Nutrient-rich and GI diet cuts eye disease risk: Study
Researchers in the US showed that specific food intake patterns are linked with substantial age-related macular degeneration (AMD) risk reductions, in what is said to be the first study to analyze these factors in combination.
Earlier studies had shown the ADM protective effects of several nutrients and of a low-glycemic index (GI) diet.
The new research led by Chung-Jung Chiu, of Tufts University, found that participants whose diets included higher levels of protective nutrients and of low-GI foods were at lowest risk for early and advanced AMD.
A food's GI value is based on how fast its carbohydrates raise the body's blood sugar levels; low GI foods have less impact on blood sugar fluctuations.
The study, published in this month’s Ophthalmology journal from the American Academy of Ophthalmology, comes at a time when ingredients that claim to aid eye health are growing in popularity, along with the science to support them.
Food sources of nutrients that support good general and eye health include: citrus fruits, vegetable oils, nuts, whole grains, dark green leafy vegetables, and cold water fish.
AMD is a disease that affects the retina, the sensitive tissue at the back of the eye that transmits images to the brain. Advanced AMD can destroy the detailed, central vision people need to read, drive, and enjoy daily life.
The study called “Dietary Compound Score and Risk of Age-Related Macular Degeneration in the Age-Related Eye Disease”, said: “Because foods provide many nutrients that may interact to modify risk for multifactorial diseases such as AMD, we (the authors) sought to develop a composite scoring system to summarize the combined effect of multiple dietary nutrients on AMD risk.
“This has not been done previously.”
The method
AMD is the leading cause of legal blindness for people over 55 years of age in the Western world, according to AMD Alliance International.
Data was analyzed for 4,003 Age-Related Eye Disease Study (AREDS) participants.
Levels of AMD-protective nutrients, including vitamins C and E, zinc, lutein, zeaxanthin, omega-3 fatty acids (DHA and EPA), as well as low-GI foods, were assessed using participants' food intake reports.
Each dietary factor score was added up to find each participant's compound score. Compound scores were related to participants' AMD risk, based on diagnostic eye photographs taken when they joined AREDS.
The authors noted that Beta-carotene, assessed in this and earlier studies, did not affect risk levels in this analysis.
Dr Chiu said: “Although the compound score may be a useful new tool for assessing nutrients in relation to AMD, specific dietary recommendations should be made only after our results are confirmed by clinical trials or prospective studies.”
Eye health ingredients
A large body of science supports the role of lutein and another eye health ingredient, zeaxanthin, against the development of AMD.
Lutein, which is found in foods including green leafy vegetables and egg yolk, has a ten-year history in the dietary supplement market as a nutrient to reduce the risk of ADM.
A recent study from China published in the British Journal of Nutrition found that supplements of lutein may also protect against the detrimental effects of long-term computer display light exposure.
Source: American Academy of Ophthalmology May 2009 Ophthalmology journal
“Combined dietary factors impact AMD risk; study finds glaucoma care cost-effective
Research highlights”
Authors: Chung-Jung Chiu, Roy C. Milton, Ronald Klein, Gary Gensler, Allen Taylor.
