How to Get Rid of Foot Odor (The Scientific Way)
Foot odor is a common problem with lots of not-so-effective treatments.
Sprays, creams, powders and insoles might minimize foot odor, but these products are designed to keep you buying them on a regular basis. Natural remedies like vinegar baths, or soaking feet with epsom salts and essential oils may have some benefits, but they're not convenient. The worst remedies are old wives' tales like "put your shoes in the freezer." Nonsense.
It's important to understand why feet stink before trying to solve the problem.
Why Most Foot Odor Treatments Fail
Brevibacteria are the cause of smelly feet. This genus of bacteria eats dead skin and creates a stinky, sulfuric waste product. You can wash your feet thoroughly, but that won't stop the bacteria in your shoes from recolonizing your feet. You can kill the bacteria in your shoes with an antibacterial spray (like Lysol), but that won't stop the waste product from stinking. You can clean your shoes thoroughly, but that won't stop new bacteria from growing on your skin.
The only way to "eliminate" foot odor is to attack all of these causes at once.
How to Prevent Foot Odor
Good foot hygiene is not complicated, but it is a process that has several steps:
Wash feet daily;
Remove dead skin from the feet;
Wear natural-fiber socks and change them daily; and
Keep footwear clean and rotate it regularly.
Washing Feet Daily
The human foot can harbor bacteria counts that are 7-12 times greater than those occurring on freshly-washed skin (elsewhere on the body), according to a 1969 Soviet space study.
Make no bones about it: Feet mush be washed often and well.
The ideal foot soap is antibacterial and moisturizing, however, some skin types react differently to soaps and detergents. For example, let’s look at tea tree oil.
A 2006 study published in Clinical Microbiology Reviews concludes that "data now supports the long-held beliefs that [tea tree oil] has antimicrobial and anti-inflammatory properties,” however, the same study also cautions that tea tree oil "can cause both irritant and allergic reactions." Talk to your dermatologist or allergist about which type of soap is best for you.
Removing Dead Skin
Dead skin is both the food and shelter for odor-causing bacteria that live on our feet. Unfortunately, moisturizer can't bring dead skin back to life and topical treatments aren't very effective at removing it. Files and pumice are two effective ways at removing dead skin, but these tools must be used carefully.
A foot file (sometimes called a pedicure rasp or callus remover) is a sharp, cheese-grater like tool that slices off dead skin. It's useful when large calluses are formed, but not as manageable for day-to-day care.
Pumice is a porous volcanic rock that can be used to exfoliate skin by rubbing the abrasive stone on dead skin. There is also synthetic pumice that is specially designed for feet. These products look like sponges, but they are made with coarse micro-plastic beads that shed during use.
(Microplastics that enter our water supply are not filtered out; the long-term impact on ocean life and human health isn’t known.)
Regardless of the tool used, removing dead skin is an ongoing process, not a one-time job. Exfoliating with a "heavy hand" can cause injury and create more dead skin as a result.
Wearing Natural-Fiber Socks
Human feet can excrete as much as eight ounces of sweat per day, according to the California Podiatric Medical Association. That moisture, coupled with the darkness within shoes, is a breeding ground for bacteria. But, the interplay between feet, socks and shoes is complicated.
Natural fibers like cotton and wool are better at absorbing moisture than synthetic fibers like polyester, whereas synthetic fibers are often designed to wick moisture away (into the shoe).
A 2014 study published in the peer-reviewed Applied and Environmental Microbiology analyzed how nine types of athletic textiles smelled after a workout. At heart, the study was a comparison between cotton and polyester: It concluded that cotton produces less odor. This is why a pair of cotton underpants might smell fresh after a workout, even if the polyester sport pants worn above them smell like body odor. Strange.
Additionally, there was a hidden surprise in the research: "Although wool was associated with high bacterial counts, the odor intensity ratings were the lowest for wool." This throws cold water on claims that wool is antimicrobial, but the fiber does minimize odors. Unfortunately, the authors did not explore this paradox.
The upshot: Natural materials like cotton and wool are better at minimizing bacterial odors.
Rotating Shoes and Keeping Them Clean
Wearing the same shoes allows larger bacterial colonies to form, according to Kenyon College's microbiology wiki. Therefore, it is better to wear shoes on an alternating schedule.
Spraying shoes with anti-bacterial spray like Lysol might kill the bacteria inside, but it won't eliminate the ammonia-like smell of the bacteria's waste product. One way to kill bacteria and remove its' waste product is to swab the inside of a shoe with alcohol.
70%-concentrated isopropyl alcohol (i.e. rubbing alcohol) is highly effective at killing bacteria, but, it can damage the finish of many shoes, as well as stiffen plastic or degrade leather. Apply it carefully.
Interestingly, a 2006 study published in the Canadian Journal of Microbiology found that citral, citronellal, and geraniol -- three ingredients that are often found in all-natural bug sprays -- inhibit the production of isovaleric acid, a bacterial byproduct that causes foot odor. Indeed, an occasional spritz of citronella can keep shoes smelling fresh in between wear.
Foot odor is natural and it can't be eliminated entirely, but, it can be reduced to the extent that it becomes imperceptible. This doesn't require expensive products or oddball remedies, rather, it takes good hygiene and an understanding of why feet and shoes get smelly in the first place.