Chlorogenic acids are cholegogues; their regular ingestion helps the flow of bile and thus reduces the adverse effects of bile stagnation. Chlorogenic acids (see basic structure, below) are found in all higher plants and are understood to have a role in the plant's response to stress, particularly to damage such as breaking of leaves and flowers or nicking the skin of fruits (1). The quantities present in most plants are miniscule, and thus they do not play an important part in human diet or herbal medicines. However, a few plants accumulate chlorogenic acids in quantities sufficient to have a physiological effect. The primary dietary source of chlorogenic acid is coffee; the green coffee beans typically contain 6-7% of this component (range: 4-10%); roasted coffee beans contain somewhat less, as the roasting transforms chlorogenic acids into other molecules, which may still retain the same functions.
It has been estimated that coffee drinkers may consume about a gram of chlorogenic acid each day. This amount of chlorogenic acid, when consumed regularly, appears to be sufficient to yield obvious therapeutic effects. Women are at greatest risk of forming gallstones, about twice that for men. In a large study conducted by Harvard University tracking of over 80,000 women, it was found that regular coffee intake reduced gallstone formation (2). The researchers correlated daily coffee consumption with incidence of gallbladder surgery due to stones: with increasing coffee consumption, gallstone surgery went down compared to those who did not drink coffee: 1 cup per day had no evident effect, but 2 cups per day reduced the incidence of the surgery by 9%, 3 cups reduced the incidence by 22%, and 4 or more cups reduced the incidence by 28%. Clearly, 3 cups per day, which is a typical amount for people who drink coffee routinely, had a dramatic effect.
Further, coffee consumption was associated with a lower risk of a variety of liver diseases, including liver cirrhosis and liver cancer (3, 4). This effect may come from a combination of cholagogue action (keeping toxins and fats flowing with the bile) and antioxidant effects (chlorogenic acid is a potent antioxidant and coffee drinking is one of the main sources of antioxidant activity in the American diet).
In response to the growing evidence of the value of chlorogenic acid, green coffee bean extracts, standardized to 50% chlorogenic acid, have been produced and sold has health products. Chlorogenic acid is also found as a significant component in certain commonly used medicinal herbs. In Chinese medicine, the primary source is lonicera flowers (jinyinhua); extracts are standardized according to chlorogenic acid content, often at 25% of the extract. Eucommia bark and gardenia fruit are also major sources, with extracts standardized to 20% chlorogenic acid. These extracts would yield a dose of about 1 gram of chlorogenic acids in 4-5 grams of extract, a rather large amount. Other Chinese herbs known for their chlorogenic acid content include chrysanthemum flower, crataegus fruit, artemisia leaves, and epimedium leaves.
In Western herbal medicine, an herb especially known for its chlorogenic acid content is artichoke leaves; the extracts are usually standardized to 15% of this compound. Other medicinal herbs known for content of chlorogenic acid include burdock root, dandelion root, and echinacea root. When using any of these herbs (Western or Chinese) and the concentrated herb extracts, other compounds that may contribute to a therapeutic benefit are also present. For example, artichoke leaves contain caffeol quinic acids (as found in roasted coffee) and cynarin, which is reputed to relieve abdominal gas and bloating, symptoms that occur with gallstones and poor bile flow.
While chlorogenic acids are not the only compounds that serve well as cholagogues, the evidence for their effectiveness is by far the strongest. This is primarily because of the coffee research which has allowed for tracking of large numbers of people over a long period of time. For other herbs, their effects on bile flow are usually observed in laboratory animal experiments, though the action might also be inferred from routine use of herbs in clinical applications of treating gallstones, abdominal bloating, upper abdominal pain, and constipation. In a data base for herbs, 140 species (representing 90 genera) were listed as cholagogues.