Casting doubt on calcium and vitamin D

New study says supplements may not protect older adults against bone breaks, fractures

One of the most contentious questions in nutrition science over the past decade has been whether older adults should be taking supplemental vitamin D and calcium. As the world’s population ages and broken bones and fractures become even more of a public health concern, with huge social and economic consequences, researchers have been trying to make sense of conflicting studies on the association between supplements and fracture risk.

A study published in the Journal of the American Medical Association on Tuesday took a fresh look at this issue by analyzing 33 randomized clinical trials involving a total of more than 50,000 adults over the age of 50. Each of these previous research papers involved comparing calcium, vitamin D or both with a placebo or no treatment. The analysis, conducted by Jia-Guo Zhao of Tianjin Hospital in China, was focused on older adults who live in the general community and did not include those in nursing homes, hospitals and other facilities.

The conclusion was clear: Vitamin D and calcium supplements do not seem to be warranted to prevent bone breaks or hip fractures in those adults. Such supplements had no clear benefit regardless of dose, the gender of the patient, history of fractures or the amount of calcium in the diet.

The U.S. Preventive Services Task Force (UPSTF), an influential federal advisory body, has raised questions about these supplements since 2013, when it issued recommendations saying evidence to support the benefit of the supplements in older adults without osteoporosis or vitamin D deficiency was “insufficient.”

Marion Nestle, a professor emerita of food sciences and nutrition at New York University, wrote in an opinion piece at that time that the UPSTF’s statement should caution clinicians “to think carefully before advising calcium and vitamin D supplementation for healthy individuals.”

She said this weak bone health involves many different aspects of eating and activity. “Bone preservation throughout life requires eating healthfully, engaging in weightbearing activity, avoiding excessive alcohol and not smoking — good advice for everyone,” Nestle said.

Vitamin D is not a vitamin but a hormone that is produced in reaction to sunlight and seems to have many different roles in the body related to bones, cancer, heart disease, diabetes, immune function and re- productive health.

Daniel Fabricant, president of the Natural Products Association, which represents manufacturers and retailers of dietary supplements, said the study draws its conclusions with “too broad of a brush.” He said it focuses on the healthiest segment of the population by looking at people who are able to live at home.

Calcium and vitamin D have been known to be important to bone maintenance for a long time, and the best ways to get the daily recommended doses are the natural way. For calcium, that means eating dairy products such as milk, cheese, yogurt or calcium-rich leafy greens. For vitamin D, that means getting some sun exposure. Only a few foods contain vitamin D, and they include fatty fish like salmon.

The issue is many Americans don’t get enough calcium or vitamin D — which is why the debate over supplements has become so important. In 2010, the Institute of Medicine released recommendations tripling the daily intake of vitamin D for most people to 600 IU per day and raising the calcium intake to 1,000 milligrams. While that report has few explicit mentions of supplements, the use of supplements seems assumed, and it includes a lot of discussion about the importance of setting and following upper limits for intake of vitamin D and calcium.