|October 26, 2012|
Boosting calcium intake, especially from supplements, won’t improve bone mass, according to a study published online Oct. 15 in The Journal of Clinical Endocrinology & Metabolism (PDF).
John J.B. Anderson, PhD, nutrition professor emeritus at UNC Gillings School of Global Public Health, led the study, which assessed benefits of calcium intake on bone mineral density in elderly adults and determined that older adults would be better served by taking in calcium from foods.
Kathy Roggenkamp, MA, biostatistics instructor, and C.M. Suchindran, PhD, professor of biostatistics, co-authored the study.
Bone mineral density (BMD) naturally declines with age. Spine and hip fractures are particularly common as the body ages. Not only are such fractures painful experiences that impair daily functioning, but they incur enormous medical costs in repair and rehabilitation. Physicians and other health professionals long have recommended that older adults take calcium supplements to reduce risk of skeletal fractures. Too much calcium, however, may increase risk of renal stones and of heart and other cardiovascular diseases.
Anderson’s results confirm previous studies that have implied calcium intake above the recommended dietary allowance (RDA) offers little or no protection against common fractures and might not be worth the risk of incurring kidney stones or cardiovascular problems.
“As the bone density measurements of aging men and women naturally decline,” the authors wrote, “an increase in calcium consumption via supplements by health-conscious older individuals to try to counteract this downward trend is a questionable strategy for trying to improve bone density or to prevent fractures.”
Anderson and colleagues studied a total of 2,940 men and women ages 50 and older. They looked at femoral BMD in 1,556 participants and spinal BMD in the remaining 1,384 subjects, dividing them into two groups – 50- to 70-year-olds and those 71 and older. Each cohort was divided into three levels: no supplemental intake, supplement level below or equal to the subgroup median and supplement level above the subgroup median.
The National Health and Nutrition Examination Survey of the Centers for Disease Control and Prevention collected the dietary information by twice asking subjects for a 24-hour dietary recall, first in person, followed up with a telephone call. The interviews revealed that a high percentage of older adults do not meet their RDA of calcium from diet alone. Many miss the mark despite taking supplements.
The study revealed no significant differences in BMD for men and women in the 50- to 70-year-old age group. In the group of people 71 and older, results were mixed.
The finding that calcium supplements had practically no impact on bone density in older adults raises concerns about the benefit of consuming the supplements. The extra calcium does not appear to be absorbed by bone. It might be excreted through the urine instead, potentially contributing to kidney stones, or it might attach to atherosclerotic plaques in arteries or heart valves.”Health professionals’ advice regarding calcium may need to be modified,” Anderson concluded.