Bacteria are the reason behind most foot odor, including the one that makes boots smelly. Each foot creates about half a pint of perspiration daily, which soaks into socks and the lining of shoes and boots. When coupled with the heat created by the foot, the wet fabric becomes the ideal medium for bacterial growth, which leads to the odor, according to HowStuffWorks.
Staphylococcus epidermidis and Bacillus subtilis are two examples of bacteria that normally live on the skin of the feet. These bacteria consume leucine, an amino acid created in the sweat produced by the feet. As these organisms consume leucine, they produce isovaleric acid, a gas that is responsible for foot odor. Individuals who have a higher concentration of Bacillus subtilis create more unpleasant odors than others. If foot odor has an ammonia or sulfur smell, a different microorganism, Brevibacterium linens is the likely culprit. In addition to the unpleasant foot odor, this bacterium provides the characteristic smell of Limburger cheese.
Dr. Scholl's offers several suggestions to prevent smelly boots. Dry, well-ventilated feet prevent the moisture needed for bacteria to grow. Wearing the same shoes without providing time for them to dry thoroughly increases the growth of bacteria. Clean cotton socks help to wick the perspiration away from the skin without soaking the shoes. Good daily hygiene, including washing and drying the feet well, helps to keep odors away.