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This is a data point of one, and I am certainly not implying that there is only one kind diet that works for everyone, but:

Every time I've lost a significant amount of weight (currently at -70 lbs from my peak) it's because I have drastically reduced sugar/carbohydrate content---while continuing to guzzle aspartame-based diet soda like water.

So either: 1.) I'm an outlier, 2.) These results are only relevant to saccharine sweeteners, and not aspartame, 3.) These results are bunk, like so many other nutritional studies, or, 4.) Low carbohydrate intake offsets any negative effects

This isn't a nutritional study?
This article mostly doesn't claim that diet sodas inhibit weight loss. In fact the biggest focus of the article is research suggesting that some food additives (not necessarily those in diet sodas) have helped the pathogen clostridium difficile to evolve in a way that's more dangerous to people.

Even where the article discusses diet sodas, it doesn't specifically say that they inhibit weight loss but that they might cause other kinds of harmful metabolic effects through their effect on the microbiome—and that this mechanism is suggested by research but not yet well-established. It also admits that some of those effects, if they exist, could vary widely between people.

That might be one reason that evidence nutrition has seemed so hard to pin down: if many of the effects depend on people's microbiomes, then some studies might be almost impossible to replicate in a different population, or maybe even in a different generation of research subjects. It might be true that some large group of people did very well eating one way, and that a different group did very well eating very differently, even if it seems like the advice that you'd draw from these observations is directly contradictory.

Most of the things I’ve read about diet soda were more related to individuals with insulin resistance, and problems related to that.

Soda is bad for other reasons too. The carbonic acid will rot your teeth.

Do you have a source on the carbonic acid rotting your teeth? I thought it was the phosphoric acid. Carbonic acid is an incredibly weak acid.
I have had the exact same experience as you. FWIW.
Article opens with, "There are lots of reasons to avoid processed foods. They’re often packed with sugar, fat and salt, and they tend to lack certain nutrients critical to health, like fiber."

Diet coke has no sugar, no fat, and less than 100 mg sodium. The specific results from Nature are about trehalose, a sugar not found in diet coke. I'm not aware of any diet soda that contains it, either. I realize it's an opinion piece, but pseudoscience and speculative articles should not be the domain of NYT.

Of note, the zero-calorie definition of artificial sweeteners is based on the amount excreted in urine/stool: It should be very close to the ingested amount. I find it hard to believe the conclusion drawn by the authors that other sweeteners (sucralose and saccharin), are consumed by bacteria since the amount ingested matches the amount excreted.

If you read the full article instead of just the opening, you get to it:

The prevalence of inflammatory bowel disease has, it’s worth noting, sharply increased in recent decades.

Then there are artificial sweeteners like sucralose and saccharin, which we consume in diet sodas and “sugar-free” snacks in hopes of cutting calories. Our bodies can’t directly digest most of them — they’re meant to pass right through — but it turns out that the microbes inhabiting our colons can metabolize the sweeteners, potentially to our detriment.

Scientists at the Weizmann Institute of Science in Israel have found that, in mice, saccharin causes glucose intolerance, a marker of impending diabetes — and one disease that those who eat these sweeteners are probably trying to avoid. When the scientists transplanted microbes from mice fed saccharine to mice that hadn’t consumed the sweetener, the recipient animals developed glucose intolerance as well, suggesting that the microbiome that was warped by the sweetener, not the sweetener itself, was causing the problems.

What diet soda contains saccharin? Also, that study only looks at saccharin. What about sucralose?
> What diet soda contains saccharin?

The only one I can think of is Tab. I tried it once, and I couldn't finish a can.

The study investigates three non-caloric artificial sweeteners: saccharin, sucralose, and aspartame.

"To determine the effects of NAS on glucose homeostasis, we addedcommercial formulations of saccharin, sucralose or aspartame to the drinking water of lean 10-week-old C57Bl/6 mice"

"Notably, at week 11, the three mouse groups that consumed water, glucose and sucrose featured comparable glucose tolerance curves, whereas all three NAS-consuming mousegroups developed marked glucose intolerance (P , 0.001, Fig. 1a, b)."

The article probably only talks about saccharin specifically because, as the study states: "...saccharin exerted the most pronounced effect, [so] we further studied its role as a prototype artificial sweetener."

Besides Tab, Diet Coke from a fountain contains saccharin: https://www.foodnavigator.com/Article/2008/04/17/Coca-Cola-w...

(Trying to find another source, I believe Diet Pepsi from a fountain does as well, to extend shelf life.)

Wow that blows my mind. No wonder soda from fountain tastes different, and I am not even talking about only the low-calorie ones. I thought it was merely due to some sort of imprecision in dispensing the concentrate.
Someone tried to rekindle the 1970’s saccharin scare in the early 90’s and a bunch of sodas and gums switched to aspartame. Which may be worse for you...
Pink Sweet & Low sweetener (saccharine) packets are in almost every coffee or brunch place I've ever been to.
Your claim about artificial sweeteners not touched by digestion and metabolism is generally not true. Aspartame is broken down in the digestive tract, for example, as is neotame. Glycyrrhizin is broken down in the gut and then metabolized in the liver. I would expect it's the same for sugar alcohols, they are metabolized by gut bacteria and can cause bloating because of that.
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Diet soda is either on the same level of harm as seltzer, or is worse. But I believe both to be healthier than any sugared soda.

Different diet sodas use different artificial sweeteners, so diet soda cannot be treated as a single group. Diet Coke uses only aspartame as sweetener; Coke Zero combines aspartame and acesulfame K to create a more realistic taste.

I readily believe that any diet soda sweetened purely with aspartame is harmless. The chemical structure of aspartame is such that stomach acids should break it down into aspartic acid, phenylalanine, and methanol, the first two being ordinary amino acids. Methanol sounds threatening, but very little aspartame is needed to sweeten a beverage. I thus have no problem drinking diet coke.

What's more unclear is whether the sugar-like taste of artificial sweeteners affect the body's blood sugar regulation.

>diet soda sweetened purely with aspartame is harmless

You also have to consider other additives in the soda, such as acids that can damage your teeth, and the caffeine in diet coke.

True, and even if you've removed everything and are left with water, you have to consider the possibility of drinking too much water.
> stomach acids should break it down

"should", but it's really hard to find reliable information as to what actually happens since the internet is filled with FUD websites claiming aspartame gave their brother/grandma/cat/chair cancer.

> Methanol sounds threatening, but very little aspartame is needed to sweeten a beverage

Methanol is very toxic to humans, so that's a good thing.

> What's more unclear is whether the sugar-like taste of artificial sweeteners affect the body's blood sugar regulation.

Why would it?

The only legitimate health risk I can ever find from criticisms of diet soda is that due to it being sweet and delicious it might make you eat more and then you’ll get fat. Which is a legitimate issue but more of a personal problem than a problem with diet soda in and of itself.
If a substance significantly alters the metabolism of it's users that's not a "personal problem," it's a "side effect."
> Why would it?

I believe the theory goes something like: the taste of sweetness causes changes in the body in preparation for a carbohydrate load.

How much truth there is in this claim is left as an exercise for the reader.

Well, merely swishing liquids with carbohydrates around in your mouth and the spitting it out can increase athletic performance in athletic activities lasting over 1 hour!

From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3916844/ :

> Carbohydrate (CHO) mouth rinse is defined as a CHO fluid distribution around the mouth for 5 to 10 s with subsequent expulsion by spitting. The utilization of either a low-concentrated 6.0% to 6.4% glucose or partially hydrolyzed maltodextrin are the most common CHO used, with the latter being colorless and tasteless when dissolved in water.

...

> CHO mouth rinse seems to improve performance during moderate- to high-intensity exercise (~60% to 75% VO2max), of at least 1 h duration. It is probable that the mechanism involved in this improvement may not be metabolic but neural, via oral CHO receptors (glucose and maltodextrin) that activate brain regions related to the sensation of reward and pleasure.

Note that it apparently isn't taste that is having the effect, as (according to this paper) maltodextrin, when dissolved in water, doesn't have a taste. So apparently there's some mechanism other than either ingestion (metabolic) or taste.

I thought that there had been studies that proved insulin spikes in response to sweet flavors even without caloric content? Not that I have links to them on hand.
Fairly certain I have, at least, seen the headlines.

I meant my last line not as a disputation against, but only as an indicator that I was, at the time, too lazy to provide references.

Ah, yes. Sometimes I'm amused by the expectation of HN readers that anyone commenting will have kept an exhaustive bibliography of everything they've ever read.
> it's really hard to find reliable information as to what actually happens since the internet is filled with FUD websites claiming aspartame gave their brother/grandma/cat/chair cancer.

The burden of proof should probably be on the side of those asserting safety of novel food components, and if that means waiting a full generation for the data to come in, so be it (note that animal tests don't really tell us enough, because metabolism doesn't seem that well conserved between species; there are plenty of things that humans can eat safely that animals can't and vice versa)

Human metabolism and our food has coevolved over thousands of years, and we have evidence in the fossil record that shifts in diet (e.g. agriculture, pastoralism) had negative impacts on human health (worse teeth, shorter, weaker bones) until either our genomes or microbiomes adjusted.

If you decide to consume large quantities of novel ingredients in combinations that no humans have ever eaten before in our evolutionary history, then sure, it may turn out just fine—but metabolism is an intricate dance and there are a lot of ways to screw it up.

"Eat food, not too much, mostly plants." and "Don't eat anything your great grandmother wouldn't recognize as food." seem like sensible advice for people who can afford to follow it [1].

[1] https://www.webmd.com/food-recipes/news/20090323/7-rules-for...

> and if that means waiting a full generation for the data to come in, so be it

I think we're pretty close to having a full generation's worth of data, considering it was approved by the FDA in 1981.

I'm not particularly young and my great grandmother lived into the mid-90s. This would amusingly give me significant leeway. In my own quest to solve my stomach ailments I permanently quit soda and juices, switching to carbonated water. Helped tremendously.
Diet soda is either on the same level of harm as seltzer, or is worse.

What's wrong with seltzer?

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Nothing.
Not true, any carbonated beverage is acidic and not so great for your teeth. As with most things moderation is the way to go, but still, carbonated beverages are decidedly not good for you.
At what point is the only thing left to be decidedly good for you plain water?

I wonder what is the pH of glass of carbonated water with a squeeze of lime?

That’s a good question, and if you’ll permit me, I’ll give the answer in two parts. The acidity of seltzer is roughly the acidity of orange juice, so a squirt of lime in your water is just nowhere close. It is also true that most of what we should be drinking is water. I realize that’s not the first choice for people raised on juice, milk, and soda, but it’s certainly the most healthy.

Remember that I mentioned moderation though? A glass or two of OJ, lemonade, tea, coffee, or seltzer a day isn’t going to materially impact your health assuming you’re not diabetic, and practice good oral hygiene. There are also many worse things for your teeth than seltzer, such as potato chips, and poor oral hygiene. If most of what you’re drinking is water, don’t sweat the glass or two of something other than water. Unfortunately too many poeple drink very little unadulterated water, and it does impact their health.

Moderation is the key.

Why are potato chips bad for your teeth? They are mostly oil and salt.
They’re mostly starch, which the enzymes in your mouth convert to sugar.
They get stuck in between, and in your gums, in a way that (obviously) liquids don’t.
It's not what they are made of, it's the effect they have. Bits get stuck between your teeth and gums, and this encourages bacteria to grow and establish biofilms, which once established can start causing tooth decay. Long term, they can cause a lot of damage.
Can you neutralize the harm by drinking through a straw?
Unfortunately, not even plain water is uncontroversial.
He's not wrong, matter of quantity: https://en.wikipedia.org/wiki/Water_intoxication

('Notable cases' include recorded death.)

Yeah but that's way way past the point where it's very uncomfortable to drink more water. It's not something that can happen to you without warning (or while you're enjoying the process).
Anecdote: My mother got quite sick while drinking a huge amount of water in preparation for a religious 26 hour fast.
Was she comfortable drinking that amount, or was she forcing herself to?
Well obviously any lifeform has water problems. Like any other lifeform, our life depends on remaining within osmotic balance with whatever we drink and eat.

That said, the amount of ways your body adapts to osmotic balance problems is in the dozens, so poisoning your body with water, while possible, is hard to the tune of it requires something like drinking 20 liters of water in less than an hour. I mean, it seems to be possible but I cannot imagine succeeding at that even if I'm trying. That's 2 full buckets (and that's just LD50, as in, if you're >70kg it's more than that).

There is an exception: purified water. You cannot drink mineral-poor* or distillated water safely in even small quantities. Why not ? Because that will locally, suddenly and very strongly disrupt the osmotic balance in what you bring it into contact with. It probably not kill you (not without repeated application), but it may cause serious issues in your mouth, throat and stomach. It should also not be used to make coffee or tea and drunk, that merely lessens the effect it doesn't stop it.

* mineral-poor water is something used in chemical and medical laboratories

I was thinking of things like fluoride, water chlorination, etc. It's also possible to drink water that is "too filtered" and doesn't have enough minerals in it which can apparently cause issues.
Carbonated water typically have a pH around 4, adding lime juice may reduce it slightly further, but not by a huge margin.

Acidity of most beverages on its own is usually not problematic as saliva (buffered at 6.5 pH) rapidly restores normal pH. It does become an issue if the salivary glands are damaged (as in the case of meth users) or stomach acid comes into contact with teeth.(severe acid reflux or bulimia) However these cannot be considered normal.

The number one cause of dental cavities is always sugar.

Pretty sure your teeth can rebuild the top layers fine. I think it's really far from decidedly bad for you? By that token plain water is also bad if not taken in moderation because it can kill you.
So, tooth enamel can be removed mechanically (overbrushing, injury...), but more typically it’s demineralized and breaks down. In the first case you’re shit out of luck, you’re unable to make new enamel. The good news is that deminerlized enamel can be restored if it’s not too far gone, which is what fluoride is trying to do in your toothpaste.

So no, there is a rebuilding process, but the kind of damage done by acidic substances (including the excretions of bacteria) can sometimes be reversed to some extent. The trend is usually erosion however, and moderate intake of something like seltzer or soda is at least an order of magnitude less than straight water. In addition, while water toxicity is a thing, you’d have to overcome a pretty strong urge to vomit. Short of that, water is doing you no harm, and will never contribute to the erosion of your dental enamel.

There's a new fluoride replacement called novamine that is apparently significantly better at re-mineralizing teeth.
Novamin is technically a desensitising agent by blocking tubules on exposed dentin (boney tissue below enamel). There is some evidence suggesting it may aid remineralisation in combination with fluoride, however it is far from conclusive.

A number of toothpaste brands in Japan claims to remineralise teeth with a hydroxyapatite based formula but the results are yet to be confirmed.

Dentists have been using zinc oxide gels and other material to seal exposed dentin but the results are mixed and eventually the filling will fail. Once cavities reach a certain size not much can be done about it.

I've been conducting an informal science experiment with my family for the past 20 years. My wife, my older son (19), my younger son (15) and I have ONLY drink carbonated water. Period. Every drink, every meal.

My kids have no cavities / perfect teeth. My wife and I, by that age range, had tons of cavities.

Did you drink well or city water as a child? The fluoride in the water could be a factor as well.
In a family with radically diverse genetics, and radically diverse oral health outcomes seemingly independent of oral care: congratulations on hitting the genetic lottery!
We just drink soda water.
Sure but do you get it in a can/bottle or make it yourself? The latter done with public tap water would still contain fluoride.
Safeway Refreshe. For 19 years.
Keep in mind that "acidic" should be kept in perspective. Carbonated beverages:

More acidic than: water milk tea ice tea beer

About that same as: coffee (coffee with milk, however, is essentially not acidic) wine (depends a bit on the kind of wine, sweet wine is less acidic) orange juice (from sweet oranges, the sour ones are usually less acidic)

Less acidic than: lemon juice (coke is a LOT less acidic than lemon juice)* grape juice (esp. when adding lemon juice for more sweetener) lime juice things like "lemon ice tea" (and of course actual tea with lemon in it. It depends on how much lemon. If you add enough lemon to allow for much additional sweetness, it will be a lot more acidic than carbonated beverages)

With fruit things can vary. Apparently the rule is, the sweeter, the more acidic (the opposite of what your tastebuds will tell you, although it's really more a case of if you taste sweetness you ignore sourness. Sweet taste doesn't necessarily mean something is acidic, obviously, but (from a certain level) it does mean you won't notice at all whether something is acidic or not, or how much).

If you're worried about this, even a small sip of milk will eliminate any acidity in your mouth in seconds (milliseconds actually).

* I've heard of medical cases where people managed to dissolve their stomach lining by drinking pure lemon juice (about 1.5 liter), and died due to the stomach juices coming into the abdominal cavity. Yes, that's right, your stomach lining, specifically designed to be able to handle strong acidity, cannot deal with lemon juice.

When my close friend got bariatric surgery, the doctors told him the carbonatiob would expand his stomach much faster and so seltzer was forbidden forever. Might also apply to all stomachs.
There are videos that show that most of the carbonation effervesces in your esophagus and mouth, and most of the carbonation is gone by the time it reaches your stomach.
This means nothing for a normal person. Stomachs are massively elastic under normal circumstances.
Not quite nothing, there's a reason people get their stomachs stapled.
Reading the thread, the comment you responded to was using "normal person" as a contrast against someone who had undergone bariatric surgery (which stomach stapling is a variety of).
There are numerous studies showing positive effects of seltzer, and a few suggesting negative effects. But in what world can we compare this to diet soda?
Please link to the studies.
Aren't diet sodas much more acidic than seltzer? That could affect dental health certainly (but almost certainly less than sugared soda).
Seltzer affects dental health.
I meant the increased acidity of diet soda would have different affects on dental health compared to seltzer.
What I've heard from a friend that supposedly knows a lot about chemistry and physics is that aspartame is very bad for your health. Unfortunately I have no other data point, but... Anyone else able to shed some light on whether aspartame is good or not?
Aspartame has been tested like crazy and does not have any known dramatic effects on health. As you mentioned, it's very sweet per molecule, much sweeter than most other artificial / sugary sweeteners, and so you don't have to use very much.

Some other artificial sweeteners, like saccharin, aren't nearly as sweet per molecule, and you have to add a lot to get the desired effect. They also have an apparent effect on glucose intolerance related to one's gut biome, and it's not due to the taste - you can transfer the biome alone between mice and get a similar impact.

Example source: https://www.nature.com/articles/nature13793

I remember researching this topic in a biochem class. Aspartame turned out to be the artificial sweetener with the most potential side effects i studied.

E.g. it seems to affect brain functioning IIRC

> I readily believe that any diet soda sweetened purely with aspartame is harmless. The chemical structure of aspartame is such that stomach acids should break it down into aspartic acid, phenylalanine, and methanol, the first two being ordinary amino acids.

I think the article is saying that it isn't that simple, because even small amounts of certain additives can change the microbiome.

More articles:

https://www.npr.org/sections/thesalt/2014/09/17/349270927/di...

https://www.scientificamerican.com/article/artificial-sweete...

>> What's more unclear is whether the sugar-like taste of artificial sweeteners affect the body's blood sugar regulation.

How is this unclear... every study I've seen shows that artificial sweeteners are similarly obesogenic to actual sugar. Some of them also spike blood sugar quite a bit.

Several studies have also showed that artificial sweeteners change gut bacteria. One study I can't find right now showed a single dose of sucralose significantly changed gut bacteria composition. Here is an article about this concept from Sci Am https://www.scientificamerican.com/article/artificial-sweete...

Soylent used to contain 12g of trehalose per serving, and I’m wondering if that might have some impact? Based on this research it seems likely. I’m not sure if they switched out the trehalose for isomaltulose, and I don’t know if isomaltulose would have similar effects on the GI tract. I find this portion of the Soylent Wikipedia page interesting though:

Later versions of the product lowered the amount of fiber content, but this did not stop the reports of gastrointestinal problems.

Soluble fiber usually produces more bloating, maybe that's what they're referring to?
Clickbait title. The only germs loving diet soda would be the potential shifts in gut biome as a result of saccharine consumption, which would only apply to Tab.

    "The scientists also fed a small group of healthy people saccharin-sweetened drinks for a week. In a subset of volunteers, microbial shifts occurred, accompanied by mounting glucose intolerance. So for some people, diet sodas may not be any healthier than regular sodas."
The Nature study has a better title:

    "Dietary trehalose enhances virulence of epidemic Clostridium difficile"
https://www.nature.com/articles/nature25178.epdf
Tab? Are you joking?

The point isn’t about one specific chemical, but rather the principal that the prevalence of non-nutritious, edible chemicals seriously augments the dark, warm controlled environments of our guts.

Nutrient capture as a whole, shifts in a way that, at the bottom of the tract, there are chemicals that humans leave unused, but which are still useful to certain opportunistic organisms.

If only those chemicals are available, and normal food is absent, every member of the environment is forced to deal with scarcity, and the strongest survive, and fill the void if they can.

If those organisms are forced to opperate with greater efficiency, then their capacity to deal with adversity offers them an advantage as an invasive species, and they will prevail in general, everywhere, not just in the adverse scenario.

Yes, Tab. Exactly.

Which other diet sodas were identified as having "germs that love diet soda"?

The studies show effects for trehalose and saccharine. No diet soda contains trehalose, only Tab contains saccharine.

Any effect from the non-nutritive sweeteners in other diet sodas did not appear in the studies, so they focused on saccharine.

There may be more subtle effects from those sweeteners, or future effects from those sweeteners, but we haven't found them yet, extrapolation from a general principle not withstanding.

"Germs that love Tab" wouldn't draw as many clicks as the current title.

This article is an amazing test of reading comprehension.
Funny how the narrative goes from "microbiome helps you adapt to new foods" except when it doesn't and it then becomes this super sensitive thing that breaks down when approached by any foreign substance.

In every test done with a different substance the question needs to be, how much was it given to the subjects? (g/kg body weight). A lot of tests are done with excessive amounts (which are fine for testing purposes, but doesn't mean the effect will be as pronounced in smaller amounts)

I'll get the sugar-free soda as opposed to something that is the definition of high glycemic index empty calories. Or even better, just water.