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What's Up Docs?

Doctors’ Notes: Body Odour

June 23, 2026 • 30m

Summary

⏱️ 7 min read

Overview

Doctors Chris and Xand Van Tulleken continue their conversation with Professor Matthew Cobb about the science of smell, exploring how our olfactory system works, how it compares to other animals, and the fascinating ways smell influences human behavior and evolution. They conduct a live experiment with pig pheromones, revealing the genetic variations in how different people perceive the same odor, and discuss Matthew's groundbreaking research on Neanderthal smell receptors.

Deodorant Science and Safety

The doctors address listener questions about deodorants before diving into their conversation with Matthew Cobb. They explain how antiperspirants work using aluminum salts to plug sweat glands and discuss the safety concerns around aluminum-based products. Evidence from major medical bodies shows no convincing link between aluminum deodorants and breast cancer or Alzheimer's disease, though they acknowledge this remains an understandable concern for many people.

  • Antiperspirants use aluminum salts that dissolve in sweat to form a gel that plugs sweat glands
  • For maximum effectiveness, apply antiperspirant at night when sweat production is lower, allowing the aluminum salts to form plugs before being washed away
  • Large reviews have not found convincing evidence linking aluminum-based deodorants to breast cancer or Alzheimer's disease
  • No major medical body or cancer/Alzheimer's charity recommends against using deodorants
" If you want maximum protection from smelling, you should apply your antiperspirant at night when you generally have slightly lower sweat production so the aluminium salts enter the sweat ducts, form plugs before they get washed away by sweating. "

The Magic and Importance of Smell

Matthew Cobb explains why smell is far more significant than most people realize. The COVID-19 pandemic highlighted this when many people lost their sense of smell and discovered that food became tasteless, since most flavor perception comes from smell rather than taste. Beyond enjoyment, smell is crucial for safety and social connection, making it essential to overall well-being and happiness.

  • Most of our perception of flavor is based on smell, not taste, which became apparent when pandemic patients lost their sense of smell
  • Humans have around 400 genes encoding smell receptors, but can detect far more than 400 smells because each receptor detects multiple smells and each smell activates multiple receptors
  • Smell detection happens in mucus-bathing neurons at eye level behind your nose, not in the air - humans evolved from fish and our neurons would die if exposed directly to air
  • Molecular chaperones protect smell molecules from being degraded in the mucus layer and deliver them to receptors
" The first wave of the pandemic was, everybody knows, many people lost their sense of smell. And all of a sudden, they discovered that food didn't taste of stuff, because most of our perception of flavour is, in fact, based on our sense of smell, not on our taste. "
" Despite what you may think, you are not detecting odours, chemicals in the air. Right. So just remember, basically, you're a fish. OK, humans, we come ultimately from the sea. "

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