Olive oil, the cardiovascular and coronary risks

Authors: Euro sciences Communication in collaboration with the Atherosclerosis Research Institute Munster, Germany.

The olive oil and the cardiovascular risk

Introduction

Several factors are the cause or atherosclerosis and of coronary diseases, but some of them can be modified. Food factors, particularly fats, are directly bound to CHD development. Most North and West European diets contain high quantities of saturated fatty acids( SFA) and this is to be connected to the high death-rate due to CHD in these regions. On the contrary, a lower CHD effect can be found in the Mediterranean countries where people are bound to follow the traditional Mediterranean diet deriving most of its fats from olive oil. Scientific researches show how the olive oil can have beneficial effects on lipid metabolism ( see the dossier “ The olive oil and its effects on lipid metabolism”), on blood pressure, on diabetics and on the mechanism of coagulation, playing a key-role in CHD prevention.

The olive oil and the hypertension

A deep link between diet and blood pressure has been stressed by scientific studies. Vegetarians and people following the Mediterranean diet use moderate quantities of olive oil, cereals, fruit and vegetables and low quantities of food rich in saturated fatty acids like butter, milk-products, cheese and meat. Blood pressure is generally lower in these groups of populations than others.

Positive factors of the Mediterranean diet

- Few fatty acids
- A lot of monounsaturated fatty acids( Mufa, from olive oil)
- A lot of complex carbohydrates and fibres
- A lot of micronourishes ( as potassium, calcium, magnesium and vitamins)
- A little salt
Although the anti-hypertensive elements of the Mediterranean diet have not been detected, studies pick out a combination of favourable factors ( see the box) working for blood-pressure lowering. A recent study suggests the olive oil added to a non- modified diet can have a beneficial effect on blood-pressure, an effect due only to the olive oil and not simply connected to its monounsaturated fatty acids.

The olive oil and the diabetics

Diet control and weight-loss are key-elements for the prevention and cure of not insulin-dependent Diabetes Mellitus (NIDDM). The patients who run the risk and the NIDDM patients have always been suggested to reduce the total use of fats, especially fatty acids, thus giving more room to complex carbohydrates. Anyway some researchers have found out that a diet with a few fats and lots of carbohydrates can increase the triglycerides and a diet rich in MUFA and a few carbohydrates could be advisable for the NIDDM patients. The so-called MUFA- diets with low SFA- quantities seem to improve the lipid layout and are associated with a better glycolic control compared to the diets rich in carbohydrates. The typical Mediterranean diet rich in fibres, carbohydrates and MUFA, but poor in SFA, is the ideal diet for diabetic people. The total content in fats can be daily modified according to the personal, individual needs, just changing the quantity of the olive oil.

Olive oil and obesity

Obesity is undoubtedly the main risk of cardiovascular diseases, because of its negative effects on the lipid balance, on blood-pressure and because of its association to NIDDM. From a caloric point of view food rich in fats is believed to be the main cause of the obesity. Therefore , the traditional Mediterranean diet, with cereals, vegetables and pulses, with a low energetic content, seems to match the obesity prevention, though it has a quite high content of olive oil. Epidemiologic studies show how the Mediterranean people suffer from obesity less than other countries.

The olive oil and the thrombogenic risk

There is some evidence that the coagulation factors are influenced by nourishment. n-3 PUFA were shown to have a strong influence on the platelet function, while the n-6 PUFA effects are still contradictory. Even if the positive MUFA effects are not available, yet, the most studies on thrombosis suggest how the above described, typical Mediterranean diet seems to have all the qualities to prevent from thrombosis.

Olive oil and coronary diseases

The Seven Countries Study, the important study investigation on CHD and the Mediterranean Diet links, demonstrated a direct connection with MUFA consumption and 15-year-survival. Almost 13000 men (aged 40-59 years) joined this study, and the death-rate, due to CHD during the 15-year-follow up, turned to be inferior in those countries where MUFA consumption is higher and SFA consumption is lower. Countries joining the Seven Countries Study:
- Italy
- Greece
- Yugoslavia
- Holland
- Finland
- USA
- Japan
Some evidence coming from the Greek Isle of Crete demonstrates the death-rate due to CHD was lower during the study, showing clearly that the capacity of the oleic acid (mainly derived from the olive oil) to lower the cholesterol in the blood together with the other beneficial effects, provide a tangible heart-protection. Unfortunately, since the Seven Countries Study started in the first 60’s, food habits have rapidly been modifying in the Mediterranean countries, where the attention to cardiovascular diseases is progressively decreasing. Researches on food habits stress how strong an increase of animal food consumption is to be recorded (meat, milk, milk-products) together with the use of fats different from olive oil. These changes have provoked a high cardiovascular risk as the cholesterol level, more obesity and hypertension – this trend can be modified maintaining and promoting the traditional diets in the Mediterranean Regions. Nevertheless some recent epidemiologic studies, dated back from 1992 to 1994, still show a clear beneficial effect of the Mediterranean diet, with a death- rate due to CHD lower in the Mediterranean Regions compared to western Europe and USA.

Intervention studies

The most intervention studies on food have always been addressed to a reduction of unsaturated fatty acids, carbohydrates and/or PUFA increase. The positive results confirmed the necessity to reduce saturated fats in the diet. No intervention and epidemiologic study has specifically investigated on MUFA effects in the primary CHD prevention. Anyway several studies on controlled diets have underlined how MUFA diets really lower the LDL and the HDL cholesterol level in the blood thus reducing cases of Ischemia and hearth-diseases or mortality due to cardiovascular diseases.

Dietary guidelines

Several health national organizations provide dietary guidelines for CHD prevention. These guidelines are as follows:
- total fats should be 30% of the assumed energy;
- SFA quantity should be reduced under 10%;
- PUFA quantity should not overcome the assumed energy, not over 7,8%;
- MUFA quantity should provide up to 15% of the assumed energy;
- the cholesterol assumed from food should be less than 300grams per day;
- carbohydrates and fibres consumption should be reduced.
The Mediterranean diet is surely an excellent example of how these advice can be followed every day. The Mediterranean diet implies a high quantity of vegetarian products (like bread, cereals, fruit and vegetables) and an adequate quantity of animal products. The olive oil is the key-source and provides high MUFA elements.