COMMENTARY

Age-Related Macular Degeneration and Calcium Supplements: Is There a Reason to Change Clinical Practice?

Charles C. Wykoff, MD, PhD

Disclosures

August 14, 2015

In This Article

A Societal Burden

Vision is central to most aspects of daily life. Multiple surveys report that Americans fear blindness more than most other disabilities, including losing a limb, deafness, using a wheelchair, and mental illness.[1]

Age-related macular degeneration (AMD) is a leading cause of blindness around the world.[2] It is a multifactorial disease with many risk factors. Nonmodifiable risk factors include age, genetic predisposition, and female sex.[3] Modifiable risk factors such as smoking[4] and the consumption of specific antioxidants and minerals are based on the prospective randomized Age-Related Eye Disease Study (AREDS)[5] and AREDS2.[6] Other dietary modifications and lifestyle habits may also affect the AMD risk profile.[7,8,9]

Calcium and the Human Body

Calcium is the most abundant mineral in the body. It plays key physiologic roles in muscle function, nerve transmission, vascular tone, and hormone secretion. Even while participating in these important functions, the majority of calcium in the human body, approximately 99%, is stored in bones and teeth.[10] It can be ingested from foods, medications (eg, antacids), or as a supplement. Approximately 43% of the US population and up to 70% of older women regularly consume dietary supplements containing calcium.[11]

In the short term, inadequate calcium consumption typically produces no symptoms. Serum calcium is strictly regulated and typically does not vary with dietary fluctuation because bones serve as a reservoir. Bone itself undergoes continuous remodeling, a balance between resorption and deposition. In older adults, particularly among postmenopausal women and especially in the setting of inadequate calcium intake over the long term, bone resorption can exceed formation and potentially result in osteopenia.

Osteopenia, or low bone mass, affects approximately 34 million Americans and can lead to osteoporosis if left unmanaged. Osteoporosis affects more than 10 million American adults and is characterized by brittle and fragile bones. It is a common cause of fractures, including those involving the wrist, hip, vertebrae, pelvis, and ribs,[12] and is responsible for an estimated 1.5 million fractures annually in the United States alone.[13] Critically, supplementation with calcium and vitamin D is effective in reducing fractures in older adults.[14]

Because of the key role of calcium in human health and skeletal integrity, the Institute of Medicine of the National Academies established a recommended dietary allowance (RDA), defined as the average daily intake that is sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy individuals. All adults who are 19-50 years of age are recommended to consume 1000 mg of calcium daily; women older than 50 years of age and men older than 70 years are recommended to increase calcium intake to 1200 mg daily.[15] These amounts can be achieved through a combination of diet and supplements.

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