This article is part two of a 3-part series on healthy oils for heart patients. In part one, we discussed the role of healthy oils in fighting heart disease, and some of the research about the impact of switching from saturated fats to monounsaturated and polyunsaturated fats. Once we know what types of oils we are looking for, how do we make healthy choices for cooking oils?
The most important consideration for heart patients is probably the saturated fat content. As we saw in part 1 of this series, replacing saturated fats with monounsaturated, and especially polyunsaturated fats, has been shown to reduce the risk of heart disease.
All oils contain at least some saturated fat, but the healthiest ones contain only small amounts. The range from most to least is demonstrated by coconut oil, which is almost entirely saturated fat, to canola, almond, flaxseed and safflower oils, which have only the smallest amounts of saturated fat. Oils that are also low in saturated fat include olive, avocado, peanut, soybean, sunflower, walnut and grapeseed.
Because polyunsaturated fats (PUFAs) have been shown to play an even greater role in heart health than monounsaturated fats (see part 1 for links to research), some dietitians suggest that heart patients consider those highest in PUFAs, which include flaxseed, grapeseed and safflower oils. Close behind those are walnut, and sunflower oils.
A second major consideration is how the oils are made, meaning whether they are derived from solvent extraction (chemical processing), or pressed, and whether they are refined or unrefined.
Finally, the oil’s smoke point is critical to choosing the right oil for the right purpose.
Pressed or Extracted Oils
Pressed Oils means the oils are obtained through placing the vegetable or seed under mechanical pressure until the oil is extracted. Expeller pressing can generate high levels of heat, which can affect the quality of the oil.
Cold-pressing is designed to minimize the use of heat, and is believed to better preserve the flavor of the oil, retain more of the essential fatty acids and reduce degradation that causes oils to begin to oxidize. Cold pressed oils are typically unrefined, since the refining process relies on heat. Cold-pressed oils are also among the most expensive, since this process removes the least amount of oil. Often additional oil is extracted through solvent processing from products left over after cold pressing.
Solvent extracted oils are among the least expensive, because the processing is less expensive and removes more of the oil. Soybean, canola, palm and corn oils are among many examples of solvent extracted oils. With this process, the seeds are ground, mixed with a chemical solvent that releases the oils, then the oils are heated to remove the solvent. (One source explains the process here.) Critics suggest that traces of the solvent (such as hexane) can remain, and that the heat destroys essential fatty acids in the oils.
Refined or unrefined
Refining uses high temperatures to bleach and deodorize oils, to remove the natural flavor and aroma of the nuts they are derived from, so that the oils can blend with various foods without adding their own flavor or aroma. Solvent-extracted oils are typically refined. Unrefined oils retain more of the essential fatty acids and nutrients of the oil.
Refined, bleached and deodorized: “RBD” oils are those that have been “refined, bleached and deodorized.” This processing occurs with solvent extracted oils and with some expeller pressed oils, where the desired product is an oil free of odors and tastes that might distract from the food being cooked.
Extra virgin olive oil is cold-pressed and extracted from the first pressing of the olives. The first press is considered to produce the highest quality, and the processing without heat or chemicals retains the most nutrition without oxidation or loss of integrity of the oil.
While cold-pressed, unrefined oils probably retain the most essential fatty acids, enzymes, and other nutrients, for most people there is no getting around the need for at least some extracted, refined oils. Refined oils have a higher smoke point, and almost any use of oil that involves cooking will, by necessity, involve heating it. The choice might come down to saturated fat content, as described above, smoke point, and cost.
What about smoke points?
To gain the most from healthy antioxidants, consider using at least some oil that is cold pressed, for foods that will not require heating, like salad dressing or for drizzling on bread or vegetables. Flaxseed oil is very high in polyunsaturated fats and ideal for this purpose. It can be mixed with other cold-pressed oils to customize the flavor you want.
For cooking, you will want to use an oil with a smoke point that’s suited to the form of cooking you are using, because once an oil reaches its smoke point, it begins to break down (not to mention creating smoke, which can release toxic compounds and becomes a problem with a broiler or indoor grill).
Oils best for cold use (drizzling, salad dressings and dips) include flaxseed, walnut, and extra virgin or cold pressed olive oil.
For sautéing and pan frying, oils with a smoke point between about 350-425 degrees (Fahrenheit) should work well. Examples include sesame, grapeseed, light (refined) olive oil and any of the oils that work at higher temperatures.
For roasting or grilling, a higher smoke point is desirable, as temperatures might exceed 400-450 degrees. These include almond, soybean, and canola oils (as well as those that work at higher temperatures.
For searing or broiling, consider oils with the highest smoke points, potentially exceeding 475-500 degrees, which include avocado, peanut, safflower and sunflower oils.
Estimates of oil smoke points vary from one manufacturer to another, and refined oils have higher smoke points than unrefined, because many of the enzymes and compounds that produce smoke have been removed. The important thing to know is that when an oil goes from a shimmering, glistening state to producing a hint of smoke, the compounds have begun to break down. At the very least, remove it from the heat; if it has begun to produce smoke, it should probably be discarded and replaced with fresh oil. Reusing oil reduces its nutrients and smoke point, and is not recommended.
As a heart patient looking to reduce the risks associated with saturated fats, the first consideration might be to use only oils that have minimal saturated fat content. Consider using some cold pressed oils in salad dressings, dips and other cold preparations, but unrefined or cold pressed oils are not suggested for high temperature cooking.
Part 3 of this series will compare all the features we have discussed, side by side.