Too much diet soda?
June 22, 2013 8:24 AM   Subscribe

What are the health risks if a person drinks diet sodas pretty much to the exclusion of water or any other type of beverage? Average amount consumed is 3.75 liters a day, about a liter is caffeine free, brand name is any and all.

While personal stories are ok, I'm primarily interested in actual studies that show findings or links to professional judgements.
posted by Brent Parker to Health & Fitness (27 answers total) 7 users marked this as a favorite
The answer as of now is that nobody really knows. There were some studies published last year linking diet soda consumption to elevated risk of cardiovascular disease, but they had methodological flaws. See here.

Essentially, you're participating in a large-scale cohort study on the safety of diet soda. The first generation to drink these soft drinks in earnest is still with us, and the jury's still out on health consequences.
posted by killdevil at 8:30 AM on June 22, 2013 [2 favorites]

Response by poster: This person is not me.
posted by Brent Parker at 8:45 AM on June 22, 2013

Here's an article I read a few weeks back comparing the effects on teeth between a user of meth and a woman who drank 2 liters of diet soda a year for 3-5 years (note that both had poor oral hygiene).

Anecdotally, I used to occasionally work with a guy who drank nothing but Diet Coke and Diet Mt. Dew. The days we worked together (about twice a year), he got through a 12-pack over the course of the day and then had to hit vending machines when he ran out. A 12-pack equals a little over 4 liters. He had really dreadful flaky patches of skin all over his face, was very overweight, and had a variety of health problems affiliated with obesity. I saw him once when he had cut down on the soda considerably (down to maybe 4 cans a day?) and he was still overweight but his skin looked much better.
posted by jabes at 8:48 AM on June 22, 2013

That's a lot of carbonation, other things aside. If you think about nothing but teeth and pH, that should make you think of another health angle that most overlook when pondering this very question.

Rotty chompers!
posted by oceanjesse at 8:54 AM on June 22, 2013

A friend of mine told me she experienced years of what sounds like (to me) degenerative neuropathy - tingling, numbness, confusion. She gave up aspartame and her symptoms went away. I'd normally demand more scientific reasoning than anecdote like this, but, seriously... why risk it? I won't touch the stuff now.
posted by heatherfl at 8:59 AM on June 22, 2013

There's no fluoride in most sodas, so you don't get the benefits of fluoride strengthening your teeth -- so even sugar-free sodas can contribute to weaker teeth.
posted by katemonster at 9:00 AM on June 22, 2013

Just FYI, the "study" about diet soda and teeth is neither a study nor a comparison between drugs and diet soda. It's B.S. Some dentist looked at three of his patients, one of whom was a crack addict, one of whom was a meth addict, and one of whom had not visited a dentist in 20 years. The latter two were the "soda drinkers" in the "study." There may be a lot of problems with drinking too much diet soda, but there is no proof that meth mouth is one of them.

I will say, anecdotally, that when I started drinking my diet soda through a straw, all of my problems with tooth sensitivity to cold and heat gradually went away. YMMV.
posted by decathecting at 9:19 AM on June 22, 2013 [3 favorites]

Diet soda consumption has been correlated with weight gain and type-2 diabetes risk in some studies, but not in others, and no mechanism has ever been observed in controlled experiments. Diet soda consumption has been linked to poor dental health. Some people report negative reactions to artificial sweeteners (e.g. headaches from consuming aspartame), but presumably if this were the case for your friend they wouldn't be drinking so much diet soda. You can read a bunch of citations on Is diet soda bad for you?
posted by ludwig_van at 9:20 AM on June 22, 2013 [1 favorite]

There's a recent study about artificial sweeteners and depression, although it seems, without reading the actual research, to be another one of those large-scale correlation things rather than a direct causative link.
posted by restless_nomad at 9:40 AM on June 22, 2013 [1 favorite]

Back when I did drink soda, when I drank too much to the exclusion of water I would get back pain, in the kidney area. Every time.

I quit drinking diet Coke a month after my boss died of a brain tumor. She was as bad of a Diet Coke fiend as me. Correlation is not causation, but whatever.
posted by St. Alia of the Bunnies at 9:47 AM on June 22, 2013

Some think that excessive consumption of carbonated drinks is linked to gastric reflux. (Article).
posted by Snerd at 9:49 AM on June 22, 2013

I used to drink massive amounts of diet soda. Now I don't drink it at all, mostly because I have small children and I am aware of the example I'm setting.

One thing to keep in mind is that many of the studies about aspartame were financed by the sugar industry, who is anxious to cast any and all artificial sweeteners in a negative light. So when you do read those studies, keep the bigger picture in mind.
posted by ambrosia at 10:06 AM on June 22, 2013

I love diet soda. To the point where I have to very carefully control the amount I let myself keep in the house or I will drink about as much as described in the question to the exclusion of water. The main effect I've had when I do do that is it just wrecks my guts. Upset stomach, diarrhea, the whole terrible mess. Also, the one time I had a kidney stone, it was when I was drinking nothing but diet soda. That wasn't fun.

However, my dad, who is diabetic, has subsisted on caffiene-free diet soda (generic store brand, too, whoof is it bad) pretty much entirely for around twenty years and other than diabetes, which was pre-existing and Type I, he has no unusual effects.

I should note I'm drinking a Coke Zero right now. Curse you, you delicious aspertamey mistress.
posted by whitneyarner at 11:17 AM on June 22, 2013 [3 favorites]

dude teeth.
your teeth are basically getting an continous acid attack through the day.

if you drink it to the exclusion of water, I imagine you drink some right before brushing teeth on ocassion. with your teeth weakened by the acids, you're basically brushing of your enamel; you're begging for some bad oral hygiene.

with your blood sugar also spiked constantly, things like tiredness and lack of focus should possibly be part of your routine but who knows.

take care of your teeth. try to cut down the soda to when you have meals and always swish your mouth with some water right after.
posted by ahtlast93 at 12:16 PM on June 22, 2013 [1 favorite]

with your blood sugar also spiked constantly

Diet soda generally doesn't have sugar in it.
posted by Justinian at 1:06 PM on June 22, 2013 [1 favorite]

My mother drank diet sodas almost exclusively for many years, and she is suffering early onset osteoporosis. According to her doctors, who have banned all soda from her diet, the phosphoric acid in soda may be responsible for leaching calcium from her bones. (Some online references with citations to corroborating research: and

It may be that women are more susceptible to this process, especially if their diet is already poor in calcium and other nutrients needed for bone health, but it is something to be aware of.
posted by at 1:48 PM on June 22, 2013

One finding indicates that the gastrointestinal tract and the pancreas can detect sweet foods and drinks with receptors that are virtually identical to those in the mouth. That causes an increased release of hormones, such as insulin. Some animal studies also have found that when receptors in the gut are activated by artificial sweeteners, the absorption of glucose also increases.

This is the interesting bit of the link invisible ink posted. It is, I understand, fairly new work that's been done on this.
posted by ambrosen at 2:20 PM on June 22, 2013

At the kinds of quantity you're talking about there are weird kinds of things that you have to pay attention to. Does the preferred brand contain Brominated Vegetable Oil, possibly abbreviated BVO?

Horowitz BZ. Bromism from excessive cola consumption. J Toxicol Clin Toxicol. 1997;35(3):315-20.
Bromism is an unusual occurrence. Historically bromism has been known to occur with chronic ingestion of bromide salts used as sleep medications. In this case, excessive consumption of a cola with brominated vegetable oil caused a severe case of bromism. The patient presented with headache, fatigue, ataxia, and memory loss which progressed over 30 days. He consumed 2 to 4 L of cola containing brominated vegetable oil on a daily basis before presenting with these symptoms. His significantly elevated serum chloride, as measured by ion specific methods, and negative anion gaps were overlooked during a prior hospitalization and emergency department visits. A focal neurologic finding of right eyelid ptosis led to an extensive evaluation for a central nervous system lesion. The patient continued to deteriorate, until he was no longer able to walk. A diagnosis of severe bromism was eventually made and his serum bromide was confirmed at 3180 mg/L (39.8 mmol/L). Despite saline loading the patient failed to improve but subsequent hemodialysis dramatically cleared his clinical condition, and reduced his serum bromide levels. The unilateral eyelid ptosis, a rarely reported finding in bromism, also resolved with hemodialysis. A negative anion gap or an elevated serum chloride should prompt an evaluation for bromism. In this case hemodialysis dramatically improved the patient's clinical condition and reduced the half-life of bromide to 1.38 h.
posted by Blasdelb at 5:33 PM on June 22, 2013 [1 favorite]

Really if whomever has the strangely high daily consumption of soda has concerns about its impact on their health, there is no substitute for visiting a registered dietician* to get it properly assessed by someone who actually knows what their doing. Diet and the absurd and obscure quirks of its biochemistry are honestly both way more complicated and way more understood that most laymen can reasonably understand. This is a very good question to have, where the consumption mentioned really is big enough for concern, and its also a really good one to ask of someone who can actually answer it.

*The difference between a nutritionist and a dietician is like the difference between a toothologist and a dentist. Dentists are licensed by the state and reviewed by their peers to ensure adequate ethics and competency, whereas a toothologist would not only be unvouched for but would be conspicuously so. Nutritionists are the same way, anyone can call themselves a nutritionist, all the way up to the hydrogen peroxide injecting and laser reikii ends of the woo spectrum, while a Registered Dietician is a physician who must complete years of graduate study in an accredited University, complete 900 hours of supervised practice, complete an appropriately ridiculous exam, and continue their education in order to continue calling themselves a dietician. This is not a question about how to feel better about one's diet but a specific question that requires actual expertise and experience practicing to answer, you are looking for a dietician.
posted by Blasdelb at 5:47 PM on June 22, 2013

I know someone who did this. I don't have a link, but I remember hearing a news report that aspartame had been linked to the kind of cancer that ultimately killed him, in his forties. He would also sometimes get extreme leg cramps that would go away if he drank some milk.

I have also heard that aspartame is related to arthritis.
posted by Comet Bug at 8:05 PM on June 22, 2013

I think this quote from the snopes article about aspartame is interesting, "There were well over 100 separate toxicological and clinical studies conducted to establish the safety of aspartame before it was approved for regulatory acceptance. Since its approval in 1981 by the USFDA, there have been many additional studies performed to follow up on some of the more creditable reports of aspartame- mediated adverse effects." That is from someone with FDA which suggests to me that this an often studied substance. The lack of conclusive proof of specific ill effects from something that is so often studied is enough for me.

I also think that the corn lobby in America is powerful enough to exploit anything they could to discredit aspartame. The fact that they haven't been able to also indicates to me that there isn't enough conclusive proof of aspartame being a secret poison/cancer causer/brain scrambler.
posted by soelo at 9:02 PM on June 22, 2013

I did an extensive literature review of cola consumption and aspartame research about 5 years ago after having an argument with one of those people who believe it bad for you intuitively and think you are crazy if you don't. The overwhelming evidence is that aspartame is incredibly safe and that was after thousands of studies (albeit all short term rather than lifetime or animal model research). I think there were three studies that found possible negative effects and they were very tentative findings that had many subsequent refutations. I came away from that research wondering if aspartame was the safest thing you could ever consume!


I'm 46 and have been a heavy diet coke drinker for a couple of decades. My teeth are fine (not sparkling American teeth mind you but I haven't had a cavity in over 30 years).

The real issue that concerns me and that people here have mentioned is the displacement issue. Diet cola consumption displaces juices and milk which may result in some dietary deficiencies. While I don't believe it is addictive I do think it is very habit forming (at least for me). I never researched the phosphoric acid issue.

I am also quite ambivalent about whether it messes with satiation detection and blood sugar homoeostasis by destroying sweetness as a signal. I am not good at this but I suspect this issue preceded my regular consumption of diet cola.
posted by srboisvert at 9:06 PM on June 22, 2013 [2 favorites]

Anecdotally it's linked to depression. It's something you see discussed as a trigger on mental health boards, e.g..
posted by professor plum with a rope at 1:36 AM on June 23, 2013

Anecdotally diet soda is also thought by some to be a godsend, providing delicious taste and refreshment without the disadvantages of constant sugar intake and containing (compared to water) a possible positive or negative health effect that is nevertheless minuscule---lost in the noise of daily living.
posted by Mapes at 5:32 AM on June 23, 2013 [1 favorite]

with your blood sugar also spiked constantly

Diet soda generally doesn't have sugar in it.

The theory is that the sweet taste of the soda causes insulin to spike, in preparation for digesting all that delicious sugar that your tastebuds are telling your pancreas is coming. Since there isn't any actual sugar in the drink, this causes temporarily low blood sugar. Which then the body has to correct for by spiking the blood sugar back up and that overshooting the normal is the blood sugar spike they refer to.

I don't know if it is true, but it makes a certain kind of sense.

I also anecdotally find that too much aspartame causes my tinnitus to get worse.

Also, the last thing I personally noticed is that I sometimes have the gut wrecking, gerd phenomenon when I drink certain sodas. But through careful research and testing, I figured out that it wasn't the aspartame, it was the sodium benzoate. When I avoid things with that in them, the gerd disappears. (Same thing with headaches and monosodium glutamate) The research can say that there isn't any statistical correlation in a population, but I'm damn sure I am personally sensitive to these things.
posted by gjc at 10:28 AM on June 23, 2013

The theory is that the sweet taste of the soda causes insulin to spike, in preparation for digesting all that delicious sugar that your tastebuds are telling your pancreas is coming. Since there isn't any actual sugar in the drink, this causes temporarily low blood sugar. Which then the body has to correct for by spiking the blood sugar back up and that overshooting the normal is the blood sugar spike they refer to.

I don't know if it is true, but it makes a certain kind of sense.

This is pure unsubstantiated and easily disproved bunk. Diabetics can drink diet colas (and the American Diabetic Association considers it harmless) because they have no effect at all on blood glucose levels.
posted by srboisvert at 1:15 PM on June 23, 2013 [3 favorites]

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