Millions may be taking vitamin D unnecessarily, analysis suggests

October 24, 2012 by Serena Gordon, Healthday Reporter
Millions may be taking vitamin D unnecessarily, analysis suggests
Health experts disagree on safe levels needed to prevent illness.

(HealthDay)—Under the latest guidelines from the Institute of Medicine, it's possible that almost 80 million Americans who've previously been considered as having low levels of vitamin D don't need supplements of this nutrient at all, according to a new study.

Older guidelines had suggested that anyone with a blood level of that was less than 30 per milliliter (ng/mL) needed to boost their levels, but the newer Institute of Medicine (IOM) guidelines say that a minimum level of 20 ng/mL is sufficient.

However, not all experts agree with the new guidelines from the IOM, a nonprofit American organization that dispenses health advice.

"The IOM guidelines are so different than the Endocrine Society's guidelines that this study will just add to the controversy," said lead study author Dr. Holly Kramer, an associate professor of medicine at Loyola University Medical Center in Maywood, Ill. "We really need clinical trials to settle the whole issue, but what's clear is that these threshold levels make a huge difference in how many people would be taking vitamin D."

The Endocrine Society is an international group of endocrinologists.

Why worry about your vitamin D intake? Vitamin D is essential for good , and it's necessary to prevent the disease known as rickets. The nutrient has also been implicated as potentially beneficial for a number of conditions. Low levels of vitamin D have been associated with higher risks of some , and may make people more susceptible to infection.

In addition, noted Dr. Robert Heaney, a professor of medicine at Creighton University in Omaha, Neb., low vitamin D has also been associated with , and the —a group of symptoms that signal higher risk for diabetes and heart disease.

Heaney is a member of the Endocrine Society's task force on vitamin D guidelines.

"Vitamin D is necessary in most cells in our body, probably all cells," Heaney said. "When you have adequate vitamin D, all of the body's systems tend to work well." But, "there is no consensus on what normal levels are in the field of nutrition," he added.

For the current study, Kramer and her colleagues reviewed data on more than 15,000 adults from the third U.S. National Health and Nutrition Examination Survey and linked that information to 18 years of information from the National Death Index to determine if vitamin D had an effect on mortality rates.

The researchers found that in people with impaired kidney function, about 35 percent had vitamin D levels below 20 ng/mL. In people with healthy kidneys, about 30 percent had levels below 20 ng/mL, according to the study.

But for the older, higher vitamin D threshold, 76.5 percent of people with impaired kidney function would be considered to have low levels of vitamin D, as would 70.5 percent of people with healthy kidneys.

"Even under the new guidelines, there are still a fair number of people who are considered deficient or insufficient," Kramer said.

There was a big difference in mortality rates for those who had the lowest levels of vitamin D—less than 12 ng/mL —compared to those with levels between 24 and 30 ng/mL. But after that, Kramer said, there wasn't much difference in mortality between the groups.

Heaney also noted how findings varied according to vitamin D levels.

He said that while there wasn't a huge effect from group to group depending on vitamin D levels, there was "a continuing downward trend" with less mortality as vitamin D levels went up.

So where does that leave people trying to decide whether to take the supplements?

Kramer said that right now the decision may depend on your personal situation, and suggested talking to your doctor about whether extra vitamin D is necessary for you. People with certain medical conditions need to be on vitamin D. But, she said that others are taking supplements who don't need to and that it's just a waste of their money.

For his part, Heaney noted that taking vitamin D and other nutrients may be akin to changing the oil in your car. "If you don't change the oil, your car runs well now, but it may break down sooner," he said.

In terms of side effects, Kramer said, too much vitamin D can increase the risk of kidney stones, but in general, it's a well-tolerated supplement. The upper safe limit for daily intake is 4,000 international units, according to the U.S. Office of Dietary Supplements, though most people take a much lower dose.

Results of Kramer's study are published in the Oct. 24 issue of the journal PLoS ONE.

Explore further: Low vitamin D levels linked to weight gain in some older women

More information: To learn more about vitamin D, visit the U.S. government's Office of Dietary Supplements.

Related Stories

Low vitamin D levels linked to weight gain in some older women

June 25, 2012
Older women with insufficient levels of Vitamin D gained more weight than those with sufficient levels of the vitamin, according to a new study funded by the National Institutes of Health and published online in the Journal ...

Low levels of vitamin D are associated with mortality in older adults

October 2, 2012
Low levels of vitamin D and high levels of parathyroid hormone are associated with increased mortality in African American and Caucasian older adults, according to a new study accepted for publication in The Endocrine Society's ...

Vitamin D deficiency high among trauma patients

February 7, 2012
New research presented at the 2012 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) found that 77 percent of trauma patients had deficient or insufficient levels of vitamin D.

Low vitamin D levels are related to decreased response to osteoporosis medicine

June 6, 2011
Women with low bone density are seven times more likely to benefit from a bisphosphonate drug when their vitamin D blood levels are above recent recommendations from the Institute of Medicine (IOM) as adequate for bone health. ...

Low vitamin D level is linked to greater chance of risk factors for Type 2 diabetes

June 25, 2012
A new study presents more evidence of a possible link between low vitamin D levels and a higher risk of Type 2 diabetes and heart disease. The results to be presented at The Endocrine Society's 94th Annual Meeting in Houston.

Recommended for you

Warning labels can help reduce soda consumption and obesity, new study suggests

December 15, 2017
Labels that warn people about the risks of drinking soda and other sugar-sweetened beverages can lower obesity and overweight prevalence, suggests a new Johns Hopkins Bloomberg School of Public Health study.

Office work can be a pain in the neck

December 15, 2017
Neck pain is a common condition among office workers, but regular workplace exercises can prevent and reduce it, a University of Queensland study has found.

Regular takeaways linked to kids' heart disease and diabetes risk factors

December 14, 2017
Kids who regularly eat take-away meals may be boosting their risk factors for heart disease and diabetes, suggests research published online in the Archives of Disease in Childhood.

Simulation model finds Cure Violence program and targeted policing curb urban violence

December 14, 2017
When communities and police work together to deter urban violence, they can achieve better outcomes with fewer resources than when each works in isolation, a simulation model created by researchers at the UC Davis Violence ...

One in five patients report discrimination in health care

December 14, 2017
Almost one in five older patients with a chronic disease reported experiencing health care discrimination of one type or another in a large national survey that asked about their daily experiences of discrimination between ...

Your pets can't put your aging on 'paws'

December 14, 2017
(HealthDay)—In a finding that's sure to ruffle some fur and feathers, scientists report that having a pet doesn't fend off age-related declines in physical or mental health.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.