This article written independently by The British Nutrition Foundation (www.nutrition.org.uk), outlining the nutritional composition of different culinary oils.
All edible oils contain a mixture of different types of fat but the proportions of each vary. For health, it is best to choose oils which contain lesser amounts of saturated fat for everyday use and use those which are high in saturated fat (such as palm oil and coconut oil) sparingly. This is because saturated fat is known to raise blood cholesterol and high blood cholesterol is a risk factor for heart disease.
All edible oils contain some saturated fat but the ones which contain the least include rapeseed, linseed, walnut, sunflower and olive oil. While the essential fatty acid linoleic acid (omega-6) is present in large amounts in many edible oils, the other essential fatty acid, alpha linolenic acid (omega-3), is found in significant amounts in only a small number of oils including rapeseed, soya, walnut and linseed oils.
In the UK, our average intake of saturated fat is above the recommended maximum of 11% of food energy set by the Department of Health. In fact, average intake in adults (aged 19-64 years) is 12.7% and it is slightly higher in older people (13.4% in those aged 65 years and over). So, we all need to reduce our intake by at least 10%. Consumption of monounsaturated and/or polyunsaturated fat in replacement of saturated fat has been shown to lower blood cholesterol. Blood cholesterol lowering may reduce the risk of heart disease.
Some scientists are concerned that an imbalance between the amount of omega 6 and omega 3 fatty acids in the Western diet is having adverse effects on our health. This hypothesis is mainly derived from observations that suggest that as intakes of omega 6 fatty acids have increased and intakes of omega 3 fatty acids have decreased over the last 150 years, there has been a parallel increase in the incidence of heart disease in the developed world.
Theories suggest that a diet with a large amount of omega 6 compared to omega 3 fatty acids might limit the production of the long chain omega 3 fatty acids known as EPA and DHA, which have anti-inflammatory properties and so are important for health. However, studies have not supported these theories and most experts believe that replacing saturated fat in the diet with omega 3 and omega 6 fatty acids, particularly long chain omega 3 fatty acids which are found in fish oil, will reduce heart disease risk.
As well as containing the lowest amount of saturated fat of the oils listed above, rapeseed oil is high in monounsaturated fat and omega 3 fatty acids and contains both of the essential fatty acids (alpha linolenic acid and linoleic acid). Cold pressed rapeseed oil also contains polyphenols, plant sterols and carotenoids.