Traditionally, the market for eye health ingredients has been an issue for healthcare companies focusing on vitamins and tablets to maintain and improve vision. However, the rise of the dietary supplements and functional food sector has prompted this market to divert towards preventative medicine. Ingredients rich in preventative compounds have been researched in relation to their positive effect against age-related eye conditions such as age-related macular-degeneration (AMD) and cataracts since these diseases are normally a result of age, environment, tobacco abuse and inadequate diet.
The market for eye health ingredients addressing various eye diseases is in a stage of growth, spurred by modern lifestyles and unhealthy diets. With the rise in interest from the supplement and natural extract sectors, a new genre of specific eye health ingredients has emerged with proven benefits on eye health. These ingredients include:
Lutein is a member of the xanthophylls group of carotenoids and is found in spinach, kale and other green leafy vegetables, marigold flowers and algae. A small portion of the lutein market has traditionally been used as a colorant in the food industry and is given the E-number E161b.
Lutein is present in the macula (central optical) region of the retina and along with zeaxanthin it plays a significant role in eye health. The macula is a small area of the retina responsible for central vision. Lutein also acts as an antioxidant to protect the cornea (transparent front portion of the eye covering the pupil) from oxidative stress and high-energy light. Lutein can absorb blue light and hence appears yellow at low concentrations and orange-red at high concentrations. Traditionally, lutein was used in the meat industry to add colour to chicken feed. This fortification then led to the colouring of egg yolk for feed fortification. New research has now identified the benefits of lutein on eye health with over 300 peer-reviewed studies documenting beneficial effects.
Zeaxanthin is recognised as one of the two macular pigments responsible for the yellow colour of the macula lutea in the eye. This pigment is found in corn, marigolds and saffron. Zeaxanthin, in combination with lutein, is said to play a role in the protection of the retina against light-induced damage. Chemically, zeaxanthin differs from lutein in the location of its double bond allowing for two chiral centres while lutein possesses three. In addition, the stereoisomer meso-zeaxanthin is produced in the macula by lutein in the absence of normal zeaxanthin. Zeaxanthin and lutein are distributed within the macula at different locations pertaining to their function within the eye. Lutein is in the periphery while zeaxanthin is placed in the centre in the fovea. Zeaxanthin is implicated towards central vision, contrast sensitivity and glare reduction. Lutein helps with night, low light and peripheral vision. Dietary supplementation of zeaxanthin works to maintain pigment levels in the eye and filter out damaging blue light.
Within carotenoids, astaxanthin falls under the sub class of xanthophylls known to impart orange colour to yellow pigments in a variety of fruits and vegetables. Astaxanthin produces a dark red pigment and is found primarily in marine life forms such as algae, aquatic animals and birds. Well-known astaxanthin-containing species include the micro algae, salmon, trout, red sea bream, shrimp and lobster, as well as in birds such as flamingo and quail. However, only phytoplankton, algae, plants and certain bacteria and fungi synthesize astaxanthin. Animals, including humans, must consume carotenoids as part of their diet and rely on this external supply. Marine animals such as salmon consume krill and other organisms that ingest astaxanthin-containing algae and plankton as a major part of their diets. This nutrient, therefore, moves up the food chain providing essential nutrition.
Astaxanthin is available either as a dry powder, a cold-water-soluble powder or in tablet form. The synthetic variety is only available as a powder and is only available in 8.0 and 10.0 percent concentrations. The natural source is available as a powder, beadlet or softgel in lower concentrations, typically around 1.0 to 2.0 percent, depending on the source.
Beta-carotene is an active pharmaceutical ingredient and a well-known carotenoid. The ingredient is found in carrots and green leafy vegetables such as spinach, kale and cabbage. Beta-carotene is a key eye health ingredient commonly found in multivitamin tablets. This carotenoid is included in the tablets because of its provitamin A activity. The ingredient acts as a precursor of vitamin A that is converted to the vitamin by the body. While other carotenoids also perform this function, they can only create one molecule of vitamin A. Beta-carotene, conversely, generates two molecules of vitamin A, which are then broken down into retinol. Additionally, beta-carotene also acts as an antioxidant thereby promoting free radical scavenging which is the key cause of age-related macular degeneration (AMD).
Traditionally, beta-carotene has been used as a pigment in food colour; however, with rising scientific backing, this ingredient has found increased usage in the dietary supplement sector. There are two kinds of beta-carotene; synthetic, which is usually referred to as nature identical, and the naturally extracted variety. While synthetic beta-carotene is chemically synthesised, natural beta-carotene can be extracted from carrots, yams and other yellow or orange plant material. It can also be extracted from the alga Dunaliella salina or from the fungi Blakeslea trispora, which are grown using fermentation technology. Natural beta-carotene is primarily used in eye health supplements.