07-Mar-2008 - Supplements of lutein and a range of antioxidants did not benefit the health of normal eyes, possibly highlighting the importance of doses, suggests new research from England.
Daily supplements of lutein (six milligrams), vitamins A, C, and E, zinc, and copper, had no effect on the visual function of 46 healthy participants, according to results of the new randomised controlled trial published in the journal Clinical Nutrition. The results suggest that low-dose lutein may not be enough to produce a beneficial effect on eye health, coming, as they do, hot on the heels of a study by researchers from the University of Georgia, Athens (USA) that reported that six months of supplementation with lutein (10 mg) could improve the health of normal eyes, particularly in relation to glare (Optometry and Vision Science, Feb. 2008, Vol. 85, pp. 82-88).
Talking to NutraIngredients.com, lead author Hannah Bartlett from Aston University in Birmingham said that the most obvious explanation for the difference in results was the different doses used. "The fact that no effect was seen with a six milligram dose and that a positive effect was seen with 12 mg dose suggests that there may be a dose effect," said Bartlett. "
[There is also] the LAST study run by Stuart Richer that found a positive effect of 10 mg /day on people with age-related macular disease."Bartlett also indicated to this website that the glare sensitivity test used by the University of Georgia researchers could have been more sensitive, and capable of picking up smaller changes.
No benefits from low doses
Frank Eperjesi and Bartlett randomly assigned 21 of the volunteers to receive the lutein-antioxidant supplement, and 25 to placebo for nine months. The supplement contained 6 mg of lutein, 750 micrograms of vitamin A, 250 mg vitamin C, 34 mg vitamin E, 10 mg zinc, and 0.5 mg copper. The supplements were produced by Quest Vitamins.
Twenty-nine (15 from the placebo) of the subjects completed 18 months of supplementation. After nine or 18 months, Bartlett and Eperjesi found no statistically significant differences between the groups with respect to far and near visual acuity, contrast sensitivity, and photostress recovery time. This led them to conclude: "There was no evidence of effect of 9 or 18 months of daily supplementation with a lutein-based nutritional supplement on visual function in this group of people with healthy eyes."
Seeing the bigger picture
Numerous studies have reported positive results that support the role of lutein and zeaxanthin for eye health, with the majority supporting their role against AMD, the leading cause of legal blindness for people over 55 years of age in the Western world, according to AMD Alliance International. The studies mentioned are relatively small. More definitive answers concerning lutein and eye health would be provided by the AREDS II trial, added Bartlett.
The trial aims to build in the positive results from the original AREDS study.The AREDS formula, the patent for which is held by Bausch and Lomb, comprises vitamins C and E, beta carotene, zinc and copper. AREDS2 will include the antioxidant carotenoids lutein and zeaxanthin, and the omega-3 fatty acids DHA and EPA.
Source: Clinical NutritionPublished online ahead of print 4 March 2008, doi:"A randomised controlled trial investigating the effect of lutein and antioxidant dietary supplementation on visual function in healthy eyes"Authors: H.E. Bartlett and F. Eperjesi