16/03/2024
Our reliance on eyesight is almost absolute It is taken for granted that over the course of a lifetime, the eyes will continue to relay the surfeit of visual information the brain needs to help navigate our environments and interact with the world and people around us. But vision comes at a cost that is exacted each day we open our eyes that may lead to small changes in vision and, eventually, visual impairment.
When asked, most people rank vision loss as one of the worst possible health outcomes: more than losing hearing, memory, speech, or a limb.1 It is not hard to see why; vision impairment and blindness are less about the physiological outcome (i.e., not being able to see) and more about the consequence: a disconnection from the world and loss of independence that healthy vision provides.
VISION LOSS AT A GLANCE
1 in 7 or 1.3 billion people in the world live with some form of vision impairment. Most of them are 50+
Top causes of visual impairment include uncorrected refractive errors, cataracts and AMD
By 2020 increases in conditions like diabetic retinopathy may lead to a 3-fold increase in blindness
80% of all cases of visual impairment are avoidable
A solution is in sight
There are known and cost-effective interventions, including early and adequate dietary intake of the macular carotenoids: lutein, RR-zeaxanthin and RS [meso]- zeaxanthin. Consistent and daily intake of these nutrients play a key role in visual function and protection, especially from the constant exposure to blue light.
BLUE LIGHT AT A GLANCE
Unlike UV light blue light penetrates deep in the eye, impacting retinal cells directly
AMD risk increases about 38% with sunlight exposure
10 hours per day are spent on digital devices by the average adult
Short term effects of blue light exposure from digital devices include eye strain and physical discomfort
We live in a blue world
The scientific consensus is that visible light is both necessary for vision and harmful due to excessive or prolonged exposure. Light-mediated damage plays a role in many common forms of blindness, including age-related macular degeneration (AMD).4 Photooxidation—the production of free radicals induced by exposure to radiant energy like light—is akin to the sunburn that results from ultraviolet light. Photooxidation from blue light is the most common form of damage that can occur in the retina.
Like ultraviolet light, sunlight continues to be the major contributor of blue light but the increasing reliance on digital devices has extended exposure into almost every facet of daily life. It is the daily exposure to blue light and the photooxidation that ensues that leads to small, imperceptible changes in retinal cells over a lifetime can manifest as age-related visual impairment. To mitigate the effects of blue light the eyes have evolved to have mechanisms to help reduce the effects of blue light by incorporating “filters” that absorb high energy wavelengths and reduce photooxidation.
ESSENTIALITY AT A GLANCE
5 groups of essential nutrients include
1. Water
2. Vitamins
3. Minerals
4. Amino acids
5. Some fatty acids
(e.g., alpha-linolenic acid)
The macular carotenoids
Lutein and the zeaxanthin isomers (RR-zeaxanthin and RS [meso]-zeaxanthin) are critical for protecting the eye on a daily basis—so much so that their concentrations in the retina are three times the amount of carotenoids in normal human sera. Because the body cannot synthesize the macular carotenoids, dietary intake is the only way to ensure optimal levels in the retina to protect against daily blue light exposure. Their importance in eye health has sparked discussions about their essentiality and the need for daily supplementation.
Why supplementing with macular carotenoids is essential
Currently, there is no defined requirement for the major dietary carotenoids as they do not fulfill the criteria of an essential nutrient like vitamins and minerals. However, there is enough data to suggest that lutein and the zeaxanthin isomers may be considered “conditionally essential”–nutrients that are usually synthesized or present in adequate amounts endogenously, but under certain circumstances may require additional supplementation.
The 3 criteria for conditionally essential— and why the macular carotenoids meet these requirements include....
1. Decline of plasma levels of the nutrients into the subnormal range
Dietary intake and serum level of lutein and zeaxanthin isomers are positively correlated to MPOD in human subjects. When fed xanthophyll-free diets, monkeys showed an almost total loss of MPOD. Therefore, dietary modification influences plasma levels and, subsequently, retinal deposition of macular carotenoids.
2. Replenishment by dietary supplementation of the nutrient
Epidemiological data suggests that diets rich in macular carotenoids decrease AMD risk.Subjects consuming lutein experienced a tenfold increase in serum concentrations and a 21 to 39 percent increase in MPOD. The investigators estimated that supplementing with lutein may have produced a 30–40% reduction in blue light reaching the photoreceptors. Daily consumption of spinach and corn resulted in a significant increase in MPOD compared to baseline.19 Several studies by Stringham have shown that there are significant increases in both serum and MPOD levels in as little as 8 weeks in subjects supplementing with a formula containing lutein, RR- and RS-zeaxanthin [Stringham BA study LAMA1 and LAMA2; BLUE]. Supplementing with Lutemax 2020 significantly reduced the number of TUNEL- positive cells as well as down regulating p-JNK, GRP78, p-PERK, ATF4 and ATF6, which are thought to contribute to endoplasmic reticulum stress and retinal damage.
There is a growing body of research to support the conditional essentiality of the macular carotenoids for eye health. Their importance in eye health should not be understated especially considering growing prevalence of AMD, one of the leading causes of vision impairment globally.
3. Appearance of chemical, structural, or functional abnormalities
Several studies correlate low macular carotenoid levels and increased risk of age-related macular degeneration. Sun exposure, the primary source of blue light exposure, can increase the risk of AMD by as much as 38 percent. The European Eye Study (EUREYE) further supports the importance of adequate dietary antioxidant intake – including zeaxanthin – to help protect against blue light exposure. Researchers found that when there was a significant association between AMD and low antioxidant status. In a case-control study of donor eyes with and without AMD, the concentration of lutein and zeaxanthin was significantly less in eyes with AMD. A study by Yu provides a mechanism by which exposure to blue light damages retinal cells by promoting endoplasmic reticulum stress that can lead to cellular apoptosis.
Blue light is a growing concern...But there is a solution
There is a strong case for supplementation to compensate for lifestyle, dietary and biological factors, which together dictate a higher need to replenish macular carotenoids daily. Consumers of all ages continue to be bombarded by blue light at every turn, if not from their digital devices, TV screens and LED lighting, then from sunlight, which continues to be the biggest source. In 2017, the B.L.U.E. (Blue Light User Exposure) study was published. It was the first to demonstrate a direct link between supplementation with all three macular carotenoids and their ability to protect against the effects of prolonged blue light exposure from digital devices. The findings from this study helped open a new market, allowing companies to tap a new audience of consumers skewing a lot younger than previous target groups. The B.L.U.E. study demonstrated that healthy vision can be a relevant and important concern for younger consumers looking for solutions to address a growing need to protect and preserve healthy vision from increasing blue light exposure, coupled with the desire to fill nutrient gaps and overall well-being.
