Healthy Cooking Oils: Which Is the Right Choice for You?​

“No other food comes close to extra-virgin olive oil for the prevention and treatment of chronic disease,” says Mary Flynn, a research dietitian at the Miriam Hospital in Providence, Rhode Island, and associate professor of nutrition at Brown University.

Extra-virgin olive oil has been studied perhaps more than any other oil, and a strong and convincing body of evidence has linked it to a variety of health benefits, including a lower risk of cardiovascular disease, type 2 diabetes, some cancers and even dementia.

Extra-virgin olive oil also may be a big part of the reason the Mediterranean diet is so effective at protecting against chronic disease.

Flynn says the oil is healthy, not just because of its monounsaturated fat but also because it is jam-packed with antioxidants called polyphenols that fight cell damage. Some manufacturers have even started to market “high-phenolic olive oils” that have more antioxidants than ordinary extra-virgin olive oil. Flynn says early studies indicate those oils likely have more health benefits, but she notes that there are different types of phenols and researchers are still trying to determine which phenols are most important for health.

4. Get an antioxidant boost by choosing unrefined, virgin or cold-pressed oils.

Most supermarket oils in the United States are extracted from their source by using high heat or chemicals. That process, called refining, removes residue and results in a clearer, more stable oil with a more consistent color and odor.

However, the refining process also removes beneficial nutrients, says Selina Wang, a food scientist at the University of California, Davis, who studies oils. 

Unrefined oils, on the other hand, are mechanically extracted or pressed out of fresh fruit, seeds or nuts. Called “virgin” or “cold-pressed” oils, they tend to be more expensive, but they contain more nutrients and antioxidants to reduce inflammation.

“When our bodies age, it makes these free radicals, and antioxidants protect us from further degradation from these free radicals,” Wang explains.  

All extra-virgin olive oils are unrefined, because U.S. and international food regulations require olive oils labeled “extra-virgin” to have been extracted without chemicals or heat. There is no similar requirement for the word “cold-pressed,” however, so that term on a label is a less reliable indicator of oil quality.  ​

5. Canola oil isn’t toxic.

Some people have expressed concerns that canola oil is toxic, because a solvent called hexane is used to extract it from grape seeds as part of the refining process.

Bhupathiraju says hexane has been used to make refined oils for years, and there is no evidence that it’s associated with a health risk. “You also get exposed to hexane when you’re pumping gasoline,” she says. “Compared to how much you breathe in [at the gas pump], the amount you get in canola oil is insignificant.”

Bhupathiraju notes that canola oil is very low in saturated fat (around 7 percent) and is high in healthy monounsaturated fats, omega-3s and phytosterols, which are known to reduce the absorption of cholesterol in the body.

However, Flynn points out that canola oil is also easily oxidized, meaning that it may release harmful compounds when it’s exposed to high heat — so it should be avoided for frying or other high-heat cooking methods. 

6. Watch out for fake oils and inaccurate labels.

A variety of studies over the years in the United States and around the world have found that many extra-virgin olive oils do not meet the legally required standards to be labeled “extra-virgin.” In other words, they’re fake.  

A 2010 study by Wang and her colleagues found that two-thirds of extra-virgin olive oil imports didn’t meet the standards. Wang says she believes olive oil quality has improved since then.

To ensure you are getting a higher-quality extra-virgin olive oil, you can look for a certification seal on the label from the California Olive Oil Commission (COOC) and the North American Olive Oil Association (NAOOA), or one with “100 percent Qualita Italiana” (for Italian oils).

More recently, avocado oil has come under fire. In a 2020 investigation, Wang’s lab found that an astounding 82 percent of store-bought “avocado” oils were either rancid or were not avocado oil at all.  

“In some cases, oil labeled as avocado oil turned out to be 100 percent soybean oil,” Wang says. “Since then I have been very vocal that we need to have standards for avocado oil. It’s not regulated at all.”

In Wang’s study, none of the “virgin” avocado oils tested was up to par, and only two brands of refined avocado oil (Chosen Foods and Marianne’s) were pure and non-oxidized.

Wang says she has been working with the U.S. Department of Agriculture to develop standards for avocado oil.

7. Buy the freshest oil you can find.

Think of virgin oil as a fresh product that should be consumed quickly, Wang says, because oils oxidize and degrade over time.

If the oil has a “best before” date, choose the one with the latest date possible. If the oil has a “harvest date,” that’s even better, Wang says. Look for one within the last year.

Premium oils tend to sit on grocery store shelves longer because of their higher price point, Wang says, so there is often no correlation between price and quality. “If it’s two or three years old, that oil is no longer good — but the price is still high,” she explains.

8. Consider the packaging.

Oil in a clear plastic bottle is already oxidizing and aging as it sits on the shelf. Instead, choose a dark glass container or tin that protects the oil from light and air. Glass is better than plastic because plastic has some air permeability, Wang says.

Some manufacturers have started selling extra-virgin olive oil in boxes, and that’s a great option, Wang says. “Boxes are good because each time you cook with olive oil in a bottle, you open the top and pour some out. During that time, oxygen gets into the bottle. The more oxygen in the bottle, the faster [the oil] will oxidize,” Wang explains. “The way the boxes are designed, you push a button and the oil comes out, but the box remains sealed.”

Wang suggests buying only as much oil as you can use within three to four months, because it starts to deteriorate as soon as it’s opened and exposed to air.

9. Even healthy oils should be used in moderation.

No matter how healthy your oil is, it’s best to use it in moderation, Gans suggests.

All types of fats, including healthy oils, are high in calories — about 120 per tablespoon. Too many calories can lead to excess weight, which increases your risk of chronic disease and other health problems.

Also remember that oils are just one part of a healthy diet. Your best bet is to pair them with plenty of fruits, vegetables and whole grains.