News Release

Iron-binding compounds decrease body odor

Peer-Reviewed Publication

American Society for Microbiology

SALT LAKE CITY – May 20, 2002 -- Iron in human sweat is a necessary ingredient for bacteria to create the compounds responsible for body odor, and fortifying deodorants with an active system that starves these bacteria of iron significantly decreases body odor.

“Sweat itself does not smell. The bacteria on our skin are responsible for producing the malodor. They feed themselves on the secretions of glands in the underarm, producing odorous molecules as a byproduct. Traditional deodorants use ethanol to kill axillary bacteria. Unfortunately, the ethanol evaporates and the bacteria quickly grow back, ” says Dr. Andrew Landa of the Unilever Research & Development Laboratory in Port Sunlight in the United Kingdom. Dr. Landa and his colleagues present their findings at 102nd General Meeting of the American Society for Microbiology.

Dr. Landa and colleagues identified iron as the trace metal whose deprivation had a strong effect on axillary bacterial growth. Further investigations with iron-chelating agents demonstrated that a number of compounds with high affinities for iron showed optimal activity. One candidate molecule, diethylenetriaminepentaacetic acid (DTPA), was capable of effectively inhibiting bacterial growth on the skin of the lower back of human volunteers.

However, when there is little or no free iron available, some bacteria can use iron from other sources such as iron-carrying proteins, which are also present in sweat. In order to minimize this, an additional molecule, butylated hydroxytoluene (BHT), which can release iron from the iron-carrying protein transferrin, was added. The released iron is then bound by DTPA, before the axillary bacteria can consume it, leaving the bacteria with very little iron and almost unable to grow. A deodorancy efficacy test of the combination of DTPA & BHT showed deodorancy benefits over and above that provided by DTPA alone.

The combination of DTPA & BHT, tested on 50 people for two weeks, was very effective in limiting bacterial growth in the axilla. The average total number of aerobic bacteria in the DTPA & BHT treated axillae was reduced by more than 90% compared with the standard deodorant treated axillae. This was reflected in much lower levels of underarm malodor. After this study, the levels of bacteria in the underarms rapidly returned to pre-use levels after ending product usage.

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This release is a summary of a presentation from the 102nd General Meeting of the American Society for Microbiology, May 19-23, 2002, in Salt Lake City, Utah. Additional information on these and other presentations at the 102nd ASM General Meeting can be found online at http://www.asmusa.org/pcsrc/gm2002/presskit.htm or by contacting Jim Sliwa (jsliwa@asmusa.org) in the ASM Office of Communications. The phone number for the General Meeting Press Room is (801) 534-4720 and will be active from 10:00 a.m. MDT, May 19 until 12:00 noon MDT, May 23.


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