Oaks Herb Description – Dosage and Useful Properties
17 November 2007Taxonomic class
Fagaceae
Common Trade Names
Multi-ingredient preparations: Conchae Compound, Eichenrinden_ Extrakt, Entero-Sanol, Hamon No. 14, Kernosan Elixir, Menodoron, Peerless Composition Essence, Pektan N, Silvapin, Tisanes de I’Abbe, Tonsilgon-N, Traxaton, White Oak Bark, White Oak Inner Bark, Wild Countryside White Oak
Common Forms
Available as capsules, decoctions, extracts, unground or powdered oak bark, oak galls, ointments, ooze (a tea of oak bark), and tincture. Oak bark is included in some prepared herbal mixtures and several commercially prepared GI remedies, such as Entero-Sanol.
Source
Oak bark is obtained from the English oak, Quercus robur, and the durmast oak, Q. petraea, members of the beech family. Oaks are slowÂgrowing deciduous trees that occur in Eurasia, North America, and Australia. The bark is taken from young branches and twigs and can be up to 4 mm thick; it is grayish brown on the outside and brownish red on the inner surface.
Oak galls are abnormal growths produced on oak stems and leaves, primarily by insects and nematodes. Many galls are rich in tannins. The leading gallmakers are tiny gall-wasps, which belong to the genus Cynips (Cynipidae family). The insect pierces the shoots and young boughs of the oak and deposits its egg in the Wound. After hatching from the egg, the larva secretes an enzyme-containing fluid that changes starch in adjacent oak cells into sugar, which the larva consumes as a food source. This sugar is also used by growing plant cells, which form a large, protective growth around the developing insect. When the insect reaches the adult stage, it eats its way out of the gal!.
Chemical Components
Oak bark contains tannins, including quercitannic acid and varying amounts of catechins, ellagitannins, and proanthocyanidins. The galls contain tannic acid, gallic acid, resin, calcium oxalate, and starch. Acorns contain primarily tannic acid, gallic acid, and pyrogallol. The content of the tree components varies, depending on the time of harvesting and age of the branches, galls, or acorns. Other compounds found in the bark and galls include beta-sitosterol, friedelin, leucocyanidin, leucodelphinidin, levulin, pectin, quercetin, quercin, quercitol, and the glycoside quercitrin.
Actions
The active ingredients associated with oak bark and galls are the tannins. These highly astringent compounds act locally by precipitating proteins and decreasing cell membrane permeability. Tannic acid exerts astringent action on the mucous membranes of the GI tract; it can also be absorbed from damaged skin and mucous membranes. Although several properties have been reported for other components of oak, these chemicals exist in trace amounts and are unlikely to have clinical effects.
Quercitrin and quercetin have been reported to exert a vasodilating effect. However, studies have found that quercetin is extensively bound to cellular proteins and that it has no effect on CV or thrombogenic risk factors .
Reported Uses
Traditionally, oak bark has been used as an anti-inflammatory, an antiseptic, and an astringent. Although oak galls may be used instead of the bark in small quantities, their use internally is not recommended. Astringent compresses were commonly applied to treat contact dermatitis and eczema in their early, weeping stage. Decoctions, such as vaginal douches, were used to treat leukorrhea; they were also used externally to treat anal fissures, small burns and other dermatologic conditions, foot odor, eye inflammation, hemorrhoids, and varicose veins. A decoction was also reportedly used as a gargle to treat bleeding gums, laryngitis, sore throat, and tonsillitis.
Powdered oak bark was used as a snuff to treat nasal polyps and sprinlded on weeping eczema to dry the affected area. The German Commission E recommends the external use of oak bark for inflammatory skin disorders and the internal use for the local treatment of acute diarrhea and mild inflammatory conditions of the oral cavity, pharyngeal region, and urogenital areas.
Tannic acid has been used in suppositories for hemorrhoids, locally for sore throat and stomatitis, and to harden nipples during breastÂfeeding. It has been shown to inhibit gastric enzyme activity in pigs, an effect attributed to its antisecretory and antiulcerative properties .
Other claims advanced for tannic acid include its use as an antimutagenic, an antinephritic, an antioxidant, an antiviral, a bactericidal, a cancer preventive, a hepatoprotective, an immunosuppressant, a psychotropic, and a viricide.
Dosage
As an antidiarrheal, German Commission E recommends 3 g of the powdered oak bark or equivalent preparations P.O. daily. If diarrhea persists for longer than 4 days, the patient should consult a health care provider. Alternatively, 1 cup of tea P.O. t.i.d., made by adding 1 g of finely cut or coarsely powdered drug or 1 or 2 tsp of chopped bark to 500 ml of water, or 1 tsp of bark per 250 ml of water, boiled for 15 minutes, strained, cooled, and used undiluted.
Baths: 5 g of drug per 1 L of water. Several ready-to-use oak bark extracts are available; typically, 1 to 3 tsp are added to a partial bath.
Capsules: 2 capsules P.O. with meals t.i.d.
Compress, rinse, gargle: Prepare fresh decoction daily by boiling 20 g of drug per 1 L water for 10 to 15 minutes. Use strained liquid undiluted; apply compresses loosely to the affected area to enable free evaporation. External application should typically be needed for only a few days and should not exceed 3 weeks.
Tincture: 1 to 2 ml P.O. t.i.d.
Adverse Reactions
GI: abdominal pain, constipation (with possible fecal impaction), gastroenteritis, hepatic necrosis (with more than 1 g of tannins), hepatotoxicity (with tannic acid enemas and prolonged skin application), indigestion, nausea, vomiting.
GU: nephritis (with tannic or gallic acid in animals).
Respiratory: respiratory failure (with tannic or gallic acid in animals).
Skin: rash around the anus followed by a generalized nonspecific rash and blisters on the roof of the mouth (reported after ingestion of White Oak Bark Tablets).
Other: death (with tannic acid enemas, prolonged skin application). Interactions
Alkaloids, glycosides, heavy metal salts: Precipitation and reduced absorption of these drugs. Avoid administration with oak products internally.
Contraindications and Precautions
Avoid using oak products in pregnant or breast-feeding patients; effects are unknown. External use is contraindicated if extensive skin surface damage is present. Full baths are contraindicated, according to the German Commission E, in patients with discharging, extensively large eczema and skin injuries; febrile and infectious diseases; New York Heart Association classes III and IV; and hypertonia state IV (World Health Organization).
Special Considerations
Caution the patient to avoid having oak come in contact with areas of extensive skin damage, large areas of the body, or the eyes. Instruct him to wash the exposed areas of skin with soap and water and to flush the eyes with tepid water for at least 15 minutes if contact occurs.
Advise women to avoid using oak during pregnancy or when breastÂfeeding.
Caution the patient to avoid full-body baths with the herb.
Advise the patient not to take the herb internally for longer than a few weeks.
Points of Interest
Oaks have a long history of medical use.
At one time, tannic acid was included in barium enemas. Because of reports of some deaths from hepatic necrosis, such use is no longer recommended.
White oak bark (Q. alba) makes a yellowish tea with a slightly bitter, astringent taste.
Commentary
Limited external use of oak decoctions may provide some relief for certain forms of dermatitis, such as eczema and contact dermatitis, and minor burns. Although there are anecdotal reports of the herb’s use internally for diarrhea, clinical studies are lacking. This treatment is not recommended until safety and efficacy data are available.
Tagged under:Herbal Medicines
