What is the story with “pyrrolizidine alkaloids” in Butterbur, Coltsfoot and Comfrey?
About 3% of flowering plants contain a group of chemical compounds called pyrrolizidine alkaloids (PAs); Comfrey, Coltsfoot and Butterbur are in this group of plants. PAs can have a toxic effect on the liver when taken orally in large amounts or for extended periods of time. The amount of PAs in plants can vary greatly depending upon the botanical species and variety, growing conditions, plant part, and time of harvest. Occasional, small amounts of PAs are harmless to the body, but they can be cumulative. Children, the elderly and those with liver disease are more easily harmed by PAs, and the fetus is particularly susceptible.
