Fatty acids and antioxidants in older adults with visual impairment: A contribution to Healthy Ageing

Abstract

[eng] This research aims to study the effect of supplementation with docosahexaenoic acid (DHA) and antioxidants in older adults diagnosed with age-related macular degeneration or cataracts to contribute to preventive nutritional care and healthy ageing. This study involves a randomised and observed-blinded trial that included 106 patients >50 years of age with a previous diagnosis of Age-Related-Macular Degeneration (AMD) and was conducted in nine sites in Spain and Portugal between November 2014 and April 2018. We study the effect of a 2-year intervention with a nutritional supplement. Plasma samples were analysed at baseline and after 12 and 24 months to determine the fatty acid (FA) status. The omega-3 index (O3I) was additionally calculated to assess the coronary heart disease (CHD) mortality risk. Additionally, a review of another visual impairment and the effects on antioxidants was made to support the nutrition strategies as an essential factor for healthy ageing. The FA levels at baseline showed no differences between groups. However, at month 12 and 24-month follow-up, the mean changes in the polyunsaturated fatty acids (PUFAs) were statistically significantly different between the intervention and control groups except for the total omega-6 (n-6) long-chain (LC) PUFAs; thus, DHA, total omega-3 (n-3) PUFAs and total n-3 LCPUFAs showed a greater increase with the intervention than with the control treatment, with an effect size that was moderate to large. In contrast, the total n-6 PUFAs, total n-6 LCPUFAs and the ratios of n-6/n-3 PUFAs and LCPUFAs showed a greater decrease in the intervention group than in the control group. On the primary visual acuity assessment after a year, ETDRS letters had decreased with the intervention (N = 45; mean change −1.73, 95% CI −3.28 to −0.19) and in the control group (N = 48; mean change −0.10, 95% CI −2.03 to 1.83), for an estimated treatment difference between the intervention and control groups of –1.63 (95% CI –0.83 to 4.09; p = 0.192). The O3I at baseline exhibited both study groups at the second highest cardiovascular risk category (O3I >2.9 - 4.0). Nonetheless, by the 2-year intervention, the supplemented patients presented an O3I of 4.16%, reaching the second-best category of low risk for cardiovascular diseases (O3I >4.0 – 5.2), while the control group remained the same. Additionally, a review was conducted on the role of the antioxidant vitamin C in cataracts, another common eye disease to back up nutritional strategies as an essential factor in healthy ageing. While dietary intake of vitamin C might have a positive effect in cataracts, its supplementation does not show the same effect. The protective effects of vitamin C in cataracts still need to be clarified; further assessments are encouraged. The collection of analyses performed in this research allows us to confirm: 1)The link between FAs and health; 2) that DHA supplementation is promising to slow the progression of visual acuity loss in the older adult population with a previous AMD diagnosis; 3) the need to balance n-6, and n-3 proportions; 4) that DHA supplementation optimizes two markers of health, n6-n3 ratio and the O3I; 5) the antioxidant effect of vitamin C in cataracts remains unclear. Altogether, these

results endorse the role of nutrition in healthy ageing decreasing the risk for NCDs, which are responsible for poor health and quality of life.