Olive oil and cardiovascular diseases
Arteriosclerosis is a condition in which cholesterol-rich deposits, known as atheromas, accumulate on the inner walls of the arteries. Over time, these deposits narrow the arteries and reduce the flow of blood to tissues and organs.
The progression of arteriosclerosis is influenced by several factors, the most significant being:
- high blood cholesterol
- high blood pressure
- diabetes
- cigarette smoking
These factors contribute to the gradual deterioration of the arteries and increase the risk of serious cardiovascular events.
What is arteriosclerosis?
Arteriosclerosis is a condition in which cholesterol-rich deposits, known as atheromas, accumulate on the inner walls of the arteries. Over time, these deposits narrow the arteries and reduce the flow of blood to tissues and organs.
This process can impair the proper functioning of vital organs such as the heart and the brain, as well as other parts of the body.
Consequences of arteriosclerosis
When arteriosclerosis affects the heart, it can lead to:
- angina
- heart attack
- an increased risk of sudden cardiac death
When it affects the brain, it may cause cerebral thrombosis, which can result in:
- muscular paralysis
- loss of cognitive capacity
- an increased risk of dementia
Another serious complication occurs when a fatty plaque ruptures, sometimes due to increased blood pressure. When this happens, small blood vessels within the plaque may break, triggering the aggregation of platelets (thrombocytes). These cells cluster together to form a thrombus, or blood clot.
If the clot travels through the bloodstream and becomes larger than the vessel through which it passes, it can cause a complete blockage of blood flow, leading to the death of the affected tissue or organ.
Olive oil and arteriosclerosis
Research has shown that olive oil may help prevent the formation of blood clots and platelet aggregation.
Diets rich in olive oil may help limit excessive blood coagulation, which in turn reduces the likelihood of clot formation associated with fatty foods. This effect has been linked to the lower incidence of heart disease observed in populations where olive oil is the principal dietary fat.
What is cholesterol?
Cholesterol is a fatty substance found in foods of animal origin. Diets high in animal fats can increase blood cholesterol levels, which is one of the major risk factors for cardiovascular disease.
In the bloodstream, fats (triglycerides) and cholesterol are transported by lipoproteins.
Cholesterol attached to low-density lipoproteins — including very low-density lipoproteins (VLDL) and low-density lipoproteins (LDL) — is considered atherogenic, meaning it can damage artery walls and contribute to plaque formation. This type of cholesterol is commonly referred to as “bad cholesterol.”
By contrast, cholesterol carried by high-density lipoproteins (HDL) is known as “good cholesterol.” HDL plays a protective role by removing excess cholesterol from cells, transporting it to the liver and facilitating its elimination through bile.
Olive oil and cholesterol
Olive oil consumption has been shown to reduce total blood cholesterol, LDL cholesterol and triglyceride levels.
At the same time, it does not reduce HDL cholesterol levels, and may even increase them. Since HDL helps remove cholesterol from the bloodstream and prevents the formation of fatty deposits in arteries, this effect contributes to cardiovascular protection.
The beneficial effects of olive oil consumption have been observed both in:
- primary prevention, by reducing the risk of developing cardiovascular disease
- secondary prevention, by helping prevent recurrence after a first coronary event
Current research is also highlighting the effectiveness of the Mediterranean diet in preventing secondary coronary events. In addition, studies suggest that olive oil may have a positive influence on mood and may help reduce depression associated with cardiovascular events.
These findings are particularly relevant given the high prevalence of depression in modern societies and its recognised role as a risk factor for recurrent heart disease.
When arteriosclerosis affects the heart, it can lead to:
- angina
- heart attack
- an increased risk of sudden cardiac death
When it affects the brain, it may cause cerebral thrombosis, which can result in:
- muscular paralysis
- loss of cognitive capacity
- an increased risk of dementia
Arteriosclerosis may also affect the aorta and the arteries of the legs, causing pain, difficulty in walking and, in severe cases, necrosis or gangrene.
The antioxidant properties of olive oil
What are antioxidants and oxidative stress?
Oxidation is a natural process that occurs not only during the production and storage of oils but also within the human body. Continuous metabolic reactions produce molecules known as free radicals, or peroxidants.
Under normal conditions, these molecules do not cause significant harm because the body possesses antioxidant defence systems that help maintain a balance. When this balance is disrupted, however, oxidative stress occurs. This condition can damage cellular components, impair normal cell functions and eventually lead to cell death.
Oxidation also plays a role in the ageing process of cells. Lipid or fat peroxidation — the oxidation of fats — tends to increase with the number of double bonds present in a molecule. This explains why oleic acid, the main fatty acid in olive oil, is relatively resistant to oxidation.
Cell membranes contain large amounts of fats and cholesterol, and their composition is influenced by diet. When a diet contains a high proportion of olive oil, cell membranes become more resistant to oxidative damage, helping to slow cellular deterioration and potentially delaying aspects of the ageing process.
Around 1.5% of olive oil consists of the unsaponifiable fraction, which contains various bioactive compounds, including antioxidants. Virgin olive oil contains particularly high concentrations of these substances and other minor components.
Antioxidants in olive oil
Olive oil contains several types of antioxidant compounds, including:
- Vitamin E (alpha-tocopherol)
- Carotenoids
- Phenolic compounds
Phenolic compounds include both simple phenols, such as hydroxytyrosol, and complex phenols, such as oleuropein. Their antioxidant activity has been demonstrated in laboratory studies (in vitro) and more recently in studies involving living organisms (in vivo).
These compounds contribute to the protective effects of olive oil, which have been associated with the prevention of certain diseases and with processes related to ageing.
The phenolic content of olive oil can vary depending on several factors, including:
- climatic conditions in the production area
- the stage of ripeness at harvest
- the timing of harvest
- oil production methods
- storage conditions
Phenolic compounds exhibit a wide range of biological activities. For example:
- Hydroxytyrosol has anti-inflammatory properties and can inhibit platelet aggregation.
- Oleuropein promotes the production of nitric oxide, a powerful vasodilator, and also has strong antibacterial properties.
Oxidised low-density lipoproteins (oxidised LDL) are known to be atherogenic, meaning they contribute to the development of arterial plaque. Olive oil has been shown to have a protective effect against LDL oxidation, helping to reduce this risk.
In addition, the antioxidants present in olive oil help protect cells throughout the body from the toxic effects of oxidative molecules.
Olive oil and cancer
Cancer is one of the leading causes of death in developed countries, and its incidence continues to increase worldwide.
Research has increasingly shown that diet plays an important role in the development of many types of malignant tumours. One of the mechanisms involved is cellular oxidation, which can damage DNA and contribute to the transformation of normal cells into cancerous ones. Cells that are more susceptible to oxidative damage may therefore present a higher risk of cancer development.
The types of cancer most frequently associated with dietary factors include:
- colorectal cancer
- prostate cancer
- breast cancer
Recent research suggests that the type of dietary fat consumed may be more relevant to cancer risk than the total quantity of fat in the diet.
What is cancer?
A tumour is an abnormal swelling or growth of body tissue. Tumours can be either benign or malignant.
Benign tumours remain confined to their original location. They form a localised mass of cells that is usually encapsulated and rarely life-threatening.
Malignant tumours, or cancers, behave differently. They invade surrounding tissues and may spread to other parts of the body through the bloodstream or lymphatic system, forming secondary tumours known as metastases. The rate at which tumours grow and spread varies depending on the type of cancer.
The development of tumours is influenced by a combination of factors, including:
- environmental factors, such as radiation and certain chemical substances present in foods
- genetic factors
In many types of cancer, environmental influences — including diet — play a particularly important role.
Olive oil and cancer
Epidemiological studies suggest that olive oil may exert a protective effect against certain malignant tumours, including cancers of the breast, prostate, endometrium and digestive tract.
Several studies have indicated that diets in which olive oil is the principal source of fat are associated with a lower risk of breast cancer. One possible explanation is related to the presence of toxins that can damage DNA when introduced through the diet. During their metabolism in the liver, these substances may generate free radicals, which in turn can attack cellular DNA.
To counteract these harmful molecules, the body requires antioxidants and protective nutrients, many of which are present in olive oil.
Research has also reported an association between olive-oil-rich diets and a reduced risk of bowel cancer. This protective effect appears to be observed independently of the amount of fruit and vegetables consumed in the diet.
More recent studies have explored the protective role of olive oil in colon cancer, as well as its metabolic effects in chronic liver disease and inflammatory intestinal disorders such as Crohn’s disease. Some experimental findings suggest that olive oil may have beneficial effects on pre-cancerous lesions.
In studies comparing different dietary patterns, researchers observed that diets rich in olive oil:
- reduced the number of cancerous lesions
- resulted in fewer tumours developing
- produced tumours that were less aggressive and had a better prognosis
Possible mechanisms of protection
These beneficial effects may partly be explained by oleic acid, the main monounsaturated fatty acid found in olive oil. Oleic acid has been shown to reduce the production of prostaglandins derived from arachidonic acid, compounds that play a role in tumour development.
Other components of olive oil may also contribute to its protective properties. These include:
- antioxidants
- flavonoids
- polyphenols
- squalene
Squalene, in particular, has been associated with protective effects on the skin and may help reduce the incidence of melanoma.
Olive oil also enhances the flavour of foods such as vegetables and legumes, which themselves are known to play an important role in cancer prevention.
Recent research is also investigating the potential protective role of olive oil against childhood leukaemia and certain cancers, such as oesophageal squamous cell carcinoma.
Continuing research
Although many studies point to beneficial associations between olive oil consumption and cancer prevention, the precise mechanisms involved are still being investigated.
Current scientific evidence suggests that olive oil may act at multiple stages in the development of cancer, helping to prevent or slow the processes involved in tumour formation and growth. Further research will continue to clarify the extent and nature of these protective effects.
Olive oil and blood pressure
A number of studies have identified a close relationship between diet and blood pressure. Certain foods and dietary patterns can influence blood pressure levels, sometimes independently of their effect on body weight.
What is high blood pressure?
High blood pressure, also known as arterial hypertension, is generally defined as blood pressure that consistently exceeds 140/90 mmHg.
Hypertension is one of the major cardiovascular risk factors associated with the development of arteriosclerosis. Alongside high blood cholesterol, smoking, obesity and diabetes, it represents one of the most significant health concerns in industrialised societies.
Lifestyle factors, including diet and physical activity, can play an important role in the development and management of high blood pressure.
Approximately one in four adults is affected by hypertension. This condition increases the risk of premature death, primarily because of the damage it can cause to arteries throughout the body, particularly those supplying blood to the heart, kidneys, brain and eyes.
Olive oil and blood pressure
Although the precise components of the Mediterranean diet responsible for lowering blood pressure have not been fully identified, research has shown that olive oil plays a significant role.
Studies have demonstrated that adding olive oil to a diet — without making any other dietary changes — can lead to a measurable reduction in blood pressure. This effect appears to be specific to olive oil.
Regular consumption of olive oil has been associated with reductions in both:
- systolic blood pressure (the maximum pressure during heart contraction)
- diastolic blood pressure (the minimum pressure between heartbeats)
Recent research also suggests that olive oil consumption may allow hypertensive patients to reduce the daily dosage of medication required to control blood pressure. This effect may be linked to the action of polyphenols present in olive oil, which are thought to influence the production of nitric oxide, a compound that plays a role in regulating blood vessel dilation.
Olive oil and diabetes
What is diabetes?
Diabetes mellitus is one of the major health challenges in developed countries and ranks among the leading causes of death. It is a metabolic disease that can lead to serious complications affecting overall health, including:
- cardiovascular diseases
- kidney failure
- vision loss or blindness
- peripheral circulation disorders
There are two main types of diabetes mellitus:
- Type 1 diabetes (insulin-dependent diabetes), which usually develops in children and adolescents and requires insulin treatment.
- Type 2 diabetes (non-insulin-dependent diabetes), which generally appears in adulthood, often after the age of 40, and is frequently associated with overweight or obesity.
Type 2 diabetes is the most common form of the disease and often does not initially require insulin treatment.
Diabetes is typically diagnosed when blood glucose levels are abnormally high. A person is considered diabetic when blood sugar levels exceed:
- 126 mg/dl in fasting conditions, or
- 200 mg/dl two hours after a glucose tolerance test.
A related condition, known as glucose intolerance or prediabetes, occurs when blood sugar levels are elevated (between 110 and 125 mg/dl) but not yet high enough to be classified as diabetes. Individuals in this situation have a higher risk of developing diabetes in the future.
Olive oil and obesity
A diet rich in olive oil may not only help manage diabetes but also contribute to preventing or delaying its onset.
Olive oil may help by improving several metabolic factors associated with diabetes, including:
- reducing insulin resistance
- raising HDL (“good”) cholesterol levels
- lowering triglycerides
- improving blood glucose control
- reducing blood pressure
Research has shown that a dietary pattern rich in olive oil, low in saturated fats, and moderately high in carbohydrates and soluble fibre — particularly from fruit, vegetables, legumes and whole grains — can be especially beneficial for people with diabetes.
In addition to lowering LDL (“bad”) cholesterol, this type of diet improves blood sugar regulation and enhances insulin sensitivity, helping the body use insulin more effectively.
These beneficial effects have been documented in studies involving both children and adults with diabetes.
Olive oil and obesity
What is obesity?
Obesity, or being overweight, occurs when the body accumulates excess energy reserves, mainly in the form of body fat. This happens when energy intake from food exceeds the amount of energy expended through daily activities, physical exercise and the body’s basal metabolic functions.
Weight management therefore depends on maintaining a balance between energy intake and energy expenditure. When energy expenditure is greater than energy intake, the body begins to use stored energy reserves, leading to weight loss.
A well-designed weight-reduction diet should:
- provide less energy than is required to maintain body weight
- supply adequate amounts of all essential nutrients
- be acceptable, affordable and palatable
Olive oil and obesity
Olive oil is a food of high nutritional and biological value. Like all fats and oils, it is energy-dense, providing approximately 9 kilocalories per gram. At first glance, this might suggest that its consumption could contribute to weight gain.
However, observations of traditional dietary patterns show that rates of obesity have historically been lower in Mediterranean populations, despite their relatively high consumption of olive oil.
Research has also indicated that diets rich in olive oil may lead to greater and longer-lasting weight loss compared with very low-fat diets. One reason may be that such diets are more satisfying and easier to maintain, partly because olive oil enhances the flavour of foods and encourages the consumption of vegetables and other healthy foods.
As a result, olive oil can be part of a balanced dietary pattern that supports healthy weight management, particularly when combined with a varied diet and an active lifestyle.
Olive oil and the immune system
Research has shown that olive oil may also play an important role in supporting the immune system, which protects the body against external threats.
What is the immune system?
The immune system is responsible for defending the body against foreign substances, such as toxins, microorganisms, parasites and abnormal cellular processes such as tumour development. It operates through a coordinated set of specific and non-specific defence mechanisms.
The non-specific (or innate) immune system provides the body’s first line of defence against microorganisms. It includes physical and biochemical barriers such as:
- the skin
- mucous membranes
- the complement system (a group of about 20 proteins produced in the liver that help destroy microorganisms)
- hormonal and other biological factors
These defences act in a similar way against most invading organisms and do not depend on previous exposure.
The specific immune response, by contrast, is activated after the body encounters a particular foreign substance. This response involves specialised immune cells, including:
- B lymphocytes, which form part of the humoral immune system and produce antibodies
- T lymphocytes, which are responsible for cellular immune responses
While innate immunity reacts in a general way to many microbes, the specific immune response adapts to the characteristics of each pathogen in order to eliminate it as effectively as possible.
Olive oil and immune function
Studies have indicated that regular consumption of olive oil may strengthen the immune system’s ability to respond to infections caused by microorganisms, bacteria and viruses.
It has long been recognised that deficiencies in vitamins and minerals can impair immune function. More recently, research has also shown that the fatty acids present in olive oil may influence several aspects of immune activity.
These fatty acids appear to play a role in regulating certain immunological parameters, including the proliferation of lymphocytes stimulated by specific mitogens affecting both B cells and T cells.
In addition, fatty acids found in olive oil are involved in the regulation of inflammatory processes. For this reason, they may contribute to the management of certain autoimmune conditions and help support the overall balance of the immune system.
Olive oil and rheumatoid arthritis
Rheumatoid arthritis is a chronic inflammatory autoimmune disease that primarily affects the joints. Its exact causes remain unknown, although several factors may contribute to its development, including:
- genetic predisposition
- infections
- hormonal influences
- dietary factors
Some earlier studies suggested that olive oil consumption might help reduce symptoms of rheumatoid arthritis, although clear evidence of a protective effect was initially limited.
More recent research has provided stronger indications that regular consumption of olive oil may reduce the risk of developing rheumatoid arthritis. According to the findings of one study, individuals whose diets contained higher amounts of olive oil had a lower risk of developing the disease.
The study reported that people who consumed little olive oil were approximately 2.5 times more likely to develop rheumatoid arthritis than those who consumed it more frequently.
Although the exact mechanisms are not yet fully understood, researchers suggest that the antioxidants present in olive oil may contribute to these beneficial effects.
Olive oil and the digestive system
Once consumed, olive oil has several effects throughout the digestive system. Since ancient times it has been recommended for a variety of digestive disorders, and its beneficial properties are now supported by epidemiological research and scientific studies.
Olive oil and the stomach
When olive oil reaches the stomach, it does not reduce the tone of the lower oesophageal sphincter, the muscular ring located at the base of the oesophagus. As a result, it helps reduce the risk of reflux, preventing food and gastric juices from flowing back from the stomach into the oesophagus.
Olive oil also partially slows gastric motility, meaning that the contents of the stomach are released more gradually into the duodenum. This slower emptying can create a greater sensation of satiety and may help facilitate the digestion and absorption of nutrients in the intestine.
Olive oil and the hepato-biliary system
Olive oil also influences the hepato-biliary system, which includes the liver, gall bladder and bile ducts.
It acts as a cholagogue, promoting optimal bile drainage and helping the gall bladder empty effectively. In addition, it has a cholecystokinetic effect, meaning that it stimulates the contraction of the gall bladder. These actions can be beneficial in the prevention and management of certain biliary tract disorders.
Olive oil also stimulates the production of bile salts in the liver and increases the amount of cholesterol excreted in bile.
By supporting healthy gall bladder activity, olive oil facilitates the digestion of dietary fats, which are emulsified by bile. This process may also help reduce the risk of gallstone formation.
Olive oil and the pancreas
Consumption of olive oil stimulates a moderate secretion of digestive enzymes by the pancreas. This allows the pancreas to function efficiently without excessive stimulation.
For this reason, olive oil is often considered suitable in dietary management of conditions where pancreatic function needs to be preserved, such as:
- pancreatic insufficiency
- chronic pancreatitis
- cystic fibrosis
- malabsorption syndromes
Olive oil and the intestines
Olive oil contains sitosterol, a plant sterol that can partially inhibit the absorption of cholesterol in the small intestine.
It also promotes the absorption of several important nutrients, including:
- calcium
- iron
- magnesium
Overall, olive oil is easily digested and well absorbed by the body. In addition, it has a mild laxative effect, which may help relieve constipation and support digestive comfort.
Olive oil during pregnancy and childhood
Olive oil can play an important role in nutrition during pregnancy and early childhood. Adequate consumption of healthy fats during pregnancy contributes to the proper development of the foetus, while insufficient intake may negatively affect certain aspects of growth.
Studies have suggested that babies born to mothers who consumed olive oil during pregnancy may show favourable postnatal development, including improvements in parameters such as height, weight, behaviour and psychomotor reflexes.
Vitamin E is one of the nutrients required for foetal development. Newborn babies also need sufficient vitamin E to help protect their cells against oxidative stress, which increases when they move from the low-oxygen environment of the womb to breathing air after birth. Although olive oil is not extremely rich in vitamin E, it contains adequate amounts, partly because its natural resistance to oxidation helps preserve this vitamin.
For these reasons, both the quantity and quality of foods consumed during pregnancy are important. Maternal nutrition influences the metabolic adaptations that occur during pregnancy and plays a role in the functional relationship between mother and foetus.
Olive oil and breastfeeding
During childbirth and the early stages of breastfeeding, vitamin E from the mother’s bloodstream becomes concentrated in the mammary glands. As a result, breast milk provides the newborn with a continued supply of this nutrient. Maintaining adequate vitamin E levels during breastfeeding is therefore important.
Vitamin E is also recommended for premature infants and newborns with certain medical conditions, such as kidney or pancreatic disorders, due to its beneficial effects on the hepato-biliary system.
Olive oil contributes not only vitamin E but also essential fatty acids, which are important for infant development. The ratio of linoleic acid to linolenic acid in olive oil is similar to that found in breast milk.
The beneficial effects of oleic acid, the main fatty acid in olive oil, extend beyond pregnancy. In addition to its well-documented role in preventing hypercholesterolaemia and atherosclerosis — processes that can begin early in life — oleic acid may also support growth, bone mineralisation and development during infancy.
Dietary requirements during pregnancy and early childhood
During pregnancy and breastfeeding, it is generally recommended to increase the intake of healthy fats, particularly monounsaturated fats, while limiting saturated fats and cholesterol. As with any dietary plan, overall nutritional balance and appropriate calorie intake remain essential to avoid excessive weight gain.
Children under three years of age have different nutritional needs from older children. At this stage of development, around 40% of their energy intake comes from fats, whether through breast milk or other types of milk.
Maintaining an appropriate balance of nutrients and energy intake is essential to support healthy growth and development during early childhood.
Olive oil and ageing
Olive oil contains a variety of antioxidant compounds, including vitamin E and polyphenols, which play an important biological role in neutralising free radicals. These molecules are involved in the development of certain chronic diseases and in the ageing process.
By helping to limit oxidative damage, antioxidants may contribute to healthier ageing and increased life expectancy, as suggested by several epidemiological studies.
Diet is known to influence many conditions associated with ageing, including osteoporosis and cognitive decline.
What is osteoporosis?
Osteoporosis is a condition characterised by a reduction in bone mass and bone density, which increases the risk of fractures.
Two main forms are commonly identified:
- Type I osteoporosis, which generally affects post-menopausal women in middle age
- Type II osteoporosis, which occurs mainly in older adults
Olive oil and osteoporosis
Olive oil appears to have a beneficial effect on bone health. Studies suggest that bone mineralisation and calcification may improve with higher olive oil consumption.
Olive oil also supports the absorption of calcium, an essential mineral for bone formation. For this reason, it may play an important role both during growth and in the prevention of osteoporosis later in life.
Olive oil and cognitive function
Diets rich in olive oil may also help protect against age-related cognitive decline. Research conducted among older adults has shown that individuals whose diets contain higher amounts of monounsaturated fats — particularly olive oil — tend to have a lower risk of memory loss.
Although the exact mechanisms are still being studied, one explanation is that monounsaturated fatty acids help maintain the structure and function of brain cell membranes. The body’s demand for these fatty acids may increase with age, making them particularly important in older adults.
In the same studies, the amount of olive oil consumed was inversely associated with cognitive decline, including memory loss, dementia and Alzheimer’s disease.
These findings suggest that olive oil, as part of a balanced diet such as the Mediterranean diet, may contribute to maintaining cognitive health during ageing.
Olive oil and skin health
As humans age, the skin undergoes gradual structural and functional changes that can affect its strength, elasticity and ability to repair itself.
Over time, several transformations occur in skin tissue. Among the most notable are:
- thinning of the dermis and epidermis, the inner and outer layers of the skin
- loss of elasticity
- reduced cushioning between the dermis and epidermis
- increased fibrosis, with accumulation of collagen
- a decreased capacity of skin tissue to repair damage and protect itself
External factors, particularly exposure to sunlight, can accelerate these ageing processes. Ultraviolet radiation generates free radicals, molecules that can damage cells and contribute to premature ageing of the skin.
Although the body has natural defence mechanisms that help neutralise free radicals, it is possible to reduce their harmful effects through substances that limit oxidative damage. Olive oil is considered one such natural protective agent, partly because its lipid composition is very similar to that of human skin.
In addition to polyphenols, olive oil contains several vitamins, including vitamins A, D, E and K. Among these, vitamin E plays a particularly important role as an antioxidant, helping protect cells against oxidative damage.
Researchers have also suggested that the antioxidant properties of olive oil may contribute to protecting skin cells from continuous oxidative damage, a process associated with the development of some types of skin cancer.
Although studies — particularly those focusing on vitamin E and oleic acid — are ongoing, definitive conclusions require long-term observation. Current research nevertheless suggests that oleic acid, the principal fatty acid in olive oil, may play an important role in helping counteract oxidative stress affecting the skin.
