Key points What is the impact of dietary sodium intake on blood pressure in middle-aged and elderly people? Findings In this prospectively assigned diet-order crossover study of 213 people, 1 week of a low-sodium diet resulted in an average 8 mm Hg reduction in systolic blood pressure compared with a high-sodium diet, with few adverse events. The low-sodium diet reduced systolic blood pressure in almost 75% of people compared to the high-sodium diet. Meaning In this trial, the blood pressure-lowering effect of dietary sodium reduction was comparable to that of a commonly used first-line antihypertensive drug. Importance Dietary sodium recommendations are debated in part due to the variable response of blood pressure (BP) to sodium intake. Furthermore, the effect of dietary sodium on blood pressure among people taking antihypertensive medications is poorly studied. |
Goals
To examine the distribution of individual BP response to dietary sodium, the difference in BP between individuals assigned to first consume a high- or low-sodium diet, and whether these varied by baseline BP and use of antihypertensive medications. .
Design, environment and participants
Prospectively assigned diet order with crossover in community participants enrolled between April 2021 and February 2023 in 2 US cities. A total of 213 people aged 50 to 75 years, including those with normotension (25%), controlled hypertension ( 20%), uncontrolled hypertension (31%), and untreated hypertension (25%), attended a baseline visit while consuming their usual and then completed high- and low-sodium diets for 1 week.
Intervention
High-sodium (approximately 2,200 mg of sodium added daily to the usual diet) and low-sodium (approximately 500 mg daily total) diets.
Main results and measures
Average 24-hour ambulatory systolic and diastolic BP, mean arterial pressure, and pulse pressure.
Results
Among the 213 participants who completed the high- and low-sodium diet visits, the average age was 61 years, 65% were women, and 64% were black.
While consuming usual, high-sodium, and low-sodium diets, participants’ median systolic blood pressure measurements were 125, 126, and 119 mm Hg, respectively.
The median intraindividual change in mean arterial pressure between the high- and low-sodium diets was 4 mm Hg (IQR, 0-8 mm Hg; P < 0.001), which did not differ significantly by hypertension status. Compared with the high-sodium diet, the low-sodium diet induced a decrease in mean arterial pressure in 73.4% of individuals.
The commonly used threshold of a decrease of 5 mm Hg or more in mean blood pressure between a high-sodium diet and a low-sodium diet classified 46% of people as "salt sensitive."
At the end of the first week of dietary intervention, the mean difference in systolic BP between individuals assigned to a high-sodium diet and a low-sodium diet was 8 mm Hg (95% CI, 4-11 mm Hg; P < 0.001) that was mostly similar across subgroups of age, sex, race, hypertension, baseline blood pressure, diabetes, and body mass index.
Adverse events were mild and were reported by 9.9% and 8.0% of people while consuming high- and low-sodium diets, respectively.
Conclusions and relevance Reducing dietary sodium significantly reduced blood pressure in most middle-aged and elderly adults. The decrease in BP from a high- to low-sodium diet was independent of hypertension status and use of antihypertensive medications, was generally consistent across subgroups, and did not result in an excess of adverse events. Final message
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Trial Registration ClinicalTrials.gov Identifier: NCT04258332
