There is obviously no definite answer for this question (yet!). However, in Europe, the Mediterranean diet considered to be an effective prevention against cardio-vascular diseases (everything related to the heart), diabetes and even cancer (1, 2) . This dietary pattern emerged in 1940s and 1950s in Spain, Italy and Greece.
The Mediterranean Dietary Pattern is high monounsaturated fats (coming from vegetable oils), fresh fruit and vegetables, fish, moderate (!) intake of alcohol, low intake of red meat, low-fat dairy. It is also characterised in low intake of refined sugars and saturated fats.
It is also important to understand, that in this case we are talking about "healthy" as "not leading to the disease/malfunction of the organism".