There's a whole market for aluminium-free deodorants. They're marketed as natural or vaguely better for you. But hold up a sec: why are you avoiding aluminium, which (unlike those natural deodorants) can actually stop you from sweating? It's fine.
Photo: Melanie Allan
Aluminium — yes, the same metal that "tinfoil" and soft drink cans are made of — turns up in trace amounts in the brains of Alzheimer's patients and in breast tumours. However, people who work with aluminium don't develop dementia or Alzheimer's at higher rates than anyone else and aluminium is found in healthy breast tissue at the same rates it's found in tumours.
There is zero evidence that avoiding aluminium will reduce your risk of either condition.
That email said that antiperspirants work by "inhibiting the body from purging toxins from below the armpits". According to this story, the unspecified "toxins" build up in the lymph nodes of the armpits, and cause breast cancer in the areas of the breast nearest the armpits.
This story is all wrong: that's not how sweat glands work. That's not how lymph nodes work. That's not how cancer works. Most breast tumours are in the "upper outer quadrant" of the breast, but only because that area has the most breast tissue. Research on an aluminium-cancer link has so far failed to turn up any convincing evidence.
What does aluminium actually do?
Aluminium-containing ingredients are in deodorants — technically, only in the ones labelled antiperspirants — because they can plug up sweat glands. They literally stop you from sweating.
Once sweat is on your skin, bacteria eat the sweat and excrete stinky chemicals. So the other active components of deodorants (natural or otherwise) either kill the bacteria, or provide a fragrance to cover up the stink. Some non-aluminium deodorants will include an ingredient like cornstarch that helps to absorb moisture so that even though you're still sweating, you won't feel as wet.
If you prefer non-aluminium deodorants, great! But it seems people often suffer through natural deodorants because they're afraid of the aluminium ones, not because they enjoy the alternatives.
So if you're avoiding the stuff that actually works because you're afraid it will harm you somehow, relax. Few things are proven in this world — researchers are still working on that aluminium/cancer link just in case — but it's not the kind of thing that should keep you up at night.