Body Odor: Smelly feet and Underarms, Reasons, Symptoms and Treatment

Introduction 

Smelly feet, also known as bromodosis, can be embarrassing and uncomfortable. This condition, is known as smelly feet or foot odor, caused primarily due to the interaction of bacteria residing on the skin with sweat. Similarly, the apocrine sweat glands, which are concentrated in areas like the UNDERARMS, release a type of sweat that contains proteins and lipids. When this sweat comes into contact with bacteria on the skin's surface, it can lead to the production of odor. While the condition is generally not a serious health concern, it can lead to discomfort and self-consciousness.

Areas mainly responsible for Body odor

What is in the sweat that cause bad Odor?

• The sweat glands found in the feet and underarms are primarily Eccrine glands: These glands are particularly important for thermoregulation, helping the body cool down by producing a watery sweat that evaporates on the skin surface.
• But in addition to eccrine glands, there are also Apocrine glands: These glands become more active during puberty and is associated with the production of a thicker, milky sweat. Apocrine sweat contains proteins, and lipids, which can serve as a nutrient source for bacteria on the skin. As the bacteria feed on the proteins and lipids in sweat, they release Volatile Organic Compounds (VOCs) that give rise to the unpleasant smell commonly experienced in areas with a high concentration of sweat glands, such as the feet and underarms. These VOCs are typically small molecules that can easily evaporate into the air.

Skin Glands

The specific VOCs generated during the breakdown of proteins in sweat can vary, but some common compounds include:

1.  Short-Chain Fatty Acids: Bacteria can break down amino acids (proteins), into short-chain fatty acids such as propionic acid, have distinct, pungent, rancid, sour smell and Isovaleric Acid which has a strong, unpleasant cheesy-smelling odor

2.  Sulfur Compounds: Bacteria breakdown certain sulfur-containing amino acids, like cysteine and methionine, into hydrogen sulfide with strong rotten eggs offensive odors and methanethiol, which has sulphur, garlic smell.

Reason for body odor

Bacteria breaks proteins into smelly VOCs and thiols

Several types of bacteria that naturally reside on the skin thrive in warm, moist environments, making areas such as the armpits, groin, and feet particularly susceptible to the development of body odor. Here are some of the bacterial species commonly involved in this process:

1. Corynebacteria: Members of the Corynebacterium genus such as Corynebacterium striatum, Corynebacterium jeikeium and Corynebacterium bovis commonly found on human skin can break down amino acids in sweat into smelly short chain fatty acids.

2.  Staphylococcus: Staphylococcus epidermidis and Staphylococcus hominis are examples of bacteria found on the skin. They contribute to the breakdown of sweat components, into unpleasant cheesy-smelling Isovaleric Acid in feet. Staphylococcus hominis is responsible for producing stinky odor thioalcohols in underarms.

3. Propionibacteria: Propionibacteria, such as Propionibacterium acnes, contribute to the production of odorous compounds propionic acid with pungent, rancid smell a characteristic scent of body odor.

4. Brevibacterium: Brevibacterium species are found on human skin and contribute to the breakdown of sweat, producing smelly compounds such as propionic acid, Isovaleric Acid, short chain fatty acids, hydrogen sulfide and methanethiol

The exact composition of body odor can vary among individuals due to factors like genetics and diet.

What is the role of genetics in body odor?

Sweat itself is generally odorless. Genetic variations can influence the number, size, and activity of sweat glands. Some individuals may have a greater number of active sweat glands, leading to increased perspiration (hyperhidrosis). This supports the growth of various types of bacteria which affects the overall odor of the body.

Some people have active ABCC11 gene encodes a protein called multidrug resistance-associated protein 8 (MRP8). The MRP8 protein, plays a role in transporting the compounds formed in the body such as 3-methyl-2-hexenoic acid (3M2H) and peptide conjugated Cys-Gly-3M3SH (3-methyl-3-sulfanylhexan-1-ol) across the skin membrane into the armpit sweat. Bacteria Staphylococcus hominis producing the enzyme CT-lyase converts Cys-Gly-3M3SH into the pungent thioalcohol, 3M3SH which is associated with underarm sweat bad smell. People with non-functional ABCC11 gene do not have 3M2H and Cys-Gly-3M3SH in their sweat hence no bad odor.

Genetic variations can also influence the composition of sweat and the types of bacteria present affecting the overall scent. For example, some people may naturally produce more sulfur-containing compounds in their sweat such as cysteine and methionine and Brevibacterium species breakdown these into bad smelling hydrogen sulphide and methanethiol.

What is the role of diet in body odor?

Diet can influence body odor, through the types of compounds consumed that may be excreted through sweat and other bodily fluids:

1.  Spices and Strongly Aromatic Foods: Certain foods, especially those with strong flavors and aromas, can impact body odor. Things like garlic, onions, curry, and cumin contain volatile compounds that can be excreted through sweat and breath, contributing to an individual's scent.

Things containing VOCs

2.  Red Meat and Sulfur-Containing Foods: Red meat and sulfur-containing foods, such as cruciferous vegetables (e.g., broccoli, cabbage, Brussels sprouts), eggs, and some types of seafood, contain sulfur compounds. These compounds can be metabolized by the body and excreted through sweat, potentially contributing to rotten eggs like body odor.

3.  Alcohol and Caffeine: Consumption of alcohol and caffeine can affect the body's hydration levels and alter the composition of sweat. Dehydration can lead to more concentrated and potentially odorous sweat.

Foods and beverages causing bad body odor

How to prevent or treat bad body Odor?

Here are some general tips to help prevent or minimize body Odor:

1.    Personal Hygiene:

• Regular Showering or cleaning the affected areas such as armpits, groin area and feet atleast thrice in a day to remove bacteria and smelly sweat that contributes to odor.
• Use of Antibacterial Soap or medicated cleanser containing benzoyl peroxide regularly to kill odor-causing bacteria on the skin.
• Antibacterial oils can be applied which may prevent the growth of microbes and also would not allow sweat to stay on the skin surface but oil may stain the cloths. A thin layer on clean and dry groin area and between the fingers of feet can be effective to control bad odor.
• Shaving of armpits and groin area which will allow to evaporate sweat along with use of sweat absorbing breathable cotton fabrics.
• Use Antiperspirants to reduce sweat production which will help to control bacterial growth by reducing moisture.
• Spray water mixed apple cider vinegar or lemon juice on to the affected area to prevent the growth of microbes
• Reduce stress as it can trigger sweating and contribute to body odor.

Maintain personal hygiene

2.    Dietary Modifications:

• Limit intake of foods known to contribute to body odor, such as garlic, onions, spicy foods, and certain types of fish.
• Drink plenty of water to help dilute sweat and reduce concentration of odor-causing compounds.

3.    Medical Interventions:

• Botox Injections in some cases can be used to reduce sweating in specific areas temporarily.
• Use of electromagnetic waves to destroy sweat glands.

Electromagnetic waves to destroy sweat glands

It's essential to recognize that some level of body odor is natural, and individual preferences for scents vary. However, if body odor is causing distress or discomfort, the tips mentioned above can help manage and minimize it. If home remedies and lifestyle changes are not effective, seeking guidance from a healthcare professional is recommended.