Key Points:
- LowSalt4Life 2 is a 6-month randomized controlled trial evaluating a mobile application-based sodium-focused JITAI among adults with HTN
- The results showed that a just-in-time adaptive mobile application (JITAI) intervention did not significantly reduce systolic blood pressure compared with app-based usual care alone.
- The intervention improved diastolic blood pressure and dietary potassium intake but had no significant effect on sodium intake.
- These findings highlight the challenges of translating digital behavioral interventions into clinically meaningful blood pressure reduction.
Excess dietary sodium intake remains a major contributor to hypertension and cardiovascular disease, with most Americans consuming well above recommended limits. Although sodium restriction is known to lower blood pressure, sustained adherence remains difficult, particularly in real-world settings such as grocery stores and restaurants where most dietary sodium is consumed.
During the Featured Clinical Research Session at the American College of Cardiology 2026 Scientific Sessions on Sunday, March 29, 2026, Dr. Michael Dorsch of the University of Michigan, presented results from the LowSalt4Life 2 trial, evaluating a novel mobile health intervention designed to promote low-sodium dietary choices in real time.
Funded by the National Heart, Lung, and Blood Institute (NHLBI), LowSalt4Life 2 (NCT05396001) was a 6-month, prospective, randomized controlled trial assessing a smartphone-based just-in-time adaptive intervention (JITAI) among adults with hypertension. A total of 410 participants were randomized 1:1 to either the LowSalt4Life app with JITAI (App+JITAI) or the app alone. At 2 months, participants in the intervention arm were further randomized to either continue the standard JITAI or receive a personalized version driven by reinforcement learning algorithms. The design manuscript was published in the American Heart Journal in February 2026.
The intervention leveraged smartphone sensors and geolocation to identify when participants were in grocery stores or restaurants and delivered tailored push notifications encouraging lower-sodium food choices. The app also enabled barcode scanning and provided real-time nutritional feedback using a traffic-light system to guide healthier decisions. The primary endpoint was change in systolic blood pressure (SBP) at 2 months. Secondary endpoints included diastolic blood pressure, achievement of blood pressure goals, dietary sodium and potassium intake, and medication changes.
At 2 months, there was no significant difference in systolic blood pressure between the App+JITAI group and the app-alone group (between-group difference ~1.7 mmHg; p=0.116). However, the intervention was associated with a modest but statistically significant reduction in diastolic blood pressure (~1.3 mmHg difference; p=0.017).
There was no significant improvement in sodium intake between groups, suggesting limited behavioral impact on the primary dietary target. In contrast, potassium intake improved significantly in the intervention group (p=0.011), along with a modest improvement in the sodium-to-potassium ratio (p=0.043). The proportion of patients achieving target blood pressure (<130/80 mmHg) did not differ significantly between groups, nor were there meaningful differences in antihypertensive medication adjustments.
App engagement was significantly higher in the intervention arm, and exploratory analyses suggested that greater app usage was associated with larger reductions in blood pressure, highlighting the importance of sustained user interaction.
Despite promising mechanistic design, the intervention did not translate into meaningful reductions in systolic blood pressure. As investigators noted, the use of an active control (app alone), high baseline patient motivation, and potential “attention effects” may have attenuated differences between groups.
“These findings suggest that while digital health interventions can influence certain behaviors and intermediate outcomes, achieving clinically meaningful reductions in blood pressure remains challenging,” the investigators concluded.
Limitations of the study include its enrollment of predominantly smartphone-literate participants from a single academic center, which may limit generalizability. Additionally, the active control design, where all participants received a mobile app and blood pressure monitoring, may have reduced the observable treatment effect.
LowSalt4Life 2 provides important insights into the evolving role of mobile health technologies in hypertension management. While the intervention demonstrated feasibility and engagement, future work will need to refine personalization strategies and behavioral targeting to achieve clinically meaningful improvements in cardiovascular outcomes.