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

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

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.

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)

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)

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

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.

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.