There have been no valid studies on this. The BHB "study" was a vague claim with no proof to back it up.
Snakes live long and healthy lives in captivity when fed diets not supplemented with vitamins.
With regards to diet and nutrition; the keys are to avoid the tendency to over feed and to also feed a diet appropriate to the species you keep. Not all snakes are rodent eaters in the wild. They become obligate rodent eaters for the convenience of their keeper.
Some species do better on other reptiles, amphibians or birds.