Will changing to a Mediterranean diet improve cholesterol in patients with coronary heart disease?

This study compared the Mediterranean diet (MD) with the low-fat diet (LFD) in patients with coronary artery disease (CAD). It found that after 3 months the MD was associated with higher omega-3 levels than the LFD.

Cholesterol is the name commonly used for the fats in the blood. Cholesterol can block the arteries and lead to heart attacks or strokes. Omega-3 fatty acids (OFAs) are another type of fat that actually help to reduce cholesterol levels. OFAs are found in oily fish and are often associated with the Mediterranean diet. EPA and DHA are two types of OFAs that have a positive effect on cholesterol levels.

Increasing OFA levels and reducing cholesterol can reduce the risk of heart disease. It is not clear if changing to a Mediterranean diet can help to reduce cholesterol and increase OFA levels in patients with established CAD.

This study involved 132 Italian patients with CAD. Patients were divided into two groups. Group 1 was assigned to follow a Mediterranean diet (MD), group 2 followed a low-fat diet (LFD). The main difference between the diets was that the MD contained more fish and nuts. Patients attended monthly checkups to review their diet.  Blood samples were taken at the start and after 3 months, and the levels of different fats in the blood were measured. After 3 months the "Mediterranean-ness" of a patient's diet was measured using the MD adherence screening questionnaire (MeDAS).  

Patients whose diet had become more Mediterranean had higher levels of EPA and DHA omega-3 fatty acids in their blood after 3 months. The MeDAS score improved by 2.6 points in the MD group and by 1 point in the LFD group.

This study showed that following a Mediterranean diet increases the omega-3 levels in the blood for patients with CAD. 

This study involved Italian patients only, most of whom already follow a Mediterranean diet to some degree. Further studies are needed to see if these findings apply to other countries and ethnicities.