In the complex and fascinating mechanism of vision, light is filtered by the different parts of the eye, such as the cornea, lens and vitreous humor before reaching the retina. The photoreceptors in the retina convert light into electrical impulses which are then conveyed to the brain through appropriate cells and the optic nerve. In the retina, due to the complexity of the processes in place, cellular respiration is faster than in any other tissue in the body and this exposes the eye to a greater risk of suffering from oxidative stress. What can be done to counteract the damage caused by free radicals that can lead, in the long term, to an increased risk of developing diseases such as macular degeneration or cataracts? Not only that, is it also possible to act in case of vision problems such as myopia, dry and tired eye? Nutrition can also help in these cases. In fact, even if the retina is actively protected by what is called the brain blood barrier, some antioxidant substances taken through diet, such as anthocyanins, can overcome this barrier, reach the tissues of the eye and act with antioxidant and anti-inflammatory properties (Kalt et al, Adv Nutr, 2020). A valuable source of anthocyanins are blueberries and studies have shown that integrating ever greater doses of blueberries into the diet also increases, in a directly proportional way, the amount of anthocyanins in the eye (Kalt et al, J Agric Food Chem, 2010). Clearly, as with any other food, you should never overdo it but let's see why it is a good choice to integrate blueberries in a healthy and balanced diet.
Blueberries and visual diseases such as cataracts, glaucoma and macular degenerations
Several studies have shown that there is an association between blueberry consumption and a reduced risk of developing macular degeneration (Kalt et al, Adv Nutr, 2020). The anthocyanins of blueberries, following a prolonged intake of at least a month, have also been found to be useful in helping to stabilize intraocular pressure, even in the case of diagnosed glaucoma (Kalt et al, Adv Nutr, 2020). In fact, it seems that the action of the anthocyanins in blueberries is aimed at relaxing the ciliary muscle which controls the production of aqueous humor and contributes to the regulation of ocular pressure (Nomi et al, Molecules, 2019). In general, blueberries help to counteract oxidative stress but also inflammation in the retina, which is the distinctive feature of various eye diseases, preserving photoreceptors, which are nerve cells responsible for transforming light into an electrical response. (Kalt et al, Adv Nutr, 2020). Researchers believe that blueberry extracts may help, given these properties, counteract diabetic retinopathy as well (Huang et al, Oxid Med Cell Longev, 2018). Instead, to date, research has not yet been able to understand whether blueberries can also be protective against cataracts.
Blueberries and vision
Anthocyanins in blueberries have been shown to improve vision accommodation and reduce eye fatigue in people with myopia (Kalt et al, Adv Nutr, 2020). It is believed that this effect is due to an improvement in visual sensitivity to contrasts and relaxation of the ciliary muscle, responsible for accommodating distant vision (Nomi et al, Molecules, 2019). Not only that, the intake of blueberries for at least 3 weeks is also linked to a better and faster recovery capacity following dazzle by light (Kalt et al, Adv Nutr, 2020 - Kalt et al, J Agric Food Chem, 2014). Finally, good news also for those who have to spend many hours in front of a computer screen and at the end of the day find themselves fighting with tired eyesight and eye irritation. In fact, the intake of blueberry extracts, for at least two months, led to an improvement in the stability of vision and of all those symptoms related to ocular fatigue, such as blurred vision, pain and sensation of heavy eyelids (Ozawa et al, J Nutr Health Aging, 2015).
All the ways to integrate blueberries into your diet
You can consume fresh blueberries when it is in season but also frozen all year round. In fact, the anthocyanin content is preserved in frozen blueberries and therefore their antioxidant and protective capacity for eyesight (Kalt et al, Adv Nutr, 2020). Not only that, there are also blueberry extracts. Indeed, several studies on the beneficial effects of blueberry on sight have been carried out with extracts that you can find in chemist's and herbalist's shops. In this case, however, ask your doctor for advice before starting treatment, especially if you are taking anticoagulant drugs as blueberry has an antiplatelet action (Chan et al, Molecules, 2020). Finally, blueberry juice is also rich in anthocyanins and therefore has antioxidant and sight-saving properties (Ma et al, Int J Mol, Sci, 2018). On the other hand, dried blueberries lose a lot of their properties as the amount of anthocyanins is reduced.