Filed under: General Health
I recently wrote a blog refuting the recent IOM report on vitamin D, because I believe, along with the leading vitamin D researchers, that the report was off-base and gave poor recommendations.
This belief caused a reader to issue a response to my blog in the comment section. I thought his comment, and my response, needed to be seen by those of you who don’t read the comments section of past blog posts! It is long and in-depth, but enjoy!
Let me first say I agree D3 is a worthwhile supplement to take on a daily basis, and I have no vested (i.e., career) interest in whether the recommended intake of D3 increases or decreases. I am simply a methodologist/statistician who thoroughly understands the methodological shortcomings of this literature. I have served as lead statistician on numerous studies out of endocrinology (among many other areas and disciplines) and simply let the numbers do the talking! What is provided below is my honest, unbiased methodologist’s view of the D3 literature.
With that said, I purchased your supplemental Nutrition Guide with Eric’s Show & Go that was filled with great information, but I cringed when you stated you can safely have serum 25(OH)D of 50-80ng/mL. You not only have an incredibly high range, but your language indicates individuals should be on the high end of this range. You even go so far as to insinuate a reader with serum 25(OH)D of 20ng/mL could never get into your recommended range without ingesting an unsafe dosage of D3.
Nevertheless, I digress. I believe you should reconsider your quick critique of the review article describing the Institute of Medicine’s (IOM) daily D3 recommendations, and, further, reconsider your own recommendations to your clients and readers! The IOM recommended an optimal serum 25(OH)D of 20ng/mL. This recommendation was not only to maximize protection to the public, but was based heavily on the consistently emerging body of literature suggesting the benefits of increasing D3 intake plateau with serum 25(OH)D around 20ng/mL. Thus, there is absolutely no reason to increase dosage to increase serum 25(OH)D if no additional benefit is observed. The IOM go on stating individuals can safely ingest to 4000IUs of D3 daily; however, this is the threshold where adverse events have been shown in the literature. That is, ingesting more than 4000IUs is associated increased probability of adverse events. In addition, you are clearly aware that studies have shown serum levels above 50ng/mL increase the probability of adverse outcomes (e.g., kidney stones), especially with younger adults, but whether you choose to recognize these studies is debatable.
There is no doubt in my mind that you already knew some (or all) of this information. Coming from someone who just plain understands research, I urge you to critique studies suggesting health benefits of D3 with the same rigor you applied to studies suggesting adverse events. Any D3 study suggesting an increased health benefit must be viewed with caution—aside from probably the benefits to bone health, which has been shown to be a most consistent finding. No long-term safety studies for D3 have been published. This is a HUGE consideration. Further, you were quick to state that research suggesting adverse events with D3 supplementation are flawed methodologically, but you fail to state that ALL research is flawed. This includes studies suggesting health benefits of D3, which are essentially association studies that are inherently unable to imply causality. Further, if believe you are adequately critiquing the literature, you obviously know statistical significance (i.e., p < .05) means nothing. Thus, you already know that any D3 study with a large enough sample is guaranteed to indicate statistical significance. If you didn’t know this, however, then I recommend finding an individual with a background who can explain the literature to you, in an unbiased manner. It will make you a more informed nutritionist who is able to project ACCURATE information to your clients and readers!
While I appreciate the well thought-out comment, I do not appreciate the condescending tone. Yes I do understand the limitations of statistical significance, and I do know that most of the vitamin D data is based on observational studies, but there are actually many controlled trials on vitamin D supplementation above 600IU showing many benefits. As for pointing out the flaws, I simply stated that other vitamin D researchers have pointed out the flaws in the methodology, not me. I am not a vitamin D researcher.
However, here are a few items for you to consider. The IOM wants people between 20-29.9ng/mL because in their estimation that provided the best protection for bone health. However, There is a lot more to vitamin D than bone health.
Beyond that, there are many researchers on vitamin D who roundly disagree with the recommendation. One would be Robert Heaney of Creighton University, one of the leading bone researchers in the world. He recently wrote a letter to the Annals of Internal Medicine about some literature reviews that they had published on vitamin D. In it he stated that doses ranging from 4000-5000IU/day (to reach 30-40ng/mL)are not high, and are actually within our normal physiological range since these values are consistent with those found in healthy individuals living in conditions similar to our ancestors. He also pointed out that outdoor summer workers often have blood levels of 48 to 80ng/mL, without reported adverse affects. In fact, the National Institutes of Health states that the normal range for vitamin D status is 30-74ng/mL.
And since we are on the topic, lets take a look at a recent controlled trial on vitamin D supplementation. A recent 16 week study compared supplementation of 400IU/day to 2000IU/day. 2000IU/day beat 400IU/day in every measure. The vitamin D status in the 400IU group went from 13.6 to 23.9ng/mL (in your optimal range), while the 2000IU group went from 13.3 to 34.3ng/mL (in my optimal range). Aortic stiffness decreased and body fat mass was inversely associated in the 2000IU group, while the 400IU group actually had an increase in aortic stiffness and no association with body fat mass.
Granted that is one study (and there are many more), but it did find that more than 29.9ng/mL did provide greater benefit than being below it. Seems to be an additional benefit to me.
We also know that pregnant and lactating women need more vitamin D. It has been shown that breast-feeding women need at least 2,000 to 4,000IU/day to normalize their vitamin D status, and to normalize the vitamin D status of their feeding baby. Less than that is ineffective.
Now would I have worded the Show and Go recommendations differently if I were to write it now, probably yes, but I don’t think it was the evil you have made it out to be. To get from 20ng/mL to my stated range of 50-80ng/mL would take approximately 3000IU/day, which is below the IOM upper limit of 4000IU/day, how is this dangerous? You also state that research has clearly shown that intakes above 4000IU/day is associated with increased probability of adverse events. Where is this research? The IOM also stated that 10,000IU/day might lead to toxicity, yet they did not produce any reproducible evidence that that level has ever caused toxicity in humans.
The data on vitamin D is certainly not conclusive, but since we know that at least 30-40ng/mL (and higher) is normal in people living in conditions similar to our ancestors (ie – getting plenty of sunlight and eating real food), I don’t see how that range is dangerous. Might different populations have different ranges? Yes, possibly. Might being near 80ng/mL not be the best idea? Yes, possibly (though many researchers and the vitamin D council would disagree). Is 20ng/mL optimal? No, and the research does not agree with that (I just showed one example of many). What is optimal? It depends on many factors, but I think being anywhere from 30-50ng/mL is probably a pretty safe bet, though individual differences are definitely possible, and there are populations who might not want to elevate their vitamin D status.
To cap this off, the Institute of Medicine consulted with 14 vitamin D experts about their recommendations. These 14 experts all provided reports on the recommendation, and yet these 14 reports have been suppressed. They won’t let us know what these vitamin D experts (including Robert Heaney) had to say about their report, interesting… Also of note the Canadian Cancer Society, the Canadian Pediatrics Society, and Osteoporosis Canada all decided to maintain their current recommendations of 800 to 2000IU/day of vitamin D, despite the IOM report.
Like I said in the blog, get yourself tested. You should know your levels before you start supplementing, to know where you are compared to where you want to be. Discuss your results with your doctor, and most importantly, educate yourself.
For more information on the topic, and for more reading from experts who roundly disagree with the report, see below. FNB stands for Food and Nutrition Board, which was technically the arm of the Institute of Medicine who released the report.
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