I asked registered dietitians which cooking oils they really use—here’s what they said

From sunflower oil that’s fortified with vitamin D to genetically engineered omega-3 oils, it seems a new generation of cooking fats are promising to squeeze even greater nutritional benefits.

But some dietitians say the marketing can run ahead of the evidence.

“I do not believe every oil needs to function as a supplement or superfood,” says registered dietitian Johannah Katz. “Sometimes, an oil earns its place in the kitchen because it helps make vegetables, whole grains, fish, tofu, or other nutritious foods more enjoyable.”

I spoke to Katz, and Olivia Hamilton, a registered dietitian at meal delivery service Factor, to find out which oils they use.

1. Extra-virgin olive oil

“Extra-virgin olive oil is the oil I use most often,” says Katz. “I use it in salad dressings, to finish meals, and for everyday sautéing and roasting.

“It’s rich in monounsaturated fat [a type of healthy dietary fat] and also contains phenolic compounds that may contribute antioxidant and anti-inflammatory effects.”

While Katz is a fan of extra-virgin olive oil, she says that the social-media-fueled wellness trend of taking olive oil shots isn’t better than simply using it in cooking and on food.

“The research supporting extra-virgin olive oil generally examines regular intake or a Mediterranean dietary pattern, not the ritual of swallowing it alone or taking it on an empty stomach,” she tells Fit&Well.

“Using olive oil with food may be more practical because it can replace butter or other fats higher in saturated fat and make vegetables, beans, whole grains, and other nutrient-dense foods more appealing.

“A shot also provides a concentrated source of calories without necessarily improving the overall quality of the meal—and it may cause nausea, reflux, cramping, or diarrhea in some people.”

Meanwhile, Hamilton shares that quality extra-virgin olive oil is her first choice for dressings, dips or low-heat cooking and she often uses it in place of butter.

“Nothing beats a baguette soaked in olive oil and red pepper flakes!” she says.

“I will also reach for olive oil as a base for most pasta sauces in lieu of heavy creams.

“Add in a healthy dose of fresh herbs and lemon juice, and you have a refreshing and nutrient-dense pasta sauce.”

2. High-polyphenol olive oil

Katz highlighted a type of extra virgin olive oil that has a high-polyphenol count, explaining that it could have additional benefits for blood lipids—fats in your bloodstream that the body needs for energy.

“There is legitimate science behind olive-oil polyphenols. In a small randomized crossover trial involving 200 healthy men, researchers compared olive oils with low, medium and high levels of polyphenols.

“They found that HDL (‘good’) cholesterol increased progressively with the polyphenol content of the oil, while some markers of lipid oxidation—a process in which fats react with oxygen and produce potentially damaging compounds—also improved.”

Katz says that while high-polyphenol oil has some health benefits, don’t be fooled by marketing language that promises the world.

“I would describe high-polyphenol oil as a potentially beneficial version of an already health-promoting food, not as a miracle product,” she says.

“Words such as ‘supercharged’, ‘longevity oil,’ and ‘activated’ are marketing language and do not automatically indicate that a product has been shown to prevent disease or extend lifespan.”

Plus, the polyphenol level varies depending on the olive variety, growing conditions, harvesting, processing, age, and storage. Katz also points to the fact that some people might not like the often peppery taste of this type of oil.

3. Avocado oil

Katz values avocado oil for its neutral flavor when cooking at high temperatures.

“I tend to use refined avocado oil for roasting vegetables, high-heat sautéing, searing proteins, and air-fryer recipes because its neutral flavor does not compete with the other ingredients.

“I would not necessarily say avocado oil is nutritionally ‘better’ than extra-virgin olive oil.

”Avocado oil is rich in monounsaturated fat, especially oleic acid. Its fatty-acid composition also gives it reasonable oxidative stability during cooking, although like any oil, research suggests that its quality will decline with prolonged or repeated high-heat exposure.”

Hamilton says avocado oil is commonly used in her kitchen, too.

“It is low in saturated fats—which are helpful to limit, especially if you are genetically predisposed to high blood cholesterol levels like me.”

Hamilton also prefers avocado oil for some higher-temperature cooking because refined avocado oil typically has a high smoke point.

This is important, she says, because “with all oils you want to refrain from repeatedly heating them to ultra-high temperatures for long periods of time as it can degrade the healthful compounds.”

4. Sesame oil

With its toasted flavor, sesame oil works well in Asian dishes and Katz always has a bottle in her kitchen.

“Sesame contains lignans such as sesamin and sesamolin: compounds that have been studied for effects on cardiovascular and metabolic health,” she says.

A 2025 systematic review and meta-analysis of 11 randomized trials found that sesame oil improved several blood-lipid measures in adults with metabolic conditions, although Katz says the evidence should be kept in perspective.

She uses toasted sesame oil in stir-fries, marinades and dressings, often adding it towards the end of cooking.

“A flavorful oil can make vegetables, whole grains, lean proteins, and other nutrient-dense foods more enjoyable without needing a large quantity,” she says.

“I would view the lignans and unsaturated fats as an added benefit rather than a reason to consume large amounts of sesame oil for medicinal purposes.”

Are fortified oils worth the money?

What about the increasingly sophisticated oils promising extra benefits?

Katz sees potential. “Vitamin D-fortified sunflower oil could be a useful delivery vehicle for populations with low vitamin D intake,” she says, but it isn’t automatically better for everyone.

“Consumers do not need a cabinet of expensive functional oils to eat well,” Katz adds. “A fresh, good-quality extra-virgin olive oil can be an excellent primary oil.”

Hamilton agrees that enhanced oils aren't inherently bad, but says they aren't essential either. “You do not need a $30 bottle of oil or a $4 daily olive oil shot to be healthy,” she says.

Her alternatives are decidedly simpler: “Increasing your consumption of fruit and vegetables. Swapping butter for olive oil. Going on daily walks.”