Science Update

Visual Impairment Associated With Increased All-Cause Mortality: Can Carotenoids Help?

Severe visual impairment (SVI) and blindness are predicted to affect approximately 900 million people globally by the year 2050. Currently, 295 million people have moderate-to-severe visual impairment, 258 million are mildly affected, and 43 million people are blind. Although blindness in adults ages 50 years and older has decreased by nearly 29% worldwide in the last 30 years due to population growth, the number of people with severe visual impairment and blindness is expected to double over the next 30 years.

According to a meta-analysis of 48,000 people from 17 studies in The Lancet Global Health, individuals with SVI had an 89% increased risk of all-cause mortality compared to those with normal vision. Participants with mild visual impairment had a 29% higher risk of mortality. According to the study, “four of five cases of vision impairment and blindness are preventable or correctable” including the leading causes of vision loss, which are cataracts and uncorrected refractive errors (the unmet need for glasses). The lead author states, “there is an important opportunity to promote not only health and well-being, but also longevity by correcting, rehabilitating, and preventing avoidable vision loss.”

There are several nutritional considerations for supporting vision and overall ocular health. Supplementation of specific nutrients — vitamin A, quercetin, omega-3 fish oils, astaxanthin, vitamin C, N-acetylcysteine, and bilberry — have been shown to promote eye health and potentially improve the rates of ocular diseases due to their roles in helping to support antioxidant status within the eyes.

However, the macular carotenoids — lutein, zeaxanthin, and meso-zeaxanthin — take the stage when it comes to bolstering macular pigment optical density (MPOD), which has been shown to prevent or slow the progression of age-related macular degeneration. Of all the carotenoids found in nature, only lutein and zeaxanthin (and their metabolites) are located within the macula, where they are found in the highest concentration within the human body, as they are able to cross the blood–ocular barrier. Six-month supplementation with these three carotenoids derived from a marigold extract was shown to significantly improve MPOD, all visual performance measures, sleep quality, eyestrain, visual fatigue, and headache frequency in healthy young adults with high screen time exposure. Results from a double-blind, placebo-controlled trial showed that 12-month supplementation with 10 mg of lutein and 2 mg of total zeaxanthin significantly improved recovery of repeated exposure to photostress, disability glare thresholds, and MPOD from baseline compared to a placebo.

Regular eye exams are critical for all ages, especially for adults ages 50 and older. Aside from routine eye screenings, dietary and lifestyle habits contribute significantly to eye health, and addressing these factors should be the first line of defense in the prevention of severe visual impairment and blindness. Reducing photo-oxidation from chronic screen time exposure (i.e., smartphones, TV, tablets, and laptops) and direct sunlight, along with managing normal blood sugar levels, consuming a micronutrient-rich diet, not smoking, and moderating alcohol intake, are all important factors to consider to support eye health and reduce the risk of eye disease and visual loss.

By Caitlin Higgins, LDN, CNS, MS