Rigorous studies showed no benefit from supplements, and they are not recommended
A batch-specific Certificate of Analysis (COA) ships with every order, documenting the identity and HPLC purity of the material you receive
For human relevance, sufficient published, peer-reviewed controlled human studies and regulatory review would be necessary
There are lots of medical grade skin care brands out there and while they are all much of a muchness, some are better for some people than others, depending on the skin issues youre trying to address
There are several B12 supplements available in the market
But the responsible interpretation is simple: watch the official documents, separate advisory review from approval, separate pharmacy access from research-vendor marketing, and keep your own tracking clean