The global survey, that combines data on sodium intake and figures on deaths from heart-related conditions in 2010, suggests that 15% of all deaths from heart attacks and strokes in the world (2.3 million deaths) were caused by eating too much salt.
According to the data from 50 countries around the world, the country with the highest salt-related deaths is the Ukraine, followed closely by Russia. Countries with the lowest level of salt-implicated heart deaths were Qatar and Kenya.
"National and global public health measures, such as comprehensive sodium reduction programs, could potentially save millions of lives," said Dr Dariush Mozaffarian from Harvard Medical School and the Harvard School of Public Health – lead author of the study.
Presented at the American Heart Association Meeting, the new study findings are based on data from the 2010 Global Burden of Diseases Study in combination with a meta-analysis of 107 trials relating to salt intake and blood pressure and cardiovascular disease risk.
Sodium is a vital nutrient and is necessary for the body to function. However the average daily salt consumption in the western world (between 10 and 12 grams) vastly exceeds maximum recommendations from WHO/FAO of 5 grams per day.
Such high intakes of dietary sodium have been linked to negative health impacts, including the development of hypertension, cardiovascular disease, certain cancers, and other health problems.
In countries like the UK, Ireland, the USA, and other industrialized countries, over 80% of salt intake comes from processed foods – meaning many consumers do not realise they are consuming such high quantities. Because of this, reducing the sodium content in food products has become a major issue for the processed-food sector.
The process of reducing salt levels in foods is an on-going process within the industry, with many now acknowledging that high sodium levels in some foods must be tackled.
However, the reduction of salt in processed foods is a major challenge because in addition to flavour enhancement, the food industry has historically added salt (sodium chloride) to foods to enhance shelf life, modify flavour, enhance functionality, and control fermentation.
Mozaffarian and his colleagues analysed 247 surveys of adult sodium intake, from 50 countries that formed part of the 2010 Global Burden of Diseases Study.
In addition, the team determined how dietary sodium affects risk of cardiovascular disease by performing a meta-analysis of 107 randomised, prospective trials that measured how sodium affects blood pressure, and a meta-analysis of how these differences in blood pressure relate to the risk of developing cardiovascular disease compared with consuming no more than 1,000 mg per day of sodium (which the researchers defined as an optimal amount of sodium for adults).
While an estimated 2.3 million deaths were linked to excessive salt consumption, the authors noted that their study only finds an association between salt intake and heart-related deaths, and cannot confirm a cause-and-effect relationship.
Of these 2.3 million deaths, nearly 1 million of them – 40% of all salt-related deaths - were premature, occurring in people 69 years of age and younger, the team said.
Further analysis showed that 84% of the deaths due to eating too much sodium were in low and middle-income countries, rather than high-income countries.