Is Corn Oil Healthy? A Deep Dive Into Its Nutrition Profile

In the past decade, healthy fats have made a monumental comeback. But there's still some confusion about which fats are healthy and which ones aren't, especially when it comes to cooking. Olive oil gets a lot of praise, but what about other cooking oils, like corn oil?

Corn oil is an industrial seed oil that's made from the seed (or kernel) of corn.

Like the vegetable (or grain, depending on when it's harvested), corn oil has a golden yellow hue. Some say corn oil has a slightly buttery flavor, but for the most part, it's very neutral. This makes it a popular choice in packaged and processed goods.

There's a lot of processing involved to make corn oil. Typically, the oil is mechanically and/or chemically extracted and then refined (e.g., using a solvent like hexane), according to holistic registered dietitian Michelle Shapiro, R.D., of Michelle Shapiro Nutrition LLC.

"During mechanical (physical) extraction, the germ component is separated from the kernel during the milling process to produce flour. The leftover germ is dried and then pressed using a hydraulic or screw press (i.e., "expeller-pressed"), to yield the liquid oil portion. To isolate the oil from physical contaminants, the product is washed with a chemical solvent, usually, hexane, which is evaporated to yield the oil itself," she says.

After the physical extraction comes a chemical refining process. The goal here is to remove any unwanted contaminants that negatively affect taste, odor, shelf life, and/or smoke point (among other things). Shapiro explains that chemical refining involves six main steps1: degumming, neutralization, washing/drying, bleaching, dewaxing, and deodorizing. 

All this processing comes with a major downside. "Though the purpose of the extraction and refining process is to remove undesirable compounds from the oil, it may also remove desirable compounds such as certain vitamins or antioxidants," Shapiro says.

Some of these compounds may include beneficial fatty acids and antioxidant-rich color pigments.

Corn oil4 contains 28% monounsaturated fat, 53% polyunsaturated fat, and 13% saturated fat. Breaking it down even further, corn oil contains 52% omega-6 and 1% omega-3 polyunsaturated fat. 

"Both omega-6 and omega-3 polyunsaturated fats are essential for our bodies to function; however, the ratio of each is very important to consider," says Shapiro. The ideal ratio of omega-6 to omega-3 is likely around the 2:1 range, she notes, but the average American diet contains a ratio of 20:1. "This means that we are consuming too many foods rich in pro-inflammatory omega-6 fats, and not enough sources of anti-inflammatory omega-3 fats." 

Some of the vitamin E in corn oil is lost during the refining process, but a tablespoon still contains close to 2 milligrams. This is about 13% of what people 14 years and older need for the day5.

Vitamin E is a fat-soluble vitamin that acts as an antioxidant in the body. It protects cell membranes6 and shields your body from damage caused by free radicals. It also protects your skin7 from sun damage.

Corn oil also provides essential fatty acids9. One of these is linoleic acid, which plays a role in keeping your skin, cell membranes, and immune system healthy.

One of the biggest downsides of corn oil is its unfavorable lipid profile (higher proportion of omega-6 to omega-3 fats) that can cause proinflammatory effects11 in the body, according to Shapiro.

Corn oil is also stripped of many of its nutrients and antioxidant compounds during its extensive refining process. Not to mention that over 90% of the corn grown in the U.S. is genetically modified.

Emerging research—a handful of animal studies—has found that corn oil may contribute to insulin resistance.

So, what's the bottom line? Is corn oil good or bad for health? The answer really depends on how you're using it, but with the way it's used today, most experts, including Shapiro, recommend reaching for something else instead.

While corn oil isn't intrinsically bad, it's highly processed and often used in unhealthy preparations like frying. Like popular vegetable oils such as canola oil, it's also high in over-consumed omega-6 fatty acids. Over time, eating a lot of it can become pro-inflammatory and do more harm than good.

Olive oil (particularly EVOO) is beloved by health experts everywhere—largely because of its favorable fat profile and the fact that there's a lot of scientific evidence to back up its health benefits.

According to Jessica Cording, R.D., olive oil contains antioxidants and other health-promoting compounds that have proven health benefits. It also has more monounsaturated fatty acids15, which help reduce LDL and increase HDL.

Butter got a bad rap in the '90s, but it's been making a comeback16 in recent years.

Butter is 63% saturated fat, 26% monounsaturated fat, and 4% polyunsaturated fat. While the high saturated fat content might make you raise an eyebrow, there's emerging evidence that it may not be as bad as once thought. That doesn't mean you should slather all your meals in butter, but it does mean that, in moderation, it can be a healthful addition to your diet.

Vegetable oils are derived from plant sources—the most common being soybeans, rapeseed/canola, corn, sunflower, and palm. The vegetable oils in grocery stores are typically canola or soybean oils, or a combination of both.

Canola oil and corn oil are similar in a lot of ways. Both oils are high in polyunsaturated fats and provide vitamin E. They're both neutral-tasting and very highly refined.