A low-salt diet could damage hearts, according to a new study published in the prestigious medical journal The Lancet. However, that research is already under fire from medical investigators who take issue with the authors' methods and conclusions.
McMaster University researchers conducted a study showing that dietary restrictions of sodium only benefited patients who already experience high blood pressure (HBP). The investigation even seemed to suggest that low-salt diets could actually increase the risk of heart trouble.
The Population Health Research Institute (PHRI) at the Canadian university examined health records of over 130,000 subjects, living in 49 nations worldwide. Investigators looked for correlations in heart disease, stroke, and deaths among subjects with both normal and high blood pressure. They found all three conditions were more common among those on a low-salt diet than among subjects consuming average levels of sodium.
"While our data highlights the importance of reducing high salt intake in people with hypertension, it does not support reducing salt intake to low levels. Our findings are important because they show that lowering sodium is best targeted at those with hypertension who also consume high sodium diets," said Andrew Mente, a clinical epidemiologist at McMaster.
The investigation classified subjects into three groups, based on the amount of sodium they consumed on a daily basis. Those with moderate levels of salt intake were found to be at the lowest risk of suffering from circulatory problems.
Francesco Cappuccio, leader of the Collaborating Center for Nutrition at the World Health Organization denounced the study, as well as The Lancet for publishing the investigation.
Urine samples were collected in the morning, and this data was then extrapolated to day-long levels of excretion. According to Cappuccio, the mathematical methods used to do this were inadequate to get an accurate reading. He also stated that subjects in the study were sickly patients, each taking several medications, and that they were already at risk of death.
Cappuccio states the new study consists of a rehashing of an older investigation that was the target of numerous criticisms. Although the current examination is larger than the previous study, Cappuccio worries the larger sample size just compounds errors.
The original journal article was published in the online version of The Lancet on May 20.
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