More: Fry veggies in olive oil to get maximum heath benefits (21. January 2016)Frying in Extra Virgin Olive Oil (EVOO) improves the chemical compounds present in the vegetables, reveals a new study.
Researchers from the University of Granada (UGR) in Spain have proven that frying in EVOO -- unrefined oil and the highest-quality olive oil -- is the cooking method that increases the phenolic -- chemical compounds -- fractions present in raw vegetables used especially in Mediterranean diet (potato, pumpkin, tomato and eggplant).
The study apparently only looked at extra virgin olive oil, no refined olive oils or rapeseed / canola etc. Which surprises me since I've been led to believe that refined oils are better, i.e develops less unhealthy compounds when exposed to heat.