Nov 1, 2014
By Vanessa Caceres; Reviewed by Paul S. Bernstein, MD, PhD
Salt Lake City—The macular pigment carotenoids lutein and zeaxanthin are well known within ocular nutrition for their role in protecting against age-related macular degeneration (AMD).
However, their power to assist with visual function may go beyond just AMD, said Paul S. Bernstein, MD, PhD, Mary Boesche Professor of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City.
Lutein and zeaxanthin are two of 600 carotenoids found in nature. However, there are only 50 that humans consume, and just 10 to 15 that are absorbed, Dr. Bernstein said.
“Lutein and zeaxanthin are the only two carotenoids found in the retina itself,” he said.
Lutein is found in dark green and leafy vegetables like kale and spinach as well as in egg yolks. Zeaxanthin is found in orange and yellow fruits and vegetables like corn and orange peppers as well as in egg yolks.
The value of lutein and zeaxanthin in the quest to protect against AMD led Age-Related Eye Disease Study 2 (AREDS2) researchers to test the addition of 10 mg of lutein and 2 mg of zeaxanthin to the original AREDS formula as a substitute for beta carotene.1
It was thought that the two carotenoids would be safe and effective substitutes for beta carotene, Dr. Bernstein said, referring to concerns of putting users, particularly smokers, at higher risk for lung cancer from the high beta carotene concentration in the original AREDS supplement.
Now, Dr. Bernstein and colleagues are turning their attention to the importance of lutein and zeaxanthin in early life, specifically how supplementation with the two carotenoids may help with visual acuity and foveal development. He and fellow researchers have developed a way to measure their presence in babies after birth by viewing the infant macular pigment with use of an imaging system (RetCam, Clarity Medical Systems).2
“We did a study in 2013 where we showed how macular pigment was detectable shortly after birth and develops through age 7,” Dr. Bernstein said. “Yet, premature babies don’t have any macular pigment at all.”3
This research may help provide future clues to the role of macular carotenoids in modulating the risk of retinopathy of prematurity, according to Dr. Bernstein.
A related study conducted by Dr. Bernstein and colleagues focused on 14 full-term newborn infants and their mothers, during which serum carotenoids of the mother and child were measured by high-pressure liquid chromatography, and macular pigment imaging took place with the imaging system.4
“In that study, we were able to show that macular pigment levels were influenced by maternal nutritional status,” Dr. Bernstein said. “If the mother has a high level in her serum and presumably her diet, that’s passed on to the baby at birth.”
Researchers are now preparing to begin a supplementation study with prenatal vitamins fortified with lutein and zeaxanthin.
“We’ll measure the macular pigment in a randomized controlled trial and see how it affects visual function for at least a year,” he said.
The study of macular carotenoids may also prove valuable because diseases like AMD are thought to depend on light and oxidative stress that accumulates over one’s lifetime, including childhood, Dr. Bernstein said.
Circling back to AMD
Although Dr. Bernstein is focusing now on the role of lutein and zeaxanthin in a younger population, he believes these two carotenoids still play a key role in preventing AMD.
Adult children who bring in their parents with AMD for anti-vascular endothelial growth factor injections often inquire about the connection between nutrition and AMD, Dr. Bernstein explained.
“The answer is, we don’t know for certain what they should do,” he said. “It was hard enough to do the AREDS and AREDS2 studies to tease out the effects of nutrition on a high-risk elderly population. A comparable prospective study on young healthy people would be prohibitively long and expensive.
“For the adult children, I tell them that diet is very important,” Dr. Bernstein said. “Changing your diet at age 40 is very doable, and adding more fruits and vegetables will have benefits that go beyond the eyes. Younger patients can also take supplements, but diet is the preferred way to go.”
For someone who has AMD and is older, supplementation may be an easier route. Changing dietary habits in the elderly may be difficult.
“The number one public health approach to preventing AMD will be to improve the American diet, but we still have much to learn about the proper role for lutein and zeaxanthin supplementation for optimal ocular health and performance throughout the entire lifespan,” he said.
AREDS2 Study Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA 2013;309:2005-2015.
Sharifzadeh M, Bernstein PS, Gellermann W. Reflection-based imaging of macular pigment distributions in infants and children. J Biomed Opt. 2013;18:116001.
Bernstein PS, Sharifzadeh M, Liu A, et al. Blue-light reflectance imaging of macular pigment in infants and children. Invest Ophthalmol Vis Sci. 2013;54:4034-4040.
Henriksen BS, Chan G, Hoffman RO, Sharifzadeh M, Ermakov IV, Gellermann W, Bernstein PS. Interrelationships between maternal carotenoid status and newborn infant macular pigment optical density and carotenoid status. Invest Ophthalmol Vis Sci. 2013;54:5568-5578.