It's a known for many kinds of lizards, but very debatable for snakes. I'd expect it to be more beneficial to snakes that are active in the daylight hours, as that's how
they evolved. Things like gopher/bull/pine snakes, or coachwhips (which hardly anyone keeps). Snakes are said to get all the vitamins they need from their prey, & I
mostly agree, but I have noticed improved appetites (more feisty, actually) in snakes that I've taken outside for some brief sunshine (only at conducive temperatures!).

Vitamin supplements are never as good as the real thing, & same goes for UVB lights instead of sunshine. But bottom line is I'm not sure we have the definitive answer
on this yet...opinions & experience vary, & it's not yet proven as far as I know. So do what your "gut" tells you, or "error on the side of caution" as they say.

The other thing with supplements is that some need to be in proper combination with other nutrients to work & do no harm...so be careful what you may throw out of
balance. Research on snakes just isn't a big draw for grant money, know what I mean?

Really depends WHO told you this also: even many veterinarians, the ones that aren't personally that into snake-keeping- sometimes give this "advice" based on their
assumptions...it doesn't make it true, however...again, I'm not sure anyone has done enough research to answer, or maybe only on some species? Better to ask the
top breeders of whatever kind you're wondering about...see what 2 out of 3 tells you.