The microbes that make socks smelly can survive on unwashed fabric for months. (Credit: Krakenimages.com/Shutterstock)
It’s pretty normal to wear the same pair of jeans, a jumper or even a t-shirt more than once. But what about your socks?
If you knew what really lived in your socks after even one day of wearing, you might just think twice about doing it.
Our feet are home to a microscopic rainforest of bacteria and fungi – typically containing up to 1,000 different bacterial and fungal species. The foot also has a more diverse range of fungi living on it than any other region of the human body.
The foot skin also contains one of the highest amount of sweat glands in the human body.
Most foot bacteria and fungi prefer to live in the warm, moist areas between your toes where they dine on the nutrients within your sweat and dead skin cells. The waste products produced by these microbes are the reason why feet, socks and shoes can become smelly.
For instance, the bacteria Staphylococcal hominis produces an alcohol from the sweat it consumes that makes a rotten onion smell. Staphylococcus epidermis, on the other hand, produces a compound that has a cheese smell. Corynebacterium, another member of the foot microbiome, creates an acid which is described as having a goat-like smell.
The more our feet sweat, the more nutrients available for the foot’s bacteria to eat and the stronger the odor will be. As socks can trap sweat in, this creates an even more optimal environment for odor-producing bacteria. And, these bacteria can survive on fabric for months. For instance, bacteria can survive on cotton for up to 90 days. So if you re-wear unwashed socks, you’re only allowing more bacteria to grow and thrive.
The types of microbes resident in your socks don’t just include those that normally call the foot microbiome home. They also include microbes that come from the surrounding environment – such as your floors at home or in the gym or even the ground outside.
In a study which looked at the microbial content of clothing which had only been worn once, socks had the highest microbial count compared to other types of clothing. Socks had between 8-9 million bacteria per sample, while t-shirts only had around 83,000 bacteria per sample.
Species profiling of socks shows they harbor both harmless skin bacteria, as well as potential pathogens such as Aspergillus, Candida and Cryptococcus which can cause respiratory and gut infections.
The microbes living in your socks can also transfer to any surface they come in contact with – including your shoes, bed, couch or floor. This means dirty socks could spread the fungus which causes Athlete’s foot, a contagious infection that affects the skin on and around the toes.
This is why it’s especially key that those with Athlete’s foot don’t share socks or shoes with other people, and avoid walking in just their socks or barefoot in gym locker rooms or bathrooms.
What’s living in your socks also colonizes your shoes. This is why you might not want to wear the same pair of shoes for too many days in a row, so any sweat has time to fully dry between wears and to prevent further bacterial growth and odors.
Foot Hygiene
To cut down on smelly feet and reduce the number of bacteria growing on your feet and in your socks, it’s a good idea to avoid wearing socks or shoes that make the feet sweat.
Washing your feet twice daily may help reduce foot odor by inhibiting bacterial growth. Foot antiperspirants can also help, as these stop the sweat – thereby inhibiting bacterial growth.
It’s also possible to buy socks which are directly antimicrobial to the foot bacteria. Antimicrobial socks, which contain heavy metals such as silver or zinc, can kill the bacteria which cause foot odor. Bamboo socks allow more air flow, which means sweat more readily evaporates – making the environment less hospitable for odor-producing bacteria.
Antimicrobial socks might therefore be exempt from the single-use rule depending on their capacity to kill bacteria and fungi and prevent sweat accumulation.
But for those who wear socks that are made out of cotton, wool or synthetic fibers, it’s best to only wear them once to prevent smelly feet and avoid foot infections.
It’s also important to make sure you’re washing your socks properly between uses. If your feet aren’t unusually smelly, it’s fine to wash them in warm water that’s between 30-40°C with a mild detergent.
However, not all bacteria and fungi will be killed using this method. So to thoroughly sanitize socks, use an enzyme-containing detergent and wash at a temperature of 60°C. The enzymes help to detach microbes from the socks while the high temperature kills them.
If a low temperature wash is unavoidable then ironing the socks with a hot steam iron (which can reach temperatures of up to 180–220°C) is more than enough kill any residual bacteria and inactivate the spores of any fungi – including the one that causes Athlete’s foot.
Drying the socks outdoors is also a good idea as the UV radiation in sunlight is antimicrobial to most sock bacteria and fungi.
While socks might be a commonly re-worn clothing item, as a microbiologist I’d say it’s best you change your socks daily to keep feet fresh and clean.
Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of Leicester. She does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
I am surprised to read wool socks should not be worn more than one day, based on what I see about wool socks. The advertising for wool socks state wool socks can be worn for as long as a week. This is due to wool socks having natural anti-mycobacterial properties. Same thing for Alpaca socks.
I wouldn’t recommend doing so on a regular basis, but yes, you can wear the same pair of socks two days in a row BUT that depends.
1. Level of exertion
2. Do the shoes breath?
3. Are your shoes and feet dry?
4. Do you rotate your shoes or just wear the same sneakers every day?
5, Your age. I’m 64, and don’t really need to meticulously scrub my feet anymore. When I was a kid, I would practically boil them and they still stunk.
This sounds more like the author’s experiences than a scientific generalization. In addition to the type of daily activities one engages in, especially whether you get your socks wet, genetics plays a big role in foot perspiration and even in the types of bacterial colonies. I could easily wear the same pair of socks for two weeks and you would not be able to pick them out of a drawer surrounded by identical pairs of clean socks. In contrast, I have a very fit and healthy friend who finds he sometimes needs to change socks twice a day. There is some evidence that soaps can play an adverse role by disrupting one’s healthy skin environment.