Whether we are frying some haloumi for a weekend breakfast, swapping out butter in baking for canola oil, or adding a splash of olive oil to stop our pasta from going gluggy (a tip from Maggie Beers I learnt on the weekend); most of us have a staple bottle, or two in our pantries. But what are the differences between between the oils? Should we all be going loco for coco? Or does olive oil still stand the test of time?
Chewing the fat of the issue
Before talking about oils, it is important to recognise that these fall under the banner of dietary fats and are mostly differentiated by small changes in structure (saturation, chain length) from solid fats such as ghee, lard and butter. The fats we find in foods can be broadly categorised as: saturated, unsaturated and trans fats. Saturated fats are those that are predominantly derived from animal sources, for example: full cream dairy, visible fat on meat, butter and lard. We also find saturated fats added to many processed cakes, biscuits and fried take away foods. Plant oils such as coconut and palm also possess a high proportion of saturated fatty acids. Saturated fats have long been considered to be ‘bad’ fats as they raise the levels of LDL (bad) cholesterol in the body leading to increased risk of heart disease and stroke. Recently this cholesterol link has come under fire from coconut oil enthusiasts (more on this below). However, evidence against a high intake of saturated fats from any source goes beyond just the heart and cardiovascular system. Recently high intake of saturated fats and increase in total cholesterol have been shown to bump up risk of developing Dementia (Barnard et al., 2014). Further research has shown that a high fat intake, particularly saturated fat, increases risk of breast, uterine, prostate and colorectal cancer (Sieri et al., 2014; Bandera et al., 2007; Reddy, 2002; Pelser et al., 2013). There are also some newly established links between saturated fat intake and a less healthy population of gut bacteria. Saturated fats may increase numbers of inflammatory gut microbes, leading to increased risk of inflammatory bowel disease (Conlon & Bird, 2015).
Trans fats act similarly to saturated fats in the body, and may even contribute more to disease risk. Trans fats are naturally occurring in small amounts in dairy products and some meats, but are more often created by manufacturers for deep-frying foods and use in baked products like biscuits, cakes, pastries and buns. Manufacturers prefer these fats due to their stability at high temperatures. The intake of trans fat has been associated with coronary heart disease, sudden death from cardiac causes, and diabetes (Mozaffarian et al, 2006).
Unsaturated fats are found mainly in plant foods and include: avocadoes, nuts, vegetable oils, soya beans, fish and olives. They are considered to be ‘good’ fats not only because they raise the levels of HDL (good) cholesterol and decrease levels of LDL (bad) cholesterol in the body, but because there are a plethora of health benefits that are associated with unsaturated omega 3 fats. These benefits range from reducing levels of inflammation in the body to protecting cognitive function. (Barnard et al, 2014). All the other wonderful properties would fill pages so we will save these for another time.
Which oil is the right choice?
You can be forgiven for a bit of confusion now about the type of ‘fat’ or ‘oil’ you should be choosing, so let’s take a look.
Olives are known to be full of unsaturated fats and this oil has long been heralded for its cardiovascular benefits. Olive oil, particularly Extra Virgin olive oil, is the main fat within a Mediterranean-style diet and it has been established that this sort of diet is beneficial for weight control and heart health. What does the ‘Extra Virgin’ part mean? Extra Virgin olive oil has not been refined or extracted using chemicals or heat, leaving it high in antioxidants and good fats. Whereas, other oils such as light olive oils, are usually extracted using chemicals meaning the health benefits and taste are not the same. Some olive oils will also be labelled ‘cold-pressed’ which means there was no heat used to extract the oil, again preserving nutrients. A good recommendation for Extra Virgin olive oil is use on salads and dipping for breads due to a slightly lower smoke point (point at which the oil burns). Plain olive oil may be better for use in cooking; grilling and lightly sautéing with a smoke point between 160-200 degrees Celsius.
Canola oil is derived from a specially cultivated version of rapeseed. It has higher levels of unsaturated fats than olive oil, although it lacks the antioxidants due to being more highly refined. Canola oil has a smoke point of 200 degrees Celsius making it a good choice for higher temperature cooking such as stif-frying and frying. Canola oil can be used successfully in baking as it has a much more subtle flavour than olive oil.
Sunflower oil is made from compressing the seeds from sunflowers and is a good source of both unsaturated fats and Vitamin E. Vitamin E plays an antioxidant role within the body. Sunflower oil also has a high smoke point, estimated at above 200 degrees Celsius, which makes it suitable for frying.
Coconut oil is made from the flesh of coconuts and has a fat profile quite different to the oils considered so far. Coconut oil is 92% saturated fat (more than butter), which is where the concern lies. Many proponents of this oil argue that the saturated fat in coconut oil behaves similarly to good fats. However, research has shown that while HDL (good) cholesterol generally rises with a higher intake of coconut oil, so does LDL (bad) and Total Cholesterol. Coconut oil has a strong flavour with a smoke point of 177 degrees Celsius. It is most useful in Thai/Vietnamese cooking, or where a coconut flavour is desired.
This oil, derived from peanuts, is very popular in Asian cooking. Its fat profile is very similar to olive oil; however, its strong taste means it is often best in dishes that demand certain flavours. It has the highest smoke point of any of the oils discussed thus far at 230 degrees Celsius. If you’re thinking about deep frying (not that we encourage this) then you’ve found a good choice.
Overall, we should be looking to have a moderate fat intake in our diets, which includes plenty of unsaturated fats such as those present in olives, canola oil, sunflower oil, nuts, avocadoes and fish. We should be aiming to decrease the amount of saturated fat we are eating particularly from animal sources, in order to achieve good cardiovascular, brain and gut health. When considering which oil to choose, think about what food preparation methods you will be using and which flavours you’d like imparted. A good oil is an important foundation for any dish.
Bandera, E., Kushi, L., Moore, D., Gifkins, D. & McCullough, M. (2007). Dietary Lipids and Endometrial Cancer: The Current Epidemiologic Evidence. Available: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2601627/
Barnard, N. , Bunner, A. & Agarwal, U. (2014). Saturated and trans fats and Dementia: a systematic review. Available: http://www.sciencedirect.com/science/article/pii/S0197458014003558
Conlon, M. & Bird, A. (2015). The Impact of Diet and Lifestyle on Gut Microbiota and Human Health. Available: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303825/
Mozaffarian, Dariush ; Katan, Martijn B ; Ascherio, Alberto ; Stampfer, Meir J ; Willett, Walter C (2006) Trans Fatty Acids and Cardiovascular Disease NEJM,Vol.354(15), pp.1601-1613
Pelser, C., Mondul, A., Hollenbeck, A. & Park, Y. (2013). Dietary fat, fatty acids, and risk of prostrate cancer in the NIH-AARP diet and health study. Available: http://www.ncbi.nlm.nih.gov/pubmed/23549401
Reddy, B. (2002). Types and amount of dietary fat and colon cancer risk: Prevention by omega-3 fatty acid-rich diets. Available: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2723490/
Sieri, S et al. (2014). Dietary Fat Intake and Development of Specific Breast Cancer Subtypes. JNCI, Vol. 106(5), dju068.
This blog is a combined effort with contributions from guest blogger Shannon Morley APD.