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United States Department of Agriculture

Agricultural Research Service

Research Project: ABSORPTION AND METABOLISM OF ESSENTIAL MINERAL NUTRIENTS IN CHILDREN

Location: Children's Nutrition Research Center

Title: Effect of tannic acid on iron absorption in straw-colored fruit bats(Eidolon helvum)

Authors
item Levin, Shana -
item Chen, Zhensheng -
item Abrams, Steven -

Submitted to: Journal of Zoo Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2009
Publication Date: June 15, 2010
Citation: Levin, S.R., Chen, Z., Abrams, S.A. 2010. Effect of tannic acid on iron absorption in straw-colored fruit bats(Eidolon helvum). Journal of Zoo Biology. 29(3):335-343.

Interpretive Summary: Too much absorption and subsequent storage of dietary iron has been found in a variety of captively held birds and mammals, including fruit bats. It is thought that feeding a diet that is low in iron can prevent the onset of this disease; however, manufacturing a diet with commonly available foodstuffs that contain a sufficiently low iron concentration is difficult. An alternative is to feed captive animals that may be susceptible to these disease potential substances, such as tannins that may bind to iron and block its absorption. Using stable isotope methods established in humans, we measured iron bioavailability in straw-colored fruit bats (Eidolon helvum), and tested whether tannic acid significantly reduced the extent of iron absorption. Regardless of dose, tannic acid significantly reduced iron absorption (by 40%) and in the absence of tannic acid, iron absorption was high (up to 30%), more so than in humans. This means that tannic acid could be considered for use in the care of captive birds and mammals to prevent them from absorbing too much iron. Information gained from this study provides information to better understand iron absorption in mammals and humans.

Technical Abstract: Excessive absorption and subsequent storage of dietary iron has been found in a variety of captively held birds and mammals, including fruit bats. It is thought that feeding a diet that is low in iron can prevent the onset of this disease; however, manufacturing a diet with commonly available foodstuffs that contains a sufficiently low iron concentration is difficult. An alternative is to feed captive animals that may be susceptible to this disease potential iron chelators such as tannins that may bind to iron and block its absorption. Using stable isotope methods established in humans, we measured iron bioavailability in straw-colored fruit bats (Eidolon helvum) and tested whether tannic acid significantly reduced the extent of iron absorption. Regardless of dose, tannic acid significantly reduced iron absorption (by 40%) and in the absence of tannic acid, iron absorption was extensive in this species (up to 30%), more so than in humans. Species susceptible to iron storage disease may efficiently absorb iron in the gut regardless of iron status, and supplementing these species with tannic acid in captivity may provide an alternative or additional means of preventing the development of this disease.

Last Modified: 8/19/2014
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