With the European manufacturers closed, they used to extract from Tapioca and this natural form was always -1 charged.
We are left with dubious sources. Pharma grade still counts for independent testing and quality but best to dilute the Pharma in water then run a bit of current through it to make sure its negative charged.
Other natural forms like AMLA won't work too slow to extract and one should keep Bioflavenoids to a minimum they will also slow activation.
The faster the better and dosage can be determined by bowel tollerance.