LOS ANGELES—Daily consumption of more than the American Heart Association’s (AHA) recommended amount of 1,500 mg of sodium contributes to a higher stroke risk, according to the results of a study presented at the 2011 International Stroke Conference. Persons who consume more than 4,000 mg/day of sodium have a greater than 2.5-fold increased risk of stroke, compared with those who consume fewer than 1,500 mg/day, reported Hannah Gardener, ScD.
Using data from the Northern Manhattan Study, Dr. Gardener, Assistant Scientist, Department of Neurology, University of Miami Miller School of Medicine, and colleagues investigated the relationship between sodium consumption and risk of stroke among a multi-ethnic population.
“The results of our study suggest that the new AHA strategic dietary goals will help promote ideal cardiovascular and brain health, and this evidence may be used in campaigns aimed at reducing cardiovascular disease risk by targeting dietary behavior,” Dr. Gardener stated.
The researchers administered food frequency questionnaires to 3,166 participants. Individual responses were excluded from the final study cohort if the person had experienced a previous myocardial infarction, had improbably high- or low-calorie consumption, or reported sodium intake of more than 10,000 mg per day. The final cohort included 2,657 individuals; the majority were women (64%), and the mean age was 69. Participants were followed up annually for incidence of stroke, myocardial infarction, and death.
Few People Heed Sodium Intake Recommendations
The investigators grouped responses into five categories of daily sodium intake at baseline (fewer than 1,500 mg, 1,500 to 2,400 mg, 2,400 to 3,000 mg, 3,000 to 4,000 mg, more than 4,000 mg) and found that 88% of the study population consumed more than the AHA-recommended 1,500 mg per day, and only one-third met the US Dietary Guideline of less than 2,300 mg per day.
The majority of participants (27%) consumed between 1,500 and 2,400 mg/day, 17% between 2,400 and 3,000 mg/day, 23% between 3,000 and 4,000 mg/day, and 21% more than 4,000 mg/day. The average sodium intake was 3,031 mg daily, more than twice the AHA’s recommended amount.
During an average follow-up of 10 years, the researchers recorded 227 new stroke incidents.
Small Dietary Changes Can Lead to Substantially Lower Stroke Risk
Dr. Gardener’s group observed an 18% increased risk of stroke for each 500 mg per day increase in sodium consumption after adjusting for demographics, behavioral risk factors, and vascular disease risk factors (including diabetes, hypercholesterolemia, hypertension, previous cardiac disease, and BMI).
“When we assessed sodium in categories, we saw a slight, but not statistically significant, increase in stroke risk among those who consumed between 1,500 and 4,000 mg per day; however, those who consumed more than 4,000 mg per day had a 2.67-fold increased risk of stroke as compared to those who consumed less than 1,500 mg per day,” Dr. Gardener reported.
Dr. Gardener noted that even fairly small changes in diet could amount to substantial changes in the risk of stroke.
“The take-home message is that high-sodium intake is a risk factor for ischemic stroke among people with hypertension as well as among those without hypertension, underscoring the importance of limiting consumption of high-sodium foods for stroke prevention,” she said.
—Ariel Jones