Despite 91%* jump in sales, experts cautious about “benefits” of high levels
(COLUMBUS, Ohio) – It is one of the hottest supplements on the market.* Between August 2009 and 2010 sales of vitamin D shot up a staggering 91%* - and for good reason. Good levels of vitamin D have been linked to everything from building stronger bones to reducing your risk of certain types of cancer.
But exactly what is a “good level”? And just how much vitamin D and calcium should we be getting on a daily basis? Those are questions that some experts say have gone unanswered for too long.
“The last time that vitamin D and calcium nutritional requirements were assessed was almost 15 years ago” says Dr. Steven K. Clinton, director of the Prostate and Genitourinary Oncology Clinic at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute.
So Clinton, and 13 other experts from the US and Canada set out to change that. Selected by the Institute of Medicine/National Academy of Sciences, the team was asked to review volumes of research on vitamin D and calcium, and establish more up-to-date recommendations for daily intake.
“The last time vitamin D and calcium was assessed was back in 1997. Since then, there have literally been thousands of publications in the scientific literature” said Clinton. “The explosion in research suggested that it was time to reassess these requirements.”
For months, Clinton and his colleagues pored over thousands of studies on vitamin D and calcium, looking into its role in everything from heart health to cancer prevention. What they found answered some questions, but raised even more.
“It turned out that the only outcome where the research was sufficient and compelling, was in bone health” said Clinton, which isn’t surprising. For decades doctors have known that calcium and vitamin D could strengthen bones, particularly in certain age groups that need it most, like adolescents and older women.
But what about the link between vitamin D and it’s role in things like cancer and heart disease? “One should not conclude that vitamin D has no relationship to these outcomes, because, indeed, the research is exciting and compelling” said Clinton. “But - we lack dose-response data that is going to tell us the optimum level of intake. We really need a great deal of additional human research, particularly, with different doses of vitamin D.”
In other words, vitamin D may, indeed, play a role in other disease processes in the body. However, nothing has been definitively proven and, more importantly, doctors can’t say yet with any certainty how much vitamin D and calcium we need on a daily basis to protect ourselves from those other diseases.
With that in mind, the panel of experts did revise their recommendations for daily intake, suggesting that people from ages 1 to 70 get 600 international units (IU) per day and those over age 71 should get 800 IU. No one should get more than 4,000.
What does that mean? Basically, a couple of glasses of milk or juice fortified with vitamin D and about 15 minutes a day in the sun, provides most of us all the vitamin D we need. Vitamin D is unique, in that our bodies make it when exposed to sunlight. So, dietary intake and supplements, especially, aren’t as crucial as with other vitamins.
The idea of “more is better” doesn’t apply in this case and, in fact, could be dangerous. “As higher levels of vitamin D come into play, you’re beginning to see an increase in risk for toxicity” said Clinton. Too much vitamin D and calcium can lead to everything from heart rhythm problems to kidney stones.
“We thought that ultimately choosing a level of 4,000 was one that gave a margin of safety for public health recommendations” he added.
Still, there are instances where vitamin D supplements may be helpful. Len Fisher, for example, is battling prostate cancer and even though he runs outdoors every day for hours at a time, his doctor saw a need for supplements.
“As part of a routine blood test he found I was just a little bit low on my vitamin D levels, so now I’m taking two thousand units of vitamin D a day” said Fisher.
For most of us, experts say we should check with our doctors before adding any supplements to our diets. “Each individual has to be looked at as a unique case” said Clinton. “The amount of vitamin D that they should consume should be tailored or personalized to their own needs.”
**Vitamin D Sales, SPINS, Inc. 2010. From industry research article, combining US-F,M,D and Natural Channel markets, August 2009-2010. Online at: http://newhope360.com/vitamins/vitamin-d-sales-soar-91-its-not-all-smooth-sailing
**Dietary Reference Intakes for Calcium and Vitamin D, Institute of Medicine of The National Academies, November 2010. Online at: http://www.iom.edu/~/media/Files/Report%20Files/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Vitamin%20D%20and%20Calcium%202010%20Report%20Brief.pdf