Taurine deficiency may be a lot more common than scientists believe. I believe taurine is an essential nutrient, as we cannot make enough to meet even the synthesis of the strongest bile acids, but if not essential, taurine is likely conditionally essential in anyone deficient in vitamin B6.
The precursor is cysteine and vitamin B6 is required in two additional steps to make taurine, and vitamin B6 deficiency is more common than scientists believe, and there are at least 3 demands on the limited cysteine pool with a higher priority than taurine:
- Protein synthesis
- Glutathione synthesis
- Coenzyme A synthesis
- Everything else – activated sulfate for polysaccharide synthesis, hydrogen sulfide, taurine, etc.
Taurine is very likely 4th priority or even lower.