Chios Mastic in Well-Controlled Hypertension: Findings From the HYPER-MASTIC Randomized Controlled Trial.

title: "Chios Mastic and Well-Controlled Hypertension: Findings From the HYPER-MASTIC Trial"

description: "A double-blind, placebo-controlled trial finds no added blood pressure reduction from Chios mastic in well-controlled hypertension, with biologically interesting vascular signals in higher-risk participants."

study_type: "RCT"

sample_size: 106

journal: "Pharmacology Research & Perspectives"

pubmed_id: "42885189"

TL;DR

In adults with stable, well-controlled hypertension, three months of Chios mastic supplementation did not further lower 24-hour blood pressure compared with placebo. Gene expression changes related to vascular integrity appeared in a higher-risk subgroup, which makes this a promising lead for future trials rather than a practical recommendation today.

What the study found

Residual cardiovascular risk remains common even among people whose blood pressure is adequately controlled. Part of that risk is thought to come from low-grade inflammation, oxidative stress, and endothelial dysfunction, the impaired function of the cells lining blood vessels. Chios mastic, a resin from the *Pistacia lentiscus* var. *chia* tree grown on the Greek island of Chios, has been studied for antihypertensive, antioxidant, and vascular effects in animal models and smaller human studies. The HYPER-MASTIC trial asked whether adding it to existing blood pressure control offers any further benefit.

The trial enrolled 106 adults with stable hypertension and variable cardiovascular risk, estimated using the SCORE2 algorithm. Participants were randomly assigned to a low dose (1500 mg/day), a high dose (2800 mg/day), or placebo for three months. The primary outcomes were changes in 24-hour ambulatory systolic and diastolic blood pressure. Supplementation was well tolerated, and adherence was confirmed by dose-dependent rises in plasma masticadienonic and isomasticadienonic acids, which are markers of mastic intake. Adherence was therefore not the limiting factor in the results.

On the primary endpoints, the answer was no. There were no significant between-group differences in 24-hour systolic or diastolic blood pressure after the intervention. The investigators interpret this as likely reflecting a ceiling effect: participants' blood pressure was already well controlled at baseline, leaving little room for a further measurable drop over this period. Secondary markers of oxidative stress and proteasome activity in blood cells also did not change meaningfully across groups. Taken together, these null findings are the most robust result in the paper and should temper expectations about mastic as a general add-on for blood pressure. [E tier for blood pressure lowering in this population]

The more intriguing data came from a predefined high-risk subgroup, where transcriptomic profiling, a measure of which genes are switched on or off, revealed distinct changes in mastic-treated participants. The most notable shifts involved pathways governing endothelial junction organization and vascular integrity, which are biologically relevant to the endothelial dysfunction the trial was designed to probe. These findings are hypothesis-generating. The subgroup was predefined but small, transcriptomic changes do not automatically translate into clinical outcomes, and the study was not powered to detect differences in hard cardiovascular events. The authors themselves frame the result as supporting future investigation in higher-risk populations, and that framing is appropriate.

The overall picture is therefore mixed. In the population most similar to typical well-treated patients, Chios mastic did not improve the measured blood pressure outcomes. In a higher-risk slice of the same trial, the gene expression data point to vascular effects worth testing directly. Neither result supports using mastic to manage blood pressure or cardiovascular risk at this time.

What this means for you

Do not treat this as evidence that mastic lowers blood pressure. The primary endpoint was negative in people whose hypertension was already controlled.

If you have high residual cardiovascular risk, the transcriptomic signal is a reason for researchers to test mastic more rigorously, not a reason to self-prescribe. Discuss any supplement with your clinician, especially if you take antihypertensive medication.

Keep the basics as the foundation. Established approaches to vascular health include regular Zone 2 cardio, resistance training, high-fiber diet habits, reducing alcohol, and smoking cessation where relevant. Mastic is not a replacement for any of these.

Watch for the follow-up work. Trials in participants with higher baseline risk and longer follow-up will be needed before any clinical claim is reasonable.

Study details

Item	Detail
Study type	Double-blind, randomized, placebo-controlled trial
Sample size	106 adults with well-controlled hypertension
Interventions	Low-dose Chios mastic (1500 mg/day), high-dose Chios mastic (2800 mg/day), placebo
Duration	3 months
Primary outcomes	24-hour ambulatory systolic and diastolic blood pressure
Secondary outcomes	Vascular function, oxidative stress, proteasome activity, transcriptomic profiling (high-risk subgroup)
Key result	No significant between-group blood pressure differences; distinct vascular-related gene expression changes in high-risk subgroup
Journal	Pharmacology Research & Perspectives
PubMed ID	42885189

Sources

1. HYPER-MASTIC Randomized Controlled Trial, *Pharmacology Research & Perspectives*. PubMed. https://pubmed.ncbi.nlm.nih.gov/42885189/

ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.