Is it bad to cook with olive oil at high heat? What the evidence shows

You can cook with olive oil at high heat, and the popular warning that its "low smoke point" makes frying with it unsafe rests on the wrong measurement. The property that determines how an oil holds up to heat is its oxidative stability — how readily it breaks down into off-flavour and potentially harmful compounds — and by that measure olive oil is one of the more resistant common oils [s1]. The genuine caveat is narrower: no oil is immune, and heating any of them past their limits or reusing them repeatedly degrades them [s2].

Smoke point is the wrong test

Smoke point is the temperature at which an oil visibly begins to smoke, and it is easy to measure, which is probably why it dominates the advice. But smoking marks the onset of volatile breakdown; it does not track how fast the oil oxidises into the polar compounds that regulators actually use to judge a frying oil unfit. An oil can have a modest smoke point and still resist oxidation well, or a high one and oxidise quickly. Judging olive oil by smoke point alone is like judging a car by the temperature at which its paint discolours. Refining raises an oil's smoke point by stripping out the very free fatty acids and minor compounds that would otherwise smoke early — but some of those compounds are the antioxidants that protect the oil from oxidising in the first place, which is why a higher smoke point is not the same as better performance in the pan.

What frying tests actually show

A Portuguese study put olive oil through domestic deep-frying and tracked it until the total polar compounds reached the maximum legal value of 25% — the point at which a frying oil should be discarded [s1]. Every olive oil category lasted longer than a commercial vegetable-oil blend used for comparison: from 24 to 27 hours of frying against just 15 hours for the vegetable oil [s1]. That was true even though the vegetable oil contained significantly more vitamin E [s1]. Extra-virgin oil carrying a Protected Designation of Origin showed the lowest levels of oxidation and hydrolysis and the most natural antioxidants, and the authors concluded that olive oil is "clearly resistant to frying conditions" regardless of the commercial grade chosen [s1].

Why it holds up

The explanation is in the fat itself. Per 100 grams, olive oil is 72.961 grams monounsaturated fat, 13.808 grams saturated fat and only 10.523 grams polyunsaturated fat [s3]. Polyunsaturated fats carry multiple double bonds, and each one is a site where oxygen can attack under heat, so oils rich in them oxidise fastest. Olive oil's profile is the opposite of that vulnerability: mostly monounsaturated fat, which has a single double bond, with a comparatively small polyunsaturated fraction [s3]. On top of the fatty-acid mix, virgin olive oils carry natural phenolic antioxidants that further slow oxidation — the very compounds the frying study found were highest in the most stable oils [s1].

The honest caveat

Stability is not immunity, and it would be dishonest to pretend heating olive oil does nothing. A 2025 study heated five common oils — olive, rapeseed, sunflower, sesame and peanut — to 190°C in a fryer and, using high-field nuclear magnetic resonance, found a significant rise in aldehyde compounds in all of them, including genotoxic and cytotoxic α,β-unsaturated aldehydes [s2]. The same study found light exposure alone generated these compounds too, which is why oils are best stored in the dark [s2]. Every oil degrades with enough heat and time; the practical differences are how quickly, and how much you push it.

The bottom line

For ordinary cooking — sautéing, roasting, and even shallow or deep frying — olive oil is a reasonable and, on the frying-stability evidence, comparatively good choice [s1]. The advice worth keeping is not "never heat olive oil" but the general rule that applies to every oil: do not heat it until it is smoking hard, do not reuse the same oil many times, and store it away from light [s2]. The smoke-point scare aimed specifically at olive oil is not supported by how the oil behaves when it is actually heated.

This article is informational and is not medical advice.

Sources

• Olive oil stability under deep-frying conditions — Food and Chemical Toxicology, 2010
• Analysis of the Generation of Harmful Aldehydes in Edible Oils During Sunlight Exposure and Deep-Frying — Foods, 2025
• Oil, olive, salad or cooking (FDC ID 171413) — USDA FoodData Central, 2019