Panel Doubts Benefit of Low-Dose Vitamin D and Calcium

After reviewing recent scientific data, the U.S. Preventive Services Task Force (USPSTF), a federally appointed panel of primary care providers, has recommended against the use of low-dose vitamin D and calcium supplements-specifically for protection against osteoporosis-related fractures and cancers.

A brief fact sheet of this draft recommendation is available to download here.

The panel reviewed 16 randomized controlled trials on vitamin D (with or without calcium) and fracture incidence, with vitamin D doses ranging from 300 IU to 1370 IU.

The IOM currently recommends that adults consume 600 to 800 IU of vitamin D and at least 1000 mg of calcium daily.

“In postmenopausal women, there is adequate evidence that daily supplementation with 400 IU of vitamin D3 combined with 1000 mg of calcium carbonate has no effect on the incidence of osteoporotic fractures,” the panel concluded. “However, there is inadequate evidence regarding the effect of higher doses of combined vitamin D and calcium supplementation on fracture incidence in postmenopausal women.”

The Task Force also concluded that there is adequate evidence that supplementing with 400 IU of vitamin D3 or greater and 1000 mg of calcium carbonate may increase one’s risk of developing kidney stones.

The notion that vitamin D and calcium may reduce fracture risk-in high doses-hasn’t been discounted in this recent review of the science. But a finding on kidney stone formation may raise some doubt as to the form in which consumers take in calcium.

In its assessment of the two nutrients for potential cancer risk reduction, the USPSTF used three large-scale human clinical trials to conclude that inadequate evidence was available to support an association.

Nutritional Outlook will report more on this story as experts become available.

Update:

The Council for Responsible Nutrition (CRN; Washington, DC) has responded to the USPSTF review, pointing out that government backing for increasing vitamin D and calcium intake is still strong. As recently as 2010, the IOM increased the recommended dietary intake levels for both nutrients.

CRN also takes issue with the Task Force’s decision to exclude available observational data on vitamin D and calcium which, when included in a December 2011 meta-analysis by the same panel, supported a conclusion that vitamin D was effective in reducing the risk of cancer and fractures in older adults.

CRN also says that the Task Force’s findings are largely based on data from the Women’s Health Initiative-a project that has been criticized for its weaknesses and which was also so big in size that it significantly influences the data in any meta-review its included in.

As for calcium and kidney stone risks, CRN says the jury is still out. “As you get closer to the [U.S. adult’s] upper intake level of calcium, you may see a higher incidence of kidney stones, whether that’s from dietary calcium or calcium supplements,” said CRN director of scientific and regulatory affairs Taylor Wallace, PhD, in an interview with Nutritional Outlook. “It’s hard top pin-point it to the form of calcium, and the benefits of calcium far outweigh the risk of developing a kidney stone.”