Oils – part 2


As discussed last week, there are a variety of oils available. Healthy oils have several benefits and should be included as part of a balanced diet, but it is important to consider the effects of heating on the oils we consume.

Heating can reduce the stability of cooking oils and depending on the smoke point, some oils can be heated to higher temperatures than others before becoming unstableThis is important because as an oil breaks down it starts to oxidize which causes it to release free radicals. Free radicals damage our cells and can lead to the development of chronic disease. Overheating or burning the oils we cook with is even more dangerous to our health.

Cheaper oils tend to be more highly processed whereas unrefined oils undergo less processing. Refined oils are typically extracted using chemical solvents, whereas unrefined oils, like those that are cold pressed, are usually extracted by pressing the seeds or plants.

Last week we spoke about olive oil, avocado oil, sesame oil, and peanut oil. This week we discussed coconut oil and some of the vegetable oils, including canola oil and sunflower oil. 

Coconut oil 

There is much controversy around the health of coconut oil. It has a smoke point of 204 degrees Celsius so is good for medium to high heat cooking, but it is primarily a saturated fat. Not all saturated fats are bad though, and as a plant source can still be considered a healthy fat.


Less healthy oils are highly refined and processed. These are either sold as individual plant oils or as blends and include vegetable oil, sunflower oil, and canola oil. 

Vegetable oil 

Vegetable oils are derived from plant sources, and several are blends of palm, sunflower, corn, canola, soybean, and safflower oils. Because they are so processed, they have fewer health benefits. Also, by having an “umbrella” name, manufacturers can freely substitute any of the oils for each other during processing. Processed oils often become rancid during processing because they are heated past their heat tolerance. This means that the oils lose stability and have higher levels of free radicals, making them bad for our health.

Canola oil 

Canola oil is marketed as healthy, but in its highly processed form it loses its health benefits. It contains a combination of mono and polyunsaturated fats, and it has a high smoke point so can be used for deep frying and high heat cooking. 

Sunflower oil 

Sunflower oil contains high levels of vitamin E, but it is also high in omega 6 fatty acids, which can be pro-inflammatory. It also has a high smoke point and so can be used for high heat cooking. 

Whichever oils we choose to cook with, it is important to consume them in their purest and least refined form. It is also very important not to reheat or reuse our cooking oils. When oils are reheated, they produce toxic elements called aldehydes. These toxic elements increase free radical production leading to inflammation in our bodies and ultimately increased risk for obesity, diabetes, and heart disease. 

Listen to my interview with Brad Kirsten from Radio Cape Pulpit on 3 August 2023 to learn more. Listen to my next interview on Thursday at 7.45am.