When Too Much Calcium Might Be a Bad Thing

Age-related macular degeneration and calcium supplementation may be linked in older adults

(RxWiki News) If a supplement is good for, say, bone health, most people would feel wise to use it. However, the situation can get sticky when that same supplement is tied to an increased risk of other health issues.

A new study found that adults who got too much calcium through supplements had a higher risk of a common and serious vision issue.

"Despite widespread use of calcium supplementation among elderly people, little is known about the association between such consumption and the prevalence of age-related macular degeneration (AMD) in the United States," explained the authors of this study, led by Caitlin L. M. Kakigi, BA, of the University of California, San Francisco.

In AMD, damage develops in the macula — an area in the retina that helps the eyes see what's directly in front of them. Over time, AMD can cause trouble with vision. According to the National Eye Institute, AMD is the leading cause of vision loss in people aged 50 or older.

The mineral calcium is good for a number of issues in the body, such as bone health. However, Kakigi and team noted that some side effects have been tied to calcium supplementation, such as gastrointestinal issues and kidney stones. Past research has hinted that calcium might be tied to AMD, too.

To explore this topic, these researchers looked at data from the 2007 to 2008 National Health and Nutrition Examination Survey to identify 3,191 adults aged 40 or older.

These patients had all been assessed for AMD using fundus photography, a diagnostic tool that takes a photo of the inner eye. In total, 248 patients (7.8 percent) with an average age of 67.2 were found to have AMD. The average age of the patients without AMD was 55.8.

Patients provided data on their use of dietary supplements during the past month. The authors of this study split the patients into groups based on the amount of calcium they said they took.

After analyzing the data, Kakigi and team found a link between certain levels of calcium supplementation and AMD.

Patients who said they took over 800 milligrams (mg) per day were found to have 1.85 times higher odds of AMD than those who did not take calcium.

According to the National Institutes of Health, the recommended daily allowance of calcium for most adults is 1,000 mg per day.

Kakigi and team found a stronger link between high calcium supplementation and AMD among patients aged 68 or older. This might be due to a longer period of using supplements, they noted. Among patients in this age group who took over 800 mg per day, the odds of having AMD increased to 2.63 times that of those who did not use calcium supplements.

These researchers only found the increased odds of AMD among those taking over 800 mg per day of calcium — those who took less than that did not appear to have a raised risk.

"Until further prospective studies are conducted to assess this association, we would not recommend that patients discontinue taking their calcium supplements in an attempt to reduce their risk of developing AMD, particularly given the known benefits of calcium supplementation for other medical conditions," Kakigi and team wrote.

Patients should talk to their doctors about what supplements might be right for them.

This study was published online April 16 in JAMA Ophthalmology.

A number of groups funded this research, such as the Clinical and Translational Research Fellowship Program and the National Eye Institute. The authors disclosed no conflicts of interest.

Review Date: 
April 16, 2015
Last Updated:
April 20, 2015