Which oils are better?
A recent article about oils in Australian Doctor Magazine* has prompted an update on this important topic. Everyone is aware of the importance of fat content in the diet, but the detail of what fats/oils are good and what are not, and how much overall can be consumed, is not so straightforward.
Most people know to avoid ‘saturated’ fats. ‘Saturated’ is a chemical term referring to the structure of the fat molecule and including fats which are solid at room temperature such as butter and other animal derived fats. In contrast, ‘unsaturated’ fats the ‘fats’ derived from vegetable and marine sources, although not all vegetable derived oils are ‘unsaturated’. These obviously less desirable vegetable oils include coconut or palm oil (in spite of recent promotion, so check the labels on the packaging!). Another trap, that is now less of a trap because of a change in manufacturing processes, are ‘trans fats’, which are a byproduct when vegetable oils are processed a certain way (the process is called ‘hydrogenation’). Nevertheless, if oils do not state or have a significant ‘trans fats’ component, it may be best to avoid them.
The ‘unsaturated’ oils, which as I said are the preferred oils, include ‘monounsatured’ and ‘polyunsatured’ oils, the latter of which include oils such as linseed (flaxseed), soybean, sunflower, safflower and canola oil and the margarines derived from these oils by processing. Monounsaturated oils include the olive oil which contains ‘oleic acid’. The polyunsatured oils include both the ‘omega 6s’ and the ‘omega 3s’.
So…what is better amongst the unsaturated oils? The omega 3’s, which I would put in the ‘very polyunsaturated’ category, are said to have the cardiovascular benefits and include those from oily fish plus the linseed (flaxseed) oils. Margarine made from canola or soybean also have an omega 3 content, and the amount should be specified on the packaging. Some studies however have not shown a proven cardiovascular benefit. There is ongoing research about the optimal proportions of omega 3 and omega 6 oils in the diet to optimise cardiovascular health, ie avoiding an excessive ratio 6’s over the 3’s. For references:
The omega 3 oils are said to oxidise ie lose their beneficial properties, at normal cooking temperatures especially if not stored in a cool location away from sunlight, and cooking with a monounsatured oil ie extra virgin olive oil, which does not ‘smoke’ until 210 degrees, may be the preferable when selecting an oil for cooking. Linseed oil does contain omega 3s as discussed but must be refrigerated if stored for extended periods or else it becomes rancid.
For an excellent discussion of the omege 3’s, please refer to the National Heart Foundation’s website at:
*full access to Australian Doctor Magazine content is not available to the general public