BOSTONA lower sodium intake may decrease cardiovascular disease risk, according to a new study published in the journal Circulation.
Lead researcher Nancy Cook and a team from Harvard Medical School found that recent studies have raised the possibility of adverse effects of low sodium, particularly less than 2,300 mg per day, on CVD. However, they note that these findings might have resulted from suboptimal measurements of sodium and potential biases related to indication or reverse causation.
The researchers examined data from phases I and II of the Trials of Hypertension Prevention (TOHP), in which multiple 24-hour urine specimens among pre-hypertensive individuals were collected. During extended post-trial surveillance, 193 cardiovascular events or CVD deaths occurred among 2,275 participants who were not in a sodium reduction intervention. Median sodium excretion was 3,630 mg/24 hr, with 1.4% of the participants having intake <1,500 mg/24 hr and 10% having intake <2,300 mg/24 hr, consistent with national levels.
Compared to those with sodium excretion of 3,6004,800 mg/24 hr, risk for those with sodium <2,300 mg/24 hr was 32% lower after multivariable adjustment. In addition, the researchers found a linear 17% increase in risk per 1,000 mg/24 hr.
Although the study was not originally designed to test the effectiveness of lower sodium intake on CVD risk, multiple 24-hr urine samplesthe gold standard measure of sodium intakewere used to characterize usual sodium intake," said Lyn M. Steffen, University of Minnesotas School of Public Health. "In most observational studies, sodium intake has commonly been represented by a spot urine or overnight urine collection, which is not an accurate estimate of usual sodium intake and thus, previously published study results may be biased."
The studys researchers concluded that the results are consistent with overall health benefits of reducing sodium intake to the 1,500
2,300 mg/day range in the majority of the population, in agreement with current dietary guidelines."
A recent report from the Centers for Disease Control and Prevention (CDC) indicates sodium intake declined slightly during 2003-2010 in children ages 1 to 13 years, but the majority of Americans still consume excess sodium.