Effects of Tannic Acid on the Body

Tannic acid is a substance that occurs naturally in oak trees and related species. It is used as a preservative in a variety of commercially sold foods including baked goods, baking mixes, soft and hard candy, alcoholic and nonalcoholic beverages, meat products and rendered fat products. It is also used in topical medications as a fungicide and astringent, and it may be used in diarrhea treatments.

Ulcerations

• The West Virginia University Extension Office warns that high doses of tannic acid, in the form of acorns, can be dangerous to cattle.

  The FDA reviewed an array of research documentation on tannic acid in 1977. While it stated in its findings that there is no evidence of clear and present danger to the public health from food-grade tannic acid, administered in quantities of less than 100 ppm (parts per million), the agency also stated a need for further testing, based on several conflicting results obtained in laboratory animal tests.

  When tannic acid was administered at doses of 0.5, 1.0 and 2.0 grams per kilogram of body mass, abdominal lesions and ulcerations were reported in the test animals. In this test tannic acid was administered directly to the stomach through an abdominal tube. Furthermore, tannic acid is known to cause ulcerations of the mouth, esophagus and gastrointestinal tract, when consumed in large quantities by cattle allowed to graze in areas where acorns are prevalent.

Liver Failure

• Buis and Hartman performed tests on laboratory rats to determine the effects of tannic acid on the liver.

  According to Medscape Today, the first concerns about the effects of tannic acid on the liver arose as early as 1938. Doctors Wilson, Macgregor and Stewart noted that in "post-mortem examination in a series of 33 severely burned, fatal cases revealed a characteristic degeneration and necrosis of liver cells, which was much more intense than that seen in other organs." They later linked these findings to burn treatment, provided in the form of tannic acid therapy.

  By 1942 concerns among professionals escalated, and a wide range of experiments were performed, on both human and animal subjects. Early research reported "liver damage in burn patients who had some form of tannic acid therapy." Later research by Buis and Hartman confirmed these findings.

Toxic Effects

• Oak poisoning in cattle is caused by the high levels of tannic acid found in acorns in the fall.

  Oak poisoning in cattle, which leads to severe illness and often death, is directly related to the consumption of tannic acid by cattle grazing in the fall. The early symptoms of oak poisoning include constipation and decreased appetite. This may be followed by watery diarrhea, bloody diarrhea, difficulty urinating and defecating, edema (swelling) and finally death.

Birth Defects

• WebMD advises pregnant women against taking oral medications or using topical medications containing tannic acid.

  Consumption of tannic acid in large quantities by pregnant cows can result in birth defects. WebMD advises against taking oral medications or using topical creams and gels containing tannic acid if you are pregnant.