- freely available
Nutrients 2010, 2(10), 1044-1047; doi:10.3390/nu2101044
Abstract: Interest in calcium has continued since the 1980s when its role in promoting bone growth and retention was established in clinical trials of children and postmenopausal women. The human nutrition functions now attributed to calcium have expanded beyond bone health to include other conditions such as body weight maintenance. While most efforts have been focused on the findings that dietary intakes are low, there are emerging data on safety concerns of excess amounts. This Special Issue on calcium nutrition, spanning the lifecycle from critically ill neonates through to older adults, has been written by some of the leading researchers in this field.
Interest in calcium has continued since the 1980s when its role in promoting bone growth and retention was established in clinical trials of children and postmenopausal women. These studies helped establish recommended intake levels for calcium in many countries including Canada and the United States . Professional societies, mainly those in osteoporosis [2,3] and related areas  have set calcium recommendations as well. Since that time new functions have been proposed for dietary calcium, including a role in preventing body weight gain and/or promoting body weight loss, a theory that has come into its own in the past decade [5,6]. Much interest has focused on calcium intakes; using current recommended cut-offs , a high percentage of the population have inadequate intakes, even in countries where dairy consumption is encouraged [7,8]. There has been, however, concern about the safety of high doses , and setting an upper intake level (UL) for calcium intake by the Institute of Medicine in 1997  seemed to have lain this to rest. However, recent findings indicating that calcium may be linked to cardiovascular disease  have prompted a new examination of this issue.
Thus the ongoing issues and concerns related to calcium prompted the journal Nutrients to have a special issue on calcium wherein distinguished calcium researchers were invited to submit recent works or review articles on calcium. The individual articles are now all published and represent a body of work that should be useful for the nutrition community, whether scientists or practitioners, to source up-to-date information on the topics most pertinent to calcium. These papers cover calcium through the lifespan, from infancy [11,12], childhood and adolescence [12,13] and college-age subjects  though to older adults [15,16] or include issues relevant to every age group [17,18].
2. Overview of Topics in Special Issue on Calcium
Topics that are presented are related to ensuring adequate calcium intake for bone health [11,12,13,14,15,16], wherein in some of these papers bioavailability is a critical issue [11,12,16]. For infants, the nature of the tube feeding protocol as well as the type of nourishment for critically ill neonates was examined by Rogers et al.  who found human milk fortified with donor milk-based fortifier was the infant food with the least detrimental effect on calcium losses. In a review on calcium absorption by infants and children, Abrams  explains how stable-isotope based studies are the method of choice for measuring calcium absorption. For older adults, this method has been applied to a comparison of calcium supplements for postmenopausal women at risk for osteoporosis  to show the higher availability of an algal-based calcium supplement over the widely used calcium carbonate salt. Assessing calcium status in postmenopausal women, along with other bone-related nutrients such as vitamin D, and vitamin K, may be achieved through a food frequency questionnaire .
Research on whether calcium plays a role in body weight maintenance is included in this issue. Tylavsky et al.  present new data on the role of calcium intake on body composition in African-American children at risk for overweight/obesity. Soares and She-Ping-Delfos  review the literature on postprandial energy metabolism, and provide evidence that higher calcium intakes may affect energy metabolism through excretion of fecal fat.
Calcium intakes are often low. In college-age women, which is a group known to have lower than recommended calcium intakes, Douglas et al.  examine calcium intakes of students in the United States and in Croatia. Studies of children, adolescents  and young adults  in this issue provide estimates of calcium intake. In order to readily assess intakes, Pritchard et al.  provide information on development of a food frequency questionnaire that assesses calcium as well as other bone-related nutrients.
Safety of calcium is addressed by Daly and Ebeling . This timely review provides an overview of the health effects of the use of calcium supplements. There may be both risks and benefits of higher levels of supplementation but these authors indicate that moderate calcium intake, that achieved through diet and supplementation when necessary, is the best course of action.
In conclusion, topics on calcium nutrition, spanning the lifecycle from critically ill neonates through to older adults at risk for osteoporosis and written by some of the leading researchers in fields related to this nutrient, are included in the Special Issue on Calcium.
As Guest Editor I wish to thank not only the authors for accepting the invitation to write a paper for this Special Issue, but also the reviewers who provided comments. The editorial assistance of Leo Jiang and Alicia Li was invaluable.
- Standing Committee on the Scientific Evaluation of Dietary Reference Intakes; Food and Nutrition Board; Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D and Fluoride; National Academies Press: Washington, DC, USA, 1997.
- Brown, J.P.; Josse, R.G. Clinical Practice Guidelines for the Management of Osteoporosis in Canada. Can. Med. Assoc. J. 2002, 167 (Suppl. 10), S1–S34.
- Dawson-Hughes, B. National Osteoporosis Foundation Guide Committee. A Revised Clinician’s Guide to the Prevention and Treatment of Osteoporosis. Clin. Endocrinol. Metab. 2008, 93, 2463–2465, doi:10.1210/jc.2008-0926.
- SOGC. Canadian Consensus on Menopause, 2006 Update. J. Obstet. Gynaecol. Can. 2006, 28, S7–S94. 16626522
- Zemel, M.B.; Shi, H.; Greer, B.; DiRienzo, D.; Zemel, P.C. Regulation of Adiposity by Dietary Calcium. FASEB J. 2000, 14, 1132–1138. 10834935
- Zemel, M.B. Proposed Role of Calcium and Dairy Food Components in Weight Management and Metabolic Health. Phys. Sportsmed. 2009, 37, 29–39. 20058398
- Bailey, R.L.; Dodd, K.W.; Goldman, J.A.; Gahche, J.J.; Dwyer, J.T.; Moshfegh, A.J.; Sempos, C.T.; Picciano, M.F. Estimation of Total Usual Calcium and Vitamin D Intakes in the United States. J. Nutr. 2010, 140, 817–822, doi:10.3945/jn.109.118539. 20181782
- Vatanparast, H.; Dolega-Cieszowski, J.; Whiting, S.J. Adult Canadians Are Not Meeting Current Calcium Recommendations from Food and Supplement Intake. Appl. Physiol. Nutr. Metab. 2009, 34, 191–196, doi:10.1139/H09-005. 19370049
- Whiting, S.J.; Wood, R.J. Adverse Effects of High-Calcium Diets in Humans. Nutr. Rev. 1997, 55, 1–9. 9155211
- Bolland, M.J.; Avenell, A.; Baron, J.A.; Grey, A.; MacLennan, G.S.; Gamble, G.D.; Reid, I.R. Effect of Calcium Supplements on Risk of Myocardial Infarction and Cardiovascular Events: Meta-Analysis. Br. Med. J. 2010, 341, c3691, doi:10.1136/bmj.c3691.
- Rogers, S.P.; Hicks, P.D.; Hamzo, M.; Veit, L.E.; Abrams, S.A. Continuous Feedings of Fortified Human Milk Lead to Nutrient Losses of Fat, Calcium and Phosphorous. Nutrients 2010, 2, 230–240, doi:10.3390/nu2030240. 22254018
- Abrams, S.A. Calcium Absorption in Infants and Small Children: Methods of Determination and Recent Findings. Nutrients 2010, 2, 474–480, doi:10.3390/nu2040474. 22254034
- Tylavsky, F.A.; Cowan, P.A.; Hencyk, S.; Hutson, M.; Velasquez-Mieyer, P. Calcium Intake and Body Composition in African-American Children and Adolescents at Risk for Overweight and Obesity. Nutrients 2010, 2, 950–964, doi:10.3390/nu2090950. 22254064
- Douglas, C.C.; Rumbak, I.; Colić Barić, I.; Kovačina, M.; Piasek, M.; Ilich, J.Z. Are New Generations of Female College-Student Populations Meeting Calcium Requirements: Comparison of American and Croatian Female Students. Nutrients 2010, 2, 599–610, doi:10.3390/nu2060599. 22254044
- Pritchard, J.M.; Seechurn, T.; Atkinson, S.A. A Food Frequency Questionnaire for the Assessment of Calcium, Vitamin D and Vitamin K: A Pilot Validation Study. Nutrients 2010, 2, 805–819, doi:10.3390/nu2080805. 22254057
- Uenishi, K.; Fujita, T.; Ishida, H.; Fujii, Y.; Ohue, M.; Kaji, H.; Hirai, M.; Abrams, S.A. Fractional Absorption of Active Absorbable Algal Calcium (AAACa) and Calcium Carbonate Measured by a Dual Stable-Isotope Method. Nutrients 2010, 2, 752–761, doi:10.3390/nu2070752. 22254052
- Soares, M.J.; Chan She-Ping-Delfos, W.L. Postprandial Energy Metabolism in the Regulation of Body Weight: Is there a Mechanistic Role for Dietary Calcium? Nutrients 2010, 2, 586–598, doi:10.3390/nu2060586.
- Daly, R.M.; Ebeling, P.R. Is Excess Calcium Harmful to Health? Nutrients 2010, 2, 505–522, doi:10.3390/nu2050505.
© 2010 by the authors; licensee MDPI, Basel, Switzerland This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).