What the experiment found
A 2015 study examined gene activity in skin bacteria and then followed ten healthy people given vitamin B12. One developed acne about a week after supplementation. The researchers also found changes in bacterial B12-related gene activity. [1]
In cultures of the bacterium then called Propionibacterium acnes, added B12 increased production of porphyrins, compounds implicated in inflammation. These linked observations suggest a mechanism; they do not demonstrate that everyone with acne has excess B12. [1]
Why one person out of ten is not a reliable risk estimate
The small mechanistic experiment was not a large randomized trial designed to estimate acne incidence across ordinary supplement users. Baseline susceptibility, preparation and exposure matter, and bacterial culture findings are not equivalent to clinical outcomes. [1]
Investigators disclosed an acne-related patent application. That does not negate the observations, but independent replication and more representative studies are important before drawing broad treatment conclusions. [1]
Keep a suspected reaction separate from the need for treatment
If a breakout follows starting a B12 product, give the treating clinician the timing and complete ingredient list. An association in time is a reason to assess the product, not proof of the responsible ingredient. [2][1]
Confirmed B12 deficiency still needs appropriate management. Do not abandon prescribed replacement because a small acne study is being discussed online. [2][1]
Interpret the study size correctly
Imagine ten participants receive an intervention and one develops a symptom. Describing that observation is accurate; telling every future user they have a 10% risk would overstate what this study can establish.
| Detail | Interpretation |
|---|---|
| Ten supplemented volunteers | Small mechanistic sample |
| Bacterial cultures | Support a proposed pathway |
| Personal acne risk | Not reliably quantified |
Sources for this article
- Vitamin B12 modulates the transcriptome of the skin microbiota in acne pathogenesis - PubMed
Source consulted: 2026-09-19. This is a reference resource, not a claim that we conducted the studies or tested a product. - Recommendations | Vitamin B12 deficiency in over 16s: diagnosis and management | Guidance | NICE
Source consulted: 2026-09-19. This is a reference resource, not a claim that we conducted the studies or tested a product.