Because the experts say so!

The Greek diet is regarded as one of the healthiest in the world because it’s based largely around fruit and vegetables, wholegrains, fish, and a small amount of cheese and yoghurt.  This array of foods looks a lot like what I regard as a healthy, balanced diet. The Greeks are also famous for their love of olive oil, which is lower in saturated fat than butter, and therefore a good choice for cooking. Recent evidence published by the PNAS (Proceedings of the National Academy of Sciences) journal shows that the combination of olive oil and leafy salad or vegetables is what gives the Mediterranean diet its healthy edge, because the formation of nitro fatty acids between the two food groups lowers blood pressure. So I recommend that as a side, whatever you’re eating!

Who says so?

Extract from Jamie Oliver’s website.