Nutrients for eye health

IN recent years, several clinical trials and epidemiological studies have been conducted to evaluate the role of nutrients to improve or prevent visual loss in the elderly. Many of these nutrients are strong antioxidants.

Among the causes of visual loss worldwide is age-related macular degeneration (AMD). AMD is the second most common cause of blindness after cataracts in all regions. The rising prevalence of eye disease causes a major social and economic burden to countries’ healthcare costs.

AMD affects the macula, which is responsible for high-acuity daylight vision in the central area of the retina. The causes of AMD are many, and may include genetic predisposition, ageing and high oxidative stress. To date, numerous studies suggest a positive association between dietary micronutrients and decreases of progression in AMD and other eye-related diseases.

These studies have generated interest in micronutrients with antioxidant capabilities to prevent oxidative damage involved in the development of degenerative eye diseases. Thus, these micronutrients, including antioxidants, vitamins and minerals, are attractive as promising strategies for preventative intervention.

Human intervention studies demonstrate that lutein and zeaxanthin supplementations improved visual performances, such as contrast sensitivity, glare tolerance and photostress recovery. The results obtained from the Age-related Eye Disease Study 2 (AREDS 2) shows the beneficial effect of lutein and zeaxanthin supplementation related to AMD.

There are many factors affecting the degeneration of the macular pigment. Lifestyle and dietary factors are important and should be taken into consideration for prevention or slowing the progression of early AMD. Poor lifestyle choices, such as physical inactivity, poor diet and smoking can increase the risk of AMD.

A previous study showed that the inflammation of macular pigment among heavy smokers was higher than light or nonsmokers. The finding showed that serum concentrations of lutein and zeaxanthin are essential for smokers because they have lower macular pigment optical density than non-smokers. Dietary intakes of lutein and zeaxanthin also differ with age, sex and ethnicity.

There is still no established recommended daily intake for lutein and zeaxanthin, but there have been health benefits observed in studies with a daily intake of 10mg lutein and 2mg zeaxanthin, according to a 2014 study titled A double-blind, placebo-controlled study on the effects of lutein and zeaxanthin on photostress recovery, glare disability, and chromatic contrast published in Investigative Ophthalmology & Visual Science.

Supplementation of these nutrients should be in moderate doses following evidencebased recommended dosages and reference intakes and are advisable to be taken as dietary supplements.

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