Most supermarkets have entire aisles with oils. The shelves are heaving with all the cooking oils you can think of: coconut, avocado, walnut, sesame, corn, vegetable, sunflower, rapeseed just to name a few! Even the good old simple traditional olive oil has dozens of options each with enticingly branded slogans.
Which ones are best for our health? This is a question that still to this date, even with all the scientific information I have acquired, I feel doesn’t have a straight answer.
An Indian kitchen will say Ghee & coconut oil are the best cooking oils whilst a Mediterranean one will say olive oil or avocado oil… I needed to investigate and find a satisfactory answer.
I take in account 4 factors, when I choose my oils: calories, taste, cooking method and smoke point.
Let’s begin with calories
Olive, coconut, canola, and vegetable oils each provide roughly the same number of calories per tablespoon.
So fundamentally, consuming oils and fats may be satiating, but they are calorie-rich and should be consumed with some moderation.
What are these fats made of?
The composition of these fats is what impacts our bodies. Whilst some studies categorize oils according to their effect on blood cholesterol levels, some studies show the oxidation at high temperatures produce harmful, carcinogenic aldehydes and lipid peroxides.
So let’s break them down…
- Polyunsaturated fats/oils – when eaten in foods such as nuts, seeds, fish and leafy greens, they have clear health benefits. However, the benefits of consuming sunflower oil and corn oil in cooking aren’t verified.
- Monounsaturated fats/oils – you can find these in avocados, olives (my favourite snack), olive oil and super nuts like almonds and hazelnuts. Olive oil, which is approximately 76% monounsaturated, is a key component in the Mediterranean diet, which has been shown to significantly reduce the risk of heart disease.
- Saturated oils/fats – these fats are very stable at high temperatures. Usually they’re in solid form at room temperature. Although we are encouraged to switch from eating saturated fats, particularly dairy and other fats derived from animals, like butter, the benefits of doing so are being challenged.
The percentages of each in the oils below varies somewhat but these values are typical:
|Type of oil or fat||Polyunsaturated (%)||Monounsaturated (%)||Saturated (%)|
This table shows the heavily monounsaturated oils or fats that seem to be the healthiest choices, with olive oil scoring 1st place on the podium at a perfect balance of fats. Consuming monunsaturated or polyunsaturated fats can contribute to lower LDL (“bad”) cholesterol and triglyceride levels. But what happens when polyunsaturated and monounsaturated fats are heated?
Smoke it till you CHOKE IT?
When cooking with oils, heat causes them to undergo oxidation and the temperature at which this happens is called the smoke point. Of course, there is some form of oxidation in the production & shelving process where oils (like any other foods) suffer a small degree of rancidity due to light, temperature & humidity. However, many oils are not pure, unrefined or extra virgin.
In the production, extraction and processing of cheaper oils, they are highly refined through heat and chemicals to maximize yield and shelf life. This process produces harmful trans fats which have been linked to many health problems, particularly cardiovascular disease.
So when you’re looking to buy good quality fats, try and find the ones that are cold pressed, unrefined or extra virgin for optimal nutrition, taste and quality. These, however, usually have lower smoke points so are best used for dressings, drizzling or sauces.
Higher smoke point oils & fats are best for roasting, baking, sautéing and frying. And this is where it gets tricky! Healthier oils demand proper fatty acid composition (high content of monounsaturated fatty acids, such as oleic acid) but also reduced emission of potentially toxic compounds as aldehydes.
Oils like sunflower oil and vegetable oil, that are high in polyunsaturated fats, when used for frying, produce high levels of aldehydes. An Indian kitchen (certainly a Gujarati one), tends to use oils like sunflower oil regularly. Also reheating oils and re-using them even at temperatures as low as 180C (optimum deep-frying temperature) has proved to show a decrease in smoke point after each usage and therefore higher oxidisation rate and higher emissions of toxic gases & volatile liquids. Sunflower oil is high in omega-6 fatty acids which are thought to be inflammatory.
Rapeseed oil shows much more stability, with a higher smoke point and a good ratio of unsaturated fats (high in monounsaturated). Rapeseed oil is high in unsaturated fats and vitamins E and K. It contains a beneficial ratio of omega-3 to omega-6 fats, which can positively influence heart health.
An interesting study was conducted by BBC’s Trust Me, I’m a Doctor shows how different oils and fats react to heat and the consequential formation of harmful aldehydes with a very visual bar chart.
Turning oils into trans fats takes several hours, according to the Olive Oil Source. This type of transformation will not occur under normal home cooking conditions so I wouldn’t worry too much about this by-product.
How important is taste?
For different cuisines, different cooking oils are best suited. Whilst I prefer sesame oil and peanut oil for Chinese and Japanese Food, I prefer coconut oil for South Indian or Thai cuisine, olive oil for Western and European food, rapeseed and ghee for Indian food, avocado oil for Mexican cuisine
and nutty oils like walnut oil or extra virgin oil for salads and dressings.
This pretty much sums up my oil collection. In my kitchen I have a balance of good fats, both saturated and highly monounsaturated. I tend to avoid highly polyunsaturated fats and reduce cooking with highly saturated fats to a minimum, leaving them for spreading and sticking in my coffee.
There isn’t a “one glove fits all!”
Highly saturated fats like coconut oil, butter and ghee, can contribute to an increase in your blood cholesterol LDL-C (“bad cholesterol”), but are highly stable with heat. However, if you’re vegan, then they do provide you with some fatty acids you wouldn’t be getting from meats.
Highly polyunsaturated sunflower oils & vegetable oils (corn, soy, canola…) are highly processed and refined, therefore cheaper when mass produced. They present a higher health risk, containing trans fats and release toxic aldehydes when used in kitchen cooking, especially when in contact with different foods.
Highly monounsaturated fats like olive oil, nuts, avocados, coconut oil are high in calories and they have health and nutritional benefits as well as antioxidants and polyphenols (especially extra virgin olive oil). Avocado and peanut oils are also great fats for cooking.
So what oils should I cook with?
My conclusions drawn, extra virgin olive oil is the most balanced oil for cooking and the most healthy. It’s very aromatic and intense in flavour so may not always go with all cuisines, therefore my 2nd favourite, especially for shallow & deep frying, is cold pressed rapeseed oil, as my research suggests it has the lowest saturated fat of any culinary oil, only half the fat of and ten times more Omega-3 than olive oil, (7% saturated fat versus 14% in Olive oil). Both Olive oil and rapeseed oil present high smoke points therefore emit less aldehydes during cooking.
I have extensively read papers and abstracts that will contradict the benefits of highly saturated fats like coconut oil in your diet vs highly monounsaturated fats like olive oil. It’s all rather confusing and highly dependent on each individual’s blood cholesterol & history. If you have a family history of cardiovascular diseases or diabetes, then the advice is to refrain from highly saturated fats like butter & coconut oil. Otherwise, just consume fats moderately and watch out for those calories.
A simple way of health-checking your supermarket shelf bought oil, is its smell and taste. Any sign of these being off may mean your oil has gone rancid. But then who opens a bottle of oil straight from the supermarket shelf to smell & taste before buying?
Buy oils that are in small dark glass bottles. Also store your oils in cool, dark and airtight conditions to avoid oxidation.
I would suggest – firstly, avoid deep fried foods, but if you must, then opt for high smoke point fats and oils. Secondly, when you are cooking. try to minimise the amount of oils you use and eat. Soak up excess oil with a paper towel.