Fats are one of the important food categories, which are essential to any balanced healthy dish. It is imperative that we include a small amount of oils in our everyday diet to provide us with the fundamental fatty acids that our bodies cannot manufacture and are critical to proper function.
These acids are categorized into two polyunsaturated fatty acids: Linoleic acid and Alpha-linolenic acid. Cooking oils are all made up of three different types of fatty acids: monounsaturated fat (MUFA), polyunsaturated fat (PUFA), and saturated fat (SFA). Each oil is categorized based on the type of fatty acid most existent in it.

The main concern pertaining vegetable oils lies in their exposure to high temperatures, especially when used in repeated heating (reuse of frying oil), as it accelerates the oxidative decomposition of fats and depletes the natural antioxidant contents of the oil. As a result, our anti-oxidant defense mechanism weakens massively and we become vulnerable. Therefore, reheated oil should be classified as a public health risk due to the potential toxicity of the products of the thermal reaction of oil oxidation.

As for the connection between fatty acids and blood fats and their relationship to cardiovascular disease, it is well established that most studies recommend and encourage reducing the consumption of saturated fats (SFA) and replacing them with polyunsaturated and monounsaturated fatty acids (PUFA & AMP; MUFA) to reduce harmful cholesterol (LDL) and thus reduce the risk of heart
disease. Furthermore, polyunsaturated fats (PUFA) reduce the level of LDL and triglycerides in the blood (TG), and thus reduce the risk of heart disease by 29%, compared to monounsaturated fats (MUFA).

How do I choose the best oil?

Store shelves are ‘’saturated” with different types of oils at different prices. The higher price does not mean the better the brand is. Therefore you should consider some points that will help you to reach a healthy choice without compromising the taste:

1. Containers: The oil should be in dark bottles, which prevents the penetration of heat and light.

2. Expiry: It is advisable to stick to the shelf life usually mentioned on the packaging.

3. Smoke point: The degree at which the oils begin to decompose and oxidize, knowing that each oil has its own degree and should not be exposed to a higher temperature than this point. You must know that low smoking-point oils are best for garnishing, sauces, and dipping, while high smoking-point oils are best for roasting, baking, stirring, and frying.

4. Taste and nutritional value: Each oil has a special flavor, and some of them are a stronger flavor than others, this all depends on your taste and choice. As for the nutritional value, there are oils rich in calories, and they are those that contain a high percentage of saturated fats.

Canola Oil:

Smoke Point = 205 C / 401 F

Canola oil is high in monounsaturated fats, but despite this fact (62% of the fat in this oil is monounsaturated), canola oil is also a good source of trans fats. In addition, canola oil has the lowest level of saturated fat among cooking oils (7 %), and it is also one of the few oils
that contains a good vegetable source of omega-3 fats, a beneficial type of polyunsaturated fat.

Canola is a versatile, light-tasting, inexpensive cooking oil that can be used in a variety of ways, from baking and grilling to stir-frying, dipping, and salad dressing.

Sunflower oil:

Smoke Point = 225 C / 437 F

Sunflower oil is flavor-neutral and has one of the highest concentrations of polyunsaturated fat (69 %) among cooking oils. It provides some monounsaturated fat (20 %) and is low in saturated fat (11 %), making it an overall healthy choice for the heart. Sunflower is a good all-purpose oil because it can withstand high cooking temperatures.
Amongst the sunflower oils, there is a “high oleic” type where this oil has been modified to be richer in oleic acid, which boosts levels of monounsaturated fats, and high oleic oils are an alternative to trans fats, which are hydrogenated oils that can extend the shelf life Processed foods.

Olive oil:

Smoke Point = between 163C / 325 F for extra virgin olive oil and 240.5 C / 464 F for light olive oil.
Olive oil is popular cooking oil. Virgin olive oil comes from the first olive pressing of the season. This results in an oil that is less processed, which means that it is considered “unrefined.” It is also usually more expensive than other types of olive oil and contains the most antioxidants. Refined versions of olive oil, called "Pure"; are lighter in color and lighter in flavor than extra-virgin oil.
Olive oils usually contain the highest amounts of monounsaturated fats in comparison to other cooking oils.
A study in Spain of nearly 7,500 men and women at risk of heart disease found that people who were advised to eat a diet supplemented with extra virgin olive oil or nuts had a lower rate of heart attack, stroke, and death from heart-related causes, compared to people who were advised to Just following a low-fat diet in general. These findings appeared in 2013 in the New England Journal of Medicine.
The extra virgin olive oil is sometimes not the best, for example, when frying, it cannot withstand very high heat before it starts burning and smoking. Refined or pure olive oil may be more suitable for cooking at higher temperatures, but extra-virgin olive oil is a good choice for dipping or preparing salad dressings and pickles.

Corn oil:

Smoke Point = 230 C / 446 F

Corn oil is not considered a healthy oil, due to its very high-calorie count and contains equal proportions of monounsaturated fats, and saturated fats, which amount to 43%, while it contains 11% of polyunsaturated fats, and it is one of the mid-range smoke point oils, in addition to its moderate flavor, making it suitable for various cooking methods such as grilling, baking, and frying.

Although it contains some healthy ingredients, it is subjected to extensive processing and refining, which leads to oxidation, in addition, to heating it leads to the production of a highly possible carcinogenic compound called acrylamide. This compound is associated with negative impacts at the neuromuscular and hormonal functional levels. Adding to this, it is very high in calories, therefore not recommended to use on regular basis.

Coconut oil:

Smoke point = between 175 C – 232 C / 347 F - 449 F

Made from the fruits of the coconut palm tree, it has a distinctive coconut flavor that some may prefer, while it may not suit some. There are two types:

1) Refined : Smoke point = 232 C / 449 F. Ideal for cooking.
2) Virgin : Smoke point = 175 C / 347 F. Not ideal for cooking for sure.

Highly Important :
Coconut oil has been promoted as a better alternative to butter, which is a white solid at room temperature with a consistency similar to butter or ghee rather than liquid oil.
However, this is a myth as it can increase your weight due to its high 92 % saturated fat content. Therefore it is fine in small amounts. In fact, coconut oil contains more saturated fat than the same amount of butter or lard.
There are also claims that coconut oil is much better for the heart than butter, but after evaluating all the available studies, people who eat coconut oil have more LDL cholesterol levels than those who consume trans fats.
The American Heart Association committee concluded that coconut oil “increases LDL cholesterol, a known cause of heart disease, and has no known compensatory effects.”
Therefore it is not your best choice if you are health conscious.

In Summary:

We must always be careful to select the best choice, as many oils such as corn oil carry many benefits in its natural form, but what we find on store shelves is genetically modified corn oil that is exposed to manufacturing processes that hydrogenate and oxidize it causing some nutrients loss resulting in bodily harm that outweighs its benefits. There are oils such as canola oil, which carries many risks to public health, as it is the result of genetically modified rapeseed that has gone through many manufacturing processes until this oil becomes usable. Thus, oils such as olive oil that are pressed and used directly without exposing them to manufacturing processes are better for our health.
We also need to spread public awareness not to repeat the use of oil in various cooking processes and to expose it to high temperatures, because of the danger regardless of the type of oil used.

Written By: 

Dietitian Hanaa Nazzal

References:

1) "Cooking Oils And Smoke Points" Written by the MasterClass staff.

2) "Effects of Repeated Heating of Cooking Oils on Antioxidant Content and Endothelial Function" published By ResearchGate.

3) "The Effect of Coconut Oil Consumption on Cardiovascular Risk Factors" Published by the American Heart Association.

4) "Physiochemical properties of short‐term frying oil for the chicken wing and its oxidative stability in an oil‐in‐water emulsion" Published By National Library of Medicine.

5) "The Science of Cooking Oils: Which Are Really the Healthiest?" Published By Live Science