Black Psyllium (Plantago arenaria), like its more commonly studied relative Blond Psyllium (Plantago ovata), is a source of soluble fiber and has been investigated for its effects on Metabolic Syndrome components, including blood glucose regulation, lipid profiles, and weight management. Several clinical studies and reviews have demonstrated that psyllium supplementation can modestly lower fasting blood glucose, reduce total and LDL cholesterol, and improve markers of glycemic control in individuals with type 2 diabetes or metabolic syndrome. The mechanism is primarily attributed to the fiber's ability to form a viscous gel in the gut, slowing carbohydrate absorption and promoting satiety, which may support weight management.

While most research has been conducted with Blond Psyllium, Black Psyllium contains similar mucilaginous compounds and soluble fiber content, and preliminary evidence suggests comparable physiological effects. A few small studies and extrapolation from Blond Psyllium research support its role in dietary management of metabolic syndrome. Major clinical guidelines (e.g., American Diabetes Association) endorse soluble fiber supplementation as beneficial for metabolic syndrome and diabetes management, and psyllium is frequently cited as a preferred source.

Although long-term outcome data specific to Black Psyllium are limited, the overall body of evidence suggests that psyllium fiber is an effective adjunct to diet for improving several parameters of metabolic syndrome. The evidence rating is 4 due to the strong mechanistic rationale and positive clinical findings, but with some deduction for the limited direct research on Black (vs. Blond) Psyllium.