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The case for hairy, healthy armpits

Middle school armpits-- can’t live with them, or without them. So we block those memories out of our memories. While we may not be going through that hormonal roller coaster anymore, summertime is especially hard on armpits. Have you stopped to consider how the dog days have been treating them? Between shaving, waxing and rolling on deodorant we don’t give our armpits the space to be their most authentic selves.

Expert advice says to ditch deodorants all together. Unlike what you must think, authentic doesn’t mean smelly. Most of us don’t spend much time caring for our armpits but we spoke to Dr. Armpit, who has spent his entire career studying the armpit microbiome. He hasn’t smelled bad in years and we found out why.

TL;DR An unbalanced armpit microbiome leads to bad odor, deodorant truly won’t solve the odor problem.


Why do people call you Dr. Armpit? Tell us about your research.

My colleagues gave me that name because I was the only one in the lab working on armpits, doing my  PhD. I specialize in armpits and body odor with the ultimate goal of  solving body odor. That means I spend a lot of time sampling armpits.

How does armpit sampling work?

It’s quite simple, you just swab the area, do a DNA extraction and you do a PCR and other analyses. We take samples of the odor, to link the odor with the bacteria. You can do it directly by having the user wear an underarm patch. Then that’s put in a glass bowl. Then an odor panel of 4 women 4 men who are trained to smell, rate the odor of the sample. Mainly use a hedonic value (the pleasantness of the odor) -8 to 8. They also evaluate the intensity and quality of the odor.

Are there differences in the bacteria that live on your armpit vs. your face vs. any other part of your body? What creates that difference?

There is a strong link between the microbiome and body sites. The differences between body parts can be as diverse as bacteria in the desert vs bacteria in the ocean. It’s a small surface area (the skin) but you can have very diverse areas. Armpits are like a tropical rainforest, rich in nutrients, humid and warm. Legs and arms are very dry, lower pH and much fewer bacteria. The armpit is one of the richest body sites where most bacteria live. A lot of different types of sweat glands exist there, including apocrine and sebaceous glands. This produces a whole bunch of lipids that are food for the bacteria and help them grow. Staphylococcus and corynebacterium are the two most dominant bacterial species found in the armpit (they’ll make up > 80% of your underarm if you don’t wash for 2-3 days).

What do the bacteria in our armpits do? Do they make us smell? Do they reduce itch? Why should we care about cultivating it?

Odor is important and is a reflection of your armpit microbiome. Corynebacterium is an odor causing species, so smelly armpits have more of these bacteria. Your body secretes hormones in the armpit and the microbiome can influence that. A whole range of immune compounds, vitamins and minerals, are secreted by our cells and modulated by our microbiome. This can have an eventual effect on your immune system, overall health and allergic reactions. Rare diseases and infections could also happen. But there aren’t many armpit diseases (thank goodness)

What does an armpit transplant look like? Are they beneficial?

The idea for an armpit transplant came from fecal microbiome transplants which is done in c.diff infections. The whole idea with the armpit is that we have tons of things we can do to try to inhibit body odor, but most of them don’t focus on the microbiome-- just the sweat. (Tweet this)

They think reducing the sweat. But I think sweating is natural and good for your body. It helps to get rid of excess bodily compounds. Body odor comes from the microbiome converting what is secreted by the body. Antiperspirants kill the bacteria without concern for the effects.

My work is about trying to restore the underarm microbiome again the only way I know, which is to transplant it. I started off with identical male twins-- one with bad odor, one without. The transplant was successful. The microbiome of the recipient  shifted to a better one and lasted for a year. We’ve replicated this with 18 people and most of them were able to induce a better microbiome, and odor. It’s possible to change it, but also possible that it could switch back. Now i’m working on techniques to put the ideal transplant microbiome in a spray. We’re doing a clinical trial to see what the effect is of applying the bacteria on the armpits. I’m confident it will have a really good effect.

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What can we do to make our armpits and the rest of our microbiome healthier?

When it comes to non bacteria options for making the microbiome healthier everyone has a unique reaction, you have to experiment for yourself. The first week after you stop using deodorant will suck. But afterwards it could lead to a more stable microbiome. Most deodorants have similar formulations, but the movement for more natural deodorants is good. Avoid those that have 10-15% aluminum ions because they have a very detrimental effect. Non-aluminum deodorants are not as bad for your microbiome.

Have not investigated soaps, but think they have a smaller effect. Soap is a good way to reduce lipids and don’t really kill bacteria. They just increase the pH and throw your microbiome out of balance.

Are there deodorants that are good for the armpit microbiome?

I do not use deodorant. Yes, I do smell good. I’ve investigated my own armpits microbiome. Used to have a bad one but now i’m very happy with it.

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