Lead author Dr. Dariush Mozaffarian of Brigham and Women's Hospital, Harvard Medical School and the Harvard School of Public Health said the research team analyzed 247 surveys of adult sodium intake, from 1990-2010 as part of the 2010 Global Burden of Diseases Study.
The researchers said the amount of sodium people consumed was affecting their risk of cardiovascular disease.
The researchers conducted a meta-analysis of 107 randomized, prospective trials that measured how sodium affects blood pressure and a meta-analysis of how these differences in blood pressure related to the risk of developing cardiovascular disease. This data was compared with consuming no more than 1,000 milligrams per day of sodium, which the researchers defined as an optimal amount of sodium for adults.
Nearly 1 million of these deaths -- 40 percent of the total -- were premature, occurring in people age 69 and younger. Sixty percent of the deaths occurred in men and 40 percent were in women.
Among the 30 largest countries in the world, those with the highest death rates per million adults due to over consuming sodium were: Ukraine, Russia and Egypt.
The United States ranked 19th out of the 30 largest countries, with 429 deaths per million adults due to eating too much sodium.
Average daily U.S. intake of sodium is more than 3,400 mg -- about 1.5 teaspoons of salt.
The findings were presented at the American Heart Association's Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism Scientific Sessions.