Remember that old Johnny Cash song, “I Walk the Line”?
That’s what I feel like some days, when I’m trying to balance what the government currently says about vitamin D (I should be getting 400IU daily); against what my doctor says (I should be getting 1,000IU daily); against what some nutritionists and researchers are espousing: 2,000IU (or more) daily.
Now, THAT’S a lot of very different answers to what seems like a pretty simple question!
Why the disparity among sources?
Let’s look at those government guidelines. The last time recommended intake values for vitamin D were established was in 1997. These DRIs (Dietary Reference Intakes) are determined by The Institute of Medicine of the National Academies, which is responsible for coming up with dietary recommendations for over 40 vitamins, minerals, and macronutrients – values based on age, gender, and life stage.
These are the folks that figure out the fine print on the side of your vitamin jar. They’re the reason General Mills can market Total cereal as meeting “100% of your daily calcium requirement.”
Since 1997, though, it’s become increasingly clear that Americans simply don’t get enough vitamin D. Recent studies indicate that from 40% to 75% of Americans are vitamin D-deficient (depending on ethnicity, and the type of study).
And, since a lack of vitamin D is increasingly linked not only to osteoporosis, but to heart disease, diabetes, and cancer – to say nothing of the common cold – it would seem critical that we all be getting what we need.
Which brings us back to where we started: How much vitamin D DO we need?
One of the regular contributors to this site, Priya Nath Mehta (“Nathji”), posted an interesting article, ”Risk Assessment for Vitamin D,” taken from the January, 2007 American Journal of Clinical Nutrition. The article summarized the findings of a group of experts who reviewed the pooled results of 21 clinical trials examining dosage levels of vitamin D. These experts concluded that upper limits for vitamin D could be raised to 10,000IU a day.
(It should be noted that the experts quoted included some from the Washington, D.C.-based Council for Responsible Nutrition, one of the dietary supplement industry's leading trade associations.)
10,000IU daily! That’s a far cry from the current recommended 400IU.
So, who to believe? I absolutely want to get the full benefit of vitamin D. If it helps prevent heart disease, diabetes, osteoporosis, and cancer (been there, done that), I’m all for it. While sunshine was always thought to be a good source of vitamin D, dermatologists are now telling us that the risk of skin cancer trumps that benefit; we need to rely on supplements.
Thankfully, we may gain greater clarity on this subject next May, when the government releases its new dietary guidelines. Endocrinologists advising the Institute of Medicine have reportedly discussed recommended daily levels of 1,000IU to 2,000IU.
Till then, I’ll keep shooting for my doctor’s recommendation of 1,000IU via supplements. Plus I’ll tack on an additional few hundred IUs courtesy of dairy products and fortified cereal, ending up somewhere between 1,000-2,000IUs daily.
As I said at the start – I walk the line.
Published On: September 23, 2009