Lutein & Zeaxanthin Contribute to Supporting Eye Health
There have been numerous studies conducted examining the correlation between macular degeneration and the carotenoids Lutein and Zeaxanthin, and the effect these 2 substances can have upon eye health. In older generations, age-related macular degeneration (AMD) is the leading cause of blindness. It is categorised by atrophy of the macular disk. The retinal pigmented epithelium and photoreceptors (particularly the rods and the blue-light sensitive cones) are most often affected.
Several observational studies have examined the connection between lutein and Zeaxanthin concentrations in the macula, dietary intake, and macular degeneration. In the multicenter Eye Disease Case-Control study, Seddon et al eamined the relationshipa between the dietary intake of carotenoids and the risk of neovascular AMD in 356 subjects. After adjusting for risk factors, they found a 57% decreased risk for AMD in individuals with the highest intake of lutein/Zeaxanthin (6 mg daily), compared to those who consumed the lowest level (0.5 mg daily).
Other studies have examined the relationship between Lutein/Zeaxanthin intake, serum lutein/ Zeaxanthin, and macular pigment density (MPD). In 278 healthy volunteers higher levels of dietary lutein intake correlated with higher serum lutein and Zeaxanthin and significantly higher MPD.30
Bernstein et al also demonstrated lutein supplementation of 4mg daily resulted in significantly higher MPD levels in AMD patients compared to control subjects not supplementing.
Such observational studies seem to indicate maintenance of macular pigment density is critical to maintaining visual acuity and decreasing the risk of developing AMD.
Since 2001, three double-blind, intervention studies have examined the effects of lutein supplementation on vision improvement in AMD patients. In a 12-month trial of 14 AMD patients, Richer demonstrated improvements of up to 92% in visual acuity tests after subjects consumed a diet containing five ounces of spinach (approximately 14 mg lutein) 4-7 times weekly.
In 2004, Richer published the results of a follow-up study – the Lutein Antioxidant Supplementation Trial (LAST), a double-blind, randomized, placebo-controlled study. Ninety males with atrophic AMD were supplemented with either 10 mg lutein, 10mg lutein plus a broad spectrum formula containing antioxidants/vitamins/minerals, or placebo for one year. The subjects were examined for MPD, photostress recovery, contrast sensitivity, and visual acuity at baseline, and every four months until the end of the study. The most significant finding was a 36% increase in MPD in the lutein group and a 43% increase in MPD in the lutein plus antioxidant group, compared to a slight decrease in MPD in the placebo group. Lutein supplementation also resulted in significant improvements in visual acuity, objective visual function parameters, photo-stress recovery, and contrast sensitivity.
The LAST confirms lutein plays an important role in ocular health and that AMD appears to respond favourably to lutein supplementation.