Time to give your heart (and wallet) an oil change

Extreme weather events in Europe, where most of our olive oil is imported from, have led to reduced olive harvests and higher prices for olive oil on our supermarket shelves. In March it was estimated to be the highest global price in 26 years.

Only about 10 percent of the olive oil used in New Zealand is produced here, and that’s mainly extra virgin olive oil, but we too have suffered reduced production because of damage caused to olive groves by Cyclone Gabrielle and excessive rainfall. So, if you’re looking to cut back on the cost of living, what other oils can you turn to, to drizzle on salads, bake and fry with, that taste good and are kind to your heart?

Most of us are familiar with the Mediterranean-style of eating, with lots of vegetables and fruit, legumes, fish, and lashings of olive oil. This way of eating has been associated with a lower risk of heart disease and this benefit is often attributed to olive oil. But given that olive oils are now one of the priciest vegetable oils on our supermarket shelves, with extra virgin olive oil at the higher end of the range, what are the other options? Sunflower oil, soybean oil, canola oil, and rice bran oil are all much cheaper (about a quarter to a third of the price of olive oil) – so can we just use them instead, and if we do, will they be equally ‘good oils’?

It depends on what fats make up the oil, and what you want to do with them. Vegetable oils all contain different mixtures of saturated, monosaturated, and polyunsaturated fats, and these types of fats have different effects on our heart health. Saturated fats are one of the worst kinds of the fats from a health perspective.

Mono- and polyunsaturated fats are regarded as the “good” unsaturated fats. Monounsaturated fats are found in olive, peanut and canola oils, avocados, and some nuts and seeds. Polyunsaturated fats are also found in some nuts and seeds too, as well as sunflower, corn soybean, flaxseed, and canola oil.

Putting things very simply in biochemical terms, monounsaturated and polyunsaturated fats have a ‘kink’ in their structure which makes them liquid at room temperature, and the saturated fats are straight, and ‘stack’ nicely and therefore are tightly packed and are solid at room temperature.

There’s good evidence that replacing saturated fat with monounsaturated fat or polyunsaturated fat in the diet decreases blood levels of LDL cholesterol – the ‘bad’ cholesterol – and that lower levels of LDL cholesterol reduce your risk of cardiovascular disease. The evidence also shows that for cholesterol at least, polyunsaturated fats are the better of the two good fats, reducing LDL cholesterol even more so than monounsaturated fat.

Olive oil and avocado oil are mostly made up of monounsaturated fat. Coconut oil contains mainly saturated fat. So if you are going to fork out for an expensive oil, your heart would likely thank you if you chose olive oil or avocado oil before coconut oil. This is also why it is better to limit how much butter you use, which is also high in saturated fat.

Of the less expensive vegetable oils, sunflower and soybean oils are predominantly polyunsaturated fat, whereas canola and rice bran oils are more of a mix of polyunsaturated and monounsaturated fat. There is some concern circulating, especially on social media, that seed oils such as sunflower, soybean, canola, and rice bran oils cause inflammation and other side effects, but there’s no robust evidence to support these claims. And, if you were wondering about trans fats (one of the very worst kinds of fat for your heart), you can relax – regular liquid vegetable oils that you buy from the supermarket typically contain very little, if any, trans fat.

If you’re not already feeling spoiled for choice, it is worth considering what the oil is going to be used for. If, for instance, it will be used in a dressing, as an ingredient in cakes and muffins, or for frying.

For a salad dressing, olive oil or avocado oil provides a good flavour, but cheaper vegetable oils will also work just as well, and with the right flavourings such as herbs and spices, mustard, honey and so on, will taste good too.

A plain oil that doesn’t have flavour is good for baking, such as sunflower, canola, soybean, and rice-bran oils. If you’re using oil for frying, you’ll need oils with good heat stability as oils degrade with direct heating and produce compounds that may be harmful to health. Although it’s often thought you shouldn’t use olive oil in the frying pan, particularly at high temperatures, high quality extra virgin olive oil has been shown to be very heat stable during frying.

At the cheaper ‘good-for-frying’ end of the spectrum, canola and rice bran oils (high in monounsaturated fats) are better than sunflower and soybean oils, the latter of which are high in polyunsaturated fats and aren’t as heat stable.

Another thing you should pay attention to is the container it comes in. We’d recommend oil that comes in a dark-coloured bottle, because oil in clear or light-coloured glass or plastic bottles can be ‘light-struck’ and taste rancid or ‘off’. Unfortunately, a lot of the vegetable oils on our shelves come in clear containers, so if you can’t avoid choosing one, reach to the back of the shelf and pull out a bottle that has been sitting in the dark. Check the best-before date, and make sure you store your oil in a dark cupboard.

In summary, extra virgin olive oil is the most expensive but also the most versatile and stable when used for frying or as a drizzling oil on, for instance, salads, and also likely to taste the best and be good for your heart. But there are cheaper alternatives: sunflower, soybean, canola and rice bran oils for baking and in salad dressings, and canola and rice bran oils are your best bet for frying. Whichever oil you choose go for the one in the dark container or keep it somewhere dark.