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Macular Pigment Density

The macula or macula lutea ("yellow spot" in Latin) is an oval yellow area near the center of the retina of the human eye. At the centre of the macula is the fovea: with the largest concentration of cone cells (responsible for detailed vision and colour vision) in the eye and is responsible for central vision. Within the macula is the fovea - a small depression in the macula - which contains a high density of cones (photoreceptors with high acuity).

The macula has an important and naturally occurring protective substance known as the macular pigment (MP). The MP is made up of several carotenoids (phytochemicals - found in plants) commonly found in certain fruits and vegetables that provide the red, orange and yellow colors of these foods. The MP is made of three known compounds:

  • Lutein,
  • Zeaxanthin and
  • Meso-Zeaxanthin.

Lutein and zeaxanthin are obtained through food and are found primarly in broccoli, corn, squash and dark green leafy vegetables like spinach and kale. Meso-Zeaxanthin is obtained by an enzyme conversion of lutein to meso zeaxanthin in the macula. It is not found in a typical diet.

What do Lutein and Zeaxanthin do?

Lutein and Zeaxanthin are dietary carotenoids that filter damaging high energy blue wavelength light from the visible-light spectrum by as much as 90%. Lutein and Zeaxanthin are also antioxidants and therefore protect against the damage caused by free radicals. Free radicals are harmful molecules that are produced through normal body processes, such as oxygen metabolism. Environmental sources of free radicals include cigarette smoke, air pollutants, radiation, certain drugs and environmental toxins.

Why is Meso-Zeaxanthin so vital?

Meso-Zeaxanthin, the most potent antioxidant of the three carotenoids, is only found in the center portion of the macula where vision is sharpest. Meso-Zeaxanthin is obtained by an enzyme conversion of lutein to Meso-Zeaxanthin in the macula. It is not found in a typical diet. Supplementation with Meso-Zeaxanthin will ensure that this crucial component of macular pigment accumulates in the target tissue (i.e. the central macula) in a way that is not dependent on an enzyme converting lutein to Meso-Zeaxanthin which can either be absent or insufficient in conversion levels in some individuals.

In a 1994 Journal of American Medical Association report, Dr. Johanna M. Seddon and her associates at Harvard University found that 6 mg per day of lutein lead to a 43 percent lower risk for Macular Degeneration.

“When we compared the amount of macular pigment, which is comprised of lutein and zeaxanthin, present in the eyes of people with age-related macular degeneration to people without the disease, those with the lowest levels of carotenoid accumulation in the outer retina were significantly more likely to suffer from age-related macular degeneration than those with higher pigment levels, ” said Dr. Landrum. “The difference in risk between those having the highest and lowest levels was 75 percent.”

Dr. Landrum, Florida International University