Experts: Evidence for Vitamin D, calcium supplements lacking

Experts: Evidence for Vitamin D, calcium supplements lacking

POSTED: Wednesday, February 27, 2013 - 11:00am

UPDATED: Wednesday, February 27, 2013 - 11:04am

You've seen it added to cereal boxes, gallons of milk and bottles of orange juice. Experts tout its benefits -- from strong bones to a strong immune system -- and warn of the dangers of Vitamin D deficiency.

The public relations push is working; between 2002 and 2011, sales of vitamin D supplements increased from $42 million to $605 million, according to the Nutrition Business Journal.

New recommendations from the U.S. Preventative Services Task Force could bump those sales even higher, or -- if critics are right -- confuse consumers as they head down the pharmacy aisle.

After completing a review of existing research, the USPSTF, an independent panel of doctors and experts in prevention and evidence-based medicine, is advising against taking moderate amounts of Vitamin D and calcium supplements because there is not enough evidence to prove the supplements reduce the risk of bone fractures.

More specifically, the USPSTF is recommending against supplements of Vitamin D in daily doses of less than 400 IU (international units), and calcium in daily doses of less than 1,000 milligrams for post-menopausal women.

Doctors currently recommend these supplements for women to prevent fractures; approximately 56 percent of women aged 60 years and older take supplemental vitamin D, and 60 percent take a supplement containing calcium, according to the USPSTF report. The report was published in this week's edition of the Annals of Internal Medicine journal.

The task force found evidence that Vitamin D and calcium supplements increase the risk of developing kidney stones in this population, and insufficient evidence to show that the supplements reduce the risk of fractures.

Basically it boils down to this: "Don't take modest doses, they don't do any good," says Dr. Virginia Moyer, chair of the USPSTF.

More research is needed, Moyer says, to determine whether higher doses of Vitamin D or calcium would prevent fractures in older men or women. She says the task force will be looking in the future at whether doctors should be screening for Vitamin D deficiencies.

The USPSTF's recommendations don't apply to those who are prone to falling, according to the report, or those who have a history of fractures, a documented Vitamin D deficiency or a diagnosis of osteoporosis.

Vitamin D is not actually a vitamin, according to nutrition experts Marion Nestle and Malden C. Nesheim; it's a hormone produced by the body in reaction to sunlight.

"Like other hormones, vitamin D has multiple roles in the body, not all of them well-understood," the experts wrote in an editorial about the USPSTF recommendations. As such, Vitamin D supplements must be considered a form of hormone replacement therapy, they wrote, and be subjected to similar probes about efficacy, dose and side effects.

As we've seen with recommendations from this group in the past (think prostate or cervical cancer screenings), there are those that disagree with the task force's conclusion.

"These recommendations fail to recognize the well-established role of calcium and vitamin D in maintaining bone health," the Council for Responsible Nutrition said in a statement. "If these recommendations are taken to heart, or misconstrued as general recommendations against calcium and vitamin D, consumers could be compromising their bone health and missing out on important other benefits from these nutrients.

"The bottom line: calcium and vitamin D are vital to staying healthy."

The Centers for Disease Control and Prevention says African-Americans have the highest rates of Vitamin D deficiency -- along with the highest bone density and fewest fractures. Approximately 12 percent of Mexican-Americans are deficient, while only 3 percent of non-Hispanic whites are at risk.

The Institute of Medicine recommends adults get at least 800 to 1000 mg of calcium daily, depending on their age, and at least 400 IU of Vitamin D. Adults can safely absorb up to 2,500 mg of calcium and 4,000 IU of Vitamin D.

Calcium is most commonly found in dairy products like milk, cheese and yogurt, but it's also available in green leafy vegetables like spinach and kale. Vitamin D is crucial for helping your body absorb calcium, which is why the nutrients are often talked about together. Vitamin D can be found in fatty fish or fortified foods like cereal and orange juice. It's also found in sun rays, where it's absorbed through the skin. 

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