Genetic testing and nutritional supplements

November 8, 2016
New study makes a case for using genetic testing to determine if nutritional supplements will help treat AMD.

A new study makes a case for patients to undergo genetic testing to determine if nutritional supplements will help treat age-related macular degeneration (AMD). The study was presented at the American Society of Retina Specialists' 2016 Annual Meeting.

Scientists used data from the Age-Related Eye Disease Study (AREDS) from 2001. This research found that high doses of antioxidants slowed the progress of AMD. The researchers from the current study reanalyzed the AREDS results, focusing on 554 subjects who took the nutritional supplement but had no macular degeneration. By identifying genetic markers of AMD, they concluded that the AREDS formula hindered the progress of the disease the most among the subjects who showed a genetic predisposition to the condition.

The lead researcher, Carl Awh, M.D., feels that using genetic testing to find who responds best to this type of nutritional therapy is important because one small cohort who consumed the supplements experienced greater disease progression. He also points out the cost savings for genetic nonresponders who might take the supplement for years.

Despite a second independent study that found the same results as Dr. Awh—one conducted by Johanna Seddon, M.D., and published in the British Journal of Ophthalmology—Dr. Awh's research has been met with resistance. The American Academy of Ophthalmology is not convinced that genetic testing is supported by research. Plus, an experiment conducted by Emily Chew, M.D., of the National Eye Institute, was unable to replicate the results of Dr. Awh's work.

Genetic potential

"Genetic testing may play a role in risk analysis for patients with macular degeneration and can be used in conjunction with a clinical exam to help identify those most at risk of progression. But I don't think we are to the point just yet where we need to do genetic testing to figure out which vitamin supplement is best for a patient," says Steven Ferrucci, O.D., chief, Optometry Section, Sepulveda VA Medical Center in North Hills, California, and professor at Southern California College of Optometry.

One reason Dr. Ferrucci is prudent about genetic testing is because disease is a complicated multifactorial process. A genetic predisposition does not guarantee that a person will suffer from AMD.

"If you are born with good genes, you are somewhat protected. If you live poorly, you can still get macular degeneration. It is genetics plus what you do with them that will help determine if you get macular degeneration."

Benefits of nutritional supplements

Because AMD can be exacerbated by poor diet, and the subjects in the original AREDS study who took the supplement experienced decreased morbidity, Dr. Ferrucci recommends nutritional supplements to nearly all of his patients.

He feels that the AREDS2 formulation, introduced in 2013, is superior to the original AREDS supplement (which was used in these latest studies because researchers had access to the genetic profiles of subjects.) AREDS2 swaps beta carotene for the clinically proven antioxidants lutein and zeaxanthin, making the nutritional cocktail safer and more effective.

"The takeaway is that nutritional supplements work for the majority of patients with AMD and that the field of genetics is evolving," Dr. Ferrucci says. "I can foresee a time in the not-so-distant future when genetics play a big role in figuring out the correct supplementation in treatment and in helping identify those patients at high risk for macular degeneration."

The AOA follows all research closely, including potential treatments for AMD and other eye diseases; however, research is continuing on this treatment option. For more information or help for better vision, please visit the AOA website.

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