First we must explain the actions of bitters on the body. According to Simon Mills, who wrote the book “The Essential Book of Herbal Medicine“. Mr. Mills expounds on the virtues of bitters in several chapters, stating that in essence, “bitters increase appetite, bitters promote bile flow, bitters protect gut tissues and bitters enhance pancreatic function”.
My favorite bitters, which should be taken together, are: gentian root and calamus root Gentian root (Gentiana lutea) is energetically known as the coldest of all the bitter herbs. It is for the heavier person or the person who runs warm-hot. I always recommend taking gentian root with a carminative (an herb that reduces flatulence) like fennel or anise if you tend to run cool or cold.
Calamus root (Acorus calamus) is known energetically as a warming bitter and is used for people who either run cool, or who are not as robust. This herb can be made into a tea by itself because it has a pleasant taste or added with other herbs such as fennel and peppermint.