Olive Oil: The Science Behind Health Benefits

Olive oil is a key part of the Mediterranean diet, thought to have health benefits such as lowering the risk of heart disease. But how did Southern European countries come to add it to their food, and what is it doing to our health?

Olive oil has been the basis of the Mediterranean diet for thousands of years. The ancient Greek poet Homer even referred to olive oil as “liquid gold”, whilst Hippocrates called it the “great healer” and prescribed it for many medical conditions.¹

Origins & Historical Uses of Olive Oil

Although the exact origin of olive oil is unknown, the olive tree is thought to have been domesticated in the Mediterranean basin about 6000 years ago – making it one of the oldest cultivated fruit trees in the world.² Olive oil represented wealth in the Minoan civilisation, and ancient documents from Syria suggest it was five times more expensive than wine. But it wasn’t always used as a food. 

Instead, it was often used as fuel in lamps and in many rituals, such as religious ceremonies or anointing royalty and warriors. Olive oil had numerous benefits and was also used to make soap and for medicine and skincare; the Ancient Greeks even used it as a primitive contraceptive!³ Today around 90% of all olive oil is used for food,⁴ where modern science suggests it can bring health benefits to those that eat it regularly.

Olive Oil Health Benefits

Mediterraneans have been found to live longer and suffer less from heart disease than northern Europeans and Americans. One reason lies in their diet: most of the oils and fats consumed in the Mediterranean are healthier unsaturated fats as opposed to saturated fats. This observation, made by American physiologist Ancel Keys in the late 1950s, led to the formalisation of what we now call the Mediterranean diet – which characteristically includes eating a lot of olive oil.⁵ 

Discover more about the foods that make up a Mediterranean diet.

One of the benefits of olive oil is that it is very low in saturated fats: up to 85% of the fats in olive oil are monounsaturated fats (mostly oleic acid or omega-9) or the polyunsaturated fats omega-6 and omega-3, while only around 15% are saturated fats. It also contains the immune system-strengthening vitamin E and wound-healing helper vitamin K, as well as phenolic antioxidants that improve health in a number of ways.⁶  For example, these antioxidants can protect bad cholesterol from harmful oxidation – a health claim recognized and approved by the European Food Safety Authority (EFSA).⁷ 

Learn more about omega-3 and omega-6.

4 Ways Olive Oil That Can Benefit Your Health

1. A Healthy Heart

People who follow the Mediterranean diet have a reduced likelihood of suffering from stroke, heart disease and early death. Olive oil seems to be the key ingredient linked to lower rates of heart disease, and one reason could be its effect on blood pressure⁹ - olive oil contains lots of polyphenols, which help relax and dilate arteries and are thought to reduce high blood pressure. 

Other key molecules in olive oil help protect your heart by removing harmful substances from your body. ‘Free radicals’ are molecules that cause damage to your cells by a process called ‘peroxidation’, but olive oil is rich in antioxidants that neutralize these free radicals and protect your cells. Similarly, high levels of ‘bad’ cholesterol (known as low-density cholesterol, or LDL) are a major driver of heart disease, but olive oil has been found to boost the level of ‘good’ high-density cholesterol (HDL) in your blood, which removes excess LDL from your body thereby helping protect your heart health.¹⁰

2. A Healthy Body

Oleic acid and oleocanthal (an antioxidant) in extra virgin olive oil have been found to act as natural anti-inflammatory agents. Inflammation is an important part of our body’s immune defences, but it can also cause damage to our cells. Oleocanthal works in the same way as the anti-inflammatory drug ibuprofen,¹¹ helping to combat chronic low-level inflammation, while oleic acid achieves a similar effect by reducing the levels of the inflammatory marker C-Reactive Protein (CRP) in the blood. Studies are now exploring how olive oil could help treat and prevent inflammatory diseases like atherosclerosis and rheumatoid arthritis.¹²

3. A Healthy Gut

Extra virgin olive oil has antibacterial properties, especially against the bacterium Helicobacter pylori (which can cause stomach ulcers). Studies suggest that the same polyphenols in extra virgin olive oil that boost heart health may hinder foodborne pathogens like H. pylori from growing in our digestive systems, and improve gut health at the same time by acting as a prebiotic which supports the growth of healthy gut bacteria.¹³

4. A Healthy Mind

Recent analysis has suggested that olive oil, as part of a Mediterranean diet, could play a role in decreasing the risk of depression – but more evidence is still needed. So far, olive oil has been shown to boost levels of two important chemicals that help brain cells to grow and repair themselves: brain-derived neurotrophic factor (BDNF) – a lack of which has been linked to depression – and nerve growth factor (NGF). Studies also suggest that a higher intake of monounsaturated fats like those found in olive oil can improve memory and cognitive function in the elderly and reduce the risk of Alzheimer's.^14,15

Not All Olive Oil Is The Same

Different processes affect the quality of olive oil, resulting in different ‘grades’: refined or unrefined.¹⁶ Extra virgin olive oil is unrefined and obtained directly from olives using only mechanical processes and is usually more expensive and packed with healthy antioxidants. Cheaper, chemically processed olive oils (such as “virgin olive oil”, “olive-pomace oil”, or just simply “olive oil”) often have a mild taste, are lighter in colour and are lower in antioxidants, meaning they are likely to offer fewer health benefits compared to extra-virgin olive oil.^1,7 Refined olive oil is the lowest quality form of olive oil, with little aroma, flavour or colour - it cannot be sold to consumers directly, but can be sold if it is mixed with virgin olive oils.¹⁷

Olive oil provides the greatest health benefits when eaten raw, as the polyphenols and antioxidants it’s packed with start to break down when cooked at high temperatures. When heated, free fatty acids can also break down and form harmful and carcinogenic chemicals such as aldehydes - but olive oil contains mostly monounsaturated fats that are quite resistant to heat, so it’s still a good choice to cook with!^18,19