In vitro (mechanism & safety screens). Start with biochemical and cell-based assays to establish plausible antihypertensive mechanisms and screen for toxicity: (1) ACE (angiotensin-converting enzyme) inhibition and, if relevant, renin inhibition assays; (2) endothelial cell assays for nitric oxide (NO) production, eNOS phosphorylation, and protection against oxidative stress; (3) antioxidant (DPPH/ABTS/ORAC) and anti-inflammatory readouts (e.g., IL-6/TNFα production in macrophages); (4) ex-vivo vascular reactivity (wire myograph) to test vasorelaxation on isolated arteries; and (5) cytotoxicity and genotoxicity screens. These provide mechanistic justification to progress to animals and help define active dose ranges.

In vivo (proof-of-concept and safety). Use well-characterized animal hypertension models to show BP lowering and target engagement: common choices are the spontaneously hypertensive rat (SHR) for genetic hypertension, DOCA-salt or high-salt models for volume-/salt-sensitive hypertension, L-NAME for NO-deficiency models, and angiotensin II infusion for RAS-driven hypertension — each model answers different mechanistic questions. Measure BP with telemetry (gold standard) or tail-cuff with corroborating endpoints, and collect tissues (heart, kidney, aorta) for histopathology. Key in vivo readouts: systolic/diastolic BP time course, vascular reactivity, renal function (creatinine, urine albumin), cardiac/renal histology, and markers of oxidative stress/inflammation. Also do GLP-style repeated-dose safety (toxicity, body weight, liver/kidney panels, hematology) and check for off-target effects. Use a vehicle control and a positive control (e.g., low-dose ACE inhibitor) when possible.

Clinical (efficacy & safety in humans). To substantiate a structure/function or health claim you’ll typically need randomized, double-blind, placebo-controlled trials. Primary efficacy endpoints are change in clinic BP (systolic and diastolic) and, ideally, 24-hour ambulatory BP monitoring (ABPM) for robustness — ABPM is increasingly viewed as the most reliable outcome for antihypertensive interventions. Typical trial length for nutraceutical BP trials is 8–12+ weeks (longer for durable effects); include pre-specified responder analyses and a safety monitoring plan. Safety monitoring should include liver enzymes, renal function, electrolytes, ECG (if mechanism warrants), and adverse-event reporting. For claim-making, document consistency (standardized extract/marker content), batch testing, contaminants/heavy-metals, and Good Manufacturing Practice (GMP) compliance.

Critical biomarkers & outcome measures to collect across stages: clinic and ambulatory SBP/DBP, plasma renin/aldosterone/Ang-II (if probing RAS), NO metabolites or endothelial function indices, endothelin-1, NT-proBNP (cardiac strain), markers of renal injury (creatinine, urine albumin), systemic inflammation (hs-CRP), oxidative stress markers, and routine safety labs (LFTs, CBC, electrolytes). For mechanistic confirmation, measure target pathway readouts in preclinical studies (ACE activity, eNOS, oxidative stress enzymes).

Regulatory & evidence standards. Follow local regulatory frameworks: in the U.S. DSHEA/FDA covers dietary supplements — structure/function claims require truthful, non-misleading scientific substantiation and an FDA 75-day notification for new claims; health claims need much stronger evidence or approval. In the EU, EFSA publishes guidance on health-claim substantiation and safety assessment of botanicals; their guidance documents are the reference for dossier composition. Keep a dossier with quality (standardization, stability), preclinical safety, and well-designed clinical trials to support any consumer claims.

Practical study design tips (short checklist):

Standardize and chemically characterize your ingredient (marker compound, assay for content).

Do dose-ranging in animals (identify NOAEL, pharmacologically active dose).

Use placebo control, randomization, blinding, pre-registered protocol and sample-size calculation for clinical trials; include ABPM if possible.

Monitor drug-supplement interactions (esp. antihypertensives, anticoagulants).

Preserve raw data for safety signal appraisal and be conservative about clinical claims unless supported by RCT evidence.

Dear colleague I'd like to I tell you frankly that there is no clear evidence of a supplement that could do the same job as medicines for the control of hypertension .Currently the cornerstones of treatment of hypertension are lifestyle changes and medicines.

However I may add a few hints to answer your question. I feel that the best test to validate a medicine or a supplement effect on hypertension is the clinical outcome of the that medicine or supplement.

If the dietary supplement you are talking about has not been tested earlier on human beings , then you need to test it on animals first .The biochemical tests done on animals or human beings [ as mentioned by the answer of another colleague ] may not give you an answer as to what extent it can control hypertension in human beings , but it may give you a hint on the mechanism of actions of that supplement. If it has already been used on human beings and you want to enlarge further on its effects on human hypertension then for the sake of that you need to have a randomized controlled trial comparing the supplement with a validated medicine used for hypertension control and follow up both for 12 to 24 weeks to reach to your primary [ blood pressure control ] and secondary [ renal functions tests , electrolytes , renin-angiotensin -aldosterone system , ECG ,blood sugar –etc ] endpoints. Follow the European or American guidelines to diagnose hypertension. if you have a good number of patients then then you can segregate the patients to different categories ,each one will take a different dose of the dietary supplement .A statistician can help you guess the number of patient that would give your study the power to give fair conclusions .thank you

In my opinion, the main impact on the blood pressure is its level change. That is why the first and most important are the simple BP changes (decrease or increase). The most important additional parameter is a heart rate: you could speculate about the sympathetic activity changes and also use the double product (BP*HR). There are more other markers, but if you consider impact on BP these two are the most important despite their simplicity.