Studies linking vitamin D supplements to a reduction in bone fractures have been all over the map, leading to confusion in the general public. Does a daily vitamin D pill help keep bones strong… or not? A new study, released last month, may explain why previous data has been so inconsistent; and comes up with a definitive answer.
In recent years, we’ve heard more and more about vitamin D and its role as “wonder drug,” linked to prevention of everything from cancer and diabetes to cardiac disease and autoimmune conditions.
Now, if this simple vitamin truly did prevent the host of diseases its proponents claim, we’d all be taking it, no questions asked. Vitamin D supplementation of packaged foods would probably become a government mandate – just as iodine was added to salt beginning in the 1920s, to help prevent goiter.
The problem is, there SEEMS to be a connection between vitamin D and cancer, vitamin D and heart attacks, vitamin D and diabetes… but thus far, researchers have been unable to definitively prove just what that connection is.
So the studies continue.
Which is the case with a new study examining the relationship between vitamin D and bone fractures, published last month in the New England Journal of Medicine.
This most recent study is a “meta-analysis” – meaning it didn’t develop a hypothesis, recruit participants, run a test, then study the results.
Instead, researchers examined results of 12 earlier studies involving over 30,000 participants, looking for any common threads. Meta-analysis is a common type of study, as it can bring together data from researchers all over the world, looking at it with a new, broader perspective – fresh eyes, as it were.
The result? Researchers are cautiously concluding that daily vitamin D supplementation of 800IU or more reduces hip fractures by 30%, and other bone fractures by 14%, in women age 65 or older.
And why the caution? Because the study did have its limits. For instance, researchers couldn’t link the positive results to vitamin D alone, as the study subjects taking 800IUor more of vitamin D were also taking calcium supplements.
Also, the majority of participants hadn’t had their baseline vitamin D level established prior to participating in the study – though the study authors point out that results for those with or without a baseline vitamin D reading were similar.
And how does this study help explain seemingly conflicting results in previous studies linking vitamin D with bone fracture prevention?
This newest study bases its conclusion on participants consistently taking a minimum of 800IU vitamin D daily. Many earlier studies tested much lower levels of vitamin D intake; and based results on the level of vitamin D the subject was SUPPOSED to take, not what was actually taken.
In other words, some study participants may have increased their assigned 200IU by doubling their daily dose; while some may have failed to take their assigned dose every day.
For those with a scientific bent, “actual intake [was] calculated as the assigned dose plus any additional supplemental dose; adjusted for adherence.” (Smith, 2012)
“All of the problems with previous studies come from a very modest dose of vitamin D,” notes Dr Robert P. Heaney, M.D., in an editorial accompanying the study in the NEJM. “If you don’t give [study subjects] enough of the vitamin D, then you won’t see an effect.” (Vitamin D, 2012)
Heaney added, “It would appear to be prudent, and probably helpful as well, to ensure an intake at the upper end of the range” (Smith, 2012) – in other words, 800IU.
Are you a 65-year-old (or older) woman? You might consider supplementing your vitamin D intake, via diet and sunshine, with a daily 800IU vitamin D supplement. There’s a good chance you’ll lower your risk of bone fractures – particularly a devastating hip fracture, something we all want to avoid.
Smith, M. (2012, July 05). high dose vitamin d prevents fractures. Retrieved from http://www.medpagetoday.com/PrimaryCare/DietNutrition/33612
Vitamin d in high doses may prevent fractures. (2012, July 5). Retrieved from http://www.cbc.ca/news/health/story/2012/07/05/vitamin-d-fracture-prevention.html
Published On: August 08, 2012