1st – Foot odor

Cause of odor

Mainly, foot odor is caused by breeding microbes (fungi and bacteria).
A foot covered by a sock and shoe, can turn out to be around 32 degrees Celsius, with a relative humidity of 80 to 90 percent, making it an optimal environment for fungi growth. Furthermore, there is a lot of fluid that gets held between the sock and shoes when sweating. With such abundance in fluids, it makes it easier to construct an environment for bacteria to breed.
Within these conditions inside the shoe, fungi and bacteria propagate absorbing from an abundance of nutrients such as foot sweat, sebum (natural skin oils), protein blots, and the shoes' raw materials, causing this peculiar odor.

Athlete's foot

Besides foot odor, athlete's foot causes damaging effects with microbe propagation. Technically, it is a kind of cutaneous mycosis, causing the Trichophyton fungus to penetrate the foot’s skin and propagate, causing skin irritation and severe itching.

Sweaty feet

The soles of the feet are the areas within the body that sweats the most, from 20 to 50 times more than other areas of the body. If you wear shoes for 10 hours on average, 200 milliliters of sweat come out of both feet. So, why do feet sweat so much?
Although perspiration (thermal sweating) is a means to regulate a person’s body temperature, the excessive sweat (emotional sweating) from the palms of your hands or soles of your feet results from mental strain and agitation. When stress such as mental strain and agitation is thrown in, you sweat in larger quantities than usual. Furthermore, if you leave that sweat as is, the sweat pH becomes weak alkaline, creating conditions that make it even easier for microbes to breed.
The socks' purpose is to absorb and emit sweat so fluids will escape, and suppress microbe breeding.

The composition of sweat

The sweat that comes out of the sweat glands (eccrine glands) of the soles of the feet is transparent and roughly 99.5 percent fluid. Besides this, minimum amounts such as sodium ions, potassium ions, chlorine ions, carbohydrate derivatives, urea, ammonia, amino acid, fatty acid, sterol, phenol, and vitamins are present, but since there is little of the substance that is the cause of the smell, feet sweat is odor free. It is pH 5.7 to 6.5, and serves the purpose of preserving the skin surface’s mild acidity.

Where are microbes from?

We are not usually conscious of them, but microbes which are the cause of foot odor exist all over the place within everyday life. On the surface of floors or tatami mats, in dust or dirt, and there are also lots of microbes on the surface of people’s skin. Microbes that exist inside shoes are the ones that have the closest connection to feet. The inside of the shoe, which can always easily become an environment where microbes can easily breed, is the ultimate microbe hotbed.
Socks protect the feet from these microbes, such as those inside the shoes, to assist in making hygienic conditions. There are chances that virulent bacteria can be detected particularly in shoes that have been worn by an unspecified number of people such as rental bowling shoes. Those who have a scar on their feet, should beware of being infected.

Cutaneous bacteria

On human skin, there exists a large number of microbes known as cutaneous bacteria. The number of normal inhabitant for a healthy person is a hundred thousand to one million per square centimeter. The main microbe is a nonpathogenic bacteria (corynebacterium, staphylococcal bacteria, etc.) which is known to function as a barrier to prevent the propagation of harmful bacteria.

How to prevent foot odor?

The cause of foot odor is the breeding of microbes. So what can be done to not let microbes breed?

(1) Keep your feet as dry as possible

• Wear shoes with good ventilation so your feet do not sweat.
• Wear socks that absorb and desorb moisture well. Socks that are 100 percent wool are known to absorb and desorb moisture well, allowing feet to sweat less, decreasing odor.
• Change your socks as much as possible each time your socks become wet from sweat.