A Healthy Cooking Oil

Last edited, 13 April 2020.

To choose a healthy cooking oil, we can base on the following two criteria:1)  The omega-6 to omega-3 fatty acids ratio of the oil2)  The smoke point of the oil

What is a good Omega-6 to Omega-3 Ratio

The optimal ratio of omega-6:omega-3 in our diet should be 1:1

Omega-6 and Omega-3 fatty acids are essential fatty acids that our body needs.  However our modern diets may contain as much as 25 times more of omega-6 to omega-3.  

What happen if one consumes too much omega-6 fatty acids?

When omega-6 is excessive, it risks the following health concern:

  • Cardiovascular disease and stroke
  • Cancer
  • Inflammation 
  • Autoimmune disorder
  • Asthma
  • Depression
  • Neuro-degenerative disorder  

Cooking oils, specially plant oils are usually the main source of omega-6 fatty acids in our daily diet.  Most plant oils are high in omega-6 fatty acids.  To have an idea of the ratio of omega-6:omega-3 cooking oil that we commonly use, you may refer to the following table.

    OilOmega-6:Omega-3 Ratio  
    Perilla seed oil1:4   
    Macadamia nut oil1:1   
    Canola oil2.1:1   
    Soybean oil7.1:1   
    Olive oil12.8:1   
    Rice bran oil20.9:1   
    Tea seed oil31.8:1   
    Peanut oil32:0   
    Corn oil46.1:1   
    Safflower oil132.5:1   
    Sesame oil137:1  
    Cottonseed oil259.4:1   
    Grapeseed oil676.1:1 

Table 1:  Omega-6 to Omega-3 Cooking Oils Ratio
To note: Plant foods are beneficial to health.  But when oil is extracted from them, their molecular structure undergo changes and most nutrients are destroyed.  Thus high consumption of any oil is not beneficial to our body.  If one must consume oil, choose oils with the fewest disadvantages. 

Cooking Oil with the correct Smoke point 

Smoke point refers to the temperature at which cooking oil starts to smoke
Each type of cooking oil has its smoke point.  Once the temperature of its smoke point is reached, it starts to break down and produces carcinogenic substances.  One of which is Malondialdehyde which is a possibly carcinogenic substance that is cytotoxic, affects enzymatic activity and speeds up process of aging. 
The following table shows the smoking point for some of the common cooking oils.

    OilSmoke Point
    Perilla seed oil202 – 250   
    Macadamia nut oil210
    Canola oil204
    Soybean oil160
    Olive oil160
    Rice bran oil254
    Tea seed oil252
    Peanut oil160
    Corn oil160
    Safflower oil266 
    Sesame oil177
    Cottonseed oil216   
    Grapeseed oil216

Table 2:  Smoke Point for Cooking Oils
For common Asian cooking methods, temperatures can reach 190°C for stir-frying in high heat or deep-frying.  Therefore an oil with a smoke point higher than 190°C is ideal.
Based on Table 1 and Table 2, Macadamia oil and Perilla seed oil that have high smoke points of over 200°C and at the same time an ideal omega-6:omega-3 ratio.Macadamia Oil with Perilla Seed Oil therefore give a more stable blended cooking oil. 

The Don’ts 

1.  Do not reuse Cooking Oil 

It contains malondialdehyde that is a possibly carcinogenic substance.  When oil is recycled repeatedly, the level of malondialdehyde in the oil increases to 10 times or more.  Oil that is used repeatedly has lowered smoke point.  As such, toxic substances are produced more easily.  When cooking Asian dishes involving high-heat stir-frying, select cooking oils with higher smoke points. 

2. Refined oil is not safe for consumption 

Refining of the oil raises their smoke point.  During the refining process, harmful extraction agents such as hexane and heptane are added.  Though they are removed by distillation after the process, there may still be residues. 
Nutrients are also lost during the refining process. 

3. Must not contain harmful substances 

The cooking oil must not contain harmful substances like erucic acid that is commonly found in canola oil; or gossypol that may lead to chronic poisoning and affect fertility.