Maybe this will clear things up a bit

In essence the study merely says that "we don't know" and that further study is needed.  Not exactly a condemnation of Vitamin D3.

Is your advice to people who are unable or unwilling to get adequate vitamin D from sunlight or sources such as fish oil to not taken supplemental vitamin D3 in any amounts?  If such is the case, it is my very strong opinion that your advice will be harmful in far more instances than those where it might be beneficial.

OK, let's cut to the chase.

My advice is to get your vitamin D as much as possible from the sun, and secondarily when needed from natural sources such as fish oil, and then in lieu of getting adequate vitamin D from those sources for whatever reason, that it is best to supplement with reasonable amounts of vitamin D3 rather than becoming deficient in vitamin D.

Perhaps an overlooked point here is that when we limit our debate to only the pros and cons of Vitamin D3 supplementation, it may appear that I on the vitamin D3 bandwagon that would have us believe that most of our health issues can be remedied or avoided simply by taking supplemental vitamin D3.  Let me make it absolutely clear that I'm decidedly not on that bandwagon, and in that sense you and I may very likely agree that giving people the perception that all they have to do is load up with D3 and all will be fine is not a healthy message.

Trying to fix yourself or fortify yourself with a single supplement while neglecting to address your overall health needs is not what I recommend in any instance - that is just chasing a cure in a bottle the same as people try to find cures in mainstream drugs.

Rather, it is my recommendation that people make sure that they live and eat healthily and get optimum amounts of essential nutritional items on a regular basis (and as much as possible from nutrient dense foods and then food derived sources).  People who do that are not likely to have a problem with any immune suppression issues from reasonable amounts of vitamin D3 regardless of how it works.

Anyway, 'nuff debate.  I have articles to write, website pages to update, books to finish and much, much more.  Maybe even a nap . . . .