Olives are one of our oldest and healthiest foods. In Ancient Greece, olive trees were deemed so sacred that anyone found destroying one was punished by death. Despite this risk, offering an olive branch was seen as a symbol of peace and a respected gift.
Olive oil is an important component of the ultra-healthy Mediterranean diet – a way of eating that is associated with one the longest life expectancies in the world among those living in Greece, Crete and Southern Italy.
Numerous studies show that people who eat significant amounts of olives and olive oil are 10% to 20% less likely to die during the research follow-up periods from heart disease, cancer, or any other medical cause, than those who eat few, if any, olive products.
Olive oil and monounsaturated fat
Olive oil is a rich source of beneficial, monounsaturated fats which are characterised by having a single double bond. As much as 75% of the fatty acids in olive oil consist of oleic acid (sometimes referred to as an omega-9). Of the remaining fats, around 14% are saturated (containing no double bonds) and 11% are polyunsaturated (containing more than one double bond).
This healthy blend of fats is processed in the body to lower your total and ‘bad’ LDL-cholesterol without modifying your desirable ‘good’ HDL-cholesterol. This effect is augmented by the plant sterols that are also present in olive oil and which reduce absorption of cholesterol in the gut.
Did you know? 1 tablespoon olive oil contains 15g total fat of which only 2g is saturated fat. In comparison, 1 tablespoon butter contains 12g total fat, of which 8g is saturated fat.
Olive oil polyphenols
The main health benefits of olive oil, however, come from powerful antioxidants known as polyphenols. Around 30 different polyphenols have been identified in olives, with tongue-twisting names such as hydroxytyrosol, oleuropein and oleocanthal. These give olive oil its peppery zing as well as some enviable health benefits including:
- boosting the rate at which your cells burn energy
- supporting weight loss
- reducing inflammation
- suppressing joint pain
- reducing blood pressure
- reducing abnormal blood clotting
- improving glucose control
- reducing hardening an furring up of the arteries
- antimicrobial effects
- protecting the liver, heart, brain and other organs from damage.
Long-term studies consistently show that including olive oil in your diet every day increases your chance of living a long and healthy life, reducing your risk of coronary heart disease and stroke. The most recent evidence suggests regularly consuming olive oil also reduces the risk of developing dementia.
Not all olive oils are created equal, however. To get the maximum benefits you need an extra virgin olive oil that contains the highest levels of polyphenols.
Types of olive oil
Olive oil is derived from the fruit of the olive tree (Olea europaea) and these trees aren’t considered fully productive until they reach the age of 50 – 75 years.
All unripe olives start off green with a bitter taste. These are the best olives for pressing as they have the lowest acid content and produce the best oil. They also have the highest level of polyphenols.
As the olive ripens, it goes through various shades of purple to black, the flavour mellows and the percentage of energy-rich oil increases. But olives intended for producing oil are picked when unripe. They taste bitter and are totally inedible. These have a low acid content which is crucial, as the lower the acidity, the better the oil.
Extra virgin olive oil
Extra virgin olive oil is the best quality and has not been purified. Its flavour is superb as it comes from the first pressing of green olives. It therefore retains the fresh, olive aroma and has the highest content of antioxidants, including vitamin E, carotenoids and polyphenols. This grade of olive oil also has less than one per cent acidity.
Unfortunately, only around 10 per cent of olive oil is of this premium grade quality, which has a distinctive green hue and often hazes at room temperature. If you see an extra olive oil that seems unusually cheap, it is probably a ‘fake’ version made from lesser grades of olive oil with added colourings obtained from pressing the olives with some of their leaves.
Many factors affect the concentration of polyphenols produced by an olive tree, including the cultivar, stage of ripening, geographic origin, mineral content and aridity of the land. Essentially, the harsher the conditions, the more protective polyphenols the tree produces. Olive trees growing on volcanoes are particularly rich in polyphenols due to the minerals present – so much so, that some growers attempt to improve the quality of their olive oils by adding volcanic zeolite tuff to their own soils.
The length of time between harvesting the olives, pressing them to produce the olive oil, and then bottling it also affects oil quality.
The Extra Virgin Olive Oil that I recommend, Ancient Roots, is grown on a volcano in Tuscany and time between picking and bottling is less than 6 hours for maximum quality.
Virgin olive oil
Virgin olive oil is the next best in quality with a higher acidity level (up to 1.5 per cent) which gives it a slightly more piquant taste. Virgin olive oil is classed as a premium oil as it has not been purified, however, it provides fewer antioxidants – especially the all-important polyphenols – and therefore has less of the beneficial health effects obtained from consuming extra virgin olive oil.
Pure olive oil
Pure olive oil is a processed oil made by blending refined olive oil with virgin oil to get the olive flavour. Although the flavour is less pleasing, this is the most widely sold oil as it is less expensive and is also the best for cooking as it contains fewer antioxidant pigments and therefore does not smeech at high temperatures.
Investigating the health benefits of olive oil
Olive oil contains three different but synergistic ingredients that, together, provide some outstanding health benefits: polyphenols, monounsaturated oleic acid and plant sterols.
There are several theories as to why olive oil promotes longevity and weight loss. The one I find most compelling is that the monounsaturated fats and polyphenols present in extra virgin olive oil (especially oleuropein and hydroxytyrosol) increase the production and activation of regulatory cell proteins known as sirtuins (SIRTs).
SIRTs are a family of enzymes which regulate key metabolic reactions involved in cell survival, including fat burning and restoring cell balance when something goes awry (homeostasis).
SIRTs act rather like Formula 1 racing engineers, fine tuning cells’ performance by tweaking the chemical structure of specific proteins and fatty acids in the cell nucleus to switch genes on or off and regulating energy production in mitochondria – a cell’s equivalent of batteries.
So far, seven SIRT proteins have been discovered which, together:
- turbo-charge cellular energy production
- regenerate worn-out cell structures (organelles)
- boost fat burning
- promote a healthy weight loss
- activate cell defence mechanisms to reduce inflammation
- repair damaged DNA
- prolong cell survival during periods of stress caused by factors such as lack of oxygen, infection or a build-up of toxins
- lay down new neural connections within the brain to enable the formation, retention and retrieval of memories.
Both the monounsaturated fat and polyphenols found in olive oil stimulate the production and activation of SIRT-1.
SIRT1, as its name implies, was the first sirtuin protein identified in human cells and is therefore the most intensively studied. SIRT1 plays a key role in orchestrating the life cycle of each individual cell and enhances fat metabolism and mitochondrial respiration to optimise energy production.
By boosting levels of SIRT1, eating olives helps to stimulate the breakdown and burning of fat. SIRT 1 also promotes satiety to suppress appetite and decrease feelings of hunger.
By improving cell efficiency, SIRT1 enhances heart, liver and brain function, insulin secretion in the pancreas, promotes fat burning and reduces inflammation. What’s not to like?
Olive oil and weight loss
You might assume that drinking olive oil – high in fat – would increase your waistline but, paradoxically, in moderate amounts, the opposite is true. Studies consistently show that people who consume olive oil weigh less and have smaller waistlines than those who consume other types of oil.
For example, in one randomized, double-blinded, placebo-controlled clinical trial, 41 women with excess body fat were asked to take either 25 ml (just under a tablespoon) of extra virgin olive oil or soybean oil for breakfast every day for nine weeks while following a low calorie, normal fat diet. In the group taking extra virgin olive oil, fat loss was 80% higher than in those taking soybean oil -2.4 kg versus -1.3 kg). Improvements were also noticed in blood pressure and cholesterol balance. The researchers concluded that extra virgin olive oil should be included in energy-restricted programs for obesity treatment.
And to show the effect is not just in women, a group of men who were overweight or obese were asked to follow two different high-fat (40%) diets for 4 weeks each (crossing over from one to the other so they acted as their own controls). In one diet, fat was mostly in the form of monounsaturated fat and was enhanced with 20g extra virgin olive oil (added to their breakfast muesli). In the other diet, fat was mostly saturated (from creamy milk, butter and cheese).
While the men were following the olive oil enriched diet, their weight was, on average, 2.1 kg lower (with a 2.6 kg reduction in fat mass) compared to when they followed the saturated fat enriched diet. The researchers concluded that substituting dietary saturated fat with monounsaturated fat can induce a small but significant loss of body weight and fat mass without a significant change in total energy or fat intake.
I certainly take a tablespoon of my Ancient Roots extra virgin olive oil every day!
Olive oil reduces inflammation
Another reason why extra virgin olive oil promotes weight loss is through its anti-inflammatory effects. One of the key olive polyphenols, oleocanthal, has a powerful non-steroidal anti-inflammatory action (suppressing enzymes known as COX-1 and COX-2) that is ten times greater than that of ibuprofen, so that 9 mg oleocanthal is equivalent to taking 90 mg of ibuprofen.
Fat metabolism is sensitive to the effects of inflammation associated with obesity, through complicated interactions with immune chemicals. This anti-inflammatory effect may therefore promote fat burning in fat cells (adipocytes) as well as suppressing aches and pains such as those associated with arthritis.
For people with rheumatoid arthritis in particular, olive oil can suppress inflammation enough to significantly improve disease activity.
Olive oil reduces blood pressure
Numerous studies show that a regular intake of olive oil reduces blood pressure. This is partly due to its antioxidant polyphenols and partly due to its high monounsaturated fat content. The polyphenols stimulate production of nitric oxide in artery walls to trigger blood vessel dilation, while oleic acid is incorporated into blood vessel walls to make them more flexible.
Researchers have found that a higher consumption of olive oil is associated with a lower blood pressure in those following a Mediterranean style diet, young women with mild hypertension, healthy males, elderly people with hypertension, and those with type 2 diabetes.
In a cross-over clinical trial involving 24 women with raised blood pressure, each took either 60ml (2 tablespoons) of a polyphenol rich olive oil daily, or a refined olive oil containing no polyphenols, for 2 months each (with a wash-out period in between).
When taking the polyphenol rich virgin olive oil, their blood pressure was, on average, 7.91/6.65mmHg lower than when they took the refined olive oil containing no polyphenols.
In another trial, 80 per cent of people taking medication for high blood pressure were able to discontinue their drugs (with their doctor’s consent) after taking 30g to 40g extra virgin olive oil, every day for six months. All those randomised to use sunflower oil, however, continued to need their antihypertensive drugs.
Olive oil improves cholesterol balance
Olive oil contains plant sterols that have a similar structure to human cholesterol. As a result, they latch onto receptors in the gut wall that absorb cholesterol and block them so that less cholesterol is pulled into your blood stream.
Olive oil’s monounsaturated fat, oleic acid, is also processed in the liver to reduce production of harmful low-density lipoprotein (LDL) cholesterol and to lower blood levels of another type of fat, known as triglycerides. These effects are greatest with virgin and extra virgin olive oils compared with pure olive oil.
The results of ten, international, randomised controlled trials looking at how a daily intake of olive oil polyphenols affect blood fat levels found that, while they did not have a significant effect on total cholesterol, they did improve cholesterol balance by reducing ‘bad’ LDL-cholesterol and significantly increasing desirable ‘good’ HDL-cholesterol, concluding that olive oil polyphenols contribute toward maintaining lipid metabolism.
In 2011, the European Food Safety Authority (EFSA) also authorised a health claim that olive oil polyphenols protect ‘bad’ LDL cholesterol from oxidative damage. This is important as it’s oxidised cholesterol that is associated with hardening and furring up of the arteries.
Olive oil improves glucose control
The monounsaturated fats in olive oil, such as oleic acid, have beneficial effects on insulin sensitivity and glucose control. Polyphenols in extra virgin olive oil also improve insulin resistance. Together, these effects help to protect against type 2 diabetes.
The results from 29 clinical trials plus four cohort studies involving 15,784 people found that those with the highest intakes of olive oil were 16% less likely to develop type 2 diabetes than those with the lowest intakes.
In a study involving 215 overweight people with newly diagnosed type 2 diabetes, one group followed a Mediterranean-style diet rich in olive oil, while others followed a conventional low-fat, low-calorie diet, or a relatively low-carbohydrate. After four years, only 44% of those following the Mediterranean style diet needed to start glucose-lowering drugs, compared with 70% of those following the other dietary approaches. They also lost more weight and showed greater improvements in other heart disease risk factors.
Research also shows that people with type 2 diabetes who replace some dietary carbohydrate with 10g to 40g olive oil per day find their glucose control significantly improves.
Olive oil protects against coronary heart disease and stroke
In 1999, the Lyon Diet Heart Study asked people who’d already had a heart attack to follow a Mediterranean style diet. As a result of their increased consumption of olive oil and other healthy foods, they were 70% less likely to have a second heart attack than those following a ‘prudent’ supposedly healthy, low-fat, Western-type diet.
The protective effects were so striking the study was stopped 3 years early, because it was thought unethical not to advise everyone to switch to the olive-oil enriched Mediterranean way of eating.
Since then, the results from 32 trials, involving over 841,211 people confirm that those with the highest intake of olive oil are 11% less likely to die from any medical cause over the course of the studies, than those with the lowest intakes; with their risk of a heart attack reduced by 12% and the risk of a stroke reduced by 17% after taking other factors into account.
In fact, extra virgin olive oil has such beneficial effects on weight, inflammation, blood pressure, cholesterol balance and glucose control that, in combination with regular exercise and not smoking, its daily consumption as part of a Mediterranean-style diet could potentially prevent eight out of ten heart attacks and seven out of ten strokes.
Olive oil protects against premature ageing
Researchers recently discovered that following an olive-oil enriched Mediterranean style diet influences the activity of genes involved in the ageing process.
One of the main causes of ageing is damage to your genetic material (DNA). This is especially true within structures called mitochondria, which act as the cell’s batteries.
The monounsaturated fats found in olive oil provide a more stable environment when incorporated into cell membranes – including those of the mitochondria and cell nucleus. This makes them less prone to the oxidation which triggers inflammatory reactions that damage DNA and result in age-related mutations.
Research also suggests that olive oil polyphenols help to protect organ cells from damage that can lead to fatty liver disease, heart disease and a number of neurological conditions, including dementias, multiple sclerosis, Parkinson’s disease and reduced blood flow (cerebral ischaemia) related to ageing.
Within the liver, extra virgin olive oil helps to reduce fibrosis by stimulating the production of protective liver proteins and detoxification enzymes. It’s even suggested that consuming olive oil may reduce the progression of non-alcoholic fatty liver disease (NAFLD), a pathological condition in which fatty infiltration in the liver exceeds 5%–10% of its weight
How to store extra virgin olive oil
As olive oil matures, oxidation occurs which detracts from the original flavour. Keep all types of olive oil in a dark glass bottle in a cool, dark pace away from direct sunlight or heat.
A bottle of olive oil can lose 40% of its antioxidant potential during an average lifetime in the kitchen of ten months. Most oils are therefore best used within one year of pressing. Buy from outlets where turnover is high and avoid large containers (especially those made from tin or aluminium). In fact, buy all oils in small sizes and use it frequently and liberally so it’s used up more quickly, and you renew them frequently.
Cooking with olive oil
According to researchers at the University of Münster, Germany, pure olive oil remains stable at elevated temperatures due to its high levels of monounsaturated fatty acids and natural antioxidant, vitamin E. Refined olive oil can therefore be heated up to 210 degrees C before chemical changes take place.
Virgin and Extra virgin olive oils are less stable, however, due to their higher content of heat sensitive but healthy components that contribute to their colour and flavour. Because of this, virgin olive oil may cause unwanted smells or taste changes if heated above 180 degrees C.
So, I recommend you only fry or roast with pure olive oil and reserve Virgin or Extra virgin olive oils for steaming, gentle lower-temperature braising, drizzling over foods and making salad dressings.
Herby salad dressing Place 60ml (2 fl oz) extra virgin olive oil, 3 teaspoons red wine or apple cider vinegar, 1 clove crushed garlic, a handful of chopped fresh herbs and a twist of ground black pepper in a small jar with screw-top lid. Cover and shake jar to emulsify, then pour over your salad. Serve immediately.
Discard any oil that begins to smoke or smell odd during use. Ideally, cooking oils should not be re-used.
Image credit: kmn photo
