Glaucoma is a debilitating neurodegenerative eye disease that, to date, affects more than 80 million people worldwide. High intraocular pressure (IOP) is an important risk factor for the progressive loss of retinal ganglion cells that occurs in glaucoma. However, we know that some IOP-independent mechanisms also play a role in the pathogenesis of this condition. In fact, in almost half of the eyes with glaucoma there is no elevated IOP and it is likely that in this case neurodegeneration is the primary cause of the disease. This hypothesis is also confirmed by the observation that visual field deterioration continues in approximately 30-40% of patients, despite a reduction in IOP.
It has been shown that a higher intake of certain dietary componentscontained in green tea, fruit and vegetables is linked to the maintenance of lower IOP levels and, therefore, a lower incidence of glaucoma. This is due to the high concentrations of antioxidants and flavonoids contained in these nutrients, which therefore have anti-inflammatory and neuroprotective properties. In fact, food supplements have been developed that contain natural substances that, in combination with traditional therapies, can help reduce inflammation and oxidative stress, improving the outcome of ocular antihypertensive therapy and slowing the progression of glaucoma. These include, in addition to epigallocatechin gallate contained in green tea, forskolin, citicolin, homotaurine, vitamins B and E and the coenzyme Q10.
Recently, studies on nutritional approaches as adjuvants for the treatment and prevention of glaucoma have focused not only on isolated dietary components, but also on the entire diet, where interactions between different foods may give rise to potential protective effects.
Benefits of the MIND diet on the incidence of open-angle glaucoma: the Rotterdam study
Recently, the MIND diet (short for Mediterranean DASH Diet Intervention) for Neurodegenerative Retardation has been developed as a strategy to promote the healthiest possible cognitive ageing process. It is a combination of the Mediterranean diet and the DASH diet against hypertension. It has been observed that the MIND diet is indeed associated with a reduced incidence of Alzheimer's disease and that it succeeds in slowing down cognitive decline.
It should not be forgotten that the eye and brain share a common embryonic origin and that the retina and optic nerve extend from the diencephalon during embryonic development. This is why, despite their different morphology, retinal ganglion cells display the typical properties of neurons in the central nervous system. Furthermore, open-angle glaucoma (OAG) and Alzheimer's disease share multiple biochemical and pathological changes. It has therefore been hypothesised that the MIND diet may have neuroprotective effects not only on the brain, but also on the eye.
The recent Rotterdam studio showed that greater adherence to the MIND diet is associated with a reduced incidence of OAG. With no direct effect on IOP, it was hypothesised that the protective effects of the MIND diet are associated with other pathways. It was observed that a higher intake of green leafy vegetables is associated with a reduction in the risk of developing OAG by 20-30%. Furthermore, the intake of fish rich in omega-3 and omega-6 fatty acids, known for their anti-inflammatory, antiangiogenic, antithrombotic, hypolipidemic and vasodilator properties, is also a component of the MIND diet that could play an important neuroprotective role.
Finally, berries in this nutritional approach are rich in polyphenols, which have anti-proliferative, anti-diabetic, anti-cancer, anti-microbial, anti-inflammatory and anti-viral properties, along with high antioxidant capacity.
Comparing the MIND diet and the Mediterranean diet
For a more complete analysis, the study also compared the MIND diet with the Mediterranean diet, but it is important to emphasise that no significant association was observed between adherence to the Mediterranean diet, OAG or IOP. This observation is in line with other previous studies, in which a lower risk of glaucoma was reported in participants adhering to a Mediterranean lifestyle, but no significant causal association was found.
The authors of the study state, in conclusion, that the MIND diet appears to be a promising approach to maintaining ocular health and protecting the eyes from open-angle glaucoma and that it will be interesting to further investigate and confirm the results obtained.
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