Age-related macular degeneration (AMD) has been linked to supplementing more than 800 mg of calcium per day. The link was strongest in the elderly, who suffer from AMD the most. The research was a cross-sectional study of National Health and Nutrition Examination Survey (NHANES) data. The RDA for calcium (CA) for adults is 1,000 mg; 1200 mg for women over 50. However, changes to the recommended total daily intake of CA have not been suggested.
This research was conducted at the University of California, SF, and appeared in JAMA Ophthalmology April 2015. It was based on surveys of calcium supplementation and AMD. In the past, the researchers had a similar finding with self-reported glaucoma.
Significant amounts of calcium can be found in food sources including dairy products, certain green vegetables such as collards and broccoli, oranges, sardines and salmon, white beans, okra, tofu and almonds. If food sources do not provide enough calcium, many people elect to take calcium supplements. In fact, 43% of the US population claim to take CA supplementation, including 70% of older women.
Subjects who were in the top 25% of self-reported calcium intake in excess of 800 mg/day were 85% more likely to be diagnosed with age-related macular degeneration than subjects who did not take calcium supplements. The increased risk of 2.63 times applied to subjects over age 67. Younger subjects aged 40-67 did not have this association.
The researchers warn that they cannot demonstrate that the calcium supplements actually caused AMD based on this study. Further research is needed. Calcium supplements have a demonstrable impact on osteoporosis prevention and treatment, and therefore should not be discontinued if used for this or any other purpose. Additionally, vitamin D is crucial for calcium absorption, and the study did not examine this factor.
SOURCE: Self-reported Calcium Supplementation and Age-Related Macular Degeneration. Kakigi et. al. JAMA Ophthalmol. Published online April 09, 2015. doi:10.1001/jamaophthalmol.2015.0514 http://bit.ly/1avViTF