As with many other products on the market, we’re faced with a rather overwhelming choice when it comes to cooking oils. Knowing which one to use when, and which is best for your health can be confusing. It is often tempting to try out the new trending products, but are these fit for purpose?

What is oil?

Oil is essentially liquid fat. This description may sound off-putting, but fat is an important part of a balanced diet. Even though fats are often demonized due to their high-calorie content, they’re essential for health and shouldn’t be feared.

Dietary fat is a required energy source which provides the body with essential fatty acids. Essential fatty acids are vital for cell growth and functioning, as well as the functioning of the brain and nervous system. They also assist in the production of hormones which are necessary for the absorption of fat soluble vitamins A, D, E and K. ‘Essential’ means that these cannot be synthesised by the body and therefore need to be ingested from food sources.

Fats can be broken down into saturated and unsaturated fats (mono, poly and trans), all of which have varying chemical structures and physical properties.

Each oil derives its name from the nut, seed, fruit, plant or grain from which it’s extracted, and is typically referred to according to its most prevalent fat – be that saturated, poly-unsaturated (PUFA) or mono-unsaturated (MUFA)

Saturated fats

Saturated fats are those which are solid at room temperature, for example, those in meat, butter and coconut oil. Over the years, saturated fats have been attributed to heart disease, but recent research has begun to find contradictory results (1,2). That being said and due to the contrasting research over time, it is recommended that no more than 10% of your total energy per day should come from saturated fats.

Unsaturated fats

Unsaturated fats include poly (oily fish, nuts and seeds) and mono-unsaturated (avocado, olives and plant-based liquid oils e.g. canola and olive) fats, and trans-fats. Both mono and polyunsaturated fatty acids have been associated with reduced instances of heart disease (Clifton and Keogh, 2017) namely due to their ability to reduce ‘bad’ cholesterol in the body (LDL). Artificial trans-fats are made by adding hydrogen to liquid vegetable oils to make them more solid.

They give foods a more desirable taste and texture and are often used in the fast-food industry. It is recommended we consume no more than 2% of our dietary intake of fat from trans-fats mainly due to their links with increased risk of heart disease (4).

Oils can be categorised by several factors including taste, processing method and smoke point, all of which provide the oil with its unique qualities and therefore uses.

Smoke point refers to the temperature at which oil begins to burn and smoke. The smoke point varies from oil to oil based on the quality of the oil itself, the processing it has undergone, and any impurities it may contain. Refined oils are often neutral in taste and have high smoke points, whereas unrefined oils have low smoke points and tend to be more flavoursome. Heating oils beyond this point should be avoided as it results in the production of fumes and free radicals that can have detrimental effects on our bodies and our health.

What are some of the different types of oils used in cooking?

Having picked up on the uncertainty over oils, we’ve decided to give you a round-up of a few commonly used ones and the most suitable times, and ways to use them.

• Rapeseed oil – 135 calories per 15ml
  Rapeseed oil is extracted from the rapeseed plant which are widely grown in UK fields. It is used as the cooking oil of choice in the FFF kitchen due to it’s high smoke point, and low saturated fat and vitamin E content.

• Extra virgin olive oil – 135 calories per 15ml
  Olives are crushed at a mill and the oil is extracted by a mechanical process, as opposed to using heat or chemicals. This process produces unrefined, high quality oil, which is full of flavour and contains more of the natural vitamins and minerals found in olives.

• Sesame oil – 130 calories per 15ml
  Sesame seeds are pressed and crushed to produce sesame oil or it is solvent extracted and refined, producing oil of varying colours (depending on the methods used). It is usually equally high in both mono and polyunsaturated fats and relatively low in saturated fat.

• Coconut oil – 115 calories per 15ml
  Coconut oil has received the most attention in recent years. It is extracted from the fruit of a coconut palm tree after the dried meat has been smoked, sun dried or kiln dried. It is high in saturated fat, which has triggered the cause for concern. Studies have linked intake of saturated fat, with raised levels of ‘bad’ cholesterol, which has been indirectly linked with cardiovascular disease (5). However, it should be noted that there is now some research against these claims due to the type of saturated fat coconut oil contains (lauric acid) and no firm conclusion has been made to date. It has been suggested that coconut oil be used sparingly, as with other sources of saturated fat.

What are the factors to consider when choosing a cooking oil?

• Smoke point: It’s best to keep a range of oils in your kitchen for different cooking methods. For example, extra virgin olive oil is a good choice for low- to moderate-heat cooking, while avocado oil is suitable for higher-heat cooking methods like pan-frying and roasting.
• Flavour: Some oils have a more distinctive flavour than others. For example, sesame oil has a rich, nutty taste that pairs well with some recipes but can overpower others. If you’d like a more mild taste, choose avocado oil or olive oil. 
• Price: Unrefined oils, such as high-quality olive oil, tend to be pricier than more refined oils. That said, there are many affordable olive oil options on the market. Therefore, it’s best to shop around until you find a product that suits your budget.
• Container: it’s recommended to purchase oils in dark or opaque containers, which protects the oil from light and helps maintain its quality. 

So, which oil is best?

It really depends

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References

1. de Souza, R., Mente, A., Maroleanu, A., Cozma, A., Ha, V., Kishibe, T., Uleryk, E., Budylowski, P., Schünemann, H., Beyene, J. and Anand, S. (2015). Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ, p.h3978.

2. Siri-Tarino, P., Sun, Q., Hu, F. and Krauss, R. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American Journal of Clinical Nutrition, 91(3), pp.535-546.

3. Clifton, P. and Keogh, J. (2017). A systematic review of the effect of dietary saturated and polyunsaturated fat on heart disease. Nutrition, Metabolism and Cardiovascular Diseases, 27(12), pp.1060-1080.

4. Sun, Q., Ma, J., Campos, H., Hankinson, S., Manson, J., Stampfer, M., Rexrode, K., Willett, W. and Hu, F. (2007). A Prospective Study of Trans Fatty Acids in Erythrocytes and Risk of Coronary Heart Disease. Circulation, 115(14), pp.1858-1865.

5. Sacks, F., Lichtenstein, A., Wu, J., Appel, L., Creager, M., Kris-Etherton, P., Miller, M., Rimm, E., Rudel, L., Robinson, J., Stone, N. and Van Horn, L. (2017). Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association.

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