High calcium intake may slow AMD progression

Investigators evaluated the association between dietary and supplementary calcium intake with progression of AMD.

Study design

This was a secondary analysis of 4,751 patients in the Age-Related Eye Disease Study (AREDS). The authors compared patients who were in the lowest and highest quintile of dietary calcium intake.

Outcomes

Compared with individuals in the lowest quintile, patients in the highest quintile had a lower risk of developing late AMD (HR 0.73), central geographic atrophy (HR 0.64), any geographic atrophy (HR 0.80) and wet AMD (HR 0.70). The findings were similar between men and women, and for both dietary calcium and supplemental calcium. This study echoes the important findings from the Blue Mountain Eye Disease Study, which found a similar association between the development of late AMD and calcium intake.

Limitations

There is some conflicting data in the literature regarding the role of calcium intake and macular degeneration. The National Health and Nutrition Examination Survey (NHANES) published a large study in 2015, and did not find a similar association. There are inherent limitations to using patient-reported surveys to assess dietary intake as there can be quite a bit of variability in response. There were very few non-Caucasian patients in the study.

Clinical significance

It is unclear exactly why calcium supplementation would be of benefit. It is possible that patients who take higher calcium have better diets overall, so there may be some confounding variables. Encouraging patients to eat a well-balanced, nutritious diet that provides natural sources of calcium may help reduce the risk of vision loss from AMD. However, there is not enough data to recommend patients take calcium supplements to reduce AMD risk.