To understand why nutrition might help with vision health requires a rudimentary understanding of where certain natural nutritional compounds go once they make it into the body.
Beta-carotene, lutein, astaxanthinand zeaxanthin are carotenoids that all accumulate in various critical parts of the eye. Beta-carotene is vital for the integrity of various eye structures. Low intake of this carotenoid is associated with increased incidence of cataracts, which look like a blind spot in the center of vision.1
Lutein accumulates in the eye's macula and lens. The macula is a yellowish pigment in the area of the eyeball called the retina, where it filters high-energy blue wavelengths of visible light from both natural sunlight and indoor light. Lutein also quenches free radicals that can damage cells in human tissues.
The biggest study to date is the Age-Related Eye Disease Study, or AREDS. A total of 4,519 participants aged 60 to 80 years old enrolled in the study, which found that the more lutein and its carotenoid cousin zeaxanthin participants consumed led to a decreased chance of getting age-related macular degeneration.2
Age-related macular degeneration is the leading cause of blindness in the United States, and usually affects people older than 50. Research has borne out that eating foods rich in lutein, such as spinach, broccoli and kale, tends to increase the density of the macula to the point where it does not degenerate as quickly, thus delaying or eliminating the risk of these conditions.
Astaxanthin, the antioxidant present in krill oil and algae, protected against retinal damage through antioxidant mechanisms in a mouse study.3
Carotenoids and eye health
“Current evidence supports the hypothesis that the carotenoids lutein, zeaxanthin and meso-zeaxanthin are readily bioavailable, and will effectively increase macular pigment levels,” said renowned eye researcher John Landrum, Ph.D., at Florida International University. “Individuals at risk of macular degeneration or cataracts may now ensure a reasonable level of intake by supplementation.”
In one human study, 91 percent of people supplementing with lutein for six months experienced raised blood levels of lutein, and 63 percent showed a significant thickening of the macula – great news for those concerned about macular degeneration. The people responding positively to the lutein tended to be women and also those who were worse off at the start of the study – lower blood levels of lutein and zeaxanthin, a thinner macula, a thicker retina.4
Omega-3s have also been found to help with vision health. (What doesn’t omega-3s help, one might ask!) One study found that those who ate the most fish had a 38 percent reduced risk of macular degeneration compared with those who ate the least amount of fish.5
A related study found that a high omega-3 intake delayed age-related macular degeneration.6
Also, in March 2011, after a lot of haggling and complaints, the European Paliament finally supported the health claim "DHA intake contributes to the visual development of infants up to 12 months of age." Getting any health claim approved is always a long haul, and usually only happens after the science supporting the claim becomes absurdly clear.
Disclaimer: The information provided in this forum is a public service of WellWise.org, and should not in any way substitute for the advice of a qualified healthcare professional and is not intended to constitute personal medical advice.