Bitters

Bitters were widely used in the 19th century as a form of medicine, in the way we take a tonic nowadays if we are feeling off colour.  They are recommended in letters to Richard and Charlotte by Louisa and Silvanus, much as we might recommend someone should take a multi-vitamin tonic today.

Bitters were originally medicines. If you tell a bartender you have an upset stomach, he’ll probably give you a glass of soda and bitters – and it will probably work. (http://articles.latimes.com/2006/jan/25/food/fo-bitters25)

Bitters have been shown to stimulate and heighten nervous system function, as well as the immune system, helping people recover more quickly from various chronic illnesses. Bitters are often prescribed by physicians and natural health practitioners alike in many parts of Europe for mild to moderate digestive problems, such as irritable bowel syndrome, colic, gas, and constipation.
(http://www.healthy.net/scr/article.asp?Id=884)