In herbal medicine, there is a recognized fundamental linkage between the gut and systemic health in conditions as widely ranging as asthma, atopy, autoimmune disease, and even arthritis. This is important, considering that the gut plays a significant role in immune function. Herbalists emphasize the health of the digestive system, bowel movements, and any symptoms related to gut function — even mild digestive disturbances such as burping, mild constipation, inconsistent stools, or excessive flatulence are always considered significant, even if not the reason for presentation for consultation.
The herbs outlined below are useful in gastrointestinal health and disease management and are supported by traditional use or research. The lists are by no means complete, and there are differences in the potency of the actions of the individual herbs. However, by knowing the particulars of the patient, an herb might be chosen for its breadth of action when more than 1 system is involved or for a particularly strong action that is needed. Sometimes only a gentle stimulation, triggering an appropriate reflex response or dampening a response, may be all that’s needed to reach equilibrium again. The beauty and art of herbal medicine is in the selection of herbs that have appropriate action and yet are tailored for the whole health of the individual patient.
Bitters, sialogogues, and stomachics refer to herbs that improve digestive function either by increasing saliva production (sialogogue) or increasing gastric secretion (stomachic). They are frequently bitter tasting, hence “bitters.” Some early work carried out in cachectic dogs showed that a tincture of Gentian (Gentiana lutea) given by mouth increased appetite, gastric secretion and acid, and pepsin content. It is suggested that the bitter taste has a priming effect on upper digestive function, particularly when digestion is suboptimal. This is possibly mediated via a reflex vagal stimulation from bitter taste buds, causing increases in gastric acid secretion, gastrin, and gallbladder motility, and priming the pancreas (ACP 1999).
Traditionally, bitters have been an essential component of any digestive tract formula in which upper digestive tract function is impaired. Many herbs have bitter principals, including many of the alteratives, depuratives, and cholaretics. They include Oregon grape (Berberis aquifolium), Barberry (Berberis vulgaris), Bupluerum (Bupleurum falcatum), Golden seal (Hydrastis canadensis), Chamomile (Matricaria recutita), Picrorrhiza (Picrorrbiza kurroa), Baical skullcap (Scutellaria baicalensis), Dandelion (Taraxacum officinale), Thyme (Tbytnus vulgaris), and Ginger (Zingiber officinale).
Carminatives help reduce and dispel gas, and they are a feature of herbs that contain mainly volatile compounds or essential oils. Fennel (Foeniculum vulgare) has long been used to relieve the pain of intestinal spasm and gas and is an ingredient of “gripe water” that is used in infant colic. Fennel and other carminatives are thought to relax smooth muscle spasms that occur in response to gaseous distension, leading to relief of intestinal cramping. A fennel infusion in animals reduced peristalsis tone and amplitude 2 to 30 minutes after administration. In vitro studies and animal models indicate that fennel extracts modulate calcium availability and metabolism. In a multicenter, randomized, placebo-controlled trial, Fennel significantly relieved symptoms of infant colic (defined as a decrease in the number of hours spent crying weekly) compared with a placebo. Other carminatives include Ginger (Zingiber officinale), Peppermint oil (Mentha x piperita), Chamomile (Matricaria recutita), Thyme (Tbytnus vulgaris), Cinnamon (Cinnamomum zeylanicum), Lavender (Lavendula officinalis), Lemon balm (Melissa officinalis), Catnip (Nepeta cataria), Rosemary (Rosmarinus officinalis), Valerian (Valeriana spp.), Parsley (Petroselinum crispum), and Aniseed (Pimpinella anisum).
Most of the carminative herbs have spasmolytic activity. They act in various ways; for example, Chamomile’s (Matricaria recutita) activity has been attributed to apigenin, apigenin-7-O-glucoside, and a-bisabolol, which act similarly to papaverine. Peppermint oil has been shown to decrease the gut contractile response to histamine, serotonin, acetylcholine, and substance P and was shown to suppress gastric spasms in people during upper gastrointestinal endoscopy. Corydalis ambigua is a traditional anodyne for visceral pain. Others include Cramp bark (Viburnum opulus), Wild yam (Disocorea villosa), and Calendula (Calendula officinalis).
Antacid, antiulcerogenic, and antiinflammatory herbs
Several plants help protect gastric mucosa and heal ulcers. Meadowsweet (Filipendula ulmaria), which contains salicylates administered at rates of 0.7 and 1.25 ml / kg, was shown to reduce ulceration (induced by aspirin) in an in vivo study by 25.4% and 26.2%, respectively. Licorice given orally for 3 days protected rats against induced duodenal ulcers but was ineffective against acute aspirin-induced gastric ulcers. The effect of Licorice may be due to inhibition of acid-pepsin secretion and augmentation of mucosal defensive factors. These mucosal defense factors may include enhanced mucin secretion and decreased cell shedding or acceleration of mucin excretion via Licorice increasing the synthesis of glycoprotein at the gastric mucosa, prolonging the life of the epithelial cells and antipepsin activity. Oral administration of deglycyrrhizinated Licorice (380 mg, 3 times daily) to 169 patients with chronic duodenal ulcers was as effective as antacid or cimetidine treatments, indicating that constituents other than glycyrrhetic acid contribute to its antiulcer activity.
Turmeric extracts (water or ethanol) reduced gastric secretion in rabbits and increased the mucin content of gastric juice. Extracts from Lemon balm (Melissa officinalis), Chamomile (Matricaria recutita), Peppermint (Mentha x piperita), Licorice (Glycyrrhiza glabra), Angelica root (Angelica arcbangelica), Milk thistle (Silybum marianum), and greater Celadine (Chelidonium majus), singly and combined, produced a dose-dependent antiulcerogenic activity associated with reduced acid output and increased mucin secretion, increased prostaglandin E2 release, and decreased leukotrienes. An ethanolic extract of Parsley (Petroselinum crispum) protected gastric mucosa against induced ulcers in rats. Other antiulcerogenic herbs include Gotu kola (Centella asiatica) and Chamomile (Matricaria recutita), and antiinflammatory herbs include Dong guai (Angelica sinensis), Baical skullcap (Scutellaria baicalensis), Calendula (Calendula officinalis), Wild yam (Dioscorea villosa), Slippery elm (Ulmus rubra), and Marshmallow (Althaea officinalis).
Demulcents and mucilages
Demulcents are used to soothe and protect an alimentary mucous membrane (buccal, pharyngeal, oesophageal, and gastric mucosa), whereas mucilages refer to plants that contain mucilaginous substances, which cause demulcency. Marshmallow (Althaea officinalis) is a mucilage and has a demulcent action due to its high content of polysaccharide hydrocolloids, which form a protective coating on the oral and pharyngeal mucosa, soothing local irritation and inflammation.
Adhesion of constituents varies between plants. Polysaccharides from Althaea officinalis, Plantago lanceolata, Malva moschata, or Tilia cordata showed moderate bio-adhesion to epithelial tissue compared to polysaccharides from Fucus vesiculosus and Calendula officinalis, which were concentration-dependent. Histological studies of membranes indicated the presence of distinct polysaccharide layers on the apical membrane surface, which account (in part) for the therapeutic effects of mucilage-containing plants in the treatment of irritated membranes. Demulcent action is found in Marshmallow (Althaea officinalis), Slippery elm (Ulmus fulva), Sarsaparilla (Smilax ornate), Licorice (Glycyrrhiza glabra), Bladderwrack (Fucus vesiculosus), Fenugreek (Trigonella foenumgraecum), Mullein (Verbascum thapsus), Calendula (Calendula officinalis), and Corn silk (Zea May).
Intestinal astringents are most useful in acute diarrhea. Most of these herbs contain tannic acid, which precipitates protein on the mucosal surface. This acts as a barrier between tissue and irritant, and the protecting and soothing effect is enhanced by an astringent action on any exposed nerve endings so that pain is lessened. Herbs that are high in tannins are ideally used for short periods only, and they can interact with or limit absorption of some alkaline drugs. Intestinal astringents including Agrimony (Agrimonia eupatoria), Tormentil (Potentilla tormentilla), Blackberry (Rubus fructosis), and stewed Tea (Camellia sinensis).
Herbs with laxative action contain aperients, which promote a natural movement of the bowels rather than provoking them forcibly. These safe-to-use laxatives include Psyllium, Linseed, and dietary fibers, as well as Burdock (Articum lappa), Oregon grape (Berberis aquifolium), Barberry (Berberis vulgaris), Licorice (Glycchyriza glabra), Rehmannia (Rebmannia glutinosa), and Dandelion (Taraxacum officinalis).
Aloe (Aloe barbadensis) was a popular anthracene purgative until synthetic anthraquinones were introduced in veterinary medicine. Cascara (Rhamnus purshiana) was also used in cats and dogs. It has been suggested that Cascara and Buckthorn (Rhamnus frangulara) may be the preferred herbs of choice for constipation in cats. Senna pod (Cassia angustifolia) produces sublaxative effects at low doses, whereby the bowel motions are made comfortable, normal, and soft. Other laxatives include Fringe tree (Chionanthus virginicus), Fumitory (Fumaria officinalis), Licorice (Glycyrrhiza glabra), Butternut (Juglans cinerea), Yellow dock (Rumex crispus), and Fenugreek (Trigonella foenumgraecum).
When emesis is centrally initiated, the cause must be diagnosed. Conventional medications should be considered, although herbs can be given via enema. Administering herbs to a vomiting animal is not recommended; However, for chronic gastritis, demulcents (which coat, protect, lubricate, and soothe the gastric mucosa) and local gastric sedatives (antacids and stomachics) might be helpful to suppress the vomiting reflex.
Ginger (Zingiber offcinale) significantly reduced the number of vomiting episodes in healthy dogs with cisplatin-induced emesis (3 mg / kg IV), at doses as low as 25 mg / kg per os. The highest dose tested for both ethanol and acetate extracts was 200 mg / kg, which led to the fewest vomiting episodes but a shorter latency in minutes to the first episode. These doses were comparable with the antiemetic efficacy of granisetron. Because Ginger was ineffective in inhibiting apomorphine-induced emesis (which was mediated through a dopaminergic mechanism), the authors hypothesized that 5-HT3 receptors may be involved in the activity of ginger. The emetic action of the peripherally acting agent copper sulfate was also inhibited in dogs given an intragastric dose of Ginger extract. Ginger’s antiemetic activity is peripheral (it does not involve the central nervous system) and has been attributed to the combined action of zingerones and shogaols.
Many herbs have direct antimicrobial activity in the gastrointestinal tract. Berberine (in several herbs) and hydrastine (in golden seal) are some of the best studied for GIT infections. The isolated alkaloid berberine has been shown to inhibit intestinal fluid accumulation and smooth muscle contraction, reduce inflammation, and suppress bacterial enterotoxin formation. Tormentil root (Potentilla erecta) extract in controlled doses shortened the duration of rota-virus diarrhea and decreased the requirement for rehydration solutions in children suffering from rotavirus diarrhea. It also may be useful in rotaviral infections in animals.
Consider immune-modulating herbs such as Echinacea, Astragalus, Andrographis, and Picrorrhiza in microbial infections. Most herbs with antimicrobial activity have other properties, which should be considered, depending on the nature of the condition. Just some of the herbs to consider include Chamomile (Matricaria recutita), Thyme (Tbymus vulgaris) — especially against helicobacter — Picrorrhiza (Picrorrhiza kurroa), Oregon Grape (Berberis aquifolium), Barberry (Berberis vulgaris), Golden seal (Hydrastis sinensis), Fennel (Foeniculum vulgare), and Citrus seed extract (citrus spp.).
Many herbs have well researched activity against parasites. The traditional approach in veterinary medicine prior to modern anthelmintics was to use fairly toxic herbs and to purge parasites, often leading to cramping and diarrhea. Current anthelmintics pose little risk and work well; however, some people prefer not to use drugs and desire herbal options. Garlic is frequently mentioned as an effective worming agent. It has some activity against roundworm (Ascaris strongyloides) and hookworm (Ancylostoma caninum and Necator americanus). AUicin appears to be an anthelmintic constituent, but diallyl disulphide was not effective. However, garlic (whole clove) efficacy has not been well documented and may in fact be ineffective for parasite control.
The alkaloid berberine (in Barberry and Orgeon grape, among others) showed strong nematocidal activity against Toxocara canis in vitro. Hydrastine (in Golden seal) has been studied on the protoscolices of the tapeworm (Echinococcus granulosus) in vitro and in vivo. Hydrastine at 0.3% concentration produced 70% mortality of the larvae in both experiments. Cucurbitine contained in crushed pumpkin seeds is 55% efficacious against Taenia saginata.
Herbs that have been traditionally used for their anthelmintic activity in humans and animals include Wormwood (Artemesia absinthium), Butternut (Juglans cinerea), Thyme (Tbytnus vulgaris), and Ginger (Zingiber officinale). A number of herbs have shown antiprotozoal activity; they include Oregano (Oreganum vulgar e), Propolis, Sweet Annie (Artemesia annua), and berberine-containing herbs. Essential oils may also be effective, preventive, or curative treatments against several flagellated parasites; however, efficacy is not well documented and conventional treatment is more likely to be curative.
Liver and gallbladder herbs
Cholagogues, which stimulate the release and flow of bile already formed in the liver, and choleretics, which stimulate bile production by hepatocytes, are often found in bitter herbs. Cholagogues are used to improve the “cleansing of the liver” by improving bile excretion. Cholagogues include Agrimony (Agrimonia eupatoria), Oregon grape (Berberis aquifolium), Calendula (Calendula officinalis), Greater celandine (Chelidonium majus), Fringe tree (Chionanthus virginicus), Turmeric (Curcuma longa), Globe artichoke (Cynara scolymus), Wormwood (Artemesia absinthium), Picrorrhiza (Picrorrbiza kurroa), Yam (Dioscorea spp), Gentian (Gentiana luted), Chamomile (Matricaria recutita), Yellow dock (Rumex crispus), Milk thistle (Silybum marianum), and Dandelion (Taraxacum officinale). They are often combined with laxatives in the treatment of liver disease and wider liver dysfunction.
Choleretic herbs improve liver function and are particularly indicated if digestive symptoms are predominant. Most of the hepatoprotective herbs have choleretic activity. Contraindications for choleretic and cholagogues include obstructed bile ducts (e.g., bile duct or pancreas cancer), jaundice following hemolytic diseases, acute or severe hepatocellular disease (e.g., viral hepatitis, septic cholecystitis, intestinal spasm or ileus), or liver cancer. Strongly choleretic herbs include Hydrastis (golden seal), Berberis vulgaris (Barberry), and Bhelidonium (greater celandine). Bitter herbs can cause nausea in patients with liver damage so they should be avoided after hepatic restoratives have been used. Choleretics include Artemesia absinthium, Berberis vulgaris, Calendula officinalis, Chelidonium majus, Glycyrrhiza glabra, Hydrastis canadensis, Mentha x piperita, Silybum marianum, and Zingiber officinale.
Hepatotonic herbs include those with choleretic, cholagogue, hepatoprotective, or hepatorestorative properties. They include Andrographis (Andrographis panniculata), Oregon grape (Berberis aquifolium), Barberry (Berberis vulgaris), Bupleurum (Bupleurum falcatum), Fringe tree (Chionanthus virginicus), Globe artichoke (Cynara scolymus), Panax ginseng, Phyllanthus (Phyllanthus amarus), Picrorrhiza (Picrorrhiza kurroa), Dan Shen (Salvia multirrhiza), Schisandra (Schisandra chinensis), Milk thistle (Silybum marianum), and Dandelion (Taraxacum officinale). Hepatorestorative herbs restore liver paranechyma. Panax ginseng (250 500 mg / kg) accelerates liver regeneration and ameliorates liver injury after hepatectomy in dogs (Kwon 2003). In studies relating to regeneration of livers of rats subjected to partial hepatectomy, silybin from Milk thistle (Silybum marianum) increased mitotic activity of Kupffer’s cells. Globe artichoke (Cynara scolymus) is also considered to be regenerative.
The hepatoprotective herb Milk thistle (Silybum marianum) is one of the best known liver herbs. It protected against Amanita phalloides poisoning in Beagles and prevented deaths in all of the silibinin-treated dogs compared to controls. Silymarin was tested in dogs suffering from CC14 intoxication of the liver and treated dogs had significantly lower AST and ALT compared with the control CC14-intoxicated group. Other herbs with hepatoprotective properties include Burdock (Articum lappa), Andrographis (Andrographis panniculata), Bupleurum (Bupleurum falcatum), Tumeric (Curcuma longa), Globe artichoke (Cynara scolymus), Asian Ginseng (Panax ginseng), Phyllanthus (Phyllanthus amarus), Picrorrhiza (Picrorrhiza kurroa), Dan Shen (Salvia multirrhiza), Schisandra (Schisandra chinensis), and Dandelion (Taraxacum radix).
A number of herbs have traditional indications for pancreatic disorders; some have been supported by research. Fringe tree (Chionanthus virginicus) is one of the best known traditional herbs advocated for pancreatic disease, inflammatory or otherwise, and for diabetes. Gymnema (Gymnema silvestre) doubled the number of islet cells and beta cells in diabetic rats after 60 days of administration. It was suggested that it could bring about blood glucose homeostasis through increased serum insulin levels provided by repair / regeneration of the endocrine pancreas.
Emodin (in Aloe vera and other herbs) is a potent agent in the management of clinical and experimental acute pancreatitis. In experiments of induced pancreatitis in rats, the emodin-treated group had significantly lower serum amylase levels compared to controls. Emodin might upregulate gene expression, which subsequently increases DNA synthesis and protein content and then accelerates pancreatic repair and regeneration. Emodin in combination with baicalein has significant therapeutic benefits in severe acute pancreatitis in rats. Dandelion (Taraxacum officinale) showed insulin secretagogue activity, and in a study of induced pancreatitis in rats, it (10 mg / kg PO) reduced IL-6, a principal mediator of acute phase response, and TNF-α production during cholecystokinin-induced acute pancreatitis.