Glaucoma is a serious eye disease in which the optic nerve — the cable that connects your eye to your brain — gradually deteriorates, leading to loss of vision. While lowering intraocular pressure (IOP) with medicines is the mainstay of treatment, recent research suggests that certain dietary compounds may provide additional support — not as a replacement for medications, but as an adjunct.
One of the most promising groups of compounds in this regard is anthocyanins — the natural pigments that give many fruits and vegetables their deep red, purple, or blue colour. In India, while blueberries may be less common daily, there are many local anthocyanin-rich foods (such as purple corn, purple cabbage, black rice, and certain tropical berries) that may offer benefits.
Anthocyanins act in several ways that are potentially protective for the optic nerve. They are powerful antioxidants, which helps fight the damaging “oxidative stress” that can worsen nerve damage. They also help improve blood flow in small vessels, which is important because poor circulation to the optic nerve is believed to contribute to glaucoma progression.
A key mechanism appears to be through modulation of endothelin-1, a molecule that constricts blood vessels. In glaucoma, elevated endothelin-1 may worsen blood flow. Studies show that anthocyanins from black currants (“black currant anthocyanins,” BCACs) can normalise blood levels of endothelin-1, which may improve the microcirculation of the optic nerve.
What Clinical Studies Actually Show?
Some of the strongest human evidence comes from black currant anthocyanin trials in glaucoma patients:
• In a 24-month randomised, double-blind, placebo-controlled trial, patients with open-angle glaucoma took 50 mg/day of BCACs alongside their usual glaucoma eye drops. Over the two years, the group taking black currant extract had slower deterioration of their visual fields, compared to the placebo group. Interestingly, even though visual field loss slowed, there was no significant change in IOP between the groups, suggesting the benefit came from improved blood flow rather than pressure reduction.
• In another controlled study, healthy volunteers given 50 mg/day of BCACs showed a statistically significant drop in IOP within a few weeks; in glaucoma patients, IOP reduction was also observed over a longer period.
• A pilot study in normal-tension glaucoma (a type of glaucoma where IOP isn’t very high) showed that after 6 months of daily black currant anthocyanins, blood flow to the retina and optic nerve significantly increased, without changes in blood pressure or IOP.
• Furthermore, BCACs appear safe: in the long-term (2-year) trial, no major systemic side effects (like changes in blood pressure or pulse) were reported.
Recent Advances
Newer studies are exploring combined dietary supplements, rather than anthocyanins alone. For example, a 12-month study gave glaucoma patients a supplement containing citicoline, antioxidant vitamins (A, B, C, E), and black currant extract, in addition to their regular glaucoma drops. The authors saw signs of protective benefit in retinal structure and microcirculation, as measured by optical coherence tomography (OCT) and OCT angiography.
Other reviews of neuroprotection in glaucoma note that anthocyanins could be acting through multiple pathways — not just antioxidant effects, but by regulating cellular survival pathways, reducing inflammation, and improving small vessel health.
Bringing this research into an Indian context: many anthocyanin-rich foods are culturally and agriculturally accessible in India. Traditional diets with purple or dark-hued grains (like black rice), vegetables (such as purple cabbage), and locally grown berries (where available) may be leveraged. Encouraging consumption of these foods could be a realistic, low-risk adjunct to medical glaucoma treatment.
Furthermore, in Indian holistic-practice contexts, diet and nutrition are gaining more attention for eye health. A recent review in ophthalmic research emphasises the potential of antioxidant-rich foods, leafy greens, and plant flavonoids (which include anthocyanins) in supporting retinal health. Turmeric (curcumin), widely used in Indian cuisine, also shows potential anti-inflammatory benefits, though its direct role in glaucoma is still being studied.
Cautions & Limitations
• Not a standalone cure: While anthocyanin supplementation shows benefit, it does not replace standard glaucoma therapy. The trials were all done in addition to regular IOP-lowering treatment.
• Dose and purity matter: Most clinical trials used specific black currant extract, usually 50 mg/day of purified anthocyanins. Simply eating berries may not give the exact same dose, and dietary supplements vary in quality.
• Long-term data limited: Although a 2-year trial is promising, even longer-term safety and efficacy (beyond two years) are not yet fully explored.
• Bioavailability: How well anthocyanins from food or supplements reach the eye (across barriers like the retina-blood barrier) is still under investigation.
• No large Indian trials yet: Most of the strong clinical data comes from Japanese or European research. More research in Indian populations, with local dietary patterns, would strengthen recommendations.
Practical Take-Home
If you or someone you know has glaucoma and is interested in dietary support, here is a practical, evidence-informed approach:
1. Talk to your ophthalmologist before starting any supplement — especially anthocyanin extracts.
2. Add anthocyanin-rich foods to your diet: consider purple grains (black rice), deep-coloured vegetables (purple cabbage), and dark berries, if available.
3. Use standardised supplements (if recommended) carefully: for instance, the 50 mg/day black-currant anthocyanin dose is what worked in many trials.
4. Maintain your medical treatment: continue your glaucoma drops and check-ups; diet is supplementary, not a substitute.
5. Watch for future research: as more nutritional-ophthalmic studies are done in India, guidelines may become more nuanced.