Carotenoids as antioxidants have been investigated in the treatment and management of several human diseases. In this recent study, the authors conducted a metanalysis of reported clinical studies on the relationship between lutein, zeaxanthin and meso-zeaxanthin and eye disease. Having good eye sight and managing it is important in maintaining a good quality of life, particularly as we get older. Many factors can and do influence loss of vision in the elderly populations. However, we now know that there are many effective intervention strategies that can play a role in preventing and managing loss of vision. The World Health Organization estimates that up to 80% of blindness and visual loss is preventable. Oxidative stress has now been shown in many studies to be causally related to loss of vision and other eye diseases. Use of antioxidants can provide one important intervention method in the prevention of eye diseases. Carotenoids being potent antioxidants have therefore been studied in age-related eye diseases.
The present study undertook metanalysis of several clinical studies that were published in recent years. The objective was to evaluate the relationship between lutein, zeaxanthin and meso-zeaxanthin on eye health. They measured macular pigment optical density (MPOD) which measures the density of macular pigment (MP) which performs an important role in protecting the eye from blue light damage in a randomized controlled trial among patients with age related macular degeneration (AMD) and healthy subjects. They used several databases to search for studies published for their metanalysis. A total of 20 RCTs involving 938 AMD patients and 826 healthy subjects were identified. They found that supplementation with Xanthophyll carotenoids was associated with a significant increase in MPOD in both AMD patients and healthy subjects. Stratified analysis also showed a greater increase in MPOD in trials supplemented with the carotenoids individually or in combination with meso-zeaxanthin. Based on these observations in their metanalysis they concluded that lutein, zeaxanthin and meso-zeaxanthin supplementation improved MPOD in AMD patients as well as healthy subjects with a dose response relationship.
COMMENTARY: The results from this metanalysis are very encouraging in view of the importance of eye health, its prevention and management. This study is particularly significant for the elderly segment of the population since loss of sight and blindness are particularly associated with aging. Authors have extensively searched databases and used scientifically valid selection criteria to select their studies for metanalysis. Measurement of MPOD is well documented and accepted procedure to reflect on eye health. They used relevant statistical methods in evaluating the relationships between lutein, zeaxanthin and meso-zeaxanthin and MPOD. This study can clearly serve as a guideline in the prevention, treatment and management of eye health.
Ma, L., et al. 2016. Nutrients 8 (7): 426