My "On Nutrition" column in yesterday's Seattle Times focused on why picking the right oils, then using them correctly (in terms of storage and cooking temperature) is important for optimal health. It's a topic that tends to generate a lot of questions, so today I thought I would address a few of the most common ones that I've heard.
I always cook with olive oil at high heat...does this mean I should stop? I'm afraid so At least stop cooking with virgin olive oil or extra virgin olive oil at high heat. As I touched on in the column (but didn't get into in great detail due to space limitations), less refined oils are better for us because they typically retain more of the healthful compounds found in the "parent" seed, nut or fruit. However, the fact that they are less refined also makes them more fragile, so they degrade more easily (become rancid) when subjected to unfavorable storage conditions or unsuitably high temperatures. When they degrade, they produce compounds like free radicals that are decidedly NOT healthful!
On the flip side, refined oils lose many-to-most of their healthful compounds, and are often subjected to chemical extraction, deodorization and other processes that are not exactly great for us. Some oils that don't like heat are actually subjected to high heat during processing. Not good! In the end, refined oils tend to be more heat stable and be less sensitive to storage conditions, but at what health cost? At best, their refined state strips them of qualities that make their less-refined cousins healthful. At worst, the refining process makes them actually unhealthful.
So...back to olive oil. As I mentioned in the column, if you really, really want to cook at high heat with olive oil, you need to choose a refined "light" olive oil. This wont be as good for you as the virgin and extra virgin olive oils that are typically part of a Mediterranean-style diet, but at least it won't degrade when you're cooking with it.
I thought that canola oil was healthy...why isn't it on the list? Canola oil is a tricky one. Yes, it's high in heart-healthy monounsaturated fats. It's also contains omega-3 unsaturated fats, which are good for the heart and the brain. However, the process that extracts canola (short for "Canadian oil") from the rapeseed plant uses high temperatures and chemical solvents. Some of that solvent remains in the final product, and the high temperatures degrade the fragile omega-3s, turning them rancid. Because rancid oil is unappealing, even to those who don't know it's unhealthy, the oil has to be deodorized. The deodorization process converts some of the healthy omega-3s into unhealthy trans fats. And that's why it's not on my list.
I used to use canola oil when baking muffins, quick breads and the like. I switched to olive oil (virgin or extra virgin) and I have never noticed an "olivey" flavor in the final product. Just in case your curious. I sometimes use melted coconut oil.
What's special about the oils on your list? I spent a good amount of time researching this subject, cross-referencing different sources and weighing pros and cons. If you just want to know what oils are healthiest, that's not hard to find out. If you just want to know what oils are appropriate for different cooking temperatures (based on their smokepoints), that's not terribly difficult, although many oils show up at multiple temperatures, based on whether they are refined or unrefined, or have been modified to increase the percentage of a specific fatty acid (high-oleic sunflower oil, for example). A few of the smokepoint lists I consulted would make your eyes cross.
What I looked for were the intersections between healthy oils and oils that were safe for cooking. This gets harder as you move up the temperature scale, for reasons described above. The oils on my list were what I would consider "great" choices or "good" choices. I would have liked to limit the list to "great" choices, but the list would have been too small.
Some of these oils are really expensive...and so is grass-fed butter. What can I do if these don't fit in my budget? Yep, I hear that. I know that quality nut oils are expensive, in particular. And buying organic, cold expeller pressed oils, as I recommend, can be more costly. All I can say to that is: Do the best you can with the budget you have to work with. I always use organic butter, but I don't always use grass-fed butter. I tend to use my pricey nut oils for salads, and I buy brands that come in metal containers (no light exposure), then store them in the fridge. They last me a long time, and can make a simple tossed green salad something special.
I also tend to not cook at higher heats, intentionally. This helps me get around the issues of finding a healthful oil that doesn't break down under (temperature) pressure. It also means the smoke detector closest to my kitchen doesn't go off very often (which is good, because I can't reach it without a step stool). When I do occasionally break this rule, Jeff reminds me that his middle school Home Ec teacher told him that there is nothing that need to be cooked higher than medium heat. I don't really agree with that 100 percent, but the advice does seem to hold true most of the time.
If forced to choose between an oil that is healthful in its own right, and an oil that won't break down at a desired cooking temperature, I would choose the oil that won't break down. Degraded, rancid oils are so unhealthful, and I feel strongly that this factor trumps all. What's the point of using a nutrient- and phytochemical-rich oil if it ends up breaking down into free radicals? Answer: There is no point.
If temperature-appropriateness was my only concern, my list would have also included these fats and oils, in rough order of preference:
- High heat: Soybean and palm oils.
- Medium-high heat: Grapeseed oil, any sunflower oil, safflower oil, corn oil and cottonseed oil.
- Low or medium heat: Sesame oil, canola oil, non-grass fed butter, shortening or margarine that is trans fat-free. All but the sesame oil will work for baking (unless you want sesame oil flavor in your muffins!).
I beg of everyone to avoid any fat or food product that contains hydrogenated or partially hydrogenated oils (aka trans fats). They are one of the worst things you can put in your mouth, seriously.
Tomorrow I'm planning a little overview on the types of fats (saturated, unsaturated, etc.). See you then!