Bitter herbs are one of herbal medicine’s great contributions to human health. Quite simply, this category contains herbs that have a bitter taste, ranging from mildly bitter yarrow to fiercely bitter rue. Absinthin, a constituent found in wormwood, is so bitter it can be tasted even at dilutions of 1 part in 30,000 parts of water. The strong flavor is often attributed to a “bitter principle,” which can be a volatile oil, an alkaloid, an iridoid, or a sesquiterpene.
Following stimulation of the bitter receptors, located at the back of the tongue, a range of physiological responses occurs. Specific taste buds transmit the taste of bitterness to the central nervous system, triggering a number of reflexes. These reflexes have important ramifications, all of value to the digestive process and general health:
• The stimulation of the flow of digestive juices from the exocrine glands of the mouth, stomach, pancreas, duodenum, and liver aid in good digestion as well as helping a range of conditions caused by inefficient or allergy-distorted digestion.
• The flow of digestive juices triggers a stimulation of appetite. This is helpful in convalescence as well as in cases of appetite reduction.
• A range of liver activities is stimulated, including increased bile production and the release of bile from the gallbladder.
• A very mild stimulation of the endocrine glands occurs, producing insulin and glucagon secretions from the islets of Langerhans in the pancreas. Diabetics need to use bitters cautiously, as these herbs can change the blood sugar balance. In the hands of a skilled practitioner, however, bitter remedies can play a role in the treatment of non-insulin dependent diabetes.
• Bitter remedies can trigger subtle psychological effects, even acting as mild antidepressants. For example, bitters can help lift the spirits in cases of post-viral-infection depression.
• The central reflex stimulates peristalsis, an action that moves wastes through the intestines through a series of muscular contractions.
• Bitter remedies also stimulate the gut wall’s self-repair mechanisms.
Some common herbal bitters are:
Adapted from Healthy Digestion by David Hoffman (Storey Books, 2000).