Impact of n-3 polyunsaturate fatty acids supplementation on visual health throughout the life cycle: A systematic review

Abstract

Introduction: N-3 polyunsaturated fatty acids (n-3 PUFA) are important for mammals and have relevant functions in the body. These fatty acids play an important role in brain development, in the protection of the retina, and in the prevention of macular degeneration. Currently, clinical trials do not yet confirm a clear benefit of n-3 PUFA supplementation on vision throughout the life cycle. Therefore, the aim of this study is to systematically evaluate the available scientific evidence to determine the effects of n-3 PUFA supplementation on visual health throughout the life cycle. Material and Methods: A search of scientific literature was performed, based on randomized, controlled clinical studies, published in PubMed, using keywords. We included people of both sexes throughout the life cycle that evaluated the impact of n-3 PUFA supplementation on visual health. Results: Of the 87 articles included in this review, there are important contradictions in the literature regarding the effects of supplementation in pregnant women, infants and older adults. While some studies highlight beneficial effects, an equal number of studies report no impact. In the case of preschoolers and schoolchildren, predominantly positive effects were identified, especially in children with Attention Deficit Hyperactivity Disorder (ADHD). For youth and adults, the impact of supplementation varied according to the health condition assessed, mostly supporting significant benefits in individuals with dry eye symptoms. Conclusion: Evidence supports supplementation with n-3 PUFA, especially docosahexaenoic acid (DHA), to improve visual development in infants, schoolchildren, especially those with ADHD. Despite variability in visual outcomes, these findings suggest a crucial role of n-3 PUFA supplementation in visual health in the first steps of life, but in adults and older adults remain uncertain or null. Therefore, it is critical to investigate optimal dosing, duration of the intervention as the age of the participants in future research.