Effect of a dietary supplement on blood pressure and oral microbiome

ISRCTN	ISRCTN26672679
DOI	https://doi.org/10.1186/ISRCTN26672679
Sponsor	University of Tartu
Funder	Ecosh Life OÜ

Submission date: 13/05/2026
Registration date: 18/05/2026
Last edited: 18/05/2026

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Circulatory System

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Tiiu Kullisaar
Principal investigator, Public

Ravila 19
Tartu
50411
Estonia

Phone	+372 (0)53485070
Email	tiiu.kullisaar@ut.ee

Prof Reet Mändar
Scientific

Ravila 19
Tartu
50411
Estonia

Phone	+372 (0)5044291
Email	reet.mandar@ut.ee

Study information

Primary study design	Interventional
Allocation	Randomized controlled trial
Masking	Blinded (masking used)
Control	Placebo
Assignment	Parallel
Purpose	Supportive care
Scientific title	Effect of a nitrate- and flavonoid-rich supplement on blood pressure and oral microbiome in resistant hypertension
Study objectives
Ethics approval(s)	Approved 12/06/2023, University of Tartu Ethics Review Committee on Human Research (Ülikooli 18a, Tartu, 50090, Estonia; +372 (0)7376215; kaire.kallak@ut.ee), ref: 379/T-6
Health condition(s) or problem(s) studied	Essential hypertension stage I
Intervention	Patient randomization was performed by the partner institution (Ecosh Life OÜ) using a pre-established randomization scheme. The partner institution assigned each study participant a unique randomized subject number and the corresponding numbered dietary supplement kit. The randomized subject numbers and the matching kits were provided to the study nurse, who dispensed the study products to participants according to the assigned numbers. The patients were randomly divided into two groups, the intervention group and the placebo group. The intervention group received dietary supplement capsules, the placebo group received rice powder capsules. Both capsules were prepared by Ecosh Life OÜ, the capsules and packages were without visible identifiers. The daily dose of dietary supplement capsules contained the following components: hesperidin 500 mg, extract of green tea (Camellia sinensis L.) 450 mg (containing epigallocatechin-3-gallate 203 mg), citrulline malate 400 mg, extract of green coffee beans 300 mg, beetroot powder 250 mg, extract of hawthorn berry (Crataegus laevigata) 180 mg, extract of grape seed (Vitis vinifera L.) 150 mg, folic acid (vitamin B9) 800 µg. Both types of capsules were consumed once a day for 2 months. All patients continued consuming their prescribed medications during the trial period.
Intervention type	Supplement
Primary outcome measure(s)	Brachial blood pressure (BP) measured using a validated oscillometric technique (OMRON M4-I; Omron Healthcare Europe BV, Hoofddorp, the Netherlands) in a sitting position from the nondominant arm as a mean of three consecutive measurements at 5-minute intervals, at baseline and 2 months Arterial stiffness measured using sphygmocor apparatus (SphygmoCor, version 7.1; AtCor Medical, Sydney, NSW, Australia) at baseline and 2 months Peripheral pressure waveforms from the radial/femoral arteries measured using a high-fidelity micromanometer (SPT-301B; Millar Instruments, Houston, TX, USA) at baseline and 2 months Cortisol in saliva measured using standard method (ECLIA) at baseline and 2 months 8-isoprostanes in urine measured using enzyme-linked immunosorbent assay (Cayman Chemical) at baseline and 2 months Composition of salivary microbiome measured using Illumina NextSeq2000 system at baseline and 2 months
Key secondary outcome measure(s)
Completion date	24/11/2024

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	75 Years
Sex	All
Target sample size at registration	20
Total final enrolment	20
Key inclusion criteria	1. Essential hypertension stage I 2. A desire to participate 3. Age at least 18 years
Key exclusion criteria	1. Heart failure (New York Heart Association [NYHA] 3-4) 2. Diabetes
Date of first enrolment	03/09/2023
Date of final enrolment	08/09/2024

Locations

Countries of recruitment

Estonia

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No

Editorial Notes

18/05/2026: Study's existence confirmed by the University of Tartu Ethics Review Committee on Human Research.