With so many different vegetable oils available on the grocery store shelf, how do you know which one to choose? There is so much conflicting information: Is coconut oil healthy? Is it safe to heat oils? What kind of olive oil is healthiest?
The primary consideration when selecting a cooking oil should be its content of saturated fat. All oils are a mixture of three types of fats, polyunsaturated, monounsaturated and saturated. What matters most is the amount of saturated fat. Saturated fat is known to increase LDL-cholesterol (bad cholesterol), which raises the risk of cardiovascular disease (CVD).
According to a June 2017 advisory by the American Heart Association, replacing saturated fat with polyunsaturated fat reduces the risk of CVD by 29 percent.
Monounsaturated fats also help reduce the risk, but to a lesser extent than polyunsaturated fat. They are both considered healthy choices.
Another important factor in choosing a cooking oil depends on the intended use. Some oils have a higher smoking point and can therefore be heated to a higher temperature without burning and producing hazardous chemicals and fumes.
Oils with a very low smoke point such as flaxseed oil (linseed) and wheat germ oil are unstable and should not be heated to a high temperature. The smoke point of flaxseed oil is 225 degrees F. Coconut oil has a medium smoke point (350-400 degrees). The smoke point for olive oil varies between 320 degrees for extra-virgin olive oil to 468 degrees for light (refined) olive oil.
According to the U.S. Department of Agriculture, the best choices for high-temperature cooking (frying) include canola, grapeseed, soybean, peanut, sunflower, corn and safflower oil.
I recommend olive oil and canola oil as two go-to cooking oils to keep in the kitchen cabinet. Olive oil is extraordinarily rich in monounsaturated fats (73 percent) whereas canola oil is higher in polyunsaturated fats. Nutritionally, there is little difference between extra-virgin olive oil and regular (refined) or light (highly refined) olive oil, although refined olive oils can be heated to higher temperatures. For baking or high temperature use, the relatively inexpensive and neutral tasting canola oil is a better choice due to its high smoking point.
Canola oil is approximately 63 percent monounsaturated, 30 percent polyunsaturated, and only 7 percent saturated (the lowest saturated fat oil on the market), and provides omega-3 fatty acids, a potentially beneficial type of fat related to fish oil. Replacing saturated fat with canola oil reduces LDL-cholesterol (bad cholesterol).
Tropical oils such as coconut, palm and palm kernel oil are rich in saturated fat. Coconut oil is 90-92 percent saturated fat, which is even higher than butter (64 percent) or lard (25 percent). Note that the exact numbers vary. According to the AHA, coconut oil raises LDL-cholesterol as much as butter, beef fat or palm oil. Coconut oil (or coconut milk, which is also high in saturated fat) can be a tasty ingredient and as with all saturated fats can be safely consumed in moderation in the context of an overall healthy diet.
Some claims for health benefits of coconut oil are based on its content of medium chain triglycerides (MCT). Pure MCT oil has been shown to increase metabolism and weight loss. It is composed of 100 percent caprylic acid (a 12-carbon MCT) or caprylic plus capic acid (a 10-carbon MCT). In contrast, coconut oil contains 50 percent lauric and only 15 percent caprylic plus capic acid and does not increase metabolism or weight loss. There appears to be a lot more hype than science in support of health benefits for coconut oil.
In addition, the saturated fat in coconut oil raises both (bad) LDL-cholesterol and (good) HDL-cholesterol. Experts previously thought that raising HDL-cholesterol was protective against CVD; however, the current consensus is that raising HDL-cholesterol is not clearly beneficial. Since coconut oil raises both LDL-cholesterol and total cholesterol, it should be consumed only in moderation, if at all.
There are numerous other oils on the market including predominantly polyunsaturated corn, soy oil, peanut, safflower and sunflower oils and predominantly monounsaturated avocado and peanut oils.
Avocado oil, which is typically more expensive than other oils, is predominantly monounsaturated. Grape seed oil, made from leftover grape seeds from wine-making, is mostly polyunsaturated and should be stored in the refrigerator. Peanut oil is high in healthy monounsaturated fatty acids. Sesame oil contains a mixture of mostly polyunsaturated and monounsaturated and fatty acids and should be refrigerated. Sunflower oil contains mostly polyunsaturated, has a mild flavor and can be used for high temperature cooking. Vegetable oil is either 100 percent soybean oil or a mixture of vegetable oils. Soybean oil is predominantly monounsaturated and also contains some omega-3 fats.
In summary, to choose your cooking oil wisely, cook with predominantly polyunsaturated or monounsaturated fats for everyday use. Olive oil and canola oil are recommended as the two oils to use most often in the kitchen.
Sharon Himmelstein, PhD, MNS, RDN, is a Registered Dietitian Nutritionist and a member of the Academy of Nutrition and Dietetics, http://www.eatright.org, and the New Mexico Academy of Nutrition and Dietetics, http://www.eatright-nm.org.