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The future of eye health looks bright thanks to growing support around several nutrients.
When one considers all of the human senses, the ability to see clearly certainly is one of the most significant.
Eye health is an integral factor in being able to enjoy a high quality of life. Healthy vision is closely intertwined with our ability to maintain independence. In fact, vision impairment was the most feared disability among those surveyed according to the report “Vision Problems in the U.S., 2008 Update to the Fourth Edition” by volunteer organization Prevent Blindness America. Furthermore, the national burden associated with blindness and vision impairment in adults is estimated to be more than $51 billion on an annual basis.
Of the adult eye concerns, age-related macular degeneration (AMD) is the leading cause of blindness for Americans aged 50 and older. It is estimated that more than two million Americans have late AMD, while millions more suffer from earlier signs of the disease.
Effective preventive options that promote optimal visual function hold a great deal of appeal then. In this realm, therapeutic nutrition is one of the most promising. The National Eye Institute’s/National Institutes of Health’s original Age-Related Eye Disease Study (AREDS) included 3,600 participants with various stages of AMD. The results showed that a combination of antioxidants-including vitamin C, vitamin E, beta-carotene, and zinc-reduced the risk of developing AMD by 25%.
Since then, numerous studies have highlighted the benefits of additional nutrients for promoting eye health, including other carotenoids and omega-3 fatty acids. AREDS2 is an ongoing study launched in 2006 designed to assess the effectiveness of the carotenoids lutein and zeaxanthin, as well as the omega-3 fatty acids DHA and EPA, on the progression of AMD.
Preliminary results of AREDS2 are expected in 2013. However, evidence is accumulating in the form of published research for the benefits of these carotenoids and essential fatty acids in supporting a number of parameters of visual function. Some of the most recent research findings in this area are highlighted ahead.
Research indicates that intake of essential omega-3 fatty acids is correlated with a broad range of benefits for visual function. Well-known benefits of omega-3 fatty acids include anti-inflammatory effects and improvements in blood flow and blood vessel health. Furthermore, the omega-3 fatty acid DHA is one of the most abundant in brain and eye tissues, where it plays an important developmental role. Thus, it’s no surprise that these healthy fats may support healthy vision.
A prospective study published in 2011 followed the dietary habits of more than 38,000 women health professionals for more than 10 years to observe patterns correlated with the development of AMD. The women included in the study had no prior diagnosis of AMD. Dr. William Christen and colleagues from Harvard Medical School found that women consuming the highest amounts of DHA had a 38% lower risk of developing AMD, while those with the highest intake of EPA had a 35% lower risk. In terms of fish intake, those women consuming one or more servings of fish per week had a 42% lower chance of developing AMD compared to those women who consumed one or fewer servings of fish per month. According to the study authors, the research indicates that these particular omega-3 fatty acids from fish are beneficial in the primary prevention of AMD.
Further studies including omega-3 fatty acids suggest benefits for promoting healthy levels of eye moisture in cases of dry-eye syndrome. Accounting for this effect of omega-3s may be their direct anti-inflammatory and neural-health restorative benefits. Additionally, two classes of compounds known as resolvins and protectins (derivatives from EPA and DHA, and highly potent anti-inflammatory compounds) have been found to increase tear volume and decrease nerve and eye inflammation in animal studies. In humans, a pilot study published in the journal Cornea and conducted at the University of Texas Southwestern Medical Center found that the administration of a supplement containing EPA, DHA, and flaxseed oil (a source of plant-derived omega-3s) for 90 days enhanced tear production and tear volume compared to the placebo group.
Furthermore, a multicenter randomized controlled trial led by Françoise Brignole-Baudouin and colleagues and conducted in France and Italy in patients with dry-eye syndrome found that three months of supplementation with a combination of omega-3 and omega-6 fatty acids, along with certain vitamins and zinc, significantly decreased the expression of an inflammatory marker found in conjunctival tissue known as HLA-DR. The group taking the supplement also showed a trend towards improvement in symptoms of dry eye.
Lutein and zeaxanthin are xanthophyll carotenoids and are the only two carotenoids found in the retina and lens of the eye. Xanthophylls are often found in green plants where they protect plant structures from the effects of excess light. Research suggests that enhanced dietary intake of lutein and zeaxanthin in humans confers protection against the development of AMD and cataracts.
Both carotenoids serve to protect the delicate structures of the eye because of their ability to absorb blue light, preventing oxidative damage. In human eye tissue, the highest concentration of zeaxanthin is found in the central macula (in the center of the retina, where cones predominate and facilitate high visual acuity and color vision), whereas lutein concentrations are highest in the peripheral retina (which contains a mix of rods and cones).
Astaxanthin is a xanthophyll carotenoid similar to lutein and zeaxanthin. While lutein and zeaxanthin are normally found in eye tissue, astaxanthin is not. This beneficial carotenoid is a component of several foods in the diet, and the best sources of this nutrient include algae and krill. Research indicates that astaxanthin from the diet can cross the blood-brain barrier as well as the blood-retinal barrier. Emerging research in humans indicates that astaxanthin confers a broad spectrum of benefits for promoting health and well-being, including potent antioxidant protection, anti-inflammatory activity, and support for cardiovascular and nervous system function. Of unique interest is the accumulating research indicating astaxanthin’s benefits for eye health.
Lutein and Zeaxanthin
A significant amount of research over the years has indicated that reduced dietary intake of lutein is an important risk factor for the development of AMD. Additional clinical trials involving supplementation with lutein have shown benefits on a number of parameters of visual function. A recent double-blind, placebo-controlled trial conducted in Austria (known as LISA, or Lutein Intervention Study Austria) assessed the effect of lutein supplementation or placebo on macular pigment optical density (MPOD) in 126 subjects with a diagnosis of AMD. After six months of supplementation, the lutein group saw a statistically significant increase in MPOD (by an average of almost 28%) versus placebo. There was also a significant correlation between lutein supplementation and improved macular function and visual acuity after six months.
A randomized controlled trial (ZVF, or Zeaxanthin and Visual Function Study) conducted by Stuart Richer and colleagues and published in the November 2011 issue of Optometry evaluated the effects of one year of relatively high-dose zeaxanthin supplementation (8 mg) with and without lutein (9 mg), compared to the effects of lutein alone, in 60 individuals with mild to moderate AMD. The researchers found that MPOD increased similarly in both the lutein and zeaxanthin groups. In addition, the zeaxanthin group showed improvements in detailed high-contrast visual acuity and sharpened ability to discriminate shapes. Furthermore, a larger percentage of participants in this group experienced clearing of central scotomas (retinal areas with reduced light sensitivity that are common in individuals with AMD). The lutein group, on the other hand, experienced greater improvements in low-contrast visual acuity, enhanced contrast sensitivity, and improved glare recovery. In these areas, zeaxanthin supplementation showed trends towards significance, but did not reach statistical significance.
While there was significant overlap between the effects of lutein or zeaxanthin alone, the researchers’ findings indicated that zeaxanthin had greater benefits for cone-based visual function, and lutein improved rod-based visual function, thus indicating the complementary nature of both carotenoids. The combination group consumed a supplement containing near-equal doses of both carotenoids (which is an atypical ratio, in terms of dietary intake of lutein and zeaxanthin) and fared worse in terms of improvements in MPOD. This was attributed to competition for absorption in the gastrointestinal tracts and possibly to increased liver metabolism of both carotenoids, thus reducing their bioavailability.
A number of human studies concerning astaxanthin’s effect on eye health, mainly conducted in Japan, have been detailed in a recently published review paper authored by Jian-Ping Yuan and colleagues from Sun Yat-Sen University in Guangzhou, China. The results of these studies suggest that astaxanthin supplementation yields clinically significant benefits for visual acuity and accommodation time, along with improvements in eye fatigue and reduction in eye strain in computer workers. Furthermore, astaxanthin has been found to increase retinal capillary blood flow in healthy humans. Astaxanthin also was found to mediate several anti-inflammatory effects in eye tissue.
In addition to the multiple studies showing benefits for astaxanthin on eye strain and visual fatigue through increased accommodation ability in young, healthy individuals, Masayoshi Kajita and colleagues in Japan found that the administration of 6 mg of astaxanthin per day for four weeks led to significant improvements in accommodation ability (as shown by increased pupillary constriction ratio) and other symptoms of eye strain in middle-aged and older individuals (age 45 to 65) with presbyopia. The improvements included an enhanced ability to see nearby objects, reductions in eye strain, a decrease in blurred vision, and reduced shoulder and low back stiffness (common in individuals experiencing chronic eye strain).
Changes in lifestyle and dietary patterns over the years are significant contributory factors to the increasing prevalence of eye-health issues. Visual function and eye health are areas near and dear to the hearts of millions of consumers, since vision concerns are so integral to the ability to maintain independence. The continued availability of safe and effective nutritional options to address these concerns serves to positively impact the health of consumers at large by filling a crucial healthcare need. It also represents an area of significant growth potential in the nutraceutical and functional foods arena, allowing companies offering solutions for eye-health concerns an opportunity to thrive.
Astaxanthin and Eye Fatigue
While most of the supplement industry has eyed prevention for age-related eye diseases, few solutions focus on relief for tired eyes or eyestrain, such as that associated with the ubiquitous use of VDTs (video display terminals), including computers, cell phones, and other devices. “This issue represents an opportunity for the dietary supplement industry to find a truly new growth area,” says Charles DePrince, president and CEO of Fuji Health Science (Burlington, NJ).
He says that to date, Fuji’s parent company, Fuji Chemical Industry Company, Ltd., has sponsored 10 human clinical studies at six different universities and technical institutes on the use of AstaReal astaxanthin, which showed significant positive results for improving such eye-fatigue symptoms as accommodation (focus), acuity, and critical flicker fusion, as well as for reducing eye-fatigue complaints. In addition, astaxanthin supports eye health by increasing capillary blood flow and improving ciliary body function.
As DePrince continues, “The ciliary body is a small muscle in the eye responsible for controlling the lens of the eye. Like any other muscle in the body, if we overwork this tiny muscle, we will feel discomfort or pain along with other symptoms of tired eyes. Other studies have shown astaxanthin to generally increase the endurance and recovery of muscles after exercise or other forms of stress. So, whether you are a marathon runner or a computer junkie, astaxanthin may help.”
DSM Nutritional Products (Parsippany, NJ) offers a variety of ingredients for eye health. These include carotenoids FloraGLO lutein and OptiSharp zeaxanthin, omega-3 fatty acids Ropufa, as well as vitamins and minerals. Preliminary research also indicates that DSM’s geniVida genistein could play a role in relieving symptoms of dry-eye syndrome.
With regard to the ongoing AREDS2 study, DSM is providing FloraGLO lutein, OptiSharp zeaxanthin, and Ropufa omega-3 for this trial. Eye health is an area primed for significant growth, adds Aparna Parikh, senior marketing manager for FloraGLO, OptiSharp, and DSM’s eye-health platform. “This represents an area of opportunity for manufacturers of health-based ingredient products as well as functional foods and beverages. The vision-health category has shown strong growth in the last few years as consumer concern for eye health and awareness of nutritional ingredients key to eye health grows.”
Kemin Health (Des Moines, IA), which supplies FloraGLO lutein to customers through DSM, confirmed that FloraGLO (as a 20% suspension in safflower oil) has been Generally Recognized as Safe since 2007 for use in term infant formula when added in amounts up to 250 micrograms lutein per liter of formula. Most recently, in 2012, FloraGLO received a letter of non-objection from FDA for use as an ingredient in formulas intended for premature infants at levels up to 210 micrograms lutein per liter of formula.
According to Heather Richardson, brand manager for FloraGLO lutein, “A review of FDA’s listing of food ingredients and packaging that are GRAS confirms that FloraGLO lutein is the only brand of GRAS suspended lutein that has been the subject of non-objection letters from the FDA for use in both term and premature infant formula.”
A Blended Approach
ZMC USA (The Woodlands, TX) offers a full line of carotenoids that are increasingly becoming recognized for their eye-health benefits. Incorporating several carotenoids in combination are important to eye health, says the company, which offers a lutein-zeaxanthin blended combination. Scott Steinford, president of ZMC USA, says, “ZMC is the only manufacturer to not just blend the materials but, using patented technology, manufactures the ingredient to include a consistently high zeaxanthin-to-lutein ratio.”
The company also offers other nutrients, including beta-carotene. Beta-carotene has long been associated with eye health and is finding its way into eye-health formulations to support the lutein and zeaxanthin usually highlighted.
Steinford continues, “The offering of vision-care products has steadily been increasing over the past several years as a testament to the increasing concern and importance baby boomers are placing on eye health. The Natural Marketing Institute’s 2009 Health and Wellness Trends Database shows that one-fourth of a general population survey expressed vision/eye-health problems as a medical condition that [those surveyed] were most concerned about preventing. This survey of over 5,600 individuals indicated that eye health ranked higher than concerns over diabetes, stress, or immune health.”
OmniActive Health Technologies (Short Hills, NJ) offers a number of ingredients for use in dietary supplements and functional foods, including combinations of lutein and zeaxanthin. One of its more popular offerings in this area is Lutemax 2020, winner of the 2011 Global Frost & Sullivan Award for Product Differentiation Excellence.
Lutemax 2020 offers a unique combination of lutein along with enhanced levels of zeaxanthin in two of its isomeric forms-RR-zeaxanthin and RS-(meso)-zeaxanthin-in a balanced ratio. Lutemax 2020 was introduced a year and a half ago.
Philip Domenico, PhD, human nutrition scientist at OmniActive, states that, “Lutemax 2020 is the first and only food-grade lutein with enhanced levels of zeaxanthin ingredients for human consumption on the market that is produced under a fully integrated supply chain process. Our operations begin with the cultivation of marigold flowers and continue through proprietary extraction and manufacturing processes. The result is a stable, effective eye-health ingredient that is truly differentiated in today’s marketplace.”
Lutemax 2020 is available in many concentrations and delivery platforms, including vegetarian beadlets, oils suspension, and powder forms, to meet a variety of manufacturing requirements. One unique offering is a 25% vegetarian beadlet that enables customers to formulate higher-dose lutein formulas without using much bulk raw materials. This allows manufacturers to create new nutritional formulations or update their existing eye-health product offerings with an ingredient that delivers nutritionally relevant, enhanced levels of zeaxanthin isomers with lutein, at an affordable cost, the company says.
Also, according to Domenico, “Lutemax just received FDA GRAS notification, which reaffirms its safety and expands the usability of our popular eye-heath product.”