A new Finnish study indicates that increased blood levels of lutein and zeaxanthin may reduce the risk of cataracts by about 40%.
To examine whether plasma concentrations of lutein and zeaxanthin are associated with the risk of developing age-related nuclear cataracts, the observational study measured blood carotenoid concentrations and cataract cases of 1689 participants aged 61–80 years over 4 years (1). The study results showed that after adjustment for risk factors such as age, sex, BMI, smoking, alcohol consumption, serum LDL - and HDL - cholesterol, history of diabetes and hypertension, participants with the highest plasma concentrations of lutein and zeaxanthin had an over 40% lower risk of developing nuclear cataracts, compared with those with the lowest levels.
This finding was consistent with previous epidemiological studies (2, 3). The researchers noted that both carotenoids appeared to provide similar levels of protection from cataracts, an observation that would challenge the hypothesis that zeaxanthin is more important for lens health than lutein, as the lens of the eye mainly accumulates zeaxanthin. Both lutein and zeaxanthin protect liposomal membranes from light-induced oxidative stress. Zeaxanthin appears to be a more effective in protecting against UV light exposure, because lutein and zeaxanthin may be oriented differently in biological membranes.
Age-related cataracts are one of the leading causes of blindness among elderly populations worldwide. Nuclear cataracts are the most common type of cataracts among older populations and especially women. It results from the inability to sufficiently defend against or repair damage due to a variety of environmental stressors, including photochemical formation of free radicals. Reactive oxygen species can damage lens proteins and fiber cell membranes, leading to cataract formation. Lutein and zeaxanthin are the most abundant carotenoids that accumulate in the lens of the eye, where they possibly filter phototoxic blue light and neutralize reactive oxygen species.