Salt: blood pressure elevation, alternative assessments and taste sensitivity
| ISRCTN | ISRCTN14162385 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN14162385 |
| Sponsor | Lake Lucerne Institute (LLUI) |
| Funder | Lake Lucerne Institute (LLUI) |
- Submission date
- 19/02/2026
- Registration date
- 14/07/2026
- Last edited
- 14/07/2026
- Recruitment status
- Recruiting
- Overall study status
- Ongoing
- Condition category
- Circulatory System
Plain English summary of protocol
Background and study aims
High blood pressure is a leading cause of death worldwide, and for many people, the primary culprit is salt. About half of the population has a "salt-sensitive" body type, meaning their blood pressure spikes dangerously after eating salty foods, significantly increasing their risk of heart disease. Unfortunately, the current way to test for this sensitivity is an intensive three-week process involving strict diets and 24-hour monitoring, making it nearly impossible for doctors to use in everyday practice.
This study aims to assess a much faster, safer alternative: a simple 2-hour test (immediate pressor response to oral salt [IPROS]). By measuring how blood pressure reacts to a single small dose of salt during a single office visit, we hope to provide a practical tool that helps doctors identify high-risk patients and provide preventative dietary advice.
Who can participate?
Adults aged 21–50 years. Participants must have been residing in Europe for more than 1 year. All participants are required to be able to give informed consent as documented by signature. Participants in Switzerland must be able to understand English, German or Italian, participants in the UK must be able to understand English, and participants in Italy must be able to understand English or Italian.
What does the study involve?
The study begins with a registration process where participants complete an online demographic and screening questionnaire to determine their eligibility. Once informed consent is provided, participants start the first study session, which can be completed either online via a video conferencing platform or in person, based on their preference. During this initial meeting, participants are introduced to a dietary recording app, which they will then use to maintain a food diary for seven consecutive days.
Following the initial week of recording, participants attend an onsite visit at the research centre for a baseline assessment. During this session, the research team performs body composition analysis, a taste assessment, and collects a DNA sample. This visit also includes the calibration of study tools and a measurement of the body’s response to salt consumption, known as an IPROS assessment.
After the baseline visit, participants are assigned to one of two groups to begin a crossover dietary intervention. This phase involves following a specific diet for 1 week, followed by a 1-week break, and then switching to the alternative diet for the final week. At the conclusion of each dietary intervention week, participants are required to provide a 24-hour urine sample. Throughout the entire duration of the study, participants wear a validated blood pressure monitor.
What are the possible benefits and risks of participating?
There are no direct medical benefits to taking part in this study. However, participants will receive a comprehensive assessment of their blood pressure profile and how their body reacts to salt, which may provide valuable personal health insights. Furthermore, the research offers substantial contributions to science and society by evaluating the immediate pressor response to oral salt. This project aims to establish a safer, more practical diagnostic tool to replace current methods, which are often logistically difficult and carry higher safety risks.
The study involves a controlled nutritional salt intervention to establish the necessary data. This process may lead to a temporary increase in blood pressure; however, in a healthy population with normal blood pressure, this risk is considered minimal and reversible. Participants may experience minor discomforts such as increased thirst or mild fluid retention. Additionally, there is a possibility that the study could reveal previously undiagnosed pre-hypertension or hypertension. While the study itself does not provide an official medical diagnosis, researchers will advise any participant whose results suggest these conditions to follow up with a medical professional for formal confirmation and guidance.
Where is the study run from?
1. Lake Lucerne Institute (LLUI) (Switzerland)
2. St Mary’s University (UK)
3. University of Trieste (Italy) and Institute for Maternal and Child Health—IRCCS (Italy)
When is the study starting and how long is it expected to run for?
July 2026 to April 2028
Who is funding the study?
Lake Lucerne Institute (LLUI) (Switzerland)
Who is the main contact?
Dr Catherine A-M Graham, cat.graham@llui.org
Contact information
Principal investigator
Rubistrasse 9
Vitznau
6354
Switzerland
 ORCID ID |
0000-0003-2717-6324 |
|---|---|
| Phone | +41 (0)795263836 |
| yiannis.mavrommatis@llui.org |
Scientific, Public
Rubistrasse 9
Vitznau
Lucerne
6354
Switzerland
| ORCID ID |
0000-0002-9129-1151 |
|---|---|
| Phone | +41 (0)795263836 |
| cat.graham@llui.org |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Randomized controlled trial |
| Masking | Open (masking not used) |
| Control | Dose comparison |
| Assignment | Crossover |
| Purpose | Prevention, Screening |
| Scientific title | Can the immediate pressor response to oral salt be used as an alternative method to assess salt sensitive blood pressure, alongside other known blood pressure related clinical assessments? |
| Study acronym | SALT-BEATS |
| Study objectives | Aim: This project aims to develop a clinically feasible diagnostic tool for salt-sensitive blood pressure (SSBP). Primary Objective: 1. To determine how well the immediate pressor response to oral salt (IPROS) discriminates salt-sensitive from non–salt-sensitive individuals, as defined by the reference methodology. This objective is implemented to improve the ability to include SSBP stratification in future research due to the traditional method of diagnosis limiting clinical feasibility and patient safety, while current alternatives lack diagnostic validity. Secondary Objectives: 1. To assess the association of IPROS with short-term blood pressure-related risk factors of CVD, for example, nocturnal dipping, morning surge, etc. 2. To assess the association of IPROS with taste sensitivity (including threshold and preference). |
| Ethics approval(s) |
Approved 17/06/2026, Ethikkommision Nordwest und Zentralschweiz (Hebelstrasse 53, Basel, 4056, Switzerland; +41 (0)61 268 13 50; eknz@bs.ch), ref: 2026-00310 |
| Health condition(s) or problem(s) studied | Hypertension |
| Intervention | Simple randomisation using SPSS Software to either: Index test: immediate pressor response to oral salt (IPROS): After an 8-hour overnight fast, IPROS data will be collected. Briefly, blood pressure (BP) will be recorded at 10-minute intervals for 40 minutes. The recording at minute 40 will be used as the baseline rested value. Then, participants will be administered two 1 g sodium chloride tablets, each containing 1 g (394 mg of sodium). BP will be monitored at 10-minute intervals for 120 minutes. The protocol and dosage (2 g salt) is supported elsewhere. BP measurements will be made with an automated validated sphygmomanometer in the seated position, with the participants’ arms at heart level. Reference standard: salt loading protocol: All participants will undertake a 7-day high salt diet (18 g/day) and then a 7-day low salt diet (3 g/day), with a minimum 7-day washout period between. The diet record undertaken prior to the intervention will be analysed by a researcher. The participant will then be trained on how to reduce the salt content of their diet to <3 g/day. They will be provided with personalised feedback on their standard dietary intake and with standardised information sheets. During the high-salt diet, participants will be supplemented with salt tablets. BP will be monitored throughout by a validated wristband, which has the CE mark as a Class IIa medical device in accordance with the Medical Devices Regulation (EU) 2017/745. SSBP will be diagnosed when participants exhibit a mean arterial pressure (MAP) difference of ≥5 mmHg between the low and high salt diet weeks. This cut-off is deemed a clinically relevant change. |
| Intervention type | Other |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 01/04/2028 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 21 Years |
| Upper age limit | 50 Years |
| Sex | All |
| Target sample size at registration | 300 |
| Key inclusion criteria | 1. Aged 21–50 years, the cut off at age 50 years is related to the association of increased age with salt sensitivity and arterial wall thickening. 2. Participants must have been residing in Europe for more than one year. This cutoff is selected to account for the acculturation effect. 3. Both male and female participants will be recruited, sex will be used as a covariate in all following analysis. Sex is known to influence blood pressure, but difference in the prevalence of salt sensitive blood pressure are unknown. Although sex comparison is not an aim of this study, sex differences will be taken into consideration. 4. All participants are required to be able to give informed consent as documented by signature. 5. Participants in Switzerland must be able to understand English, German or Italian, participants in the UK must be able to understand English, and participants in Italy must be able to understand English or Italian. |
| Key exclusion criteria | 1. Pregnant or lactating 2. Diagnosed hypertension or other conditions known to influence blood pressure (e.g. advanced chronic kidney disease, heart failure, secondary hypertension). 3. Participants must not be taking any blood pressure regulating medication. Blood pressure medication will impact response to dietary salt. 4. Participants must not have a resting blood pressure of higher than 130/80 mmHg. |
| Date of first enrolment | 01/07/2026 |
| Date of final enrolment | 01/03/2028 |
Locations
Countries of recruitment
- United Kingdom
- England
- Italy
- Switzerland
Study participating centres
Twickenham
TW1 4SX
England
Vitznau
Lucerne
6354
Switzerland
Trieste
34149
Italy
Trieste
34127
Italy
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|
Editorial Notes
25/06/2026: Study's existence confirmed by the Ethikkommision Nordwest und Zentralschweiz.
