Olive oil is the liquid fat, or natural oil obtained from pressing whole olives. Different olives, from different countries, will each give the oil a different taste – some quite mild, and others quite peppery or bitter.
Different processing techniques will result in olive oils of different ‘grades’ – refined and unrefined.
Unrefined oils are pure and untreated, meaning that no chemicals or heat have been used in the extraction process, resulting in a purer oil with a stronger taste. Refined oils have been treated to remove any flaws and are usually lighter in colour and milder in taste.
Extra virgin olive oil is an unrefined oil made from pure, cold-pressed olives and is usually more expensive, as it’s deemed the highest quality. It has a stronger flavour and is typically darker in colour compared to other olive oils.
Other, regular or light, olive oils are usually a blend of both cold-pressed and processed oils.Nutritional profile of olive oil
Olive oil is 100% fat. One 15ml (1 tbsp) serving contains around 135 calories, and on average 14g of fat of which 2g are saturated and the rest is unsaturated fats.
Around 75% of this fat is a mono-unsaturated fat, called oleic acid, or omega-9, which is associated with multiple health benefits. The rest is poly-unsaturated fats, known as omega-6 and omega-3.
Olive oil contains vitamin E, which supports the normal function of the immune system as well as maintaining healthy skin and eyes, and is a good source of vitamin K, which is needed for blood clotting and wound healing.
It’s the oil’s antioxidant status which provides a lot of its nutritional value, graded using the ORAC (Oxygen Radical Absorbance Capacity) scale. Dietary antioxidants are found in foods and have been shown to significantly improve health. Extra virgin olive oil typically has a higher ORAC scale than refined olive oil.
Can olive oil improve heart health?
Olive oil is a key component of the Mediterranean diet, and there’s been plenty of research that demonstrates the benefits of olive oil, in particular extra virgin olive oil, for heart health. This includes its ability to reduce blood pressure and improve healthy cholesterol levels, both of which contribute to a reduced risk of heart disease.
A large review of some of these studies demonstrated how olive oil was the only source of monounsaturated fat that’s been associated with a reduced risk of both stroke and heart disease.
Can olive oil reduce inflammation?
Inflammation is thought to be one of the key drivers behind some of the world’s more chronic health problems, including Alzheimer’s and Type 2 diabetes. Research looking at the role of antioxidants and their anti-inflammatory effect, including oleic acid found in olive oil, has discovered they play a role in reducing inflammation and the marker for inflammation known as C-Reactive Protein (CRP).
Some studies have even found that extra virgin olive oil contains an antioxidant compound called oleocanthal, which shares the same pharmalogical activity as ibuprofen, thereby acting as a natural anti-inflammatory.
Part of this anti-inflammatory role has also been associated with certain positive changes in immune function in those with rheumatoid arthritis.
Can olive oil improve mood?
As part of a healthy diet (one that includes high intake of fruit and vegetable and oily fish) olive oil has been found to play a role in decreasing the risk of depression.
A 2015 study found that in older populations, a Mediterranean diet supplemented with olive oil or nuts was associated with improved cognitive function, and there’s been more studies into how it may reduce the risk of Alzheimer’s.
Other early research has suggested that olive oil may have protective effects against Type 2 diabetes and some forms of cancer – however more research is needed before we can draw any firm conclusions.
Does heating olive oil make a difference to its nutritional profile?
There is some debate around this as it’s traditionally thought that extra virgin oil was more sensitive to heat and had a lower ‘smoke point’ – once an oil reaches its smoke point it begins to change in chemical structure and may become a transfat. A 2018 study found that both extra virgin and regular olive oil both had good smoke points and are therefore fine to cook with.
As extra virgin olive oil is more expensive and has a stronger, more peppery taste it may be best kept for drizzling and dipping rather than cooking with. Refined olive oils, such as light olive oil, are much cheaper and have little or no taste which means it won’t affect the flavour of whatever you are cooking.
How can I buy the best olive oil?
Ideally, buy olive oil in a dark bottle, especially extra virgin olive oil, as light degrades the oil and can turn it rancid. This also means it’s best to store your olive oil in a cupboard and not on the kitchen surface where it can be exposed to sunlight. Dark glass bottles or stainless steel containers offer better protection than plastic bottles. Check the ‘best by’ date and if you see ‘harvest date’ or ‘pressed on’ date, it’s likely to be a higher quality oil. Different regions and oils will produce different tastes so often this is just down to preference. Healthy recipe suggestions Garlic, basil & olive oil mash Spinach & green bean salad Homemade hummus Spaghetti with leeks, peas & pesto Chicken breast with avocado salad Quinoa, lentil & feta salad Simple mashed black beans