There are an estimated 1000 species of bacteria that make up the skin microbiome. Every day scientists are discovering new ways the microbiome affects the functions of the human body, and have found it even influences whether our sweat makes us smell.Sweat is a process that helps to downregulate body temperature and is vital to keep us alive.
Sweat is produced in 2 types of glands throughout the body, the eccrine sweat glands (produce mainly water and salt) and apocrine sweat glands (potentially smelly).
There are around 2000 apocrine sweat glands in the human body, concentrated around the armpits (and groin), which produce sweat that contains proteins, fatty acids and pheromones. This mixture is made up of many carbon compounds which makes great 'food' for the microbes on the skin.
So, could your microbiome be making you smell worse?
The microbial population of the armpits influence the severity of body odour produced when the bacteria metabolise sweat.
For example, if apocrine sweat is metabolised by a bacterial population that is dominated by bacterias such as Staphylococcus and Corynebacterium it tends to produce compounds that cause high body odour.
However, if the population of bacteria is made up of a bacterial population with higher numbers of Propionibacterium, for example, fewer odour causing compounds are made resulting in low body odour.
Current research is looking into products that can re-introduce 'good' bacteria to help reduce body odour without the need for deodorants and harsh chemicals.
For example, Mother Dirt has created a mist that contains Ammonia Oxidising Bacteria; these bacteria convert the ammonia and urea in swear into byproducts that are both beneficial for the skin and non-smelly.
There are also studies being conducted into the effectiveness of 'armpit microbiome transplants'. An armpit microbiome transplant involves taking a sample of the skin microbiome from someone with low body odour and transplanting this to someone with high body odour, in the hope that the transplanted microbes will repopulate the skin and reduce body odour.
How else is your body odour determined?
The ABCC11 gene is also a determinant of body odour.
This human gene is an ABC transporter and can be found on chromosome 16.
Body odour is determined by the inheritance of a functional (G) type or non-functional (A) type of this gene:
- If there is a functional (G-type) gene produce normal compounds in sweat, these compounds are metabolised by bacteria and result in high body odour
- If there is a non-functional (A-type) gene produce fewer or none of the normal compounds usually found in sweat, when this is metabolised by bacteria results in low body odour
Fewer carbon compounds (caused by non-functional gene) as a food source shifts the microbiome population able to thrive on the skin.
How can you tell your ABCC11 gene type?
The easiest way to tell which gene type you have is by taking a closer look at your ear wax...
This is because ABCC11 influences ear wax type:
- A-type = dry ear wax
- G-type = wet ear wax
Looking at ear wax type is a good way of determining if people have functional or non-functional type of the ABCC11 gene; giving physicians a more time and cost effective alternative to genome sequencing.
The frequency of the functional and non-functional ABCC11 alleles vary depending on country.
- Functional ABCC11 genes, the variation that results in high body odour, is more frequent in Europeans and African-Americans
- However, this allele is not very frequent in Chinese and Korean populations
How else does your ABCC11 gene type affect you?
ABCC11 also impacts cancer survival!
ABCC11, also known as multidrug resistance protein 8, affects the transport of drugs, and other treatments, into and out of cells; it is involved in:
- transporting nucleotide analogues out of cells
- High expression correlates with low acute myeloid survival
- Conferring pemetrexed resistance in lung cancer
This gene is not completely bad news however, as high expression reduces colorectal cancer recurrence.
This knowledge also leads the way to finding treatments that combat the drug resistant functions of this gene to improve survival of patients receiving treatments that could be affected; ABCC11 gene can also be used as a marker when genotyping.