunity— which has been implicated in heart disease, stroke, diabetes, and other chronic conditions [3] Contribute to insulin resistance [4] Can have harmful health effects even in small amounts – for each additional 2 percent of calories from trans fat consumed daily, the risk of coronary heart disease increases by 23 percent

It’s been well known that the trans fats from hydrogenated oils are leading to deleterious health effects since a large body of research in the 1990s sounded the alarm. And the FDA has been “[taking] steps to remove artificial trans fats in processed foods” as early as 2003. In fact, the FDA set a deadline to eliminate artificial trans fats from the food supply by June 2018 which ended up getting extended to January 2020.

Yet, why are these processed oils still in nearly every processed food item in modern day grocery stores almost five years later?

Well, it turns out that the ban only applied to partially hydrogenated oils. In turn, manufacturers have switched to using fully hydrogenated oils. Unlike partial hydrogenation, full hydrogenation returns the oil to a “zero trans-fat” level.

So now let’s just do a quick recap of everything we’ve established so far:

  • Vegetable oils—which only came into existence after the invention of a chemical process called hydrogenation—grew to comprise one fifth of the calories Americans consume
  • A large body of research in the 1990s sounded the alarm on the deleterious health effects of hydrogenated oils
  • These researchers attributed the health effects of these oils to the fact that the hydrogenation process creates trans fatty acids (a “phantom fat” that humans hadn’t consumed in a material way until the invention of these oils)
  • The FDA bans partially hydrogenated oils because it’s killing America
  • Food manufacturers all switch over to fully hydrogenated oils because there’s no trans fats, so those must of course be ok for public consumption

You have to be joking. It’s almost as though food and vegetable oil manufacturers are crafting these policies…

Regulatory capture & dietary guidelines

It’s worth noting that almost every food manufacturer in the US would face negative financial consequences if vegetable oils were banned.

Basically, food manufacturers add hydrogenated oils to foods to (1) cut costs, (2) preserve foods and increase shelf life, (3) enhance texture, and (4) enhance taste (more from AHA here).

Below is additional commentary from the Harvard School of Public Health, hydrogenated oils became a mainstay in restaurants and the food industry:

“Partially hydrogenated oils don’t turn rancid as easily as non-hydrogenated fats. They can withstand repeated heating without breaking down, and the process can turn a liquid oil into a solid, which allowed for easier transportation and wider uses. This solid fat was also much less expensive than many solid animal fats. These characteristics were attractive to food makers, and partially hydrogenated oils became a mainstay in margarines, vegetable shortenings, doughnuts, commercial baked goods like packaged pastries and cookies, other snack foods, and in fast-food restaurant deep fryers.”

Naturally, a large vegetable oil industry has blossomed to meet this demand with an estimated revenue of $241 billion in 2021. And there’s quite a few examples of the lobbying they do.

One example I found pretty wild was Bunge Limited—a leading soybean oil producer in the US that does more than $60 billion in revenue today—independently filing a petition with the FDA that included a summary of human clinical studies “demonstrating the heart health potential of soybean oil—America’s most commonly used ingredient.” The FDA approved this position in July 2017, which allowed food providers to make heart health claims when food and menu items include at least 5.0 grams of soybean oil per serving.

We shouldn’t be too surprised when we hear of stuff like this though; it’s actually quite common. Corporate interests have played a role in public dietary recommendations and policy for pretty much all of the 20th century.

Of course, there’s the Proctor & Gamble and American Heart Association connection mentioned previously. But the USDA has also been riddled with controversy from the food pyramid in the 1970s to the time the New York Times exposed USDA’s under-the-table Dairy Management marketing agency.

As chair of the Department of Nutrition at Harvard School of Public Health, Dr. Walter Willett, put it in 2015: “The current system opens the guidelines up to lobbying and manipulation of data… The USDA’s primary stakeholders are major food producers and manufacturers.” The whole article, titled “Experts Say Lobbying Skewed the U.S. Dietary Guidelines” is worth reading.

And just this past March, the Cambridge Press published a report that found that 19 out of 20 members of the US 2020 Dietary Guidelines Advisory Committee had conflicts of interest with the food, and/or pharmaceutical industries and that particular actors, including Kellogg Abbott, Kraft, Mead Johnson, General Mills, Dannon, and the International Life Sciences had connections with multiple members.

US farmers have also been a major political interest for decades, and some would go as far to call it “a prime example of crony capitalism”. A natural thing to take into consideration would be the fact that corn and soybean farming—which accounted for 50.3% of all US crop cash receipts in 2021—would become even less profitable because demand for their waste products (soybean and corn oil) fell.

It’s all pretty absurd. I don’t want to get into conspiracy theory stuff, but I thought it’d be worth pointing out that food manufacturers and agricultural producers have historically had a large influence on public dietary recommendations and policy. Few would deny that obvious conflicts of interest exist.


To be clear, there are likely many factors contributing to today’s chronic disease and obesity epidemic. Sugar, pesticides, plastics, factory farms, refined carbohydrates, gluten, hyper-palatable junk food, technology, and lifestyle changes have all been accused of causing obesity and disease. However, vegetable oils look like they may be playing a much larger role in the diseases of modernity than most people realize.

Please reach out if you’d like to discuss any of these ideas further.

Sources & Further Reading