[eitland]

> If you unzip aspartame into the two amino acids and remove that methyl to become methanol, you have a tasteless mixture of pretty harmless compounds.

I'm somewhat surprised nobody has commented on this yet, so let me point it out: methanol is not harmless! It causes blindness or death.

(I don't say diet soda is harmful, only that methanol is.)

[ChuckMcM]

Your statement about the toxicology of methanol is correct, but as the article alludes too, and the referenced paper goes into detail on, the dosage is below the point where it harms people. (I don't recall off hand if they considered an infant being fed an entire can of soda in the paper so I'm not going to say that as a blanket statement)

As for the toxicology limit. If the maximum amount of methanol has been created by all of the aspartame "unzipping" even if you consumed the whole can your does will be lower than the amount needed to create harmful effects. Additionally, sodas in this state taste like crap, so unless you have no taste sensors at all you won't drink more than a gulp which lowers the dosage still further.

But that there can be methanol in an out of date soda has been the go to reason a friend of mine never drinks sugar free soda. And frankly I can respect that choice.

[eitland]

I suspected this could be the case which is why I included my disclaimer at the end :-)

Still I felt a warning was in order when someone calls methanol a harmless compound because that is absolutely not true.

[colordrops]

Is damage from methanol not cumulative? My understanding is that it rubberizes nerve and brain tissue.

[chroma]

Methanol is toxic because it is eventually metabolized into formic acid (the same venom used by ants) which interferes with cell metabolism.[1] If the amount of formic acid is high enough, cells can't maintain homeostatis and die. Certain cells with higher metabolic demands (such as nerve cells) die first. If the dosage is below that threshold, you're fine.

The FDA considers 0.5mg/kg/day of methanol to be unlikely to cause deleterious effects for a person's lifetime. For a 70kg person that would be 35mg per day. For comparison: a can of diet soda has less than 200mg of aspartame. Assuming 100% of the aspartame breaks down into phenylethylamine, aspartic acid, and methanol, then less than 10% of that mass would be methanol, or less than 20mg. So even if you drank an entire can of disgusting old diet soda every day, you'd still be below the FDA's threshold for cumulative damage and you'd be nowhere near the threshold for acute methanol poisoning.

1. https://en.wikipedia.org/wiki/Methanol_toxicity

[ajuc]

That actually made me reconsider drinking diet soda, the numbers are on the same order of magnitude I thought it would be much further apart.

Is it possible that the aspartame hydrolizes in our guts after we drank it? "Disgusting drink check" wouldn't help then.

[chroma]

Well then you got the wrong message. A glass of wine can contain over 50mg of methanol. If something's at or below the FDA reference dose, it's not worth worrying about. The FDA is rather risk-averse and tends to set limits far below what would actually cause harm.

To give you another bit of data: The metabolite of methanol that actually causes damage (formic acid) is a common food additive and is naturally present in many fruits, honey, and of course ant venom. If tiny amounts caused issues, we'd know by now.

[ajuc]

I have problems with my liver and don't drink alcohol anyway. As for FDA - they allow chlorinated chickens so I'm not so sure.

[snovv_crash]

Then you'll be horrified to find out how much methanol is in a glass of wine or a beer.

[ChuckMcM]

Apparently not at the levels of hydrolyzed aspartame: https://www.ncbi.nlm.nih.gov/books/NBK482121/

[eitland]

I'm somewhat amused that pointing out that methanol is actually deadly even if this isn't a problem in diet soda has cost me two downvotes : )

(No, I'm not complaining. I can't cash out HN karma points in Norwegian banks so to me it is just a bit puzzling because I wonder what triggered those, somewhat amusing and mildly scary.)

[h2odragon]

There's probably a surprising amount of methanol and ethanol in a gallon jug of apple cider by the time you get to the bottom of it. The better types, at least.

[majkinetor]

Poisson is in the dose, not the substance.

[zerocrates]

The usual pithy phrasing is "the dose makes the poison."

[asiachick]

avoid di-hydrogen-oxide too. it kills around 236000 people a year

[eitland]

I'm well aware (I've been part of the milk industry where farmers initentionally give it to cows to extend their lifespan and increase the yield, anyone who is new to this, see http://dhmo.org/milk.html )

I also have a sore knee after an incident relating to solid DHMO at my childrens hockey training in the weekend (my bad, I should have learned to use proper protection my now.)

That said, there is a large difference between DHMO where in its liquid form it will have a median LD50 of around 90,000 mg/kg and methanol who has a median LD50 of 810 mg/kg.