With high heat cooking, you will want to use the right oil for the job. An important factor is the cooking oil's smoke point, which can alter flavor and lead to pan fires.
Every plant-based oil has its personality quirks. Some oils impart a taste, or are too delicate to use for high heat, and others turn bitter at high temperatures. The most important factor to consider is the oil's smoke point. That's the temperature at which the oil burns.
Avocado oil can be a good choice for sauteing or frying. It has one of the highest smoke points of plant oils, at 500 F. It has also a sweet smell, and does not add any distinctive avocado flavor to dishes. To find out more about avocado oil, see my video in the Talking Vegetables series here.
In comparison, virgin coconut oil has a smoke point between 350 and 375 F, and refined coconut oil is a bit higher, at 400 F . A disadvantage to using virgin coconut oil is that it lends a distinct coconut flavor to the dish. Coconut oil also has a saturated fat content similar to butter, at 12 g, while avocado oil has a low saturated fat profile of 1.6 g per tablespoon (14 g). Avocado oil has the added benefit of being high in heart-healthy monosaturated fats. All around, avocado oil is a better choice for higher heat dishes.
Extra-virgin olive oil is perfectly suitable for medium heat cooking, and, in most cases, is a fine alternative to avocado oil, with lots of monosaturated fats as well. Refined olive oil has a slightly higher smoke point, but I personally like the flavor and unrefined qualities of extra virgin olive oil.
If your oil smokes, throw it out and open the windows. The smoke is irritating and a bitter or burnt taste will overwhelm the food. At high temperatures, oils also lose nutrients, but they do not turn toxic. Along the way, cooking became dangerous, and not because of kitchen fires. The fear was due to the misconception that cooking in high heat causes cancer.
No cancer link
According to the National Cancer Institute of the National Institutes of Health (NIH) , acrylamides are released in certain types of food, and when some foods are cooked at high temperatures. Examples are potato chips, french fries, rice, and even canned black olives. However, it's important to note that studies have not shown evidence of a link between acrylamides and cancer. Additionally, the amount of acrylamides consumed are not considered to be dangerous for now.
I assume you are not eating french fries and potato chips at every meal (and if you are, you may want to set up more structured meals). For now, no link has been established between cancer and these foods, even when cooked at high temperatures. Still, it's not the type of food to have often because of its health impact.