Study indicates an inverse correlation between macular pigment levels and AMD risk

By Katie Winchell

Lower levels of macular pigment appear to be associated with increased risk for age-related macular degeneration (AMD) in humans, according to a new study. The findings could underscore the importance of increasing macular pigment levels as a preventative measure against AMD.

It is known that lutein and zeaxanthin—the two carotenoids that comprise macular pigment—protect the retina against wavelengths of light that can initiate harmful photooxidation. Eye researchers have speculated that these carotenoids may also offer protection against AMD.

Previous investigations have found an association between low levels of lutein and zeaxanthin in the blood and increased risk for AMD. Biophysicist Richard Bone, PhD, a professor at Florida International University, took the next step. “We decided that we should go right to the nub of the matter and look at those carotenoids in the eye,” Bone said. “That was the idea of the experiment: to investigate the possible association between low levels of macular pigment and an increased risk of macular degeneration.”

Using autopsy eyes from donors with and without AMD, Bone and his colleagues separated the retinas into inner, medial, and outer regions. High performance liquid chromatography tests determined that, overall, amounts of lutein and zeaxanthin were lower in the AMD retinas. Specifically, the inner and medial sections of the AMD retinas showed the lowest levels of the carotenoids.

These data generated a new query—whether AMD contributes to pigment loss by destroying the tissues that contain the carotenoids. Bone explained, “That’s kind of important: Does the disease cause the pigment to disappear or does a lower amount of pigment lead to an increased risk of AMD? It’s a chicken-and-egg question.” 

Bone conducted a statistical analysis focused on the outer, peripheral retina, where AMD would probably not cause significant damage to the carotenoids. The results showed the experimental data to be consistent with an inverse association between risk of macular degeneration and the amount of macular pigment.

Bone is quick to point out that his findings don’t show that the relationship is causal, however. He thinks only a large-scale intervention study in which subjects are given either carotenoids or a placebo and are followed for decades to determine macular degeneration rates could clarify the relationship.

The results are intriguing, but we haven’t got a definitive connection,” Bone said. “So people should still be a little skeptical. But one thing I can say is that if I was diagnosed with the early stages of AMD, I would definitely be out there in the local health food store for my lutein supplements.”

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