Abstract
Purpose :
A healthy diet, rich in antioxidants, is protective against age-related cataract. The gut microbiome is increasingly implicated in health and disease. In this pilot study we aimed to establish whether the Healthy Eating Index (HEI, a measure of diet quality) was associated with age-related nuclear cataract (ARNC) and whether this association was mediated by specific classes of gut microbiota.
Methods :
ARNC measurements, 16S gut microbiome operational taxonomic units (OTUs) and the HEI calculated from EPIC food frequency questionnaires (FFQ) were available for 757 white female twins (mean age of 62.4, range 45.2-83.6) from the TwinsUK cohort. The median time between FFQ completion and eye examination or fecal sampling was 1 year and 5 years respectively. All associations were tested using linear and stepwise backwards regression models taking into account family structure. We adjusted for age at eye visit, age at FFQ/fecal sampling, body mass index, and technical covariates. The threshold to account for multiple testing was calculated using the number of effective tests method. Mediation was explored using Sobel-Goodman test.
Results :
HEI was inversely associated with nuclear cataract (P<0.0001). Sixty OTUs (FDR of 5%) were associated with HEI and were tested for association with ARNC. Three HEI-associated OTUs were associated with ARNC. An OTU mapping to the Ruminococcaceae family of bacteria was the most significantly associated (β(SE)=-0.02(0.01); P=0.004), but did not survive correction for multiple testing (α=0.003). Ruminococcaceae bacteria, which are important for gut health, were positively associated with HEI. The Mogibacteriaceae (β(SE)=0.02(0.01); P=0.02) family was negatively associated with HEI also supporting the protective effect of HEI. The effect of HEI on ARNC was not mediated by the bacteria as suggested by the Sobel-Goodman test (P=0.06).
Conclusions :
Our results confirm the protective link between nuclear cataract and a healthy diet, and while we found several gut microbiota associated with nuclear cataract (and a healthy diet), we found no statistical evidence of the bacteria mediating the effect of diet on cataract. A larger sample size and better matching of sampling dates would afford better power to detect the effects of bacterial classes on nuclear cataract formation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.