They have been used for over a thousand years in China – raw fo-ti mainly as a cathartic and detoxicant and is considered toxic, while cured fo-ti has tonic properties and is widely used in preventing white-hair growth and for various other conditions, and is generally considered non-toxic.
The raw fo-ti after harvest is washed off its dirt and simply dried. While the cured fo-ti is boiled in black bean broth for hours in non-iron pots until the liquid is absorbed. There are also numerous other ways to make cured fo-ti, some using wine. They all take hours, if not days, to complete. Which is why when I first noticed the ChP specified actual amounts of chemicals in its standards of identity and quality for fo-ti, I was very surprised. That was the reason I mentioned that some Chinese scientists, after having newly learned the synthetic-chemical or ‘scientific’ way, were awed by this ‘science’ and went along with their Western colleagues’ wrong thinking without seriously pondering the issues of the major differences between synthetic drugs and natural medicines.
The new standards in ChP 2015 (1% in raw fo-ti & 0.7% in cured fo-ti) of 2,3,5,4’-tetrahydroxystilbene 2-O-beta-D-glucoside (THSG) are obvious to me as a source of future trouble. After prolonged boiling, there would be practically no THSG left in the cured fo-ti. Requiring manufacturers to have 0.7% of THSG in their cured fo-ti would be impossible after all this cooking! They would have to ignore the new ChP standards to continue to produce the cured fo-ti the traditional way which would fail ChP requirements but have a safe product that they have been used for generations.
The therapy with TCM herbs and formulas has been based on experience and accumulated wisdom. It is a completely different system from modern synthetic drug therapy with its vicious cycle that I have written about for years! The two cannot be treated alike.