How the Institute of Medicine Arrived at their Vitamin D Recommendation

There are many ways to arrive at a target vitamin level. We’ve already examined some of the problems inherent to just using deficiency disease prevention and evolutionary arguments to establish an optimum intake.

If a vitamin only does one thing, then it’s easy; you set the level at whatever the body needs to do that one thing best. But what if the vitamin affects dozens of different organs, like with vitamin D? Then, it’s more difficult.

Here’s a list of the target tissues affected by vitamin D in the body. In revising their recommendations, the Institute of Medicine decided to only look at one tissue—bone, which many considered to be a mistake. 

I did like how they went about it, though. I mean, they asked the expert: the human body. When our body senses we don’t have enough active vitamin D for adequate bone health, it releases a hormone, called PTH, to boost our levels. And so, the Institute of Medicine figured, why don’t we just listen in on the body’s own innate wisdom, and find out which level of vitamin D it feels comfortable with for bone health? And that number is about 20 nanograms/ml, here as 50 nanomoles per liter. Once we fall below that, our body is like uh, oh, and starts producing this PTH to protect our bones from softening. But that’s just the bone; what about the other three dozen organs affected by vitamin D?

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

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