The dietary supplement industry is on the defensive again following an Agency for Healthcare Research and Quality expert panel’s opinion that evidence is insufficient to support vitamin D and calcium use for fracture prevention.

The U.S. Preventive Service Task Force released a meta-analysis of data Feb. 25, looking at whether available research supports an association between the use of vitamin D and calcium and fracture prevention.

The PSTF panel, chaired by Virginia Moyer from the Baylor College of Medicine, “concludes with moderate certainty that daily supplementation with 400 IU of vitamin D [cholecalciferol form] and 1,000 mg of calcium has no net benefit for the primary prevention of fractures” in postmenopausal women, according to the report.

Trials of vitamin D use alone or with calcium showed no statistically significant reduction in fractures, the panel found.

Trade groups are defending the use of the nutrients. “We know they’re effective,” said Council for Responsible Nutrition executive Taylor Wallace.

“Whether or not the numbers make sense when you crunch them through meta-analysis is one thing, but in practicality, calcium and vitamin D have their place,” said Wallace, CRN senior director for scientific and regulatory affairs.

The PSTF, which makes recommendations about clinical preventive services such as screenings, counseling services or preventive medications, concluded from its review of research that current evidence is insufficient to assess the balance of the benefit and harm of:

combined vitamin D and calcium supplementation for the primary prevention of fractures in premenopausal women or in men
daily supplementation with greater than 400 international units of vitamin D3 and greater than 1,000 mg of calcium for the primary prevention of fractures in postmenopausal women.

The 16-member panel of volunteers in the fields of preventive medicine and primary care, including internal medicine, family medicine, pediatrics, behavioral health, obstetrics/gynecology and nursing, also said that evidence does not support daily supplementation with 400 IU or less of vitamin D3 and 1,000 mg or less of calcium for the primary prevention of fractures in postmenopausal women.

According to the study published online in the Annals of Internal Medicine, the PSTF considered 16 randomized, controlled trials evaluating the use of vitamin D, with or without calcium supplementation, related to fracture prevention in adults, with a history of fractures in fewer than 26% of the subjects. Six of the studies evaluated use of vitamin D and calcium, the largest being the Women’s Health Initiative, which included 326,282 healthy, postmenopausal women ages 50 to 79.

Confusion Versus Illumination

CRN and the Natural Products Association assert that the PSTF’s conclusions could confuse consumers about the benefits of vitamin D and calcium supplementation.

“These nutrients have been shown to support bone health and it’s important that consumers get the recommended levels of both. If diet alone isn’t enough, then dietary supplements can help with getting these vital nutrients,” said Cara Welch, NPA senior VP scientific and regulatory affairs.

Supplement industry stakeholders often assert that some researchers studying whether vitamins and supplements have particular health benefits make recommendations that are contrary to the larger body of scientific evidence. They argue these studies are too focused narrowly and do not consider overall health benefits from supplementation.

Some argue that rather than limiting research on nutritional health claims to randomized controlled trials, researchers and regulators should consider measuring the physiological effects of nutrients in the body or accept a lower degree of certainty for related health benefit claims, given the low-risk profile of most nutrients Also see "Nutrition Scientists Float “Least-Harm Strategy” To Allow Health Claims" - Pink Sheet, 16 April, 2012..

Wallace said the PSTF’s review “heavily weighted” data from the WHI research, which contributed to what CRN considers an inaccurate conclusion. Subsequent to publishing their initial data on the WHI vitamin D/calcium study, the researchers released information that most of the women in the placebo group were calcium sufficient, an attribute that would skew a comparison to the control group subjects receiving daily supplementation of calcium and vitamin D.

“That would explain the null effects of the Women’s Health Initiative,” Wallace said.

“This is a very narrow set of recommendations based on just a few randomized, controlled trials that maybe weren’t the most appropriate sets of evidence to really look at this question,” he added.

Wallace also pointed out the PSTF recommendation conflicts with the Institute of Medicine’s 2010 report on vitamin D. IoM set a recommended daily dietary allowance of 600 IUs daily for ages 1 through 70 and 800 IUs for older people; and a calcium RDA of between 700 and 1,300 mg based on age and gender Also see "IoM Sets Vitamin D Intake Levels Below Experts' Expectations" - Pink Sheet, 6 December, 2010..

The PSTF report “undermines the very vast array of science out there,” he said.

However, the chairwoman of the panel that authored the IoM vitamin D report, nutrition expert Catherine Ross, says the PSTF report accurately reflects the information reviewed. PSTF “had a body of information to consider and used it,” said Ross, a professor of nutrition at Pennsylvania State University.

While a chance exists for consumer confusion stemming from the report, Ross said PSTF’s research is not intended to “advise the general population.”

“The public may be somewhat confused, as sometimes happens after nutritional studies are reported, but this is not the [PSTF's] concern. They reached a conclusion based on assessment of evidence and the public should be reassured by this recommendation,” she said.

“The public doesn't always understand well that postmenopausal osteoporosis is a multi-factorial endocrine disorder and not very responsive to nutritional supplementation with vitamin D or calcium. The [PSTF's] report may help to inform the public and improve understanding.”

Ross added that if the supplement industry wants standard-setting bodies to recognize a fracture reduction benefit for vitamin D and calcium, the association must be demonstrated.

“Industry can help fund well controlled studies, which if large will also be expensive. If well-designed, long-term studies show a benefit in the future, the standard-setting bodies will modify their recommendations,” she said.

But Wallace says long-term studies to show nutrients’ benefits in human health are problematic to conduct. Animal studies potentially could shed some light, he says.

“It’s very hard to study nutrients like calcium and vitamin D in humans. You can’t ethically deprive someone of calcium. I can’t do a bone snap test on a person to see how strong their bones are,” he said.

CRN recommends PSTF and other standard-setting panels consider evidence from animal studies, which can include “more rigorous tests” of attributes such as bone mineral density and strength.

PSTF acknowledged additional research is needed on vitamin D and calcium use and fracture prevention. In particular, the panel suggested research to:

determine whether daily supplementation with greater than 400 IU of cholecalciferol vitamin D and greater than 1,000 mg of calcium reduces fracture incidence in postmenopausal women or older men
compare the effectiveness of the cholecalciferol and ergocalciferol forms of vitamin D and of different calcium formulations
assess the potential benefits of vitamin D and calcium supplementation in early childhood on fracture incidence later in life
evaluate the effects of vitamin D supplementation on diverse populations.

AHRQ Vitamin D/Calcium Report Draws Industry Fire

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