April 2017

 

RETINA

 

Research highlight

Tracking benefits of the Mediterranean diet for AMD prevention


by Vanessa Caceres EyeWorld Contributing Writer

    Mediterranean diet

Two European studies find protective effect from the healthier Mediterranean diet

A Mediterranean diet—a way of eating favored in Mediterranean countries that emphasizes fish, whole grains, and plenty of fruits and vegetables—has received many accolades for its health benefits. It’s said to lower the risk for stroke, diabetes, and cognitive decline.
Now, two groups of European researchers believe it also can help lower the incidence of age-related macular degeneration (AMD).
In one study reported at the American Academy of Ophthalmology (AAO) annual meeting in Chicago last fall, those following a Mediterranean diet were thought to be a third less likely to develop AMD, according to Rufino Silva, MD, PhD, invited professor, Faculty of Medicine, University of Coimbra, and head of the Medical Retina Unit, Department of Ophthalmology, Coimbra Hospital and University Center, Coimbra, Portugal.
Dr. Silva and fellow investigators at the University of Coimbra analyzed 883 people age 55 or older; 449 had early stage AMD but no vision loss. There was no vision loss in the other 434 participants. Participants completed a questionnaire to log how often they ate foods closely connected with the Mediterranean diet, and they received a score from 0 to 9 based on their answers. Those adhering to the Mediterranean diet closely had a score of six or greater.
There was a lower risk of AMD found in those who more closely adhered to the Mediterranean diet. “Of those who did not closely follow the diet, 50% had AMD,” according to a press release from the AAO about the research. “Of those who did closely follow the diet (scored 6 or above), only 39% had AMD.” That resulted in a 35% lower risk.
Two intriguing trends emerged from the research. First, fruit consumption was especially protective against AMD. In those who ate about five ounces of fruit or more daily, 54.5% did not have AMD; 45.5% had AMD. Second, participants who consumed higher levels of caffeine—the equivalent of one shot of espresso—were less likely to have AMD. About 54% did not have AMD versus 45% who did.
“To the best of our knowledge, it’s the first time [caffeine] has been shown as potentially protective in AMD. Caffeine is a powerful antioxidant so, while surprising, from a biochemical standpoint it is understandable that it would be protective in AMD,” Dr. Silva said.
Although caffeine is not part of the Mediterranean diet, coffee and tea consumption are common in Mediterranean countries.
This same analysis was used for other antioxidants and found that higher consumption of beta carotene and vitamins C and E were protective against AMD.
There is ongoing research with the Coimbra Eye Study, which is a broad AMD epidemiology initiative, Dr. Silva said. “We are also repeating this nutritional study on a more coastal location, presumably with a fish-rich diet, to compare it to our current mainland results,” he said.
Although the link between a Mediterranean diet and AMD prevention needs further research, Dr. Silva believes the results give ophthalmologists one more reason to stress the importance of a healthy, fruit-rich diet.

The European Eye Study and the Mediterranean Diet

A broader study in Europe that was recently published analyzed the association between a Mediterranean diet and the prevalence of AMD.1
At seven centers in Norway, Estonia, the U.K., France, Italy, Greece, and Spain, full dietary data from 4,753 randomly sampled people over age 65 were analyzed. The average age was 73.2 years, and 55% of participants were women. Participants completed a food frequency questionnaire, which was analyzed with the use of a previously published Mediterranean Diet Score (MDS). All participants had an eye exam and digital retinal color photography. The participants were recruited in 2001 and 2002, before many of the recent findings about the Mediterranean diet were well-publicized.
A higher MDS was linked with reduced odds of neovascular AMD. “Compared with the lowest MDS adherence, those in the highest category MDS adherence showed lower odds of [neovascular] AMD,” the investigators wrote. Participants in the highest MDS category had 20% reduced odds for large drusen compared with those who had lower MDS scores.
Those more closely following a Mediterranean diet had higher serum levels of vitamin C, lutein, zeaxanthin, and beta-cryptoxanthin, which investigators noted were biomarkers of fruit and vegetable intake.
The results add to the evidence base for the Mediterranean diet’s protective effect against AMD, the investigators concluded. They encouraged further adoption of the Mediterranean diet, with an emphasis on helping others to maintain this healthier way of eating long term.
The results from these studies do not surprise dietitian Sara Hass, RDN, LDN, Chicago. “This is consistent with other studies that support this way of eating as beneficial to your health. Plant-based diets naturally supply more antioxidants and nutrients that can help fight disease while also keeping our bodies healthy,” she said.
One interesting aspect of the current research for Ms. Hass was the focus on eye health, which she sees as often ignored compared with other aspects of health. “It behooves us to find ways to prevent macular degeneration, and if diet can positively affect eye health, then it’s an area worth pursuing and promoting,” she said.
Although ophthalmologists may not always have the time or resources to discuss nutrition, Ms. Hass recommends suggesting that patients see a registered dietitian for additional guidance and help.

Reference

1. Hogg RE, et al. Mediterranean diet score and its association with age-related macular degeneration: The European Eye Study. Ophthalmology. 2017;124:82–89.

Editors’ note: Dr. Silva is a consultant for Allergan (Dublin, Ireland), Alcon (Fort Worth, Texas), and Novartis (Basel, Switzerland). His study was sponsored by the Association for Innovation and Biomedical Research on Light and Image and supported by Novartis. Ms. Hass has no financial interests related to her comments.

Contact information

Hass: shassrd@gmail.com
Silva: rufino.silva@oftalmologia.co.pt

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