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These crucial dietary nutrients protect the human eye from blue light–induced damage.
Many people consider sight to be the most important human sense. However, aside from committing to an annual vision check at the optometrist’s or ophthalmologist’s office, most of us take vision for granted. We do not understand the processes involved in vision and seldom take time to consider what we should do to preserve eye health over a lifetime.
Consider, for instance, our overexposure to certain types of light and the damage that it can inflict on our eyes. We are surrounded by light during virtually all of our waking hours. Our constant and incessant exposure to light from numerous natural, artificial, and digital light sources is unprecedented. Homes and businesses employ sunlight as natural lighting when possible. This natural light is typically augmented by indoor lighting to ensure that working areas are sufficiently well lit. Additionally, a majority of people use digital devices like computers, not only to perform their jobs but also for educational and entertainment purposes. Nowadays, people even as young as infants and toddlers are using such devices for several hours per day.
Unfortunately, many of these light sources, including the lighting within our homes and businesses as well as sunlight, contain a significant amount of blue light. In fact, energy-efficient compact fluorescent and light-emitting diode (LED) light sources emanate considerably more blue light than traditional incandescent light bulbs.
Blue light is the visible wavelengths between 400 and 500 nm that reach the photoreceptors in the retina of the eye. Ocular scientists have known for more than 30 years now that blue light can cause significant damage to the photoreceptor cells within the retina. Overexposure to these blue wavelengths of light puts our eyes at risk of damage that can result in everything from poor vision, function, and performance to possibly more serious eye conditions such as age-related macular degeneration (AMD). Therefore, people should take steps to reduce overexposure to blue light in order to mitigate subsequent negative effects on their eye health.
Additionally, anyone with hyperopia (farsightedness), astigmatism, or presbyopia (age-related farsightedness) should be even more vigilant concerning blue light exposure because eyes with these refractive errors may be even more susceptible to blue light damage. In hyperopia, astigmatism, and presbyopia, the blue wavelengths are focused more directly upon the light-sensitive cells of the eyes, increasing potential blue light–induced damage. This damage is not as likely to occur physiologically to the same extent in those with normal vision or myopia (nearsightedness). Hyperopia and astigmatism are present in 20%–50% of the global population. In fact, virtually all children are born hyperopic, and a significant number are born astigmatic. Although many children outgrow these refractive errors by early childhood, a considerable number continue to have these refractive errors throughout their lifetime. Additionally, virtually everyone will become presbyopic beyond 40 years of age, even individuals who were myopic or did not require visual correction at an earlier age.
The Role of Supplementation
It is important to understand that we can attenuate the effects of overexposure to blue light through diet and/or supplementation. First, it’s helpful to understand the roles that two important dietary xanthophyll nutrients perform in the eye.
The eye contains protective antioxidants-most importantly, lutein and zeaxanthin. These two dietary xanthophyllic carotenoids are part of the macular pigment in the retina. This macular pigment not only acts to reduce blue light–induced free radical damage in the eye; simultaneously, it is strategically located within the eye to absorb the blue wavelengths of light before they reach the photosensitive cells. This combination of activities is only achieved with dietary lutein and zeaxanthin. Although other ocular antioxidants, such as vitamins C and E and minerals such as zinc and copper, play important roles in protecting the eye from potential blue light–induced damage, none of them are capable of absorbing blue light and thus preventing it from reaching the photosensitive cells.
The human body does not make lutein and zeaxanthin, so these nutrients must be obtained from the diet. Unfortunately, most of us don’t consume enough of the foods that contain these important molecules. Based upon results from the National Health and Nutrition Examination Survey (NHANES), we know that the average total daily dietary intake of lutein and zeaxanthin in the United States is 1–2 mg. This intake is significantly below the daily dose of 10 mg of lutein and 2 mg of zeaxanthin recommended for eye health. The low daily intake of lutein and zeaxanthin has been further confirmed during assessments of macular pigment optical density (MPOD). On average, the MPOD value of the general population has been estimated at about 0.2 on a scale of 0–1.0. According to MPOD experts in the field, this MPOD average value lies at the borderline between low protection and moderate protection for eye health. This means that most of us do not have adequate protection against the daily assault of blue light on our eyes.
We can, however, protect our eyes by increasing our intake of lutein and zeaxanthin. These carotenoids are richly available in foods such as spinach, kale, and broccoli.
Alternatively, people can get these important carotenoids by taking eye-health supplements containing sufficient amounts of lutein and zeaxanthin. Many such supplements that contain 10 mg of lutein and 2 mg of zeaxanthin are available on the market today.
A diet and/or supplementation regimen rich in lutein and zeaxanthin cannot completely ensure the preservation of optimal eye health and vision; still, increasing lutein and zeaxanthin intake is a very important step that each one of us should take today to help reduce the risk of damage tomorrow and help maintain the health of our eyes.
Dr. Richard L. “Dick” Roberts is principal manager, scientific affairs and technical services, for Kemin Human Nutrition and Health (Des Moines, IA). Dr. Roberts received his BS degree in chemistry from the University of Texas at Arlington (Arlington, TX) in 1971, his MS degree in bioinorganic chemistry from Texas Tech University (Lubbock, TX) in 1974, and a PhD in analytical biochemistry from the University of Memphis (Memphis, TN) in 1995. At Kemin Human Nutrition and Health, Dr. Roberts is involved in all technical aspects of the use of lutein and zeaxanthin, two highly effective antioxidants, for the improvement of human health, especially as it pertains to the human eye, skin, and brain.