High intakes of vitamin a, beta-carotene or vitamin B1 maybe linked with a twofold reduction in risk of open-angle glaucoma compared to low intakes of the nutrients, says a new study from the Netherlands.
To investigate whether the dietary intakes of nutrients that either have antioxidative properties or influence the blood flow is associated with the incident of open-angle glaucoma (OAG), dietary intake data and cases of OAG from 3,502 participants aged 55 and older were documented over an average period of 9.7 years (1). The study results showed that participants with a high intake of retinol equivalents (preformed vitamin A or the pro-vitamin A beta-carotene) or vitamin B1 had an about half risk of OAG compared to those with a low intake of these nutrients, and risk of OAG among people with a high intake of magnesium tripled compared to those with a low intake. A significant effect of these nutrients on intraocular pressure (IOP) was not observed.
The researchers concluded that adequate intakes of retinol equivalents and vitamin B1 seem to have a protective effect against OAG, whereas magnesium intake appears to be associated with an increased risk. The findings for retinol equivalents and vitamin B1 were found to be in line with the existing hypothesis that antioxidant nutrients may be preventive for OAG. The effect of magnesium was also found be less unambiguous to interpret. The study findings might be helpful in the unraveling of the largely unknown development of OAG.
OAG is a progressive neurodegenerative disease, and together with age-related macular degeneration are the two most common causes of irreversible blindness worldwide. Apart from an increased intraocular pressure, oxidative stress and an impaired ocular blood flow are supposed to contribute to OAG. For these reasons, the effects of nutrients with anti-oxidant activity, such as carotenoids, retinol equivalents, B vitamins, vitamins C and E, are of great interest (2).