In plain terms: Arterosil HP (Rhamnan Sulfate) has not yet been tested in a human trial designed to measure the outcome relevant here. The available human research does not yet answer the question.
Arterosil HP (Rhamnan Sulfate)
The evidence as the record states it
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.
Why Grade D Route 1 and not Grade C
Grade D Route 1 applies when no qualifying human randomized trial has tested this compound or intervention against the relevant endpoint. Absence confirmed: rhamnan sulfate OR Arterosil AND randomized controlled trial[pt] AND (atherosclerosis OR endothelial OR glycocalyx) (PubMed, July 2026)
The first qualifying human RCT with a meaningful endpoint would move this to Grade C or higher, depending on what it shows.
What would move this grade
The first qualifying randomized controlled trial in humans, testing this intervention against a meaningful aging-relevant endpoint, would initiate grading. Depending on the result, it could land at any grade from A to D.