Dietary macular pigments, which can now be measured directly and accurately, are hugely important in optimizing visual function, especially as we age.
At least 700 carotenoids are found in nature. Around 50 are included in a typical human diet, 15–16 of which make their way to the circulatory system, but remarkably only three are found in the eye, where they are highly concentrated at the macula.
These yellow macular pigments—lutein, zeaxanthin and meso-zeaxanthin—have powerful antioxidant properties and play essential roles in filtering high-energy, short-wavelength blue light and in minimizing the oxidative stress that is known to be a significant factor in age-related eye disease.
Prof. John Nolan of the Nutrition Research Centre Ireland has spent 20 years researching the macular pigments—measuring them and monitoring their effects on health. He says that “the general population is highly deficient in these three carotenoids; even the healthiest person you know is deficient. Nobody is eating enough.” A deficiency in macular pigments has a real and tangible impact on day-to-day quality of life in terms of vision and cognitive function.
Carotenoids and vision
Everybody who works in eye care is aware that visual acuity does not describe the whole of visual performance, which is multifaceted and also incorporates aspects of processing speed, contrast sensitivity, glare and visual adaptation. Prof. Nolan’s European CREST trials, supported by a European Research Council Starting Grant, demonstrated that each of these individual visual functions is significantly improved by enriching the macular pigments by means of an oral supplement, not only in subjects with early age-related macular degeneration but also in healthy subjects.1,2
Blue light is a problem for visual performance and increasing its filtration—by increasing macular pigment—reduces visual discomfort and glare disability and improves photostress recovery. Another important aspect of vision is the speed of visual processing, which is strongly modifiable by increasing macular pigment.
For every 0.1 increase in macular pigment optical density, roughly 1 millisecond of reaction time can be gained.3 Increased contrast sensitivity can hugely improve a patient’s quality of life and how they feel about their vision. A patient with a medium or high level of macular pigments can of course still develop macular degeneration, but nutrition can counterbalance genetic factors and optimize their individual disease trajectory.
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