Cooking Oil Smoke Point - Why Does It Matter?

There are few things that cause chaos confusion and arguments like cooking oils. Which is best? Should they be used at all? Well, I have written a fair bit around what I feel is the right option to use and why. You can see that here and here.

So in this piece I just wanted to talk about the one thing that comes up in conversation all of the time. Smoke point! This is one of the main arguments that people use, but what does it mean and what are the issues surrounding smoke point?

What IS a smoke point

So, this may not come as a massive shock, and likely you don’t need to employ Taggart to decipher this. But, it is when a heated oil begins to smoke! Revelation I know. But the issue is, chemical changes can begin to occur at smoke point and this is what gets many people worried. Justifiably so I would say. When oils hit this point they go through some notable changes on a chemical level which can affect flavour and texture, but more importantly have some notable impacts upon health (Smith, 2018).

An oils smoke point is determined by the fatty acids it is composed of, and the presence of impurities, natural or otherwise. Many unrefined oils that would naturally contain more impurities have a lower smoke point than their refined counterparts (Johnson & DeFelice, 2020).

What changes occur at smoke point

At the moment an oil hits its smoke point, changes begin to occur. These chemical changes include oxidation, polymerisation, and hydrolysis (Lopez et al, 2021). So why would this matter? Oxidation will cause harmful free radicals to form in the oil. Polymerisation causes the formation of very large complex molecules that alter the texture of the oil, but also render many of its beneficial nutrients to no longer be bioavailable. Hydrolysis breaks down the structure of the oil, leading to the liberation of glycerol and free fatty acids.

So what does this mean for our health?

The health implications of these chemical changes really is relative to how often you use oils that have got to that temperature. If it is once in a blue moon, there is absolutely nothing to worry about. If on the other hand it happens breakfast lunch and dinner, there is a different issue. So what are the potential health implications? The most notable are:

Aldehyde formation - these substances are produced during oxidation. Many studies have shown that aldehydes have the potential to be carcinogenic and increase oxidative stress (Petersen & Abraham, 2020).

Free radical formation - these potent damaging substances have been well documented. We know they are harmful, but did you know they play a key role in the aetiology of many degenerative diseases such as cardiovascular disease and type 2 diabetes (Kumar & Goel, 2020). Keeping our free radical load as low as possible is essential.

Nutritional degradation - the final but least serious issue is that oils that have been held at smoke point will eventually degrade. This means that their fatty acid content and fat soluble nutrient content will change making them less nutritious overall (Brown et al, 2022).

Recommendations

I have documented many times my preferred choice of oil and why. Again you can find this here and here.

In general though I recommend that any stove top cooking be fast. Think stir frying or sautéing. get in. get it done. Get out. Then when you do use something like olive oil (Miller & Smith, 2021). Also. whatever you do, do NOT reuse oil. This will compound everything (Zhao et al, 2023).

For high temperature cooking - think roasting etc, I always recommend things like coconut oil that are saturated fats and are not anywhere near as susceptible to damage as liquid oils are.

References

Brown, A., et al. (2022). ‘Impact of Cooking on Fatty Acids and Vitamin Content in Oils’, Journal of Nutritional Science, 4(1), pp. 45-54.

Johnson, L., & DeFelice, N. (2020). ‘Smoke Points of Different Cooking Oils and Their Impact on Health’, Food Chemistry, 315, pp. 126284.

Kumar, P., & Goel, N. (2020). ‘Effects of Free Radicals on Health and Their Mitigation Strategies’, Critical Reviews in Food Science and Nutrition, 60(18), pp. 3031-3046.

Lopez, G., et al. (2021). ‘Chemical Reactions in Cooking Oil at High Temperatures’, International Journal of Food Science, 2021, pp. 7639105.

Miller, J., & Smith, T. (2021). ‘Choosing the Right Oil for Cooking: Smoke Points and Health Considerations’, Journal of Culinary Science & Technology, 19(3), pp. 234-247.

Petersen, D.R., & Abraham, T.M. (2019). ‘Oxidative Stress and Aldehydes in Cooking Oils: Health Implications’, Journal of Food Science, 84(8), pp. 2091-2101.

Smith, J. (2018). ‘Understanding the Smoke Point of Oils’, Culinary Nutrition Today, 2(2), pp. 10-13.

Zhao, X., et al. (2023). ‘Health Risks of Repeatedly Heated Cooking Oils’, Journal of Environmental Health, 85(6), pp. 8-15.