Recent reports question the need of calcium intakes greater than 700 to 800 mg/d to support the maintenance of bone mass and density, especially among older adults. In addition, several publications suggest that calcium supplements may not be helping older adults reduce skeletal fractures or maintain bone mass, except in truly undernourished elders who are typically institutionalized. Finally, calcium supplements may contribute to arterial and heart valvular calcifications, renal stones, and, possibly, to brain lesions and depression, but a cause-and-effect relationship has not been established. Current US intakes of calcium by adults have increased in the last couple of decades, in large part because of supplements. Because of the potential adverse effects of calcium supplements, that is, calcium loading that may result in arterial calcification and renal stones, some suggest recommendations of calcium intakes for healthy adults from food sources with only additional amounts from supplements when institutionalized or frail elderly cannot obtain enough calcium from foods. A reassessment of the recommended dietary allowances of older adults seems warranted.
John J. B. Anderson, PhD, is Professor Emeritus, Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill. He has had a career in the field of calcium and bone metabolism using laboratory-animal models, human subjects, and cells in vitro. Human studies are designed to examine the effects of nutritional factors on bone health of young adult women. Early reports have been on the relationship between dietary calcium intake and indices of bone health in late postmenopausal women. A study of female athletes at the University of North Carolina has shown that nearly all of the gain in bone mass occurs before 18 years of age. Current work focuses on the effects of estrogen-like isoflavones from soy on osteoblasts, especially the mechanism of action of genistein on bone cells. Support for these projects comes from a variety of sources. Dr Anderson is a member of the American Society of Nutritional Sciences, the American College of Nutrition, the American Society for Clinical Nutrition, the American Society for Bone and Mineral Research, and the International Bone and Mineral Society. Dr Anderson is on the editorial boards of several journals, and he is a past president of the American College of Nutrition. He continues to do some teaching, editing for journals, and manuscript writing.
Clifford J. Rosen, MD, is Senior Scientist, Maine Medical Center Research Institute, Scarborough, and Professor of Medicine, Tufts University School of Medicine, Boston, Massachusetts. He was a member of the 2011 Committee of the National Academy of Sciences which published the report on Dietary Reference Intakes: Calcium and Vitamin D. He is a prominent researcher in the bone field and he has been or continues to serve as an editor of several journals in the field.
The authors have no conflicts of interest to disclose.
Correspondence: John J. B. Anderson, PhD, Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27999 (email@example.com).