Thursday, June 16, 2011

Fact or Fiction: Aluminum and Alzheimers

Yesterday I had the very weird experience of being told that I was drinking my way to dementia.  At work.

I'll back up a bit.  It shouldn't be news to anyone who has read more than one post here that I have a rather severe sweet tooth as well as constant internal conflict trying to control it.  My usual 5-fold strategy to deal with this in my cubicle is as follows:
  1. Chew a piece of gum.
  2. Eat a small sesame crunch candy.
  3. Eat a piece of fruit.
  4. Drink a diet soda.
  5. Eat a delicious yet vastly more caloric treat.
Lately I've been trying to cut back on the gum/the convenience store downstairs hasn't stocked my favorite kind in awhile, I haven't yet replenished my stores of candy, and fruit seems to attract flies in the heat.  So that leaves the diet soda, which isn't exactly the healthier option if recent news articles are to be believed.  But aside from the dubious science, I'm really just trying to avoid caffeine in the afternoons.  The solution that a fantastic Stop N Shop special (2 12-packs for $5!) revealed to me is seltzer water.  I seem to have a pavlovian response to the can pop noise, and it seems like any form of carbonation will do the sugar-curbing trick of stopping my descent past the critical step 4.

So needless to say I've been drinking the stuff like gangbusters.  Anyway, I'm dropping an empty can in the recycling bin yesterday evening, and a woman I don't even know says: "you know you're going to get Alzheimers by drinking that."  What??

Follow-up: "Yeah, you know, the aluminum from the can affects your brain tissue and makes you senile.  You can actually see the shiny particles when you pour a can out in the sink, and if you use a straw, it just goes straight into your brain."

The ridiculousness of the shiny particle/straw thing aside, I wanted to investigate this further for my own piece of mind.  I really do drink a lot of seltzer.

Image via Amazon

Does aluminum leach into canned beverages?
Based on at least 30 minutes of scholarly research and limited access to full-text articles, I can say YES - but only a toxicologically negligible amount (<0.3 mg/day) when compared to normal dietary intake.  Bare aluminum containers (e.g. old canteens) DO have the potential to significantly leach when filled with a more acidic beverage like lemonade and left to sit for a few days, however all aluminum packaging containers are now internally lacquered.

Lacquer? Yes, all food/beverage cans are coated with a polymer on the inside to insulate the product from the packaging material, and cans actually have to go through a de-lacquering kiln during the recycling process.  And this barrier polymer directly in contact with 100 billion Al beverage cans consumed by North Americans each year is loaded with, yep, BPA.  In fact, canned foods are actually thought to be the primary route of BPA exposure, but let's leave that for the moment..

Okay, so the lacquer prevents Al from significantly leaching in cans.  But the average adult still consumes approximately 2-5 mg/day of Al from antacids, cosmetics, food additives like baking soda, naturally occuring sources like fruits and vegetables, and even minor leaching from Al cookware.  Also, there currently is no enforceable maximum contaminant level (MCL, for those in the industry) for Al in drinking water.  Is this something to worry about?

What's deal with aluminum exposure and Alzheimers?
In the 1970's, a connection between aluminum bioaccumulation and dementia was discovered from studies of long-term hemodialysis patientsDialysis encephalopathy is a syndrome specific to those with chronic renal failure on dialysis; phosphate-binding aluminum gels are used during treatment, and Al can accumulate in the brain due to the patients' inability to excrete it, causing degenerative neurological impairment.

But that doesn't seem to mean much for the general population with functioning kidneys and regular dietary exposure.  The link between Al and Alzheimers was first proposed 40 years ago, and scientists still haven't come to a conclusion whether or not there is a relationship at all, and if so, whether it is a correlation or causation situation.

In any case, the CDC has established a minumum risk level (MRL) of 1 mg/kg/day for 15-364 days for immediate duration oral exposure to aluminum.  This translates to 10 times the upper-average adult intake for a 110lb person, and much more than that if you've got any meat on your bones. 

So to summarize: unless you are actually eating the can itself, you're probably okay.  Aside from the BPA thing of course, but hey at least it's not Al-related.  If you want to be really really neurotic, studies proved that refrigeration and shortened storage time reduce leaching significantly, so drink fast and keep it cold.

And as a final piece of advice, don't listen to old ladies on the elevator.


  1. i am pretty sure everything gives you cancer now!

  2. YES YES YES! I love this blog so much. I hate old ladies on elevators advice AND the non-old-lady/non-elevator equivalents.

    I love the toxicology expertise dished in an accessible way. I love the nerdery combined with cynicism combined with diligent research/reporting.

    This post rocks.


  3. As a DPT student who just completed a neuroscience course I can tell you that Alzheimer's most certainly not caused by drinking soda out of a can... of the myriad of things to worry about this is not one of them.

  4. Just re-read this. a) you probably don't know that i'm a amateur toxicology buff. (I have 2-3 books i've read, one's ~1000 pages.) b) i'm a massive and outspoken skeptic against wrong & misinterpreted & misused science. I <3 this post.

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