Diet also helps against glaucoma. Lettuce, spinach, beetroot or celery can become precious allies for eye health and vision functionality. This emerges from a very recent scientific research published in the journal Nutrients thanks to a collaboration between Dutch scientists from the Erasmus MC University Medical Center and Australian scientists (Vergroesen et al, Nutrients, 2022).
Glaucoma, what it is and its risks
Glaucoma is a chronic and progressive disease that affects the optic nerve and can lead, if not treated properly, to visual impairment and blindness. It is estimated that more than 80 million people worldwide currently have glaucoma. Elevated intraocular pressure is one of the causes of glaucoma. However, there are also other causes independent of intraocular pressure. In fact, glaucoma can proceed even when the pressure inside the eye is under control since it is possible that less blood reaches the optic nerve due to alterations in the blood vessels. There are two types of glaucoma, open-angle glaucoma, the most frequent and chronic, due to an obstruction that prevents the outflow of aqueous humor, and closed-angle glaucoma, an acute and rarer form, in which the iris itself contracts and causes a sudden increase in eye pressure. The second case of glaucoma is an emergency and must be treated in the hospital as soon as possible. In the first case, however, the progression of the disease is slow, sometimes sneaky and without symptoms, at least not in the early stages. In addition to regular vision checks and, if diagnosed, following the treatment indicated by the specialist, what can be done at a lifestyle level to prevent or combat open-angle glaucoma? Diet also plays an interesting role in this case. It emerged, in fact, that the intake of foods rich in nitrates can have a protective action. Precisely to better understand this aspect, still little studied, Dutch and Australian scientists have developed the research we are talking about today.
How diet can protect against glaucoma
The researchers drew on data collected from a large study, the Rotterdam Study, designed to evaluate the causes of age-related diseases in the adult population. Since 1991, the study has also made available data relating to the health of eyesight of volunteers. Notably, study participants underwent eye exams every 5 years. Scientists were then able to draw on data on the health of the eyes of as many as 8679 people. These data were compared with information on eating habits from which the researchers were able to extrapolate the amount of nitrates consumed. Well, what has emerged is that the more nitrates are consumed in the diet, the more the risk of developing open-angle glaucoma is reduced. The explanation is that nitrates are a source of nitric oxide and higher nitric oxide values are associated with an enlargement of the retinal arterioles, which, in turn, leads to a reduction in the risk of open-angle glaucoma since the optic nerve is better perfused.
What to eat to protect the eyes
The daily intake of nitrates should be around 200 mg. This dose is reached by eating, for example, 100 grams of spinach, or 130 grams of beetroot, 190 grams of endive or 115 grams of kale. Therefore, we are talking about easily achievable quantities within a healthy and varied diet. Other foods that contain nitrates are celery, watercress, fennel and zucchini.