A new review from China reports that increased blood levels of antioxidant micronutrients such as vitamin E or lutein and zeaxanthin seem to be associated with a reduced risk of developing age-related cataract.
The meta-analysis included 13 observational studies investigating a potential relationship between blood levels of antioxidant micronutrients and the incidence of age-related cataract among a total of 18,999 partici-pants (1). The analysis showed that increased blood concentrations of vitamin E, lutein and zeaxanthin were linked to a cataract risk reduction of up to 30%. Higher vitamin A and C levels were associated with a 31% resp. 33% reduced cataract risk in Asian but not in Western populations.
The researchers commented that it is theoretically reasonable to deduce that antioxidants might have a pro-tective effect against cataract. Both in vitro and animal experiments have shown that oxidative stress is involved in the development of cataract, and antioxidants can limit lens damage after an oxidative insult. Thus, the elevation of antioxidant blood levels might carry benefits for age-related cataract prevention, especially for people with low levels of blood antioxidants.
Age-related cataract is the leading cause of blindness worldwide. Thus far, many observational studies have been carried out to investigate the role of supplemental or dietary antioxidant intake in the prevention of
age-related cataract, with inconsistent results. The number of randomized controlled trials (RCTs) on the topic is limited, and most of these studies involved only a few kinds of antioxidants and had a relatively short duration in view of the long-term process of cataract development. More evidence from long-term RCTs carried out in different populations is needed before practice guidelines can be established, the scientists added.