How your armpits smell – and what you do about it – interacts with the same system of microbes in your gut that protects you from pathogens.
Just like in your gut, a diverse community is living under your armpit, and your deodorant and antiperspirant may be changing more than your smell.
The microbes under our arms, on our skin, and in our guts and saliva play an important in protecting us from other microorganisms that don’t belong in our bodies.
A growing body of research shows just how important maintaining the microbiota under your arms and in this entire system is to protecting your overall health.
Recent research has shown that preventing body odor can significantly, and quickly, alter that microbiome.
Everyone has a unique microbiome that fluctuates with our environments. Our particular biomes protect us from pathogens and are part of what create our body odors.
Some have claimed that deodorants and antiperspirants may be carcinogenic, while others have said that there is not enough evidence to prove this.
Breast cancers often develop in the upper, outer region of the breast, and one study suggested that this could be linked both to the amount of tissue in the area and to the application of deodorants and antiperspirants there.
One argument is that the presence of aluminium in antiperspirants, used to stop the secretion of sweat, could be carcinogenic because the metal acts similarly to estrogen.
Currently, the National Cancer Institute of the National Institutes of Health provide some documentation of research on the subject on its website, but says that the results are inconclusive.
Deodorant and antiperspirants change your microbiome
Researchers at the North Carolina Museum of Natural Sciences in Raleigh found that the microbes under peoples’ armpits varied widely depending on whether they wore deodorant, antiperspirant, or nothing.
They found that both deodorant and antiperspirants suppressed the number and diversity of microbes in armpits.
The study analyzed samples from the armpits of 17 participants, grouped by what kind of products (if any) they used to keep their body odor under control.
Over the course of six days, the researchers swabbed the participants’ more or less sweaty armpits.
On the first day, everyone followed their usual hygiene practices. The people that wore antiperspirants had the least number of microbes, and deodorant-wearers had more microbes, but less diversity.
The types of bacteria found in each pair of pits also varied based on the kinds of products used.
The two most common bacteria in armpits are Corynebacterium and Staphylococcaceae. People that didn’t use products had more of the Corynebacterium, which is the primary cause of unpleasant armpit stench.
Those that used a product had more Staphylococcaceae in their subdued microbiomes. Staphylococcaceae can be good and bad for our systems, depending on how it’s balanced out by other microbes.
Corynebacterium, on the other hand, are more protective of our systems. Antiperspirant-wearers had a greater variety of microbes but fewer overall. Since variation has been proven to be important to our overall microbiome health, both forms of smell-prevention had advantages and disadvantages.
After that first day, the participants were asked to stop using their respective body odor-blocking products.
By the sixth and final day of the study, everyone’s microbiomes were all essentially the same, matching up with those of the people that had not used any product to begin with, though everyone’s microbiotic make up – and therefore, smell – is slightly different.
The study concluded that there is simply much more research to be done about our armpits, their smells and what they tell us about our health and ability to fight off environmental pathogens.