I also read the articles with interest. My supposition is that diet, largely based on a Mediterranean Diet, is a large part of the finding. But, I also assess that the people, culture, and politics of Spain, and indeed Portugal also assist in the study findings.
Note that I am NOT making any judgments on relative positions of one side versus the other. In that regard, this ought NOT be interpreted to be a political statement (moderators).
In my observation and over 40 years of global travel, I have observed that, relatively, those countries whose populations and societies simply get on with their lives and do not interfere with other countries issues, problems and strife, seem to be relatively more happy, healthy and longer-lived. Of course, my observations are empirical and subjective, whereas any formal study would be grounded in formal statistical methodology.
I observe and opine that, in a country such as Spain, people live their lives in peace and relative good health. Their government, while not isolationist, is not interventionist. They are neither a global superpower; nor, contending to be or remain one. Spain had that experience in the 1500 and 1600s... been there, done that...
Governmental policies are focused internally, not externally. True, Spain has some issues with migration over the fence in its' remaining North African territories. But these pale in comparison to other migration crises in other parts of the world.
Simply put, to me, Portugal and Spain represent an oasis in a turbulent world, region, and culture. I find it very safe, sane, civilized, friendly and beautiful. Originally a Europhile, I now regard myself as a Iberophile. I love everything about Portugal and Spain, formally known as Iberia, or the Iberian Peninsula.
I only wish I had discovered it when I was younger, instead of in my late 50s. But, I take the book of my life, one unfolding page at a time, and I do not look ahead to the last chapter...
If situations were favorable, I would seek to live there at least a large chunk of my year. But, like yours, my life is what it is.
Hope this helps the dialog.