When it comes to healthy cooking oils, there is plenty of unscientific information floating around the Internet. It feels like everyday you are told that the oil you have been using is now unhealthy. The latest attack has been on seed oils, such as canola, corn, cottonseed, grapeseed, rice bran, safflower, soy, and sunflower oils. The first argument is that seed oils are filled with toxic byproducts from the use of chemical solvents, such as hexane. The second argument is that seed oils are unhealthy for you because they primarily contain omega-6 polyunsaturated fat.
According to Harvard School of Public Health, the scientific evidence does not support these claims, because there is no clear evidence linking trace amounts of solvents to health issues (1). Evidence has shown that seed oils can actually help lower cholesterol, lower blood sugar, and reduce the risk of heart disease (1).
What is the best oil to use?
According to Teresa Fung at the Department of Nutrition at the Harvard School of Public Health, the nutrient makeup of your cooking oils is “not going to make a difference in terms of health, especially if you eat a healthy diet” (2). So go ahead and use your choice of minimally processed oil with moderation within the context of a well balanced diet.
Here are three main factors when considering what oil to use: saturated or unsaturated fat, stability under heated conditions, and the amount of processing.
1. Saturated or Unsaturated Fat
All fats can contain mix of three types of fat: monounsaturated fat contains omega-9 and is found in almonds, hazelnuts, avocados, sesame seeds, and olive oil; polyunsaturated fat contains omega-6 and omega-3 fatty acids and is found in fish, walnut oil, flaxseed oil, and vegetable oils; saturated fat is usually solid at room temperature and is found in animal fat, butter, coconut oil, and palm oil (3). The healthiest oils are those that are highest in monounsaturated and polyunsaturated fats, such as vegetable oil and olive oil, which can help lower your bad cholesterol, raise your good cholesterol, and reduce your risk of heart disease (4).
2. Stability Under Heated Conditions
When it comes to cooking, some oils can handle the heat, and some can’t. An oil's ‘smoke point’ is the temperature at which it will start to smoke and break down. When oil hits that temperature, the molecules start to burn, destabilize, and lose their nutrients (2). Oils that reach their smoke point also release free radicals and a substance called acrolein which can cause lung irritation (5). In a similar vein, when oils are repeatedly heated, such as in deep-frying, the oil leads to lipid oxidation, which is inextricably linked to detrimental health effects such as cardiovascular disease (6).
Here are some smoke point examples:
- Unrefined seed oils smoke at 225°F.
- Butter smokes at 302°F.
- Extra Virgin olive oil smokes at 320°F.
- Refined oils smoke between 400°F and 500°F (7).
You should choose your oils based on your cooking method. Low smoke point oils such as flaxseed oil, extra-virgin olive oil, nut oils, and sesame oil can lose flavor and denature quickly when heated, so you should reserve them for salad dressing or drizzling on your finished dishes (2). Medium smoke point oils such as avocado oil, corn oil, canola oil, or virgin olive oil can be used for sauteing over medium heat (8). High smoke point oils such as peanut oil, soybean oil, light olive oil, and grapeseed oil can be used for high-heat frying, stir-frying, or roasting (2).
3. Processing Method
The processing of your cooking oil can also dramatically change its flavor, color, smoke point, and health benefits. Highly refined oils are less expensive, have a uniform appearance, and much higher smoke points. Unrefined oils tend to be more costly, contain sediment, appear cloudier, have lower smoke points, but they do have more natural flavor (8).
Why should you even bother with using cooking oils?
Cooking oils contain fat, which is an essential macronutrient for a healthy diet that contains essential fatty acids not made by the human body. These fatty acids can help you absorb fat-soluble vitamins such as vitamins A, D, E, and K. Fat also helps facilitate the absorption of protein and the repairing of damaged tissue (9). In addition, fat is digested slower than protein or carbs, which can keep you feeling satiated longer. Fat can help regulate your metabolism and blood sugar and lower your risk for obesity, diabetes, high blood pressure, and heart disease (10).
On the culinary side, cooking with fat can produce more delicious food. Greasing a pan can prevent food from sticking. Coating veggies with oil will allow for more even cooking. Adding oil to meat will enhance texture by browning the exterior, adding crispiness, keeping in moisture, concentrating flavors, and/or increasing aromas. Fat will also coat your taste buds with a smooth mouth feel, providing pleasurable richness (11).
Five of the healthiest cooking oils according to science
1. Olive Oil
Olive oil is on top of this list because of its versatility and well documented health benefits. Olive oil is high in monounsaturated fatty acids, has antioxidant properties, and can help reduce the ‘bad’ LDL cholesterol and improve ‘good’ HDL cholesterol (12)(13). There are two main types of olive oil: unrefined or refined. Unrefined olive oil, labeled as ‘extra-virgin olive oil,’ is pressed mechanically from ripe olives and processed without high heat or chemical solvents. Due to its lower smoke point at 320°F, EVOO is best used for medium heat cooking, baking, and salad dressings (14). Refined olive oil, labeled as light olive oil, is treated with some heat and chemicals to remove impurities and boost cooking stability. With its higher smoke point of 470°F, you can cook on high heats (15). Olive oil not only tastes great but is the cornerstone of the health promoting mediterranean diet.
2. Avocado Oil
Avocado oil is similar to extra virgin olive oil, with its high monounsaturated fat contents and a high percentage of the heart-healthy fat, oleic acid (16)(17). However, it has the added advantage of having a higher smoking point at approximately 520°F, allowing for higher cooking temperatures (18). One Study found that avocado oil maintains its nutritional quality at both low and high temperatures (18). This is a great option for high heat cooking. Plus avocado oil is neutral in flavor and can be used in any dish, including baked goods.
3. Sesame Oil
Sesame oil is one of the oldest oils used in human civilization (19). It has been named the ‘Queen of Seed Oils,’ because of its resistance to oxidation and rancidity in addition to its anti-inflammatory properties (20). Sesame oil contains mostly polyunsaturated fatty acids and has a medium-high smoke point of approximately 410°F. Sesame seed oil has the added benefit of containing high amounts of vitamin K (21). It also contains anti-inflammatory compounds such as sesamol and sesaminol. which have been shown to lower cholesterol, prevent high blood pressure, increase vitamin E supplies, regulate blood sugar, and may even help with injury recovery (22)(23)(24)(25). Sesame oil works well as a general cooking oil or salad dressing. It has a mild nutty flavor that can pair well with Asian and Middle Eastern dishes. As a word of caution, toasted sesame oil should only be used to finish dishes and shouldn’t be heated.
4. Grapeseed Oil
Grapeseed oil is another great cooking oil because it is rich with polyunsaturated fatty acids such as alpha-linolenic acid, vitamins, and phenolic compounds that may have anti-inflammatory, cardioprotective, antimicrobial, and anticancer properties (26)(27). Grapeseed oil has a high smoke point of 420°F, making it ideal for high heat cooking such as sautéing, roasting, and air frying. Grapeseed oil has a neutral flavor which can be used in all types of cooking and baking. It may promote overall skin health by tightening and contracting skin cells (28). The downside of this oil is that it is derived from the seeds of grapes and requires some chemical solvents to create, which may result in trace amounts of potentially harmful impurities such as hexane (29).
5. Coconut Oil
Unlike the previous four plant based unsaturated fat oils, coconut oil contains a fair amount of saturated fat. Although coconut oil has saturated fat, it contains a rich source of medium-chain triglycerides (MCTs), which have been shown to help in weight loss, body fat regulation, and hip circumference reduction (30)(31)(32). MCTs are metabolized differently than long chain triglycerides, going straight to the liver to provide a rapid energy source similar to carbohydrates (33). There are two types of coconut oil. Unrefined coconut oil has a long shelf life but a medium smoke point of 350°F. Refined coconut oil has a more neutral flavor but has a high heat-resistance of 400°F. Both versions have powerful health benefits, such as improving cholesterol levels, killing harmful bacteria, helping with inflammation, and boosting metabolism (34)(35). The taste of coconut oil can range in intensity from distinctly tropical to almost neutral. Coconut oil is a staple in Southeast Asia, South America, and Polynesia cuisine for its warm nutty vanilla undertones.
Whichever oil you choose, do it with confidence in your knowledge of its potential health benefits.