Olive oil is a oil obtained from the pressing of olives, the fruit of the olive tree. The olives are picked and washed before being crushed, producing a paste. The paste is stirred to break down to soften (maceration) and then spun in a centrifuge to pull out the oil as well as pulling out water, the latter is then removed, leaving olive oil.
Olive oil is essentially a fat, high in monounsaturated fat and lower in saturated fat. Typically the composition of olive oil is 73% monounsaturated fat, 14% saturated fat with 9% polyunsaturated fat (Omega-6), with some Omega-3, less than 1%.
Research by the University of Glasgow seems to prove that olive oil may have many benefits in helping protect against coronary disease. Their research was based on measuring certain proteins excreted in urine using the proteomics technique.
This allowed certain markers associated with heart disease to be picked up, showing whether the ingestion of an oil was making these markers more predominant or not. Their research pointed to a reduced number of markers when cold olive oil was taken over a several week period.
The Mediterranean diet has long been advocated as a model in reducing deaths from heart disease with populations specifically pursuing this diet, living longer and being more healthier than counterparts on traditional diets. Recent research has shown (University of Glasgow), the key contributor to longevity may not be the diet itself but the copious amounts of olive oil ingested as part of this diet.
Olive oils benefits as a moisturiser require further research, as Olive oil contains low levels of oleic acid which can make the skin more susceptible to moisture loss. Eczema sufferers may be more susceptible to moisture loss using olive oil and alternative proven moisturisers may be better suited.
Cooking in olive oil may be healthier than using other oils such as vegetable oils. It's important to use the right olive oil as some olive oils are not suited to cooking.
Pure Olive Oil has a high smoke point and is ideally suited for cooking, with Extra Virgin Olive oil burning at lower temperatures and not therefore suited to cooking and more for salads and being used in it's cold form.
Light Olive oil too has a high smoke point and can be used for cooking in as much the same way as Pure Olive oil including for frying, baking and grilling.
There are four main types of olive oil, Extra Virgin olive oil, virgin olive oil, pure olive oil and light olive oil.
Extra Virgin Olive oil is the gold standard amongst olive oils, it is unrefined and has been produced from olives without using chemicals or heat, thereby retaining more nutrients. This is believed to ensure this type of olive oil retains more of its true olive taste. It is best used in it's cold form for salads, dips to dipping bread.
The other difference between this type of olive oil is its oleic acid content, which at around 1% gives it it's distinct flavour and golden green colour.
Virgin Olive oil is made using processes similar to that of Extra Virgin Olive oil but without the exacting standards of production as it's counterpart. This may contribute to a slightly higher level of oleic acid and differing less intense flavour to Extra Virgin Olive oil.
Pure Olive oil is typically a blend which contains some element of refined olive oil, that is olive oil which has been produced from olives using chemicals and/or heat. This process results in higher quantities of oleic acid, typically around 4%, a lighter colour and a less sharper taste than Extra Virgin Olive oil.
Light Olive oil has a lighter flavour than Pure Olive oil and Extra Virgin Olive oil. It is not lighter in calories just in flavour and has been refined during production.
Olive oil is a fat, therefore it is calorific and excessive consumption can lead to weight gain. General consensus is to switch other fats and oils with olive oil instead of using olive oil as supplement to other fats and oils. So instead of using butter, olive oil could be used for dipping bread.
The lower quality olive oils can be extracted using chemicals or mixed with other olive oils and as such may contain compounds detrimental to health.
The BBC's Trust me I'm a doctor program ran a test in conjunction with the University of Glasgow on the benefits of Olive oil. Drs Bill Mullen and Emilie Combet Aspray from the university ran several tests using volunteers to check the heart disease markers for various types of oils. They found those who took the olive oils in their raw form (uncooked), had lower markers for heart disease after several weeks.
Both the Extra Virgin olive oil and the normal olive oil, had the same results, when vegetable oils were tested as part of a control group, there was no change to these Coronary Artery Disease (CAD) markers.