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Study suggests iron, calcium supplements may be linked to increased risk of glaucoma
There may be an epidemiologic relationship between oxidant intake and glaucoma prevalence.
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The consumption of iron and calcium supplements was associated with significantly higher odds of self-reported glaucoma when compared to lack of oxidant supplement consumption, a study found.
“Our epidemiologic findings relate glaucoma to supplementation with the oxidants iron and calcium, which support the hypothesis that oxidative stress may play a role in glaucoma pathogenesis. If future research corroborates these findings, then there may be implications for understanding the pathogenesis and the treatment of glaucoma,” Sophia Y. Wang, lead author of the study, told Ocular Surgery News.
“Considering the common neurodegenerative features between Alzheimer’s disease, Parkinson’s disease and glaucoma and a possible epidemiologic association between these three diseases, it would not be surprising if calcium dysregulation was found to increase the risk of glaucoma,” the study authors said.
Study findings
The cross-sectional study examined data from the National Health and Nutrition Examination Survey.
Among the 3,833 study participants, there were 248 cases of self-reported glaucoma (4.7%). Those who consumed more than 800 mg per day of calcium supplements or more than 18 mg per day of iron supplements had significantly higher odds of being diagnosed with glaucoma.
Although a clear dose-response relationship between supplementary calcium or iron intake and self-reported glaucoma was not evident, the data correlation suggested a threshold level of oxidant consumption above which odds of developing glaucoma increased significantly.
The authors observed no increase in the prevalence of glaucoma when calcium and iron supplements were consumed concurrently below threshold levels; however, the concurrent consumption of both oxidants above threshold levels resulted in greater odds of glaucoma than either oxidant alone.
“It is noteworthy that the threshold levels deemed to be associated with glaucoma risk in this population-based study are considerably lower than the tolerable upper intake levels of calcium and iron,” the study authors said.
As established by the Institute of Medicine, the upper intake level for calcium is 2,000 mg per day for those over 50 years of age, while the upper intake level for iron is 45 mg per day for those over 18 years of age.
Study limitations
The study’s conclusions may have been limited by the reliance on participants’ self-reporting of prior glaucoma diagnosis, which could be affected by disease misclassification and recall bias, according to the study authors.
An additional limitation was that supplement intake information was ascertained based on 30-day recall and included participants who had been taking oxidant supplements for a long period of time as well as those who had just begun a supplementation regimen.
“Additional research needs to be done before we could make recommendations to patients regarding glaucoma and supplement use, particularly as calcium and iron supplements are often necessary for treatment of other medical conditions,” Wang said. – by Daniel R. Morgan
Reference:
- Wang SY, Singh K, Lin SC. The association between glaucoma prevalence and supplementation with the oxidants calcium and iron. Invest Ophthalmol Vis Sci. 2012;53(2):725-731.
For more information:
- Sophia Y. Wang can be reached at wang@ucsf.edu.
- Disclosure: Wang has no relevant financial disclosures.