Supplement
Arterosil HP (Rhamnan Sulfate)
No randomized trial has tested rhamnan sulfate on plaque or vascular outcomes; one small randomized trial for constipation found no effect on blood lipids.
Grade D, not yet tested: no human randomized trial has been run. This D records missing trials, not a finding that it does not work. How to read a grade →
This product contains rhamnan sulfate, a sugar compound from green seaweed. It is sold to protect the lining of blood vessels and to shrink plaque. No study in people has tested it on plaque, blood vessels or heart health. One small study tested it for constipation, and blood fats did not change. The plaque claim rests on lab work and a few people followed without a comparison group.
A letter describes the human evidence, not the product, the manufacturer, or the ingredient's worth.
See the full evidence record →Who responds: this record's trial reading reports no subgroup that identifies who responds.
No human randomized trial has tested this at the dose and form graded, so there is nothing for a higher letter to rest on. A Route 1 Grade D records the absence of trials. It is not a finding against the compound, and it is not a finding that the compound is safe, because neither has been established. It may turn out to work once someone tests it. The grade moves when a qualifying human trial reports.
No randomized trial of rhamnan sulfate on plaque or vascular outcomes; one small trial for constipation found no effect on blood lipids.
How this letter has changed · latest: October 2026 · Corrected
The record called Burke and Jennings 2023 (PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 38404609) an uncontrolled case series but not that its six patients were also on drugs, other supplements and lifestyle changes, nor that the first author sits on the maker's scientific advisory board; both are now stated. Shimada 2021 (PMID 34226572), the only randomized trial, now carries its authors' ties to a rhamnan sulfate producer, and the form note no longer says MonitumRS is the only studied extract. Letter unchanged.PMID 38404609 PMID 34226572
Every change to a letter on this site is dated and published. The full evidence log →
Commercial disclosure
EBL earns no commission on any supplement it grades. A purchase made through the dispensary link below pays EBL nothing, the practitioner discount goes to you in full. The dispensary is Fullscript, a practitioner dispensary, and many of the professional-grade brands in it are sold mainly through practitioners rather than in health food stores. Grades are assigned by published rubric before any commercial relationship exists and are never influenced by one. Full disclosure.
2 capsules/day (MonitumRS proprietary rhamnan sulfate extract from Monostroma nitidum seaweed)
MonitumRS is the only extract studied for vascular endpoints The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score., and only in an uncontrolled case series; the one randomized trial used a different producer's rhamnan sulfate for constipation. Generic seaweed supplements are not equivalent: rhamnan sulfate comes from Monostroma nitidum specifically, and other seaweed species do not contain it.
In the cited six-person report the supplement was taken daily (PMID 38404609). The summary does not state a time of day or whether it was taken with a meal. The other cited study was in mice (PMID 36332287).
Checked against the published summaries; the full papers could not be read. What the cited trials did, not a schedule. Every supplement, by trial timing →
How to buy this: quality criteria, not a brand
2 capsules/day with a meal (MonitumRS rhamnan sulfate).
MonitumRS (from Monostroma nitidum) is the ONLY studied extract. Generic seaweed products are not equivalent.
MonitumRS named on the label.
Generic “seaweed”/rhamnan products; other seaweed species (which don’t contain it).
The grade and these criteria are set only from human trials. Any purchase link is convenience and does not affect the grade.
Raised bleeding risk, on the heparin-mimetic structure. Separation from surgery on the same grounds. Long-term safety data is limited.
Anticoagulants and antiplatelets: rhamnan sulfate is a sulfated polysaccharide with heparin-like properties, so an additive effect is the expectation. This is structural reasoning, not a measured interaction; no human interaction study has been published.
Mechanism-based, no human interaction study located. The drug interactions described for Arterosil HP (Rhamnan Sulfate) are mechanism-based. A PubMed search for human interaction, pharmacokinetic or co-administration studies pairing it with anticoagulant, antiplatelet returned no results in August 2026. The caution stands on pharmacology, not on a trial, and is labeled as such. Basis: pharmacological mechanism, not a human study. Searched PubMed in August 2026: 2 queries, 0 human results.
No validated clinical biomarker A measurable sign in the body, such as a blood test value, used to track a condition or the effect of a treatment. has been established for rhamnan sulfate or glycocalyx restoration. If it is used in a research or clinician-supervised context, vascular measures such as blood pressure or arterial stiffness and standard cardiovascular risk markers may be followed, but they should not be presented as validated markers of product response.
Primary evidenceThree papers, each linked to its PubMed record.
Burke and Jennings (Integr Med, 2023; PMID 38404609): uncontrolled six-patient case series; the patients were also on drug therapy, other supplements and lifestyle changes in a functional-medicine program, so the carotid plaque change cannot be attributed to the supplement, and the first author is a Scientific Advisory Board member for Calroy Health Sciences, which makes Arterosil HP. Patil et al. (Biomaterials, 2022; PMID 36332287): rhamnan sulfate reduced atherosclerotic plaque in MICE, NIH-funded; the plaque effect was stronger and the cholesterol fall present only in females. Shimada et al. (Sci Rep, 2021; PMID 34226572): the only randomized human trial of Monostroma nitidum rhamnan sulfate, 100 mg/day for 2 weeks for low defecation frequency; stool frequency rose, body weight and blood lipids did not change; authors hold research grants from, and one is a board member of, a company that produces rhamnan sulfate. D Route 1: no controlled human trial on plaque, endothelial or vascular outcomes.
Both human studies are small, unblinded, and without placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received. controls. The glycocalyx mechanism is well-established in cardiovascular biology but Arterosil-specific human evidence is preliminary. Manufactured by Calroy Health Sciences. The in vitro and animal data is compelling but EBL does not grade on preclinical data. Grade upgrade to B requires: a randomized, placebo-controlled trial with n>50 and a validated vascular endpoint.
Educational use only · Not medical advice · Starting, stopping or changing any supplement or medication is a decision for your physician
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
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