Omega–3 fatty acid intake & the incidence of age-related macular degeneration

Results recently published from a long-term study indicate that people at risk for age-related macular degeneration (AMD) may significantly reduce the risk of this disease by increasing their dietary intake of omega-3 fatty acids from oily fish, nuts and seeds, and fish oil supplements.

Omega-3 fatty acids are important for the vascular and neural health of the retina and may influence the risk of developing age-related macular degeneration (AMD). There are two forms of AMD: dry and wet. In the dry form, normal tissue in the macula slowly disappears, leaving a pale area referred to as central geographic atrophy (CGA). In the wet form, or neovascular (NV) AMD, abnormal blood vessels grow underneath the macula. These vessels leak serum or blood and eventually cause the normal macular tissue to be replaced by scar tissue.

Researchers recently investigated whether omega-3 fatty acid intake was associated with a reduced risk of developing both wet and dry forms of AMD. The study involved 1837 people from the Age-Related Eye Diseases Study (AREDS) who were at moderate to high risk of developing AMD. Clinical measurements were obtained in this group over a period of 12 years (from 1992 to 2005).

Participants who reported the highest omega–3 fatty acid intake were 35% less likely than their peers to develop dry (CGA) AMD, and 32% less likely to develop the more common, wet form (NV) AMD.

Over the 12 years of this study, the incidence of CGA and NV AMD was lowest for those reporting the highest consumption of omega-3 fatty acids, which are found primarily in oily fish, nuts and seeds, and fish oil supplements. If these results are applied to the general population, dietary intervention may have a significant preventive effect on the development and progression of AMD.

Source: Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study, Sangiovanni et al, Am J Clin Nutr. 2009 Dec;90(6):1601-7

Source: USANA Health Sciences

High glycemic index diets increase the risk of age-related macular degeneration

A new study published in the American Journal of Clinical Nutrition examined the association between dietary glycemic index and the 10 year incidence of AMD in the Blue Mountain Eye Study population.

This was a population-based study with 3,654 participants over 49 years of age. Volunteers were examined at the beginning (1992-1994); then were reexamined after 5 years and again after 10 years.

Over 10 years, 208 of the participants developed early AMD. After adjusting for age, smoking, other risk factors, and dietary constituents, a higher average dietary glycemic index was associated with an increased 10 year risk of early AMD. Conversely, a greater consumption of cereal fiber and breads and cereals (predominantly lower glycemic index foods such as oatmeal) was associated with a reduced risk of early AMD. No relation was observed with advanced AMD.

The research suggests that a high-glycemic-index diet is a risk factor for early AMD, and low-glycemic-index foods such as oatmeal may protect against early AMD.

Source: Dietary glycemic index and the risk of age-related macular degeneration, Kaushik et al, American Journal of Clinical Nutrition, Vol. 88, No. 4, 1104-1110, October 2008

Decreased antioxidant levels increase risk of age-related macular degeneration with exposure to sunlight

The journal Archives of Ophthalmology recently reported that having reduced plasma antioxidant levels and increased exposure to sunlight increases the risk of neovascular, or advanced age-related macular degeneration (AMD).

In a recent study (titled the European Eye Study), over 4,400 participants over age 65 were analyzed for the presence of macular degeneration. Their blood plasma was evaluated for vitamins C and E, the carotenoids lutein and zeaxanthin, and the mineral zinc. Each individual also completed a questionnaire regarding their typical exposure to sunlight. This was used to estimate blue light exposure from visible light, which is known to contribute to the development of macular degeneration.

Early stage macular degeneration was detected in 2,182 participants, and 101 had the advanced form of the disease. The research found no association between blue light exposure and early macular degeneration. However, among participants in the lowest quartile (25 percent) of serum vitamin C, zeaxanthin, vitamin E and zinc, exposure to blue light significantly increased the risk of advanced macular degeneration.

Source: Sunlight exposure, antioxidants, and age-related macular degeneration; Fletcher et al; Arch Ophthalmol 2008 Oct;126(10):1396-403

Lutein and zeaxanthin may improve visual performance and reduce the effects of glare

The carotenoids lutein and zeaxanthin are most commonly linked to protection from age-related macular degeneration (AMD). In a new study conducted at the University of Georgia, lutein and zeaxanthin were found to reduce the harmful effects of glare on a test group of people with normal eyesight.

Healthy subjects with an average age of 23.9 were assigned to receive daily supplements of lutein (10 mg) and zeaxanthin (2 mg) for six months. The subjects' eyes were then tested for the effects of glare as experienced in everyday situations, including being outdoors on bright days, lengthy sessions of looking at a computer monitor, and nighttime exposure to oncoming headlights.

Following six months of supplementation, the participant's average macular pigment optical density (MPOD) increased significantly from the average value at the beginning of the study. MPOD is a measure of the eye's ability to filter short-wave light.

After testing the subjects for their performance in visual tasks following glare, researchers concluded that four to six months of supplementation with lutein and zeaxanthin significantly reduced the detrimental effects of the exposure and improved visual performance.

Source: Macular pigment and visual performance under glare conditions, Stringham and Hammond, Optom Vis Sci 2008 Feb;85(2):82-8

Macular degeneration risk is reduced in adults with high intakes of lutein and zeaxanthin

Age-Related Macular Degeneration (AMD) is a degenerative eye disease that causes damage to the macula (central retina) of the eye, impairing central vision. In a recent large study, participants with the highest intakes of the carotenoids lutein and zeaxanthin had significantly lower risk of AMD compared to those with low intakes.

Age-Related Macular Degeneration (AMD) is a degenerative eye disease that causes damage to the macula (central retina) of the eye, impairing central vision. People affected by Age-Related Macular Degeneration have difficulty reading, driving and performing activities that require clear central vision. AMD is the most common cause of vision loss in developed countries. A recent report published in the September, 2007 issue of the journal Archives of Ophthalmology added more evidence to support previous research showing that carotenoids zeaxanthin and lutein are protective against AMD. Dark green leafy vegetables are the primary dietary sources of lutein and zeaxanthin, but they are also found in some other colorful fruits and vegetables. Average dietary intake in the U.S. is only 2 mg/day, far below the 6 mg/day level most studies indicate as a minimum needed to reduce the risk of AMD. In the current report, members of the Age-Related Eye Disease Study (AREDS) Research Group evaluated the diets of 4,519 AREDS participants aged 60 to 80 years. Retinal photographs were used to divide the subjects into five categories of macular disease severity, from individuals with little or no evidence of macular degeneration (the control group) to severe, neovascular disease. Dietary questionnaires were analyzed for lutein, zeaxanthin, beta- carotene, lycopene, and other nutrient levels. Participants whose intake of lutein and zeaxanthin were greatest had a significantly lower risk of AMD than those whose intake was least, and were less likely to have large or extensive intermediate drusen, the deposits on the retina or optic nerve that characterize the disease. No risk reductions were associated with the other nutrients examined in this study.

Source:

The Relationship of Dietary Carotenoid and Vitamin A, E, and C Intake With Age-Related Macular Degeneration in a Case-Control Study: Age-Related Eye Disease Study Research Group AREDS Report No. 22, Arch Ophthalmol. 2007;125(9):1225-1232

High glycemic diets may increase the risk of age-related macular degeneration

New research shows an association between diets high in glycemic index and an increased risk of age-related macular degeneration (AMD), the number one cause of adult blindness.

The number one cause of irreversible blindness in adults is age-related macular degeneration (AMD), which seems to share several carbohydrate-related risk factors with diabetes-related diseases, including retinopathy and cardiovascular disease (CVD). In a new study published in the American Journal of Clinical Nutrition, researchers tested the theory that dietary glycemic index (GI), which has been associated with the risk of diabetes and CVD, may also increase the risk and severity of AMD in elderly populations. Over 4000 participants aged 55-80 years participated in the research and were assigned to groups according to several physical eye characteristics related to AMD. Compared with the eyes in those with the lowest GI diets, eyes in the high GI subjects had significantly higher risk of AMD progression and severity. There was a 49% increase in the risk of advanced AMD for persons who ate a diet higher than average in GI. Researchers noted that the results indicated that 20% of all AMD cases in the study would have been eliminated if the participants consumed diets with a GI below the average. The association between dietary GI and AMD suggests that reducing the dietary GI may provide one way to reduce the risk of AMD in adults.

Source: Association between dietary glycemic index and age-related macular degeneration in nondiabetic participants in the Age-Related Eye Disease Study, Chung-Jung Chiu, Roy C Milton, Gary Gensler and Allen Taylor, American Journal of Clinical Nutrition, Vol. 86, No. 1, 180-188, July 2007