Effects of a Red-Ginger-Based Multi-Nutrient Supplement on Optic Nerve Head Blood Flow in Open-Angle Glaucoma

Objectives: Glaucoma is an age-related neurodegenerative disease, characterized by retinal ganglion cell loss and progressive visual field deterioration. Beyond intraocular pressure (IOP), vascular and metabolic dysregulation contributes to optic nerve head (ONH) ischemia and neuronal vulnerability. Nutritional factors with antioxidative and vasodilatory properties may help preserve ocular perfusion. This study investigated the acute and subacute effects of a single dose of a dietary supplement containing red ginger extract (Zingiber officinale var. rubra), lutein, and vitamin B6 on ONH blood flow in patients with open-angle glaucoma (OAG). Methods: A retrospective self-controlled study was conducted at Tohoku University Hospital between August 2023 and March 2025. ONH blood flow was quantified using a laser speckle flowgraphy (LSFG) baseline one hour after and one month after continuous oral supplementation in patients with OAG. Systemic parameters, ocular biometry, and concomitant glaucoma medications were recorded in medical charts. Relative mean blur rate (MBR) changes were analyzed using a linear mixed-effects model, accounting for repeated measures and inter-eye correlations. Results: Nineteen glaucoma patients (38 eyes) were included in the acute phase and 13 patients (26 eyes) completed the one-month follow-up. After adjusting for age and sex, a single oral dose of red ginger extract significantly increased the relative MBR at 1 h (106.9 ± 3.1%; p < 0.05), and this enhancement increased after 1 month of continuous intake (115.4 ± 6.7%; p < 0.05). Greater ONH perfusion was particularly prominent in eyes with shorter axial length. Conclusions: Oral supplementation was associated with acute and short-term increases in ONH blood flow in glaucomatous eyes. Although this study was a retrospective study without a placebo-controlled comparison group, our findings offer hypothesis-generating evidence that nutritional interventions may support ocular perfusion alongside conventional glaucoma management. Future prospective randomized controlled trials are required to confirm these associations.