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.
What is soybean oil?
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.
- Calories: 120
- Total fat: 13.6 grams
- Polyunsaturated fats: 7.8 grams
- Monounsaturated fats: 3.1 grams
- Saturated fats: 2.1 grams
- Trans fats: 0.1 gram
- Protein: 0 grams
- Carbohydrates: 0 grams
- Vitamin E: 1.1 milligrams
- Vitamin K: 25 micrograms
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.
Different forms of soybean oil.
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:
- Cold-pressed: Cold-pressed oils are made without applying heat. Instead, the seeds are crushed and oil is forced out via pressure. This helps retain some of the nutrients in the oil since heat can contribute to oxidation and the breakdown of nutrients. Cording says these types of oils may not have the same neutral taste as refined oils, however, and they're more difficult to find.
- Organic: Organic soybean oil isn't easy to find either since soybeans in the U.S. are often genetically modified and treated with the herbicide glyphosate. There are some options available online, but they're more expensive than other types.
- Vegetable oil/soybean oil blends: There are two types of soybean oil blends you'll typically find: soybean oil that's blended with canola or vegetable oil, or olive oil that's cut with soybean oil. In the latter case, manufacturers usually do this to save on production costs. The oil is often marketed as olive oil, but it has a much cheaper price tag because it has lesser-quality oils mixed in.
Health benefits of soybean oil:
It may lower cholesterol.
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.
It can support heart health.
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.
It may help balance blood sugar since it's a source of fat.
"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.
It contains vitamins and some beneficial fatty acids.
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.
The downsides of soybean oil.
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:
It can be pro-inflammatory.
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.
It contains aflatoxins.
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.
It is susceptible to oxidation.
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.
Its production can be unsustainable.
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.
It may negatively impact the brain.
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, is soybean oil healthy?
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.
If you're only using cold-pressed or unrefined soybean oil occasionally and staying away from over-consuming it via processed foods, it can fit into an overall healthy diet. But if you're getting most of your soybean oil from packaged foods, using a highly processed form of it, or overheating it, it's not a great choice.
The rest of your diet matters, too. The goal is to get a good balance of fats and oils. If you're heavily using soybean oil, your consumption of omega-6 polyunsaturated fats will likely outweigh all the other types of beneficial fatty acids and you'll be setting yourself up for inflammation and other health concerns.
Instead, if you really want to use soybean oil, make it an occasional thing, and lean on avocado oil and olive oil more often.
Soybean oil vs. other oils.
So, how does soybean oil stack up to other types of oils? Let's break down three of the most common types.
Soybean oil vs. olive oil
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.
Soybean oil vs. canola 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."
Soybean oil vs. coconut oil
"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.
Frequently Asked Questions
Is soybean oil healthy for diabetics?
When it comes to diabetes, it's all about keeping blood sugar as steady as possible. Because it provides fat, soybean oil technically can help stabilize blood sugar, according to Cording, but she says it's definitely not the first fat source she'd recommend to improve glycemic control.
Is soybean oil healthy for frying?
The answer to this question goes back to the concept of oxidation. Independent of the fact that frying food is not the healthiest option, soybean oil may be especially prone to oxidation because of its high linoleic acid content. If you do decide to use soybean oil for frying, Crosby recommends keeping the temperature below 350 degrees Fahrenheit (and definitely not exceeding 375 degrees).
Is soybean oil inflammatory?
When it comes to inflammation, it's really about the overall diet pattern, according to Cording. "Any one food or meal is not necessarily going to have a profound effect on your overall health. It's long-term diet patterns that really matter," she says.
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.
Lindsay Boyers is a holistic nutritionist specializing in gut health, mood disorders, and functional nutrition. Lindsay earned a degree in food & nutrition from Framingham State University, and she holds a Certificate in Holistic Nutrition Consulting from the American College of Healthcare Sciences.
She has written twelve books and has had more than 2,000 articles published across various websites. Lindsay currently works full time as a freelance health writer. She truly believes that you can transform your life through food, proper mindset and shared experiences. That's why it's her goal to educate others, while also being open and vulnerable to create real connections with her clients and readers.