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In the news: NEI Study: No Evidence Calcium Raises Risk of AMD Progression

The Role of calcium in AMD Progression? 

Two previous studies exploring the role of dietary and supplementary calcium in AMD produced mixed results, leaving eye care professionals and their patients wondering whether extra calcium is safe or harmful for the aging eye.

In 2015, a cross-sectional analysis of the National Health and Nutrition Examination Survey (1) observed an increased prevalence of AMD among participants with supplemental calcium intake of more than 800 mg. daily.

In contrast, a 2014 analysis of the Blue Mountains Eye Study involving more than 2000 participants with a 15- year follow-up, reported a link between low dietary calcium intake and the development of late AMD (2).

Could it be that supplemental calcium as well as too little dietary calcium are both detrimental? To shed further light on this question, National Eye Institute researchers conducted a secondary analysis of 4751 participants in the AREDS trial to evaluate the association of baseline dietary and supplementary calcium intake with AMD progression (3).

Measures and Methods

Main outcomes and measures were development of late AMD, geographic atrophy (GA, central or non-central), or neovascular AMD detected on centrally graded baseline and annual fundus photographs.

Men and women with varying severity of AMD were categorized into quintiles of baseline dietary calcium intake determined by food frequency questionnaire, and energy adjusted. Baseline calcium supplement use was determined via an additional questionnaire.

Results

The analysis found that participants with the highest intake of dietary calcium compared with those in the lowest quintile had a 27% lower risk of developing late AMD, a 36% lower risk of central GA, and a 20% lower risk of developing any GA.

Participants in the highest intake of supplementary calcium had a 30% lower risk of developing neovascular or wet AMD compared with those who did not supplement.

Conclusion and Commentary

“Despite these protective associations of dietary and supplementary calcium, the results may be considered hypothesis generating, requiring validation with further investigations”, the study’s authors concluded.

An accompanying editorial (4) points out that higher intake of calcium was also associated with higher intake of lutein in this study, suggesting that the outcome might be attributed to concomitant higher lutein intake, rather than a direct effect of calcium. How calcium might beneficially affect the macula is not known.

Another interesting finding is that the size of drusen and other sub-retinal pigment epithelium deposits, which are known to contain calcium, were not associated with higher intake of this mineral.

According to the editorial, the evidence suggests that higher calcium intake is not harmful to the macula, and people taking calcium supplements can be reassured that higher calcium intake is unlikely to affect their AMD. Some 50% of men and 65% of women in the US are estimated to regularly use calcium supplements.

References

1. Kakigi CL, et al. Self-reported calcium supple-mentation and age-related macular degeneration. JAMA Ophthalmol. 133:746-754, 2015.
2. Gopinath B,, et al. Consumption of dairy products and the 15-year incidence of age-related macular degeneration. Br J Nutr. 111:1673-1679, 2014.
3. Tisdale AK, et al. Association of dietary and supplementary calcium intake with age-related macular degeneration. Age-Related Eye Disease Study Report 39. JAMA Ophthalmol. Epub Mar 21, 2019.
4. Brelén ME, et al. The question of prescribing calcium supplements to patients at high risk of age-related macular degeneration. JAMA Ophthalmol. Epub Mar 21, 2019.