Hi nyuszisue, the Mayo Clinic website and livestrong.com both list constipation as a side effect of vitamin D supplementation, so your concern is understandable.

If I were in your position and were deficient in vitamin D (actually I am), I would continue to take the D3 and try to combat the constipation in other ways. I’ve found that a simple power pudding of applesauce, bran, and prune juice has worked for me when needed:

http://www.grandmas-wisdom.com/relie...stipation.html

When I asked my doctor about possible side effects from D3, he did say that if constipation occurred, it would likely happen regardless of the dosage taken. In other words, it shouldn’t be worse with a 5000 i.u. softgel vs. a 2000 i.u. softgel. I can’t verify whether this is actually true or not, but I just thought I’d pass along the information.