News

Carotenoids may protect against age-related vision loss

February 8, 2012

A new literature analysis suggests that an increased intake of lutein and zeaxanthin may protect against late age-related macular degeneration.

The new meta-analysis included data evaluating the effects of lutein and zeaxanthin on age-related macular degeneration (AMD) prevention published in 6 long-term cohort studies (1). The results of the analysis indicate that dietary intake of lutein and zeaxanthin was significantly related with a reduction in risk of late AMD. Increased intakes of these carotenoids were not however significantly associated with a reduced risk of early AMD.

The researchers commented that these findings contrast results from almost all case-control and cross-sectional studies that have reported statistically significant associations between increased lutein and zeaxanthin intakes and reduced risk of early and late AMD (2). As cohort studies provide stronger evidence for evaluating a relationship than other observational study designs, only cohort studies were included in the current systematic review and meta-analysis.

AMD is the leading cause of vision loss and blindness among Americans who are age 65 and older. It has been reported that more than 10 million people in the USA and approximately 50 million worldwide suffer from the eye disease (3). AMD is a degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed for reading or driving. Because primarily the macula is affected in AMD, central vision loss may occur. Early AMD is characterized by yellowish deposits and pigment abnormalities in the retina, whereas late-stage manifestations encompass atrophy and scarring of the retina.

The development of AMD is complex and involves multiple genetic and environmental factors. Age, smoking, hypertension and hypercholesterolemia are counted among the most well-known risk factors. Cellular damage in the retina by oxidative stress is thought to incite the cascade of processes leading to AMD. Thus, reducing oxidative damage with antioxidant micronutrients has been evaluated in preventing or retarding progress of AMD. The Age-Related Eye Disease study (AREDS) is the only large-scale randomized controlled clinical trial showing that people at high risk of developing advanced stages of AMD lowered their risk by about 25 percent when treated with a high-dose combination of vitamin C, vitamin E, beta-carotene, and zinc (4). In the same high risk group, which included people with intermediate AMD, or advanced AMD in one eye, the nutrients reduced the risk of vision loss caused by advanced AMD by about 19%. For those study participants who had either no AMD or early AMD, the supplements did not provide any apparent benefit. Among the antioxidants, lutein and zeaxanthin were the only nutrients that were independently associated with decreased likelihood of developing AMD (5).

References

  1. Ma. L. et al. Lutein and zeaxanthin intake and the risk of age-related macular degeneration: a systematic review and meta-analysis. British Journal of Nutrition. 2012; 107:350–359.
  2.  Chiu C. J. et al. Dietary compound score and risk of age-related macular degeneration in the Age-related Eye Disease Study. Ophthalmology. 2009; 116:939–946.
  3. Klein R. et al. The epidemiology of age-related macular degeneration. Am J Ophthalmol. 2004; 137:486–495.
  4. Age-Related Eye Disease Study Research Group: A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol. 2001; 119:1417–1436.
  5. Age-Related Eye Disease Study Research Group, SanGiovanni JP, Chew EY et al.: The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22. Arch Ophthalmol. 2007; 125:1225–1232.