when it works for people, it seems to really work well for them
i suppose those who need it are severely deficient
perhaps it is something most people's body can manufacture
genetic diversity makes it challenging to figure out exactly what your body needs
someday they will be able to take a dna sample, determine your genetic profile, enabling selecti of specific products containing the exact chemicals needed
until then, we must learn how to listen to our bodies and rely on trial and error methods