I have EDS, and seem to experience an unusually strong response to taking Vitamin B12 supplements. More precisely, if I take one 500 micrograms pill of B12, in around 3 days I will have an acne outbreak, mostly on my face, and some on my shoulders. It tends to affect my cheeks, forehead, and the jaw line. Even if I take as low as 100 micrograms of B12 for a few days, I will still get the acne outbreak, although not as bad as with 500 micrograms. If I don’t take B12 for two weeks, the inflammation goes down, my skin starts feeling normal again, and I essentially have zero acne.
Now, acne outbreaks have recently been recognized as a more rare side-effect from taking B12 supplements (http://www.ncbi.nlm.nih.gov/pubmed/26109103), and it seems to occur with very high doses (http://www.livestrong.com/article/507637-why-does-vitamin-b12-cause-acne/ ).
Do any of you have similar experiences? As B12 seems to change the (amount of) molecules acne-related bacteria produce, could it be that a defective collagen, present in some EDSers, makes the skin more sensitive to these molecules, thus inducing acne even at lower doses of B12 supplements?