Is Soybean Oil Bad For You? Pros, Cons & How It Compares To Other Cooking Oils

Soybean oil is one of the most controversial oils out there (along with canola and coconut oil). Some say it can be healthy because of its high polyunsaturated fat content, while most functional medicine practitioners warn you to stay far, far away.

So, who's right? Is soybean oil bad for you, or does it have a place in a healthy diet? We tapped into nutrition experts and scientific research to get you the answer, once and for all.

Soybean oil is a cooking oil that's made from the seeds of the soybean plant. It's important to note the difference between soybean oil and soy-based food products like tofu and edamame. We're big fans of soy as a source of plant-based protein.

"The seeds get cleaned and dried, then cracked and the hull is removed. Once the bean is cracked open, it's turned into flakes, and a solvent wash removes the oil from the flakes before it's bleached and deodorized," says integrative dietitian Jessica Cording, R.D.

Soybean oil is very prevalent in processed foods because it has a neutral flavor and is cheap to make. In fact, it is the most widely consumed oil in the U.S., as well as the main oilseed produced in this country. According to the USDA, soybeans make up 90% of America's oilseed production.

In addition to its neutral flavor, soybean oil's high smoke point (450 degrees Fahrenheit) also makes it a common choice for cooking, especially in fast food restaurants.

Here's the nutritional breakdown of 1 tablespoon of soybean oil, from the USDA1:

This breakdown can differ depending on which type of oil you're using. For example, some vitamins may get stripped from the oil during the refining process, which means cold-pressed oils are typically more nutrient-dense than their highly processed counterparts.

Highly processed, refined soybean oil is the most common type of soybean oil. But you may be able to find cold-pressed and organic versions, too. Oil blends are also common. Here's what to know about each of these varieties: 

Unsaturated fats, like those found in soybean oil, are typically credited with lowering LDL (or "bad") cholesterol and raising HDL (or "good") cholesterol. And there's a decent amount of scientific evidence that backs up this benefit for soybean oil specifically. In a 2021 review2, researchers found that replacing dietary saturated fat with soybean oil could lower LDL cholesterol without increasing inflammation or oxidative stress.

Another 2021 study3 found similar results, but this one went further and looked at LDL particle size, which is an important indicator of heart disease risk. The researchers found that when compared to other oils, like hydrogenated soybean oil and a palm oil/palm kernel oil mix, soybean oil didn't raise the small size LDL particles as much. This is a worthy callout since the small size particles are associated with atherosclerosis4.

Lower LDL levels tie in to better heart health, but soybean oil may have some additional benefit here too. For starters, it contains omega-3 fatty acids, which have been linked to better heart health and a reduced risk of cardiac arrhythmias5.

According to a 2021 report6, two separate clinical trials showed increased eicosapentaenoic acid (EPA) levels and a better omega-3 index in adult overweight subjects who consumed soybean oil. This confirmed the ability of stearidonic acid (SDA)—for reference, soybean oil contains about 20% stearidonic acid7—to raise EPA plasma levels.

"Because soybean oil is a source of fat, it could be helpful for balancing blood sugar by buffering the effect of carbohydrates in a meal," says Cording. "But we could say the same for any source of fat." In short, soybean oil may help with blood sugar control because it's a fat source, but it doesn't have any other notable benefits in this department.

Soybean oil provides vitamins K and E, and it has some omega-3 fatty acids, according to Cording. These nutrients are beneficial, but soybean oil is also really high in omega-6s, which can have inflammatory effects over time. The good news is that soybean oil is low in saturated fat and trans fats.

Soybean oil is highly processed. There are many steps in its production, and solvents are used during extraction, which Cording says raises the questions: "What exactly is in those solvents?" and "Is it beneficial to be eating something that is going through so much processing?" But aside from that, there are some more specific downsides to the oil and the way it's currently used, too:

Inflammation is one of the biggest concerns surrounding soybean oil. And soybean oil can lean pro-inflammatory depending on how much you're consuming. The polyunsaturated fats in soybean oil are mostly in the form of omega-6 fatty acids. This isn't a major concern on its own, but it can be problematic when you look at what the typical American is eating.

Before oil refining, humans' diets were chock-full of omega-3 fatty acids from wild-caught fish, wild game, and natural fats. But industrialization brought a shift. As processed foods became more readily available, consumption of omega-6 fatty acids went up drastically, while intake of omega-3 fatty acids started to decrease.8

The ideal ratio of omega-6s to omega-3s is 2:19, but the average American consumes the two fats in a ratio of 10:1 to 20:1. In other words, we're collectively eating 10 to 20 times10 more omega-6 fatty acids than omega-3s. The consumption of soybean oil specifically also increased 1,000-fold11 from 1909 to 1999—and it's likely even higher now.

When consumed in such excess, omega-6 fatty acids can contribute to inflammation12—especially if you're not eating the omega-3s needed to combat these processes.

Like with peanuts, there's also a concern about aflatoxins with soy. Aflatoxins are a type of mycotoxin—or toxic compound produced by certain types of molds. In fact, aflatoxins are one of the most toxic mycotoxins13, and soybean oil can be pretty loaded with them14.

Overexposure to aflatoxins can have a number of negative health effects15, including immunosuppression, impaired growth, and even cancer. In fact, aflatoxins are recognized as a global food safety concern by the World Health Organization.

When soybean oil is exposed to heat, light, and/or oxygen, it can become oxidized. When this happens, it produces toxic byproducts and potentially harmful compounds that can negatively affect its flavor and your health.

Soybean oil is especially susceptible to oxidation because of its high linoleic content, says Guy Crosby, Ph.D., a chemist and adjunct nutrition professor at Harvard University. Linoleic acid oxidizes about 12 times faster than the monounsaturated oleic acid. Soybean oil, specifically, produces about 4.5 times more volatile compounds than olive oil.

Another problem lies in soybean oil's production. Most soy grown in the U.S. is genetically modified and sprayed with pesticides and herbicides. One of the most notable of these herbicides is glyphosate16, which has been linked to cancer17, immune issues, and inflammation. Glyphosate also drives antibiotic resistance.

But glyphosate doesn't just harm your health; it's also detrimental to the environment. Glyphosate can change the microbial composition18 of the soil, which can affect the guts of animals, plant life; reduce the nutrients in the food you eat; and reduce the carbon-capturing potential of farmland. 

There was also a 2020 preclinical study19 looking at how soybean oil may affect your brain. It's important to call out that this study involved mice and not humans, but its findings are interesting nonetheless.

Researchers fed mice three different diets—one with regular soybean oil, one with low-linoleic soybean oil, and one with coconut oil. They found that the groups fed both types of soybean oil experienced genetic changes in the brain, specifically the hypothalamus. These changes could potentially affect energy metabolism, body temperature regulation, neurotransmitter production, and proper brain function. 

"We have to be mindful that it doesn't directly correlate to what we would see in humans, but it's a good case for variety in the diet," says Cording.

So, what's the deal? Is soybean oil actually healthy? It really comes down to how you use it—and which type of soybean oil you're using.

So, how does soybean oil stack up to other types of oils? Let's break down three of the most common types.

Olive oil has a better nutritional profile overall, with two times as many monounsaturated fats and twice the vitamin E. It also has a lot of antioxidants and other compounds that have proven health benefits, including combating inflammation. 

While the smoke point is lower for olive oil, Cording says this doesn't really matter as much as most people think it does. As long as you're cooking at a reasonable temperature—about 350 degrees for olive oil—most home cooks can use either without worrying about burning your oil.

When it comes to soybean vs canola oil, it's a tossup. They're both very refined, processed oils, so Cording says it's really about how often you're using them. "Soybean oil does have more polyunsaturated fats, while canola has more monounsaturated. They both provide vitamin E and have a high smoke point," she says. "But I encourage using less refined oils more often."

"Coconut oil is in its own category because it's so different," says Cording, adding that the main type of fatty acids found in coconut oil are medium-chain triglycerides (MCTs), which your body processes differently. It's also a lot lower in omega-6s compared to soybean and canola oil, which is a plus.

It's still recommended to use coconut oil in combination with other oils, like olive and avocado oil, and it's best to choose unrefined and/or cold-pressed versions (which go through the least processing) for most purposes.

Soybean oil has some things going for it, but its downsides really outweigh its benefits. While the science isn't totally settled on all its potential ill effects, we do know that it's highly processed, heavily sprayed with pesticides, and prone to oxidation. Eating it here and there likely isn't going to have a dramatic effect on your health, but you shouldn't make it a regular part of your diet, especially in the form of processed foods. Here are a few healthier cooking oils to swap it with.