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Foot odor (also spelled foot odour) or bromodosis is a type of body odor that affects the feet of humans.
| | This article needs additional citations for verification .(May 2013) |
Foot odor (also spelled foot odour) or bromodosis is a type of body odor that affects the feet of humans.
The main cause is foot sweat (also see focal hyperhidrosis). Sweat itself is odorless; however, it creates a beneficial environment for certain bacteria to grow, producing odorous substances. These bacteria are naturally present on our skin as part of the human flora. The front part of the foot produces the most sweat. [1]
The smell is exacerbated by factors that increase sweating, such as wearing closed-toe shoes. Sports footwear such as sneakers is often heavily padded inside which provides a perfect environment to trap moisture and allow the bacteria to thrive. Socks can trap foot hair, especially on the toes, and may contribute to odor intensity by increasing surface area on which bacteria can thrive.[ citation needed ]
Given that socks directly contact the feet, their composition can affect foot odor. Synthetic materials like polyester and nylon afford less ventilation to the foot than do cotton or wool, leading to increased perspiration and odor, although they can also reduce incidence of blisters by wicking away perspiration. Many synthetic socks are treated with chemicals to help reduce odor. [2]
Wearing closed-toe shoes (e.g., ballet flats or pumps) without socks leads to accumulation of sweat, dead skin cells, dirt, and oils, further contributing to bacterial growth.
Brevibacteria are considered a major cause of foot odor because they ingest dead skin on the feet and, in the process, convert the amino acid methionine into methanethiol, a colorless gas with a distinctive sulfuric aroma. The dead skin that fuels this process is especially common on the sole and between the toes. Brevibacteria also give such cheeses as Limburger, Bel Paese, Port Salut, Pálpusztai and Munster their characteristic pungency. [3] : 103
Isovaleric acid (3-methyl butanoic acid), another source of foot odor, is produced by Staphylococcus epidermidis , a bacterial species normally resident on human skin [4] and present in several strong-smelling varieties of cheese. [5]
Other implicated microorganisms include Micrococcaceae, Corynebacterium and Pityrosporum . [6]
Bart Knols of Wageningen Agricultural University in the Netherlands received a 2006 "Ig Nobel Prize" [7] for demonstrating that the female Anopheles gambiae mosquito, known for transmitting malaria, is "attracted equally to the smell of Limburger cheese and to the smell of human feet". [8] Fredros Okumu, of the Ifakara Health Institute in Tanzania, received grants in 2009 and 2011 to develop mosquito attractants and traps to combat malaria. [9] He used a blend of eight chemicals four times more effective than actual human secretions. [10]
Maintaining good foot hygiene is the best way to prevent foot odour as it eliminates odour causing bacteria and removes dead skin cells as well as sebum. A foot file, pumice stone or chemical treatment, such as an Alpha hydroxy acid containing foot peel preparation, can be used to remove dead skin cells. [11] [12] Using antibacterial soap to wash feet daily; keeping feet dry by changing socks daily and wearing cotton or wool instead of synthetic fibres can also help reduce moisture build-up. Using medicated insoles and foot powder can also help. [13]
In some cases, medical intervention may be needed to treat the bacterial or fungal infection with a topical antibacterial or fungicide. [14] [15]
Foot odor is one of the most widespread forms of olfactophilia; [16] in a 1994 study, 45% of those with a foot fetish were found to be aroused by smelly socks and/or feet, but most importantly by the intensity of the smell produced by such bacteria. [17]
The Ig Nobel Prize is a satiric prize awarded annually since 1991 to celebrate ten unusual or trivial achievements in scientific research. Its aim is to "honor achievements that first make people laugh, and then make them think." The name of the award is a pun on the Nobel Prize, which it parodies, and on the word ignoble.
Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals.
Foot fetishism, also known as foot partialism or podophilia, is a pronounced sexual interest in feet. It is the most common form of sexual fetishism for otherwise non-sexual objects or body parts.
A deodorant is a substance applied to the body to prevent or mask body odor caused by bacterial breakdown of perspiration, for example in the armpits, groin, or feet. A subclass of deodorants, called antiperspirants, prevents sweating itself, typically by blocking sweat glands. Antiperspirants are used on a wider range of body parts, at any place where sweat would be inconvenient or unsafe, since unwanted sweating can interfere with comfort, vision, and grip. Other types of deodorant allow sweating but prevent bacterial action on sweat, since human sweat only has a noticeable smell when it is decomposed by bacteria.
Body odor or body odour (BO) is present in all animals and its intensity can be influenced by many factors. Body odor has a strong genetic basis, but can also be strongly influenced by various factors, such as sex, diet, health, and medication. The body odor of human males plays an important role in human sexual attraction, as a powerful indicator of MHC/HLA heterozygosity. Significant evidence suggests that women are attracted to men whose body odor is different from theirs, indicating that they have immune genes that are different from their own, which may produce healthier offspring.
Athlete's foot, known medically as tinea pedis, is a common skin infection of the feet caused by a fungus. Signs and symptoms often include itching, scaling, cracking and redness. In rare cases the skin may blister. Athlete's foot fungus may infect any part of the foot, but most often grows between the toes. The next most common area is the bottom of the foot. The same fungus may also affect the nails or the hands. It is a member of the group of diseases known as tinea.
Sweat glands, also known as sudoriferous or sudoriparous glands, from Latin sudor 'sweat', are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial surface by way of a duct. There are two main types of sweat glands that differ in their structure, function, secretory product, mechanism of excretion, anatomic distribution, and distribution across species:
Staphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiota and also found in marine sponges. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to form biofilms that grow on these devices. Being part of the normal skin microbiota, S. epidermidis is a frequent contaminant of specimens sent to the diagnostic laboratory.
Erythrasma is a superficial skin infection that causes brown, scaly skin patches. It is caused by Corynebacterium minutissimum bacteria, a normal part of skin flora.
3-Methylbutanoic acid, also known as β-methylbutyric acid or more commonly isovaleric acid, is a branched-chain alkyl carboxylic acid with the chemical formula (CH3)2CHCH2CO2H. It is classified as a short-chain fatty acid. Like other low-molecular-weight carboxylic acids, it has an unpleasant odor. The compound occurs naturally and can be found in many foods, such as cheese, soy milk, and apple juice.
An apocrine sweat gland is composed of a coiled secretory portion located at the junction of the dermis and subcutaneous fat, from which a straight portion inserts and secretes into the infundibular portion of the hair follicle. In humans, apocrine sweat glands are found only in certain locations of the body: the axillae (armpits), areola and nipples of the breast, ear canal, eyelids, wings of the nostril, perineal region, and some parts of the external genitalia. Modified apocrine glands include the ciliary glands in the eyelids; the ceruminous glands, which produce ear wax; and the mammary glands, which produce milk. They are distinct from eccrine sweat glands which cover the whole body.
Pitted keratolysis is a bacterial skin infection of the foot. The infection is characterized by craterlike pits on the sole of the feet and toes, particularly weight bearing areas.
Skin flora, also called skin microbiota, refers to microbiota that reside on the skin, typically human skin.
Brevibacterium linens is a gram-positive, rod-shaped bacterium. It is the type species of the family Brevibacteriaceae.
A sock is a piece of clothing worn on the feet and often covering the ankle or some part of the calf. Some types of shoes or boots are typically worn over socks. In ancient times, socks were made from leather or matted animal hair. In the late 16th century, machine-knit socks were first produced. Until the 1800s, both hand-made and machine-knit socks were manufactured, with the latter technique becoming more common in the 19th century, and continuing until the modern day.
Immersion foot syndromes are a class of foot injury caused by water absorption in the outer layer of skin. There are different subclass names for this condition based on the temperature of the water to which the foot is exposed. These include trench foot, tropical immersion foot, and warm water immersion foot. In one 3-day military study, it was found that submersion in water allowing for a higher skin temperature resulted in worse skin maceration and pain.
Smelly socks are socks that have acquired a foul odor due to prolonged wearing on feet. Their odor, which is complex and remains the object of study, is a mixture of ammonia, fatty acids, and lactic acid.
Năsal is a traditional Romanian cheese bearing the same name as the village where it is produced in the Țaga commune, Cluj County. It is a smear-ripened cheese made from cow's milk. Năsal is produced by Napolact, in a natural cave, traditionally used in the cheese-making process from the Middle Ages. Its characteristics and flavour are imparted by the unique microbiological conditions in which it is manufactured. The rock of the cave and the Brevibacterium linens bacteria which developed in it, the constant temperature and humidity, act on the cheeses produced here.
Limburger is a cheese that originated in the Herve area of the historical Duchy of Limburg, which had its capital in Limbourg-sur-Vesdre, now in the French-speaking Belgian province of Liège. The cheese is especially known for its strong smell caused by the bacterium Brevibacterium linens.
Fredros Okumu is a Kenyan parasitologist and entomologist, who currently works as director of science at the Ifakara Health Institute (IHI) in Tanzania. His primary research interests concern the interactions between humans and mosquitoes.