As the US struggles with declining life expectancy (as deaths from suicides, drug overdoses and other "deaths of despair" climb), rising infant mortality and ballooning health-care costs that preclude access to preventative care for millions of Americans - not to mention the attendant ills of rampant obesity and tobacco use), America has seen its position among the world's healthiest nations deteriorate, while, across the Atlantic, more European nations are claiming spots in the highest echelons of the global rankings.

According to Bloomberg's 2019 World Health Rankings, Spain has supplanted Italy as the world's healthiest country. In the most ranking, published in 2017, Spain had placed sixth.

Four other European nations ranked among the top 10 in 2019: Iceland (third place), Switzerland (fifth), Sweden (sixth) and Norway (ninth). Japan was the healthiest Asian nation, climbing three ranks to place fourth overall, and supplanting Singapore, which dropped to eighth. Rounding out the top ten were Australia and Israel, which ranked seventh and 10th, respectively.

Variables including life expectancy are used to rank countries, while factors like tobacco use and obesity work against the overall ranking. Environmental factors like access to clean water and sanitation are also taken into consideration. Spain has the highest life expectancy at birth among European Union nations. Out of all 169 nations that BBG tracks, only Japan and Switzerland rank higher. By 2040, Spain is forecast to have the highest lifespan, at roughly 86 years, followed by Japan, Singapore and Switzerland.

The reason? Access to primary care.

"Primary care is essentially provided by public providers, specialized family doctors and staff nurses, who provide preventive services to children, women and elderly patients, and acute and chronic care," according to the European Observatory on Health Systems and Policies 2018 review of Spain. Over the past decade, this has helped bring about a decline in deaths from heart disease and cancer. While China ranked 52nd overall, it's on track to surpass the US by 2040, according to the Institute for health metrics and evaluation.

In the Caribbean, Cuba placed highest at 30, making it the only developing nation to be ranked that high.

In North America, Canada holds the highest ranking, placing 16th overall - that's well above the US and Mexico, which rank 35th and 53rd.

The key to the healthy lifestyles of European countries, according to BBG, could be their observance of the Mediterranean diet, which is heavy in vegetables, nuts and lean proteins like fish.

Researchers say eating habits may provide clues to health levels enjoyed by Spain and Italy, as a “Mediterranean diet, supplemented with extra-virgin olive oil or nuts, had a lower rate of major cardiovascular events than those assigned to a reduced-fat diet,” according to a study led by the University of Navarra Medical School.

Many of the lowest ranking countries are located in sub-Saharan Africa, which accounted for 27 of the 30 unhealthiest nations in the ranking. Haiti, Afghanistan and Yemen were the others. Mauritius was the healthiest in Sub-Sahara, placing 74th globally due to its low rates of death by communicable disease.

See the full ranking below: