Healthy diet tied to lower cataract risk

Last Updated: 2017-06-02

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - A healthy diet is associated with a lower risk of age-related nuclear cataract (ARNC), new research from the U.K. suggests.

“Evidence of the relationship between the gut microbiome and age-related diseases and frailty is increasing. This study suggests that cataract risk may be influenced by systemic factors mediated by gut bacteria,” Dr. Christopher J. Hammond of King’s College London, who worked on the study, told Reuters Health by email.

The findings were presented May 11 at the annual meeting of the Association for Research in Vision and Ophthalmology, in Baltimore, Maryland.

“A healthy diet protects against cataract formation, possibly through antioxidant vitamins, but we do not know exactly how this happens,” explained Ekaterina Yonova, a PhD student at King’s and the first author of the conference abstract.

"Our study found differences between the gut bacteria in people who ate healthy diets compared to those who did not,” she told Reuters Health by email. “Some of these bacteria, known to be important for digesting plant material, were associated with healthy diets and may protect against cataract.”

The two researchers and their colleagues tested 757 white female twins from the TwinsUK cohort; the women’s average age was 62. Study participants completed the European Prospective Investigation into Cancer (EPIC) food frequency questionnaires (FFQs) about their food intake, had eye exams and gave stool samples.

The researchers graded the participants' Scheimpflug black-and-white lens photos using central nuclear dip score ARNC measurements; assessed 16S gut microbiome operational taxonomic units (OTUs); and calculated Healthy Eating Index (HEI) scores from the FFQs.

They tested associations using linear and stepwise backwards regression models taking family structure into account. They adjusted for age at eye visit, FFQ, and fecal sampling; body mass index; and technical covariates. And they calculated the threshold to account for multiple testing using the number of effective tests method, and they assessed mediation using the Sobel-Goodman test.

HEI was inversely associated with ARNC risk after adjustment for several factors, including age at eye visit, age at FFQ/fecal sampling, body mass index and technical covariates (p<0.0001). Sixty OTUs (5% false-discovery rate) were associated with HEI, and three of the 60 HEI-associated OTUs were associated with ARNC risk.

By OTU mapping, Ruminococcaceae bacteria were most significantly associated with ARNC (p=0.004).

While Ruminococcaceae bacteria were positively associated with HEI, pathogenic Mogibacteriaceae were negatively associated with HEI (p=0.01).

However, the authors did not find statistical significant evidence that the bacteria mediated the effect of HEI on cataract formation, according to the Sobel-Goodman test (p=0.06).

"Although we found a link between gut bacteria and the amount of age-related cataract, the study did not answer whether this link is causative (i.e., the bacteria cause/protect an individual from cataract, as opposed to, for example, both being associated with a healthy diet). This is an important question to answer if our findings are to lead to new interventions," Yonova told Reuters Health.

"Better understanding of the relationship between the gut microbiome and cataract might lead to new targeted nutritional interventions or even to the development of probiotic drugs to reduce the risk of cataract in later life," she noted.

Only women were included in the study, so the results may not be generalizable to men. The research team is planning a larger study that examines bacteria by taxonomy units and explores the diversity of gut bacteria species.

The Biotechnology and Biological Sciences Research Council (BBSRC) and the Wellcome Trust funded the study. The authors have declared no conflicts of interest.

SOURCE: http://www.arvo.org/

ARVO 2017.