Thanks to Rachel Ray and the recent popularity of the Mediterranean Diet, it seems that everyone is on the EVOO (extra virgin olive oil) bandwagon.

Certainly, healthy oils and fats are now known to have many benefits when eaten as part of a low carb, anti-inflammatory diet. But many people are not aware that the biggest trick to keeping our intake of fats healthy, is to know whether they can be heated or not — and if so, to what temperature.

In pressing nuts, seeds, grains, or olives to make oil, the pressing itself creates heat. This is why cold-pressed oils are more desirable. Keeping the temperatures down during pressing helps prevent the creation of oxidized fats. Oils are more prone to the damaging effects of heat than saturated fats, which are chemically more stable. Heating oils to higher temperatures than they can tolerate, oxidizes them and creates a potent source of free radicals — highly unstable molecules that can damage our cells.

For instance, because EVOO is from the first pressing of the olives, it has only been subjected to low heat. And because it is not further refined, it has a high concentration of plant phenols. These naturally occurring plant chemicals fight nasty free radicals and decrease inflammation, and therefore protect against heart disease and cancer.

So the last thing we want to do is to squelch the activity of these protective compounds through cooking with high heat. According to the Journal of Agricultural Food Chemistry, heating EVOO to somewhere in the range of 180°C or approximately 356°F, causes a decrease in two beneficial plant phenols.

The experts at the World’s Healthiest Foods, a website originated by the former owner of Health Valley foods, note that the more refined the oil, the more heat it can withstand. Since cold-pressed EVOO comes from the initial pressing, it is in the most unrefined state, and therefore most vulnerable to heat. They recommend heating EVOO to temperatures no higher than 250°F or what we would call “low heat”. This translates to light sautéing for short periods of time.

The best-case scenario to obtain the maximum phytochemicals with the least oxidation, would be to consume EVOO in unheated form — in other words using it in salad dressings versus cooking with it. One strategy is to play it safe by steaming vegetables in some broth or water and then drizzle the olive oil over the vegetables just before eating. This can be done with most foods and is a sure way to guard the precious phytochemicals in this health-promoting oil.

If you want to use olive oil for cooking, it is best to use an extra light olive oil, which is more refined, but can tolerate temperatures up to about 400°F. Or try other healthy oils and fats that can be used for cooking. Grapeseed oil, butter, ghee butter, coconut oil, and macadamia nut oil are all good choices.

[Ed. Note: Laura B. LaValle, RD, LD is presently the director of dietetics nutrition at LaValle Metabolic Institute (formerly part of Living Longer Institute). She offers personal nutritional counseling at LMI for clients who need help with their diet in relation to illness or disease. Laura also provides educational services in the areas of health promotion, wellness, and disease prevention. To learn more, click here.]