Digestive bitters—or just “bitters” for short—have a long history of use in herbal medicine for promoting digestion. But is there any real science supporting the use of bitter herbs for this purpose? This article will examine the history and science of bitters.
Introduction to Bitters
Bitters are substances found in a variety of herbs, and capable of strongly stimulating the bitter receptors in the taste buds at the back of the tongue. According to one theory, bitters may positively impact digestion through mediation of a nerve reflex from the bitter taste buds involving stimulation of the vagus nerve which causes an increase in gastric acid and pepsin secretion, a slight increase in gallbladder activity and a priming of the pancreas.1 It is also thought that bitters may indirectly influence lower esophageal sphincter (LES) function by increasing stomach acid, which can strengthen the LES closure to prevent reflux.2
Another theory is that bitters elicit responses that facilitate rather than stimulate digestive activity when circulation after a meal is inadequate.3 In this scenario, bitters would alter gastric circulation after a meal, which would then impact digestion.
The Historical Use of Bitters
The Ebers Papyrus4 (c. 1550 BCE), one of the oldest medical texts, describes the use of bitter herbs for digestive ailments. Ingredients like myrrh, gentian, and aloe were common. Hippocrates5 (c. 460–370 BCE) recommended “amara” (bitters) for digestion, believing bitter flavors stimulated bile production. Dioscorides in De Materia Medica6 (c. 50–70 CE) lists bitter herbs such as gentian and wormwood for stomach health. In traditional Chinese medicine, bitter-tasting herbs, such as huang lian (Coptis) and ku shen (Sophora) have been used for centuries to “clear heat” and aid digestion.7 Ayurvedic medicine emphasized the use of tikta rasa (bitter taste) herbs like neem and andrographis (the “king of bitters”) for stimulating digestion and detoxification.8 Also, herbal liqueurs, such as Swedish bitters were popularized in the 16th century by physicians like Paracelsus, and by the 18th-19th centuries, bitters like Angostura and Fernet were common digestive aids.9,10
Another interesting side bar is that the tradition of eating a salad before a meal may have its origins in stimulating digestion when the lettuce was bitter field greens. Similarly, bitter aperitifs, such as Italian amaro and fortified wines, such as vermouth, have been used for the same reason.
The Science of Bitters
Preclinical studies (i.e., studies in cell cultures or experimental animals) have suggested that bitter substances may have potent effects to stimulate the secretion of gastrointestinal (GI) hormones and modulate gut motility, via activation of bitter taste receptors located in the GI tract.11 As early as 1915, research by Moorhead demonstrated that a tincture of the bitter herb gentian (Gentiana lutea) given by mouth (i.e., tasted) to cachectic dogs (i.e., weak and wasting dogs) caused a marked increase in appetite and gastric secretion of hydrochloric acid and pepsin.12 Other research13 also published in 1915 did not find an increase in hydrochloric acid and pepsin in normal subjects in the absence of food. According to Mills and Bone,1 what we can learn from these studies is:
• Bitters increase appetite only in a malnourished or debilitated state exists in the body.
• Bitters increase digestive power mainly when it is below optimum.
• Experiments with bitters should involve the presence of food in the stomach.
Commonly Used Bitter Herbs
Gentian: The rhizome and root of gentian (Gentiana lutea) contain a range of bitter compounds including gentiamarin and gentiopicrin, amarogentin, swertiamarine, and gentianose.14 In addition to being a bitter, this herbal medicine has gastric stimulant properties, as well as the ability to promote saliva secretion and bile flow.
Traditionally, it has been used for lack of appetite, lack of gastrointestinal tone, and specifically for dyspepsia (indigestion) with anorexia. The German Commission E approved use for digestive disorders such as loss of appetite, fullness and flatulence. Gentian is used in combination with angelica root and caraway fruit or with ginger and wormwood for loss of appetite and peptic discomfort.
Dandelion: Sesquiterpene lactones are the primary bitter principles in dandelion roots and leaves.16,17 Dandelion possesses diuretic, laxative, cholagogue and antirheumatic properties. It has been used for an inflamed gallbladder, gallstones, jaundice, lack of stomach tone with constipation, muscular rheumatism, reduced urine flow, and specifically for gallbladder inflammation and dyspepsia. The German Commission E approved use of root and herb for disturbance of bile flow, stimulation of urine flow, loss of appetite and dyspepsia.15
Licorice: Various flavonoids (such as liquiritin and isoliquiritin) in licorice root contribute to its bitter taste.18 Licorice has expectorant, demulcent, antispasmodic, anti-inflammatory and laxative properties. It has been used for bronchial phlegm, bronchitis, chronic gastritis, peptic ulcer, colic and primary adrenocortical insufficiency.15
Milk Thistle: The primary bitter principles in milk thistle fruit are the flavonolignans found in the collective compound known as silymarin.19 Traditionally, milk thistle fruits have been used for disorders of the liver, spleen and gall bladder such as jaundice and gall bladder colic. Milk thistle also possesses hepatoprotective, antioxidant and bile flow stimulating properties.15,20 Modern research focuses primarily on the hepatoprotective activity of milk thistle and its use in the prophylaxis and treatment of liver damage and disease.15
Artichoke: The bitter principles in artichoke leaf are primarily the sesquiterpene lactone, cynaropicrin and the caffeoylquinic acid, cynarin.21,22 Artichoke has diuretic, bile flow promoting, cholesterol lowering, lipid lowering and liver stimulating properties.23-25 Modern use of artichoke is focused on its use in the treatment of high cholesterol and high lipoproteins, non-ulcer dyspepsia and conditions requiring an increase in bile flow.5
Conclusion
While bitters have been used historically to promote digestion, modern research has likewise suggested that they may have value for supporting digestion. Bitters may also help with a range of digestive disorders, depending on the herbal medicine being used. This article briefly reviewed a few of those herbs, but there are many more to consider.VR
References:
1 Mills S, Bone K. Principles and Practice of Phytotherapy: Modern Herbal Medicine. Churchill Livingston. 2000.
2 Herdiana Y. Functional Food in Relation to Gastroesophageal Reflux Disease (GERD). Nutrients. 2023 Aug 15;15(16):3583. doi: 10.3390/nu15163583. PMID: 37630773; PMCID: PMC10458865.
3 McMullen MK, Whitehouse JM, Towell A. Bitters: Time for a New Paradigm. Evid Based Complement Alternat Med. 2015;2015:670504. doi: 10.1155/2015/670504. Epub 2015 May 14. PMID: 26074998; PMCID: PMC4446506.
4 Bryan CP. The Papyrus Ebers: Translated from the German Version. D. Appleton. 1930.
5 Hippocrates. Hippocratic Writings. Loeb Classical Library. 1934.
6 Dioscorides. De Materia Medica. IBIS Press. 2000.
7 Chen JK, Chen TT. Chinese Medical Herbology and Pharmacology. Art of Medicine Press. 2004.
8 Lad V. Ayurveda: The Science of Self-Healing. Lotus Press. 2002.
9 Grieve M. A Modern Herbal. Harcourt, Brace & Company. 1931.
10 Foster S, Duke JA. A Field Guide to Medicinal Plants and Herbs. Houghton Mifflin Harcourt. 2014.
11 Rezaie P, Bitarafan V, Horowitz M, Feinle-Bisset C. Effects of Bitter Substances on GI Function, Energy Intake and Glycaemia-Do Preclinical Findings Translate to Outcomes in Humans? Nutrients. 2021 Apr 16;13(4):1317. doi: 10.3390/nu13041317. PMID: 33923589; PMCID: PMC8072924.
12 Moorhead LD. Contrutions to the physiology of the stomach. XXVIII Further studies on the action of the bitter tonic on the secretion of gastric juice. Journal of Pharmacology and Experimental Therapeutics. 1915; 7:577-89.
13 Carlson AJ, Torchiani B, Hallock R. Contributions to the physiology of the stomach. XXI The supposed actions of the bitter tonic on the secretion of gastric juice in man and dog. Journal of the American Medical Association. 1915; 64(1):15-17.
14 Verotta L. Isolation and HPLC determination of the active principles of Rosmarinus officinalis and Gentiana lutea. Fitoterapia 1985; 56:25–29.
15 Barnes J, Anderson LA, Phillipson JD. Herbal Medicines, 3rd Ed. Pharmaceutical Press. 2007.
16 Hausen BM. Taraxinsäure-10-O-b-D-glucopyranosid, das kontaktallergen des löwenzahns (Taraxacum officinale Wiggers). Dermatosen 1982; 30: 51–53.
17 Hänsel R et al. Sequiterpenlacton-b-D-glucopyranoside sowie ein neues eudesmanolid aus Taraxacum officinale. Phytochem 1980; 19: 857–861.
18 Mitscher LA et al. Antimicrobial agents from higher plants. Antimicrobial isoflavanoids and related substances from Glycyrrhiza glabra L. var. typica. J Nat Prod 1980; 43: 259–269.
19 Morazzoni P, Bombardelli E. Silybum marianum (Carduus marianus). Fitoterapia 1995; 66: 3–42.
20 Awang D. Milk thistle. Can Pharm J 1993; 403–404, 422.
21 Jouany JM et al. Dosage indirect de la cynaropicrine dans la Cynara scolymus (Compositae) par libération de sa chaîne latérale hydroxyméthylacrylique. Plant Méd Phytothér 1975; 9: 72–78.
22 Barbetti P et al. Grosulfeimin and new related guaianolides from Cynara scolymus L. Ars Pharmac 1992; 33: 433–439.
23 Lietti A. Choleretic and cholesterol lowering properties of two artichoke extracts. Fitoterapia 1977; 48: 153–158.
24 Adzet T et al. Hepatoprotective activity of polyphenolic compounds from Cynara scolymus against CCl4 toxicity in isolated rat hepatocytes. J Nat Prod 1987; 50: 612–617.
25 Adzet T et al. Action of an artichoke extract against CCl4-induced heptotoxicity in rats. Acta Pharm Jugosl 1987; 37: 183–187.
Gene Bruno, DBM, MHS, Professor Emeritus of Nutraceutical Science, is a writer, educator and a nutraceutical scientist with more than 45 years of experience educating natural product retailers and health care professionals and formulating natural products for dozens of dietary supplement companies. He has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications. Bruno also hosts “The Vitamin Professor Podcast” brought to you by VRM Media. He can be reached at [email protected].
