Hu Shu Wu is the oldest known supplement.

Back in the day Chinese were over run periodically by just about every neighboring warlord. One thing they all had in common was that they all felt that they were too great to die. One of the reasons for conquering this vast country was for the secret of immortality.

So they would round up all the monks, old men, and whoever the neighbors would like to rat out.

They threatened them with pain, death, and whatever. No one knew anything.

Finally they found this guy named Ho Shu Wu who was supposed to be 256 years old. (The number varies). He had black hair and seemed a healthy middle aged person. Considering he would be dead if he didn't,  he was glad to tell them the secret.

The secret was this herb. And yes he would take the royal physician to the plants.

The physician watched the man prepare a tea and drink it. The conquering Emperor observed the man drinking the tea, and ordered his physician to drink it also. In a few months the hair of the physician began to turn dark and young looking. And thicker also.

The Emperor impressed tried it also, and after a while, his hair also changed.

Ho Shu Wu now a favorite person, dissapeared.  Probably because darkening of hair is not immortality, and if he want to keep his real secret to immortality, and his life, he needed to dissappear.

It was a good thing I never took it for its hair darkening quality, because I would have been disappointed.  My hair is mostly grey.

I take it because intuitively I feel my body wants it.