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?
Hypertension
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.
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.
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.