Heart Health and the Mediterranean Diet with Professor Catherine Itsiopoulos
Heart disease is a serious condition and continues to be the leading cause of death in Australia with one person dying every 18 minutes of heart disease which equates to about 80 Australians dying of heart disease every day1.
People who smoke, have high blood pressure, high cholesterol, diabetes, are abdominally obese, or have a family history of heart disease are more likely to develop heart disease.
An extensive worldwide study including 30,000 people with and without heart disease from 52 countries around the world has shown that over 90 percent of heart disease is preventable with healthy diet and lifestyle habits such as not smoking, exercising regularly, and consuming a diet rich in plant foods, especially fresh fruits and vegetables2.
Conversely a diet of highly processed foods rich in saturated fats and trans fats (animal fats), salt, and added sugars and low in fresh fruits and vegetables is associated with increased heart disease risk. This type of eating pattern can lead to obesity, high blood pressure, high cholesterol which in turn increase heart disease risk.
The Heart Foundation’s Eating for Heart Health Guidelines recommend plenty of vegetables, fruits, wholegrains, lean protein sources such as fish, lean meat and poultry, low fat dairy foods, legumes, nuts, seeds, oils such as olive, and using herbs and spices instead of adding salt. These guidelines are based on the latest evidence of dietary patterns associated with heart health including the Mediterranean dietary pattern3.
A panel of medical experts, dietitians and health professionals recently ranked the Mediterranean diet to be the healthiest diet overall compared to 39 other diets for the fourth year running (as reported by US News). This dietary pattern scored #1 for the best plant-based diet, easiest diet to follow and best diet for healthy eating, heart health and diabetes4.
The traditional Greek Mediterranean diet is a plant based diet rich in fresh leafy green vegetables and tomatoes, onions, garlic, herbs, fresh and dried fruit, nuts and seeds, fish and seafood, whole grain sourdough bread, fermented dairy foods such as feta cheese and yoghurt, and small portions of free range lean meat and chicken and eggs, and extra virgin olive oil as the main fat.
The Mediterranean diet has consistently been shown to be protective for heart disease and the most remarkable evidence in support of the diet’s cardioprotective effects is from a large Spanish study called the Prevencion con Dieta Mediterranea Study (PREDIMED). This study tracked the health outcomes of nearly 7500 people across Spain, with risk factors for heart disease such as obesity and high blood pressure, over a period of five years. People in the study were advised to follow a Mediterranean diet supplemented with 30 g nuts (walnuts, almonds, hazelnuts) per day or 1 litre of extra-virgin olive oil per week or a standard low-fat diet. At the end of the study, the people who followed a Mediterranean diet had a 30 per cent lower chance of dying from heart disease than those who followed the standard low-fat diet.
A Mediterranean diet is protective for heart disease because it is rich in heart protective nutrients with antioxidant and anti-inflammatory properties from extra virgin olive oil, nuts, seeds, fish and seafood, leafy greens, tomatoes, garlic and onions, herbs and spices, and fresh fruit, and low in highly processed high fat foods that are associated with heart disease. The antioxidant and anti-inflammatory elements of this dietary pattern prevent low grade inflammation which occurs in the coronary artery walls as the first step in atherosclerosis –the build up of fats in the artery wall that leads to blockage and heart attack. This dietary pattern is also protective for the risk factors leading to heart disease such as obesity (especially abdominal), high blood pressure and high cholesterol and dyslipidaemia (high triglycerides and low HDL (protective) cholesterol).
The anti-inflammatory potential of the traditional Mediterranean diet is attributed to the whole cuisine, however extra virgin olive oil may be particularly important. A recent clinical study by PhD Scholar Katerina Sarapis from La Trobe University demonstrated that consumption of 60ml per day of high polyphenol rich extra virgin olive oil for three weeks resulted in a significant reduction in systolic blood pressure compared to consumption of a low polyphenol olive oil in healthy volunteers5.
The therapeutic effects of the olive tree and its products such as the olive fruit, the oil or juice of the olive fruit, and the leaves have been used for centuries in traditional medicine for heart health, diabetes, inflammation and multiple other conditions. Although extra virgin olive oil has been extensively studied in human clinical trials alongside the whole Mediterranean diet cuisine in chronic disease management, until recently little high quality research has been published on the effects of olives or olive leaf in heart health or other chronic diseases. The olive leaf contains phenolic compounds, in particular hydroxytyrosol and oleuropein, in higher concentrations that the fruit and evidence from animal studies has shown that olive leaf extract has antioxidant, anti-inflammatory, and blood pressure lowering potential. Evidence from human clinical trials is emerging showing promising results. In a recent study 60 men with borderline hypertension were randomly allocated to consume olive leaf extract or a placebo free of polyphenols daily for 6 weeks and then switched to the alternate treatment after a 4-week washout period. The study showed a significant drop in blood pressure, blood fats and markers of inflammation after the men consumed the olive leaf extract but there were no effects after the placebo6. Further high quality human clinical trials examining the health benefits of olive leaf extract over longer periods and across larger population groups are important to strengthen the evidence for its therapeutic potential as an addition to a healthy diet and lifestyle in chronic disease management.