Effect of Mediterranean diet on Various Diseases - II

Oxidative mechanism:
There is extensive evidence that oxidation of LDL plays an important role in atherogenesis. Oxidation of LDL begins with peroxidation of PUFA in the LDL molecule. The fatty acid composition of LDL is subjective to the dietary fatty acids. A high MUFA intake renders LDL more resistant to oxidation than a PUFA-rich diet. MUFA-rich diets also lead to a higher MUFA content of cell membranes and so higher cellular resistance to oxidative damage.

Dietary antioxidants found in olive oil, fruit and vegetables provide additional protection against oxidation, further reducing the risk of atherosclerosis.

Coronary heart disease:
In the Seven Countries Study2 (Italy, Greece, Yugoslavia, Finland, US, Netherlands and Japan), published in 1970, death rates at 15 years were low among populations having a high olive oil intake where SFA was low (i.e. a high MUFA: SFA ratio), specifically Greece, Italy and Yugoslavia.

On the other hand, high MUFA intake in the US seemed to be counteracted by a high SFA intake (i.e. a low MUFA: SFA intake) and CHD mortality was high.

Many randomized prevention studies have confirmed the links between dietary SFA, serum cholesterol and CHD. Most involved reducing SFA and increasing PUFA and these had positive outcomes. None of the trial diets was particularly high in MUFAs therefore the typical Mediterranean diet has not been directly tested in the primary prevention of CHD. Diets similar to the Mediterranean diet have been shown to lower serum and LDL cholesterol without adversely affecting HDL cholesterol. Such reductions result in reduced morbidity and mortality.

The Lyons Diet Heart Study in patients recovering from heart attack showed that a Mediterranean-style diet, high in monounsaturated fatty acids, even when adapted to a Western population, protects against CHD better than other recommended linoleic-acid rich diets for such patients.

The components of the Mediterranean diet have a beneficial effect on risk factors for CHD both through direct effect and by protective effects like antioxidant activity.

National and international guidelines for the prevention of coronary heart disease recommend the following:
• total dietary fat should be no more than 30 per cent of the calorie intake
• SFA should be below 10 per cent
• PUFA should be 7-10 per cent
• MUFA should be 10-15 per cent
• dietary cholesterol should be below 300mg/day
• Intake of complex carbohydrates and fiber should be increased.

The Mediterranean diet helps to achieve these as it has:
• large quantities of plant foods, bread, grain products, vegetables, legumes
• fruit
• low to moderate amounts of animal products
• olive oil as the principal source of fat with its high MUFA content
• low SFA
• high carbohydrate and fiber content.

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