A study has come out recently; a study that I am sure you are familiar with (received plenty of media attention) and a study type that is considered the gold standard in medicine (randomized controlled trial).
Let’s review this study by the core areas: who (population), how (intervention), and what (conclusions/findings):
The devil is always in the details; let’s dig into those findings.
First: seriously sick elderly folks undergoing medical treatment overall didn’t get better by any measurement. I’m not surprised. These are folks with damaged lungs at the end of their lives, getting lots of drugs, and were recruited when they were having problems. Some even continued to smoke.
Second: Seriously D deficient folks (<10 ng/mL), however, reduced their rate of flare-ups/year by 43% with D. So, D does have an effect, but it is basically a step function (more deficient get better than less deficient).
Third: The 3,200 IU/day D dose was effective at raising mean 25(OH)D levels to a stable 50-52 ng/ml. Note that it took 4 months to do so (remember D substrate starvation, basically a backlog of unmet D needs).
In my opinion, the severe D deficient group is too small to generalize conclusively.
Many worry about D toxicity. The 100,000 IU D dose resulted in no observed symptomatic calcium-related toxicity. There were 4 cases of small, temporary asymptomatic hypercalcemia peaks at 4 months that resolved quickly. There were zero cases at 8 and 12 months. I see this as the body adapting to new D levels, which increases calcium uptake, but the body always seeks to re-balance itself.
So what can we conclude?
In my opinion, it is still an open question if D might help prevent COPD before the damage is done (although I suggest people be careful in assuming D will protect them from smoking’s effects. I see this a lot: “Woohoo. I had heart surgery so I can keep on drinking, smoking, and eating Twinkies!”). Be careful reading headlines, press releases, and abstracts. The devil is always in the details.