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INTRODUCTION
Monostroma nitidum (M. nitidum) is a green alga that naturally grows on intertidal rocks in some semi-exposed, Pacific coastal regions. M. nitidum is a food that contains dietary fibers consisting of polysaccharides, minerals, and proteins. Rhamnan sulfate (RS), a sulfated polysaccharide, is the main component of the fiber extracted from Monostroma nitidum.1
RS, a soluble fiber, has been studied and shown to support a healthy glycocalyx by supporting healthy blood sugar levels,1,2 lipid levels,1,3 blood pressure,4 and body weight.1 RS also supports a healthy vascular inflammatory response,5-7 and a balanced coagulation response.1,5 The perspective is intended to examine RS's biological functions that support a healthy vasculature.
Blood Glucose Levels
Elevated blood sugar has been shown to decrease endothelial-glycocalyx volume. In 2006, Nieuwdorp et al assessed, for 10 healthy male participants, whether hyperglycemia negatively affected the endothelial glycocalyx, thus resulting in increased vascular permeability.8 Those researchers found that hyperglycemia could significantly decrease endothelial glycocalyx volume and endothelial function. They also noted increased hyaluronan levels from glycocalyx shedding and increased coagulation activity.
Dietary fibers, such as RS, support healthy blood sugar levels. The mechanisms include: (1) a delay in carbohydrate transport from the stomach to the duodenum and (2) inhibition of the small intestine's carbohydrate digestion and absorption.1
In a small study, Kamimura et al studied healthy adults' postprandial glucose levels at 30 minutes after ingesting M. nitidum powder or oral rhamnan sulfate.2 That study found a statistically significant decrease in blood glucose levels in the intervention group, regardless of whether M. nitidum powder or oral rhamnan sulfate was administered, when compared to the controls (P < .05). Those researchers suggested that M. nitidum powder or oral rhamnan sulfate may be useful for diabetic patients.
Lipid Levels
Elevated lipid levels, including an increased ratio of oxidized low-density lipoprotein (LDL) to high-density lipoprotein (HDL), can damage the endothelial glycocalyx, which leads to endothelial dysfunction. In a small six-week study, Nishikawa et al assessed, for 16 adult males with hyperlipidemia, RS's effect on serum cholesterol.3 The study found no change in HDL cholesterol levels, but for the RS group, LDL cholesterol levels were significantly lower than those of the control group (P < .05). Those researchers suggested that rhamnan sulfate can support healthy LDL/ HDL cholesterol ratios and...