Four vegetable oils you may use during frying in moderation, and six oils you must avoid for the sake of your life!
Frying is one of the most common and convenient food preparation methods. Many of us use frying one way or another, whether is deep-frying or stir-frying while preparing a meal. Although it’s used very frequently, frying is not an optimal food preparation method. First, frying reduces the nutrient content of our food. Exposing edible oils to heat significantly reduces the oils’ antioxidant content as well as the nutritional content of many other food ingredients. But, the story doesn’t end here. Not only we lose valuable nutrients, but also we create many harmful molecules in the process of frying. Heating edible oils in the presence of oxygen in the air causes the production of many harmful molecules such as lipid peroxides, cholesterol oxide, advanced glycation end products, and polymers. These molecules are contributing factors to many chronic and degenerative diseases such as cardiovascular diseases, inflammation, Alzheimer’s disease, neurodegenerative disease, Parkinson disease, ocular and kidney degeneration as well as cancer. (To learn more about these harmful compounds, check out our article honey dinner is ready. Run for your life!)
Although we started with bad news (that frying almost always results in some undesirable effect on our food), there is also some good news. The good news is that some oils are more stable than others, minimizing the extent of harm done to our food. Let’s review some of the common and less common cooking oils here:
Corn oil, sunflower oil, safflower oil, soybean oil:
Corn oil, sunflower oil, safflower oil, and soybean oil are all high in polyunsaturated fatty acids. Oils that are very high in polyunsaturated fatty acids are more reactive to oxygen when heated. In the presence of heat, the polyunsaturated fatty acids in these oils react with oxygen, giving birth to lipid peroxides. As their names represent, lipid peroxides are oxidizing agents. They enter our bodies and can oxidize our DNA, cell proteins, and lipids thereby causing a variety of chronic diseases or even death. In fact, lipid peroxides have been linked to cardiovascular diseases, inflammation, Alzheimer’s, neurodegenerative disease, Parkinson disease, cancer, ocular and kidney degeneration.
In summary, corn oil, soybean oil, sunflower oil, and safflower oil are considered very unstable in the presence of heat and thus should not be used during cooking or frying. Unfortunately, these oils are some of the most common commercially available oils promoted for cooking and frying.
An additional note on soybean oil:
Soybean oil’s bad news doesn’t end with its high production of lipid peroxide in the presence f heat. Not only soybean oil is easily oxidized when heated, but it also leads to mutagens production. Heating meat and soybean oil together (as in frying or grilling meat with soybean oil) produces mutagens, potentially contributing to the development of cancer. Also, excessive commercial soybean agriculture (used in veggie burgers, tofu, as well as soybean oil) has been responsible for significant deforestation, species extinction, and detrimental environmental damage.
Canola oil is different in its composition than the above-mentioned oils. Canola oil contains more monounsaturated fatty acids which protect it from excessive lipid peroxide production. However, canola oil has a high content of an omega 3 fatty acid, called alpha-linolenic acid. We all know that omega 3 fatty acids are generally good for us. But, alpha-linolenic acid is very unstable in high temperatures. When heated, alpha-linolenic acid gives birth to carcinogens and mutagens, contributing to the development of cancer. In fact, some studies have found a link between using canola oil during cooking and development of various cancers.
Since palm oil is high in monosaturated fatty acids, it is a relatively healthy oil for cooking. However, our palm oil consumption is harming us indirectly by harming our planet. The palm oil industry has been causing significant environmental damage such as alarming deforestation. Excessive commercial palm agriculture and timber have led to detrimental tropical deforestation in different countries, as well as greenhouse gas emissions, contributing to alarming climate changes. In addition, as a result of deforestation, many animals and species have lost their living habitats, thus facing the danger of extinction. In summary, cooking with palm is dangerous to our planet which in turn is a danger to us and our wellbeing.
peanut oil is rich in monounsaturated fatty acids which protects it from forming excessive lipid peroxides in the presence of heat and oxygen. It also has a relatively high smoking point. Peanut oil can be used as a healthy oil option for cooking.*
* Allergy warning: Peanut oil is at a disadvantage because of the rising epidemy of serious (anaphylactic) allergic reactions to peanut. Thus, cautious needs to be used if anyone in the household has any anaphylactic reactions to peanuts.
Coconut oil is one of the healthiest oils when it comes to cooking and frying. Coconut oil has a high content of saturated fatty acids as well as a high content of natural antioxidants.
Although there is a debate on the detrimental effects of saturated fatty acids on our health, this does not include coconut oil. Coconut oil’s saturated fat is plant-based. This means although it is high in saturated fat, unlike butter or other animal fats, coconut oil contains zero cholesterol content. In fact, various researches have found that frequent coconut oil consumption contributed to a reduction of total and LDL “bad” cholesterol as well as lowering triglycerides in the blood, thus promoting health.
The low degree of unsaturated fatty acids content with the presence of natural antioxidants makes coconut oil one of the most resistant oils to oxidation and thus one of the healthiest oils for occasional cooking and frying.
Avocado oil is one of the less commonly used cooking oils uuy6san the market. Avocado oil has a high smoking point and is very resistant to oxidization as well as other harmful reactions when heated. This makes avocado oil another amazing cooking oil and a great choice for occasional frying or grilling.
Similar to peanut oil, virgin and extra virgin olive oils contain a high amount of monosaturated fatty acid, which protects them from forming lipid peroxides in the presence of heat and oxygen. In addition, virgin and extra virgin olive oils contain a high content of antioxidants, called polyphenols. Polyphenols protect the olive oil during heating by scavaging the oxidizing agents. Therefore, although olive oil loses some of its antioxidants in the face of heat, it is protected from becoming saturated with harmful compounds.
These criteria make high-quality olive oil to be one of the healthiest oils when heated.
In fact, several studies have shown extra virgin oil to be the healthiest frying oil, followed closely by coconut oil and avocado oil.
Other guidelines to keep your cooking oil healthy:
– Mind your cooking temperature:
During frying or grilling, ensure to keep the temperature as low as possible. As the temperature of oil increases, it significantly becomes more prone to degradation and undesired chemical reactions. As a rule of thumb, if your oil is smoking or you smell burnt or “heated” oil, you have gone too far.
– Avoid pre-heating the oil:
Never heat the oil in an empty pot or pan. Heating oil without food ingredients significantly increases the oil’s temperature, leading to oil degradation.
– Avoid deep frying or reusing the cooking oils:
Deep frying (used to prepare chips, French fries, doughnuts, chicken wings, and many other fried foods) is even more problematic than stir-frying. Not only deep frying involves a much higher temperature compared to stir-frying, but also often involves adding new oil to an already used oil. This unhealthy practice leads to further accumulation of the harmful compounds in the oil. In addition, oils become more subjective to oxidization and degradation when they are repeatedly heated and cooled down. Oxidized fat damages kidneys, heart, and liver among many other organs. Also, eating food types that are prepared with reused oil at home or having deep fried food from fast food places are associated with high blood pressure.
In summary, best practices when it comes to cooking is to avoid frying as much as you can. You may use healthier cooking options instead. If you must fry, fry minimally, with low heat and use healthier oils. As mentioned before, among the oils reviewed in this article, extra virgin oil has been found to be the healthiest frying oil, followed closely by coconut oil and avocado oil.
May food be our medicine and not our poison!
Dr. Rasa Nikanjam, BSc, ND, A Holistic Healing Practitioner
Would you like to see how well you are using your oils? Take a self-assessment “Am I Using My Cooking Oils Correctly?” quiz to find out.
Too much information to retain? No worries. We have compiled a Healthy Cooking Oils Guide for you that summarizes everything mentioned above. Click here to access and download our Free Healthy Cooking Oils Guide.
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