These findings were presented at EPI-NPAM 2013, the Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2013 Scientific Sessions.
In the first study, Dr Saman Fahimi (Harvard School of Public Health, Boston, MA) and colleagues reported that in 2010, adults in 187 countries consumed, on average, 3950 mg sodium a day--roughly twice the maximum intake recommended by the World Health Organization (WHO) (2000 mg/day) or the AHA (1500 mg/day).
In the second study, Dr Dariush Mozaffarian (Harvard School of Public Health) and colleagues reported that in the same year, they estimate that excess dietary salt led to 2.3 million deaths from CVD worldwide and about one in 10 deaths from CVD in the US.
The average salt consumption in the US was 3600 mg/day, and the US ranked 19th of the 30 largest countries, in estimated numbers of CVD deaths that were thought to be related to excess salt consumption.
The authors told heart wire that the findings, the first to provide detailed estimates of global salt intake and its impact on heart health, should help guide public policies and physician counseling.
"Sodium intake in only six countries of 187 countries met the WHO guidelines," Fahimi said. "Therefore, implementation of sodium-reduction programs in order to reduce sodium intake of men and women of all age groups, in both developing and the developed world, should be considered as a top priority."
When counseling patients about the impact of dietary salt on heart health, physicians need to be aware that salty snacks such as peanuts and chips are not the only culprits, Mozaffarian said. "In the US and in most highly developed countries, 90% of the salt in the diet comes from packaged foods," where salt is used as a preservative; perhaps surprisingly, bread is the number-one source of salt, and cheese is a major source, he noted.
High-salt diet, a universal finding
Using data from the Global Burden of Disease study, Fahimi and colleagues reviewed national surveys of sodium intake based on 24-hour urinary sodium excretion (143 surveys) or on estimated dietary sodium intake (104 surveys).
They developed a model to estimate national, regional, and global sodium intake, by age and sex, in 1990 and 2010, from 187 surveyed countries (99% of the world's population).
Excess sodium intake was universal--seen in men and women of all ages, living in low- to high-income countries. In 2010, the average daily sodium intake exceeded 2000 mg in 181 countries and exceeded 3000 mg in 119 countries.
Sodium intake varied widely between different parts of the world. Kazakhstan had the highest sodium intake (6.0 g/day), followed by Mauritius (5.6 g/day), and Uzbekistan (5.5 g/day), whereas Kenya (1.5 g/day), Malawi (1.5 g/day), and Rwanda (1.6 g/day) had the lowest daily intake of sodium.
Model linked CVD deaths to sodium intake
To estimate how sodium intake contributed to death from CVD, Mozzaffarian and colleagues analyzed data from 247 national surveys of sodium intake in 66 countries in 2010. They performed a meta-analysis of 107 randomized controlled trials to determine the effects of sodium on blood pressure and then analyzed large prospective cohorts to determine the effects of blood pressure on CVD. They obtained the number of deaths from CVD from the Global Burden of Disease study. In their model, they assumed that the optimal intake was 1000 mg/day sodium (or 2.5 g/day salt).
Globally, of the CVD deaths attributed to high dietary sodium, 42.1% were from CHD, 41.0% were from stroke, and 16.9% were from other types of CVD.
Deaths from CVD that were related to dietary salt did not occur only in older men in wealthier countries:
Four in five deaths were in low- and middle-income countries.
40% of the deaths were in women,
One in three deaths occurred in people younger than 69.