Tannic Acid

Botanical Description & Habitat

Many Herbs contain Tannin or Tannic acid compounds.

Commercially a type of acorn from oak trees is used.

Native Americans used to derive their tannic acid from the brains of buffaloes in order to "tan" the hides.

 

Historical Properties & Uses

Because tannins are naturally astringent, almost all plants containing them are used as astringents. Tannic acids help eliminate diarrhea, reduce swelling of hemorrhoids, loosen catarrh in the respiratory system, and control various kinds of internal bleeding. Externally, tannins are beneficial in rubs for aching muscles and joints, in salves for open, slow-healing sores, and as antiseptics. Plants high in tannic acid have been used to treat cancers, but tannic acid itself has been found to be carcinogenic under certain conditions.

In very small amounts, tannic acid is approved for food use and is added to many commercial foods. Since the astringecy of tannic acid involves the precipitation of protein, the addition of protein (such as milk or cream) to a tannin-rich tea would "bind" the tannin, rendering it biologically inert.
 

Method of Action

Tannic Acid Is Astringent
The astringency of tannins comes from their ability to precipitate protein. This astringency varies from plant to plant depending upon the kinds of tannins present, the total concentration of the tannins, and ratio of the different types of tannins to each other. The two main tannins are gallic acid and catechinic acid. Another common tannin is ellagic acid.

Tannic Acid Has Antibiotic Properties
Several studies have shown tannic acid has antiviral, antimicrobial, and antibacterial properties. In many cases it acts directly on the organism to inactivate it. Tannins have also been implicated in hyaluronidase system. That is, they destroy hyaluronidase in much the same manner as does echinacea, thereby defending the cells of the body against viral invasion.
 

Drug Interactions & Precautions

Known Interactions
Solubilized tannins are inactivated by proteinaceous solvents, such as milk.

Possible Interactions
Tannins many potentiate the antibiotic activity of echinacea.

The topical application of tannic acid in conjunction with the acne product tretinoin (retinoic acid, vitamin A acid), may adversely affect the skin.
 

Safety Factors & Toxicity

In concentrated doses, tannic acid demonstrates hepatocarcinogenic properties in both animals and humans. Fatal liver damage can occur as the result of using pure tannic acid externally on burns or as an ingredient in enemas.

The real toxic agent may be digallic acid, a common impurity in tannic acid preparations. Large oral doses of tannic acid can cause nausea and vomiting. High concentrations of tannic acid extracted from nutgalls can impair vitamin B-12 in rats, by forming insoluble, non-absorbable complexes.

Herbs containing tannic acid have not been implicated in the above conditions.
 

Preparation & Administration

There is presently insufficient data on this subject.
 

References

Am Hospital Formulary Service. Am Soc of Hosp Pharm. Wash, D.C.

Bate-smith, E.C. Phytochemistry, 12, 927, 1973.

Bressler, R., M.D. Bogdonoff & G.J. Subak-Sharpe. 1981. The Physicians Drug Manual. Doubleday & Co, Inc. Garden City, NY. 1213 pp.

Carrera, G., S. Mitjavila & R. Derache. Effet de l'acide tannique sur l'absorption de la vitamine B12 chez le rat. Comptes Rendus Academie Societe Biologie (Paris), 276, 8 Jan 1973, pp. 239-242, Series D.

Goodman, L.S. & A. Gilman. 1975. Pharm Basis of Thera. MacMillan, NY.

Hansten, P.D. 1979. Drug Interactions, 4th ed. Lea & Febiger, Phila.

Kastrup, E.K., ed. 1981. Drug Facts and Comparisons, 1982 edition. Facts and Comparisions Division, J.P. Lippincott Co, Phila (St. Louis).

Leung, Albert Y. 1980. Encyclopedia of Common Natural Ingredient used in Food, Drugs and Cosmetics. John Wiley and Sons, New York. 409 pp.

List, P. & L. Hoerhammer. 1969-1976. Hagers Hanbuch der Pharmazeutischen Praxis, vols. 2-5. Springer-Verlag, Berlin.

Martin, E. Drug Interactions Index, 1978/79. J.B. Lippincott Co., Phila.

Morton, J.F. Quarterly J. Of Crude Drug Research, 12, 1829, 1972.

Mowrey, Daniel B., Ph.D. Exper. Psych., Brigham Young University. Director of Nebo Institute of Herbal Sciences. Director of Behavior Change Agent Training Institute. Director of Research, Nova Corp.

Regerat, F., A. Pourrat, D. Jean & H. Pourrat. Purification d'extraits de plantes a tanins par fermentation. Ann Pharmaceutiques Francaises, 40(2), 173-178, 1982.

Sokolova, V.E., et. al. Prikl. Biokhim. Mikrobiol., 5, 694, 1969. Through Chem Abstracts 72, 63944t, 1970.

Truhaut, R. Potential Carcinogenic Hazards From Drugs, Uicc Monograph Series, Springer-verlag, Berlin-new York, 7, 1967, p. 7-27.

Vincent, D. & G. Segonzac. Action du tanin sur l'hyaluronidase. Comptus Rendus Societe Biologie. 147(21 Nov). 1776-1779. 1953.

Vincent, D. & G. Segonzac. 1953. Comptes Rendus des Seances de la Societe de Biologie et de ses Filiales, 147. pp. 1776-1779.