Researchers estimate that 1 in 10 cardiovascular deaths each year are attributable to sodium intake above the WHO recommendations of 2 g per day.
The research team, led by Dr. Dariush Mozaffarian of the Friedman School of Nutrition Science and Policy at Tufts University in Medford, MA, recently published their findings in The New England Journal of Medicine.
Sodium is an element that occurs naturally in most foods, such as table salt, milk, beets and celery. It is also added in high amounts to processed foods, including bread and processed meats.
"However," says Dr. Mozaffarian, "the effects of excess sodium intake on cardiovascular diseases globally by age, sex, and nation had not been well established."
Excess sodium intake attributable to 1.65 million cardiovascular deaths worldwide
To gain a better insight into how excess dietary sodium influences cardiovascular health on a global scale, the research team analyzed data from 205 surveys of sodium intake representing approximately 75% of the world's adult population.
They also assessed global nutrition data in order to see how sodium intake varies by sex, age and country. Furthermore, they conducted pooled meta-analyses to measure the effects of sodium on blood pressure, and separately, the effects of blood pressure on cardiovascular diseases.
The team's findings were applied to current global rates of cardiovascular diseases, and they used this information to estimate how many deaths are caused by sodium intake above 2 g per day.
Results of the study revealed that the average worldwide sodium intake in 2010 was 3.95 g per day - almost double the daily recommendation set by the World Health Organization (WHO).
All worldwide regions had sodium intakes above the WHO recommendation. These ranged from 2.18 g per day in sub-Saharan Africa to 5.51 g per day in Central Asia.
This excess sodium intake was attributable to 1.65 million cardiovascular-related deaths worldwide - the equivalent to 1 in 10 deaths from cardiovascular causes.
The researchers found that 4 out of 5 global deaths attributable to excess sodium intake occurred in low- and middle-income countries.
How is the US affected by sodium intake?
The average daily sodium intake in the US was almost 80% higher than the WHO recommendation, at 3.6 g, and significantly higher than the 2.3 g per day intake recommended by the federal government's Dietary Guidelines for Americans.
In addition, the researchers found that daily sodium intake above 2 g accounts for around 58,000 cardiovascular-related deaths in the US each year.
Commenting on the results, study author John Powles, of the department of public health and primary care at the University of Cambridge in the UK, says:
"These new findings inform the need for strong policies to reduce dietary sodium in the United States and across the world."
From their meta-analyses, the researchers found that reducing sodium intake lowered blood pressure in all adults, particularly among blacks, older adults and those who already had high blood pressure.
"Programs to reduce sodium intake could provide a practical and cost-effective means for reducing premature deaths in adults around the world," adds Powles.
The team notes that their study is subject to some limitations. For example, estimates of sodium intake were based on urine samples, which could have underestimated actual sodium consumption.
Earlier this year, Medical News Today reported on a study published in the American Journal of Hypertension, which claimed that the US recommendation of a sodium intake of less than 2.3 g a day is "excessively and unrealistically low."