Should you opt for aluminium-free deodorant?

Summary

Podcast Summary: "Should you opt for aluminium-free deodorant?"

Podcast: What's That Rash?
Host: ABC News
Date: December 30, 2025

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Episode Overview

This episode tackles a health question that concerns many: should you choose aluminium-free (natural) deodorants over conventional ones? Dr. Norman Swan and Dr. Claire break down the science behind body odor (BO), the genetics of sweat and smell, and whether there are real health risks linked to antiperspirants, specifically the aluminium they often contain. The conversation mixes personal anecdotes, evolutionary biology, and evidence-based recommendations in a friendly, humorous style.

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Key Discussion Points & Insights

1. Personal Paranoia and Experience with Sweat & Deodorant

• Dr. Claire opens by admitting a mild paranoia about personal body odor.
  • “I am a bit paranoid about what my sweat smells like.” (01:12)
• She recounts an allergic reaction to many conventional deodorants leading to using crystal deodorant for 15+ years.
  • “I just started reacting really badly to deodorant... quite a severe allergy. So severe that I actually got bleeding in my armpits.” (03:20)

2. What Causes Body Odor?

• BO occurs where skin bacteria are most abundant, especially the armpits.
• It’s a complex interplay between genetics, skin bacteria, and the substances your sweat glands produce.
• Certain people (often of Asian descent) don’t produce the “precursor” that bacteria convert to odor, due to a mutation in the ABCC11 gene.
  • “There are people in the world who don’t produce body odor, and Claire’s male friend might be one of them. They usually have a mutation in one of two genes, but mostly a gene called ABCC11.” (05:20)
• Dry (white) earwax is tied to this same genetic mutation, as “pleiotropy”, genes with multiple effects.
  • “...the people with this genetic mutation also have white, dry earwax rather than yellow soft earwax.” (06:21)

3. Does Body Odor Have an Evolutionary Purpose?

• One hypothesis: women prefer the odor of men with a different immune “tissue type” (genetic diversity), but evidence is weak and experiments unconvincing.
• Identical twins have similar BO, underlining the genetic basis.
• Our ability to smell BO is also genetically determined.
• Humorous comparison to “the asparagus wee thing”—the difference in ability to smell is genetic.
  • “If you smelt it, you dealt it.” (09:26, Dr. Claire)

4. How Deodorants and Antiperspirants Work

• Deodorants: Combine antibacterial agents and fragrances to mask or reduce odor.
• Antiperspirants: Use aluminium salts to block sweat glands, reducing sweat and BO precursors.

5. Aluminium and Health Concerns

• Aluminium in deodorants is mostly not absorbed by the body (95% stays on the skin).
• High doses of aluminium are related to brain damage and kidney issues, but not at the levels from deodorants.
• No established link between antiperspirant use and breast cancer or general health risks.
  • “They have looked at it and haven't found any link... epidemiologically, they can't find a link between antiperspirants and breast cancer.” (11:32, Dr. Claire)
• Dr. Claire personally avoids antiperspirants to minimize unnecessary interference with natural body processes, but this is a personal choice rather than a scientific necessity.
  • “I just don't believe in... interfering with natural processes in that way.” (12:01, Dr. Claire)

6. The Myth of “Sweating Out Toxins”

• Sweating removes salt and water—not toxins.
• Blocking underarm sweat alone doesn’t affect your body’s temperature regulation or “detox” capability.
  • “All you’re sweating out is salt—sweat, salt, and water. It's not body toxins.” (12:15, Dr. Claire)

7. Cultural and Industry Influence

• The widespread use of deodorant is quite recent and largely driven by advertising that played on people’s insecurities.
• The first major antiperspirant, Odorono, was invented by a surgeon to stop hand sweat in surgery.
  • “They basically turned to the age-old advertising approach of making people feel shamed and self-conscious to sell it. And it worked.” (14:28, Dr. Norman Swan)

8. Natural Deodorants: Do They Work?

• “Natural” deodorants (without aluminium) mostly include crystal deodorants made from mineral salts.
• There’s no research supporting natural substances that genuinely act as antiperspirants—so these only control odor, not sweat.
• The best evidence for natural deodorants concerns the crystal types; they create a salty environment hostile to bacteria.
  • “The ones with the strongest evidence are indeed these crystals because they present for bacteria a toxic environment which they can't grow...” (15:42, Dr. Claire)
• Crystal deodorants can be effective but may not last as long as conventional deodorants.

9. Final Takeaways

• Crystal (mineral salt) deodorants are worth trying if you want a natural option.
• For those not allergic, conventional deodorants/antiperspirants are not found to be harmful.
• The choice is personal, with little risk either way for most people.
  • “If you want to go for a natural deodorant go for a crystal one because they do work, they haven't got stuff in them that's going to give you an allergy and you'll soon find out whether they work for you.” (17:13, Dr. Claire)

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Memorable Quotes & Notable Moments

• Dr. Claire: “My armpits looked like World War three. It was a real problem because... I do get body odour.” (03:43)
• Dr. Norman Swan: “Is axilla a nose axilla?” (01:36)
  Dr. Claire: “It’s your armpit.” (01:38)
• Dr. Claire: “If you smelt it, you dealt it.” (09:26)
• Dr. Norman Swan on deodorant marketing: “They basically turned to the age-old advertising approach of making people feel shamed and self-conscious to sell it. And it worked.” (14:28)

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Timestamps for Important Segments

• 01:07 – Hosts discuss personal attitudes toward sweating
• 03:20 – Dr. Claire shares her struggle with deodorant allergies and crystal deodorant
• 05:20 – The genetics of body odor and the ABCC11 gene
• 06:21 – Earwax types and their genetic links to body odor
• 09:03 – The genetics of smelling and BO comparison to asparagus urine
• 10:12 – The science behind deodorant and aluminium concerns
• 11:32 – Antiperspirant and breast cancer: what the evidence says
• 12:15 – Debunking sweating out toxins
• 14:28 – Origins of commercial deodorant and marketing tactics
• 15:24 – Efficacy of natural vs conventional deodorants
• 17:13 – Concluding advice: crystal deodorants are a good natural option

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Conclusion

The episode concludes that both natural (crystal) and conventional deodorants are generally safe for most people, with no proven major health risks associated with aluminium exposure through antiperspirants. For those sensitive to conventional products, crystal deodorants are an effective, allergen-free alternative. Ultimately, the decision comes down to personal preference, effectiveness, and skin tolerance.

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For further questions, listeners are encouraged to write in to the podcast, as the hosts will revisit and clarify more health curiosities in future episodes.

Transcript

[Podcast Host (Ad Read)]

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[Dr. Norman Swan]

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[Dr. Claire]

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[Dr. Claire]

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[Dr. Claire]

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[Dr. Norman Swan]

Would you consider yourself like a sweaty guy or a less sweaty guy?

[Dr. Claire]

I'm not particularly sweaty, but I must confess I am a bit paranoid about what my sweat smells like.

[Dr. Norman Swan]

Is this paranoia steeped in any particular trauma that you want to talk about?

[Dr. Claire]

Maybe if I lay on a couch and somebody went back to it, there might have been some traumatic thing where somebody stuck their axilla in my face in school, but you know, I'm not sure.

[Dr. Norman Swan]

Is exilla a nose axilla?

[Dr. Claire]

Is your armpit.

[Dr. Norman Swan]

Oh, A X, I double L A, yeah. Amazing. I love it.

[Dr. Claire]

So, you know there are people listening to us right now who will be taking their nose and putting it in their own armpit and having a sniff just to check.

[Dr. Norman Swan]

I googled axilla and I don't know what I expected, but of course there's a photograph of someone's armpit hairy or shaved? Hairy. Hairy, of course. This is what's that Rash. The show where we answer the health questions everyone is asking.

[Dr. Claire]

And this week the question is about deodorants, antiperspirants and body odour.

[Dr. Norman Swan]

So Claire asks, what is the difference between conventional deodorants and so called natural ones? She says, I gather the natural ones are aluminium free. Are conventional ones designed to stop or reduce the amount that you sweat, whereas natural ones don't? Is one healthier than the other? Claire says, do the natural ones simply provide a nice fragrance to cover the smell of your bo? My male friend doesn't use anything and when he told me I was horrified. But he doesn't smell at all. Should I go au naturel.

[Dr. Claire]

Really good set of questions, Claire. Thanks for sending them in. And I'm sure that it rings bells and anxiety moments for lots of people listening.

[Dr. Norman Swan]

So when I'm thinking about natural deodorant, Norman, I'm thinking about crystals. You can buy them in lots of shops these days, but 10, 20 years ago you really could only buy them in like natural food stores or alternative stores. So I think for me they had a whiff of like woo wellness to them.

[Dr. Claire]

Well, do you think I'm woo woo?

[Dr. Norman Swan]

No, you're the furthest thing from it.

[Dr. Claire]

Well, I use crystal deodorant.

[Podcast Host (Ad Read)]

Really?

[Dr. Norman Swan]

Okay, tell me how this came to be.

[Dr. Claire]

I don't know, maybe 15, 20 years ago or something like that. I just started reacting really badly to deodorant, regular deodorant. I never used antiperspirant, just regular deodorant. So I would try all sorts of deodorants and they all caused the same problem. Really quite a severe allergy. So severe that I actually got bleeding in my armpits.

[Dr. Norman Swan]

Oh no, fuck.

[Dr. Claire]

My armpits looked like World War three. It was a real problem because I'm not one of these people like Claire's male friend who gets no body odor. I do get body odor. So I thought, what the heck do I use? And I can't remember how I came across them, but I came across these crystal deodorants which are not woo woo. They contain high dose mineral salts which inhibit the bacteria under your arm. But what I did find was that old crystal deodorants are not the same. So I went on a journey to find the right crystal deodorant.

[Dr. Norman Swan]

A man on a quest.

[Dr. Claire]

And one day on the Gold coast in a pharmacy, I saw some crystal deodorant there and I bought it. And I've been on it ever since, in fact. So addicted to this crystal deodorant and paranoid they'll go out of business. So I keep on fawning them up. Can you just send me another six? And so my drawers are send me six full of these. But essentially the crystal deodorants do work. You just got to use them in a reasonable concentration.

[Dr. Norman Swan]

Well, okay, so you mentioned that they're made from crystal mineral salts. I think it's important to define how BO happens and why it only happens in your armpits or in specific parts of the body and not others.

[Dr. Claire]

Essentially you get body odor from areas in the body which have more skin bacteria. So a lot of this is about. It's a fascinating Story about where we get it and why. And there's a lot about genetics and evolution involved here.

[Dr. Norman Swan]

You know, I love me a deep time story that involves some evolution. Let's get into it.

[Dr. Claire]

And what does earwax have to do with body odor? That's gonna blow your ears out.

[Dr. Norman Swan]

Come on, come on, give it to me.

[Dr. Claire]

Ok. To illustrate how important genes are in the story of body odour, there are people in the world who don't produce body odour, and Claire's male friend might be one of them. And they usually have a mutation in one of two genes, but mostly a gene called ABC11.

[Dr. Norman Swan]

It sounds like you just made that up.

[Dr. Claire]

Well, people can check the show notes here to see whether I make these things up. So there are people who don't produce body odor. So you have these bacteria on your skin and various bacteria can cause body odour, but the body has got to give the bacteria, bacteria, food, if you like, that will generate the body odor. So what are called precursors? And the people with this ABC11 mutation, who are often from Asian populations, don't produce the precursor and therefore the bacteria don't have anything to metabolize to produce the body odor. And this is where earwax comes in.

[Dr. Norman Swan]

I think I know where you're going with this, but I'll let you tell the story.

[Dr. Claire]

Well, the people with this genetic mutation also have white, dry earwax rather than yellow soft earwax.

[Dr. Norman Swan]

There's two different types of earwax. Maybe you're a dry earwax person, maybe you're a wet, orangey, yellow earwax person. And so you're saying that those two things go hand in hand?

[Dr. Claire]

Yes. Could be that it's one of our favourite words, pleiotropy. Genes that have more than one effect on the body.

[Dr. Norman Swan]

Yes, exactly. So I suppose the thing is, I don't like the smell of bottom. It's obviously possible to be a human without it. Does it have some kind of purpose?

[Dr. Claire]

Well, people have wondered about that and created all sorts of hypotheses for this. So, for example, there was one famous experiment where they gave women men's T shirts to smell that they'd been wearing for a while and to tell the researchers which T shirts they preferred the smell of. And what they concluded was that there was a tissue typing mismatch, in fact, that women preferred men of a different tissue type.

[Dr. Norman Swan]

What's a tissue type? Is this like a blood type?

[Dr. Claire]

It's like your tissue type for organ donation. And the idea here Is that if you've got a mismatch, it's about genetic diversity, what have you. But let me just say that that experiment was dubious. The only women who registered this finding in terms of T shirts actually were on the pill at the time. And it's not been replicated because other people thought, well, maybe there's something to with the immune system of recognition of odors, which makes you more compatible or a much more healthier match, immune system wise, with your partner. In fact, it hasn't played out another theory for body odor because identical twins tend to have the same body order.

[Dr. Norman Swan]

That makes sense. But you said it was to do with bacteria.

[Dr. Claire]

Yes, but it's bacteria munching on the stuff that we present them with. And the stuff we present them with is largely genetically programmed. So the people in Asia who've got this mutation, or maybe Claire's boyfriend, they are not presenting the bacteria with anything to munch on and therefore body odor is not produced. And it's not guaranteed that just because you've got a certain kind of staphylococcus or Coryneobacterium in your armpit that you're going to produce a certain kind of body odor. There's a certain specificity to the body odor that you produce. The. And then you've got to add something else to this body odor story. Some people don't produce any body odor even though they've got bacteria. Some people produce different odors depending on their genes that they have. And then your ability to smell and detect body odor is also genetically determined.

[Dr. Norman Swan]

Oh, that's like the asparagus wee thing, where some people who, when they eat asparagus, it makes their way smell different and some people it doesn't. But then some people can smell the different WEE smell and other people can't. And there's not always an overlap.

[Dr. Claire]

Yes, well, in fact, some people believe that, in fact, when you eat asparagus, if your urine smells, it's actually more about the smeller than the person who's ate the asparagus. So in other words, if you smelt.

[Dr. Norman Swan]

It, you dealt it.

[Dr. Claire]

Exactly, that's right.

[Dr. Norman Swan]

So this has been somewhat of a. Somewhat of a tangent, but what I'm getting from this is BO is real. It's caused by bacteria interacting with the sweat on our bodies. And so that really kind of informs what deodorants are, whether antiperspirants or chemical deodorants, because they're really trying to interfere with that process to stop BO from forming.

[Dr. Claire]

That's right. So Deodorants are a combination of usually antibacterial agents and a fragrance, so that when you get breakthrough and you do get metabolism of the sweat, you don't notice it quite so much. Antiperspirants do interfere with the ability of your sweat glands to produce sweat, so you're not providing the raw material for the bacteria to act on. And your underarms don't show the sweat on a hot day.

[Dr. Norman Swan]

So when we're coming to natural deodorants, the ingredient in deodorants that most people seem to have issue with in terms of health things is aluminium, which is usually in antiperspirants. It's the aluminium on your sweat glands that sort of stops your sweat from being able to get out. To put it super crudely, why aluminium? Why are people concerned about health effects there?

[Dr. Claire]

Well, aluminium in high dose has been associated with brain damage and maybe dementia, and also in high doses has been associated with kidney damage. And so people have got paranoid about aluminium from pots and pans. And there really is no relationship between aluminium in cooking utensils and problems such as kidney failure and dementia. But there have been fears about aluminium over the years. And the studies that have been done on aluminium and antiperspirants is that 95% of the aluminium stays on the skin, which is where you want it to stay, because that's where it's acting and does not get into the bloodstream. So only tiny amounts get into the bloodstream and nowhere near the toxic doses that are a worry in terms of brain function and kidney function.

[Dr. Norman Swan]

Well, one of the main concerns with antiperspirants is the potential theoretical risk of breast cancer. And I think it has something to do with the fact that you're putting product in that vicinity, which we know is porous and close to the breast.

[Dr. Claire]

Yeah, they have looked at it and haven't found any link. And if you think about the way it works is that the lymphatic drainage from the armpit tends not to go to the breast. It tends to be taken from the breast. And looking at it epidemiologically, they can't find a link between antiperspirants and breast cancer. Having said all that, I wouldn't use an antiperspirant myself because I just don't believe in. Unless you have to interfering with natural processes in that way. You just don't know what you're playing with.

[Dr. Norman Swan]

You clearly don't live in Brisbane.

[Dr. Claire]

No, that's absolutely true.

[Dr. Norman Swan]

So, I mean, one of the questions that Claire asks Is. Is it unhealthy to stop up your sweat glands because it's a natural thing your body's trying to do? Is there anything to that?

[Dr. Claire]

Not in that localised area. We have a myth about sweat is that when you sweat, you're sweating out all these body toxins and all you're sweating out is salt. Sweat, salt and water. Yeah. It's not body toxins, but sweating is important. It's very important for temperature regulation and also in terms of fluid balance in your body, that if you sweat too much and you're not taking it in, you could become salt and water depleted.

[Dr. Norman Swan]

But just your underarms alone, not sweating isn't probably going to do much of a difference in that regard.

[Dr. Claire]

Correct.

[Dr. Norman Swan]

It is interesting to me. Whenever we have sort of something that feels completely ubiquitous almost, you don't argue with it. Everyone seems to use deodorant these days. It's such a new thing that we use it and that we have such a big industry around it.

[Dr. Claire]

Yeah. There is a cultural element here and that's the story in Asia with these non odor producing people with that mutation there. Certainly when you hear stories about medieval industrial London, people do talk about body odor and do talk about it being unpleasant. Not as ubiquitously as. But I think it has been an issue. Although people coming back to a previous watch that rash on showering and not washing. Some people argue that eventually you do get to the point where you stop producing body odor. Maybe you've just killed off all the bacteria. Because I think.

[Dr. Norman Swan]

Did you know that one of the first antiperspirants was actually designed by our surgeon who had invented it to keep his hands sweat free in the operating room.

[Dr. Claire]

Oh, really?

[Dr. Norman Swan]

Yeah. So when we look back in like the history of deodorants, there had been others around. But like the sort of pivotal moment for why everyone's suddenly got obsessed with their armpits happened in around 1912 and there was a high school student, Edna Murphy, and her dad had invented this antiperspirant paste that stopped his hands from sweating so that he could like do a good job as a doctor. So she patented it, Odorono, and went to the Atlantic City Exposition and tried to sell it to everyone out there, but it was, it had some problems. It was like an acid suspension. So.

[Dr. Claire]

Oh, great.

[Dr. Norman Swan]

Quite irritating.

[Dr. Claire]

No problem at all.

[Dr. Norman Swan]

That's probably why your armpit.

[Dr. Claire]

I can feel my armpits getting. So just talking about it.

[Dr. Norman Swan]

It was also red coloured.

[Dr. Claire]

Great. So again, it might have stained the.

[Dr. Norman Swan]

Clothes, but they basically turned to the Age old advertising approach of making people feel shamed and self conscious to sell it. And it worked. And so they ended up having these ads that were like, this is why people don't want to be your friend and no one wants to say anything because you stank. And they had ads in newspapers and it took off from there. And now Odorono isn't really a brand that we would hear, but they were probably the one that kickstart, started this whole industry.

[Dr. Claire]

Yeah. And they used to advertise certain soaps as well to prevent bo. And you're right, post war Bior was a big marketing angle to sell soap and cosmetic deodorants.

[Dr. Norman Swan]

So yeah, a big push there from advertising that makes it so ubiquitous. But like you say, there is science to it. So okay, now we need to talk about natural deodorants specifically and whether they do anything differently or better than conventional deodorants. Whether Claire is onto something here.

[Dr. Claire]

Well, Claire asked about aluminium and whether natural ones simply don't have aluminium in them. Our research suggests that there is no. We'll no doubt get millions of emails saying this, but we can't find evidence of a natural substance which inhibits perspiration. So really we're not talking about natural antiperspirants, we're talking about natural deodorants. And the ones with the strongest evidence are indeed these crystals because they present for bacteria a toxic environment which they can't grow because there's so many of these mineral salts around the axilla.

[Dr. Norman Swan]

So they're not just masking the fragrance, they are actually stopping the bacteria from producing the smells that we don't like so much.

[Dr. Claire]

Yeah. And the question then with crystal deodorants, do they last as long as other deodorants? Because the cosmetic deodorants have a lot of research and development in them and they do tend to last a long time. And on my end of one study with me and my best available crystal.

[Dr. Norman Swan]

Deodorant, it's an N of two because you have two armpits.

[Dr. Claire]

Oh, that's true. I could just do one.

[Dr. Norman Swan]

Oh my gosh, you should. Could you please, please do a side by side trial?

[Dr. Claire]

The problem is here you're not good at smelling your own, but you've got to choose the person who smells your armpit very carefully because they might be a non smeller and who doesn't, who can't smell body odor and they say, oh, you smell fine. Whereas then you could go to somebody who's hypersensitive odor detector because they exist as well and you can have the slightest smell that nobody else detects but they do it's a lottery you get.

[Dr. Norman Swan]

To smell you My fan theory is that Claire is actually a non smeller and her male friend does stink but she doesn't know could be but he.

[Dr. Claire]

Might be an ABC101 well what's our.

[Dr. Norman Swan]

Takeaway then for Claire? Natural deodorants yeah nah maybe yeah from.

[Dr. Claire]

My experience if you want to go for a natural deodorant go for a crystal one because they do work they haven't got stuff in them that's going to give you an allergy and you'll soon find out whether they work for.

[Dr. Norman Swan]

You yeah but is there anything harmful in the conventional ones that we have if you are not allergic as you.

[Dr. Claire]

Are not that we can find from.

[Dr. Norman Swan]

The literature, no well, thanks Claire for sending in that question. You can always send in your questions we are that rashbc.net au and we'll see you next week See you then. Sam.