Extra virgin olive oil outperformed a lineup of popular seed oils when researchers put common cooking fats through high heat, according to a 2018 laboratory study that still shapes the debate over what belongs in the pan.
The paper, Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating, published in Acta Scientific Nutritional Health, tested ten commercial oils. Researchers heated them two ways: rapidly up to 240°C (464°F), and for six hours at 180°C (356°F) — a temperature familiar to home frying and roasting. They measured oxidation, polar compounds, fatty-acid changes, trans fats and smoke points. Polar compounds are a standard marker of oil breakdown; commercial kitchens often treat roughly 25 percent as a discard threshold.
EVOO came first. Coconut oil came second.
After prolonged heating at 180°C, refined seed oils generated far more polar compounds than extra virgin olive oil: sunflower 21.75 percent, grapeseed 20.24 percent, canola 17.32 percent and rice bran 15.66 percent, compared with about 10.5 percent for EVOO in the figures widely cited from the study. Other summaries of the same work place EVOO at the bottom of the degradation table and coconut oil just behind it.
The researchers pointed to EVOO’s high oleic acid content and its natural antioxidants — particularly polyphenols — as the reason it stayed relatively stable. Oils higher in polyunsaturated fats generally degraded faster.
Smoke point was a poor predictor.
The study undercuts a rule still repeated in kitchens worldwide: pick the oil with the highest smoke point for high-heat cooking. In this experiment, a higher initial smoke point could even correlate with more polar compounds after heating. Chemical stability, fatty-acid composition and antioxidant content were more useful guides.
That finding matters in Greece, where extra virgin olive oil is not a specialty finishing drizzle but the everyday fat of the house — used for horta, potatoes, fish, beans and the Sunday roast. For years, some nutrition advice has warned cooks off EVOO at high heat because its smoke point sits below that of refined seed oils. This study says that warning misses the chemistry that actually counts.
One important caveat
The oils were heated without food. The authors note that real cooking introduces water and steam, so household results can differ. The work is also a single laboratory comparison of commercial samples, not a clinical trial of health outcomes.
Bottom line
Of the ten oils tested, extra virgin olive oil was the most heat-stable, even though it did not have the highest smoke point. For Greek households already cooking in EVOO, the science lines up with tradition: stability comes less from the temperature at which an oil first smokes, and more from how the fat is built and whether its protective compounds are still in the bottle.
Source: De Alzaa F, Guillaume C, Ravetti L. Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating. Acta Scientific Nutritional Health. 2018;2(6):2-11. https://actascientific.com/ASNH/pdf/ASNH-02-0083.pdf
