High-salt diet contributes to resistant hypertension
MedWire News: A high-salt diet makes a major contribution to the elevated blood pressure (BP) observed in hypertension resistant to medication, a small trial suggests.
The findings suggest patients with resistant hypertension are “exquisitely salt sensitive,” say the researchers.
They add: “These data emphasize that the clinical management of patients with resistant hypertension should include intensive dietary salt restriction.”
The team randomly assigned 12 individuals with resistant hypertension to a week-long diet containing low sodium of 50 mmol/day (around half a teaspoon of salt) or high levels of 250 mmol/day (around 2.5 teaspoons).
Participants then underwent a 2-week wash-out period before being crossed over to the alternative diet.
At baseline, participants were taking an average of 3.4 antihypertensive medications and had a mean office BP of 145.8/83.9 mmHg.
Mean urinary sodium excretion with the low- and high-salt diets were 46.1 versus 252.2 mmol over 24 hours. Mean office systolic and diastolic BP reduced by 22.7 and 9.1 mmHg, respectively, during the low- versus high-salt diet.
Reductions in brain natriuretic peptide, body weight, and creatinine clearance, and increases in plasma renin activity with low-salt diet were indicative of a reduction in intravascular volume, the researchers report in the journal Hypertension.
They note that although participants had previously been advised to reduce salt intake and reported having done so, baseline sodium excretion still averaged 195 mmol over 24 hours, equivalent to 11.6 g of salt per day.
Lead researcher Eduardo Pimenta (Princess Alexandra Hospital, Brisbane, Queensland, Australia) noted that three-quarters of daily sodium intake in Western countries comes from salt added in commercial food processing or during food preparation in restaurants.
He added: “Our findings lend additional support to efforts to decrease the salt content of prepared foods and support dietary guideline revisions that include salt restriction in the treatment of resistant hypertension.”
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By Anita Wilkinson