Curiosity Weekly – "Tips For Pits: The Science of Body Odor"

Host: Dr. Samantha Yammine (Dr. Sam)
Guest: Dr. Chris Callewart ("Dr. Armpit"), Microbiologist, University of Ghent
Release Date: February 18, 2026

Episode Overview

This episode plunges into the often-overlooked world of body odor—its science, origins, and what can (and can’t) be done about it. Host Dr. Sam welcomes Dr. Chris Callewart, known playfully as "Dr. Armpit," to reveal what’s really brewing under our arms and why our war on body odor may be doing more harm than good. The episode decodes how microbes, sweat, culture, genetics, and everyday habits interact to create our unique scents, and provides practical (and sometimes surprising) advice on how to manage your own aroma.

Key Discussion Points & Insights

1. The Cause of Body Odor vs. Sweat

[09:22 – 09:36]

• Body odor isn’t just about moisture; it needs both sweat and bacteria to arise.
• Specific sweat glands (apocrine) found in underarms and groin produce the thick, sticky kind of sweat that provides the raw material for odor.

Notable Quote:

"There's two reasons for body odor. One is sweat and the second is bacteria. So you need both."
— Dr. Chris Callewart [09:36]

2. The Underarm Microbiome: Diversity & Dominance

[10:31 – 10:57]

• Each underarm harbors 100–200 bacterial species, and the dominant strains determine individual scent.
• Shifts in the microbial community—especially the rise of "bad" bacteria—produce specific odors ranging from musty to oniony or even cannabis-like.

3. Evolution, Culture & Deodorant’s Surprising Effect

[11:10 – 13:24]

• Deodorant’s rise is very recent; widespread daily use only began after WWII.
• Using deodorants, especially antiperspirants, can shift the skin’s microbial balance—sometimes selecting for smellier bacteria.
• Cultural differences are profound; for example, many East Asian populations have a gene mutation that makes them nearly immune to underarm odor.

Notable Quote:

"Deodorants...cause a vast shift in microbiome...Short term you kill bacteria and less bacteria is less odor. But...bacteria adapt...and the smelly bacteria come back the fastest."
— Dr. Chris Callewart [11:10–12:24]

Science Fact:

• Koreans with dry, white earwax have a genetic mutation that leads to less smelly armpits.
  — [12:24]

4. The Social and Biological Role of Scent

[13:24 – 15:26]

• While modern humans cover up scent, in the animal kingdom, odors are crucial for communication and health signaling.
• Scent changes can indicate health issues or hormonal states (e.g., puberty, illness, diabetes).
• Dogs’ olfactory superpowers are highlighted—detecting diseases from scent cues undetectable to humans.

5. Skin Microbiome & Mosquitoes

[15:26 – 16:18]

• The composition of your skin bacteria impacts how attractive you are to mosquitoes.
• Emerging research is attempting to manipulate skin microbiomes to reduce mosquito bites and disease transmission.

Notable Project:

"We're doing a big project...trying to change the skin microbiome in order to have less mosquito attraction..."
— Dr. Chris Callewart [15:50]

6. Do Skincare Products Mess with Our Skin Bacteria?

[16:18 – 18:27]

• Antimicrobials in foot powders and antiperspirants significantly alter skin microbiota, unlike facial lotions or sunscreen.
• Use of these products can trigger a cycle where smellier, more resilient bacteria take over as the skin adapts.
• Many people get "stuck" chasing new products as their natural microbial balance is disrupted.

Notable Quote:

"It creates a little bit of a vicious circle where we apply products and we need to apply more..."
— Dr. Chris Callewart [17:46]

7. “Deodorant Detox”: Can Less Really Be More?

[18:27 – 20:14]

• Avoiding deodorant or washing less frequently can, over time, let your skin microbiome rebalance—sometimes reducing odor.
• The adjustment period can be one to two weeks of potentially stronger odor.
• The result isn't always guaranteed; sometimes "smelly" bacteria win the microbial battle.

8. The Myth of Sweat Volume and Smell

[20:14 – 21:27]

• Sweating heavily doesn’t mean you’ll necessarily smell more; the key factor is which bacteria dominate.
• Stress sweat is notably smellier due to hormonal shifts, especially adrenaline activating apocrine glands.

Notable Quote:

"It's not related to how much you sweat...it's which bacteria we have there."
— Dr. Chris Callewart [20:39]

9. Diet, Stress, and Lifestyle: Smell from Inside Out

[21:27 – 22:57]

• Diet profoundly influences your scent (e.g., red meat, caffeine, sugar, and processed foods can worsen odor).
• The gut and skin microbiomes are linked—gut health conditions like eczema, acne, and body odor are connected.

Notable Quote:

"You are what you eat, you smell how you eat."
— Dr. Chris Callewart [22:57]

10. Dr. Armpit’s Tips For Your Pits

[23:23 – 24:44]

• Dr. Callewart's personal routine: no deodorants, no shampoo.
• Tips:
  • Eat more vegetables (esp. greens like spinach/kale)
  • Favor fish and omega-3s, minimize red meat
  • Cut back on fast food, sugar, sodas, caffeine
  • Reduce stress
  • Wear cotton/natural fibers instead of synthetic
  • Don’t overestimate your odor—most people can't smell what you can

Memorable Closing Reminder:

"People always rate their underarms as worse than it is in reality... A bit of odor is perfectly okay."
— Dr. Chris Callewart [24:44]

Timestamps for Core Segments

• Intro & Vascan Peanut Patch News: 01:55 – 05:28
• Body Odor Science with Dr. Armpit Begins: 08:37
• What Causes Body Odor?: 09:22
• The Microbiome Recipe: 10:31
• History and Culture of Deodorant: 11:10
• Genetic/Cultural Differences (East Asian mutation): 12:24
• Odor as Health Signal / Animal Kingdom: 13:39
• Mosquito Attraction: 15:26
• How Products Change Our Microbes: 16:18
• Hiker “Deo Detox” Folk Wisdom: 18:27
• Sweat Volume vs. Smell – Mythbusting: 20:14
• Diet, Stress, Microbiome Interactions: 21:27
• Gut–Skin Axis: 22:04
• Tips for Happy, Healthy Pits: 23:23
• Segment Ends: 24:44

Quotes & Memorable Moments

• "If you have white, dry, flaky earwax, you have a mutation and...the bacteria cannot convert it into smelly compounds."
  — Dr. Chris Callewart [12:24]

• "We apply [deodorant], bacteria adapt, and as such we select a bit towards more smelly situations."
  — Dr. Chris Callewart [11:49]

• "If you have diabetes, people smell more sweet...or more musty as a result.”
  — Dr. Chris Callewart [14:30]

• “You can free your body of odor—not a guaranteed recipe for success. Sometimes, it’s also one of those smelly bacteria that becomes dominant.”
  — Dr. Chris Callewart [19:57]

Final Takeaways

• Body odor is a symphony conducted by your sweat glands and an orchestra of bacteria unique to you.
• Deodorant may give short-term relief but can disrupt your skin’s ecology, sometimes making things worse over time.
• Culture and genetics play a huge role in who smells, what, and why.
• Stress, diet, and fabric choices all matter.
• Your self-consciousness is probably exaggerated—everyone smells sometimes, and that’s usually okay.
• The best advice: support your body’s natural balance with gentle habits, a healthy diet, natural fibers, and don’t stress about perfection.

Follow Dr. Armpit for more fun science facts on social media!
Episode produced by Teresa Carey and the Wheelhouse DNA team.