A research study presented last week at the International Stroke Conference 2011 sponsored by the American Stroke Association (ASA) suggested that drinking daily diet soda is associated with an increased incidence of stroke.
The investigators studied 2500 people from the New York City area, and compared the occurrence of stroke over 9 years with each individual's reported consumption of diet soda. They found that, among those who reported drinking daily diet soda, the risk of having a stroke was almost 50% higher than for individuals who said they drank no soda.
This study has received much media attention, as one might predict. And as usual, the popular media seems to have been unable to provide any perspective regarding the legitimacy of the findings, leaving their viewers, listeners and readers with the impression that diet soda is yet one more of the hundreds of commonly encountered substances which scientists have determined will kill us. (The fact that there's anybody left to listen to such stories is a clear indication that not all of these scientists have been correct.)
So does diet soda really cause strokes?
Well, if it does, this is not the study that has demonstrated it.
Based on all the reports I have read, this study appears not to have been conducted with sufficient rigor to even make a legitimate association between diet soda consumption and strokes, let alone demonstrate a cause-and-effect relationship. As just one example: While the investigators controlled for the confounding risk factors of smoking, exercise, physical activity, and calorie consumption, they apparently failed to account for obesity.
If diet soda drinkers were, on average, more overweight than non-diet-soda drinkers (a not implausible possibility, since overweight individuals may be more likely to drink diet soda), and were therefore more likely to have metabolic syndrome (for instance), that difference itself could easily account for the increased risk of stroke.
Furthermore, the investigators were completely unable to postulate a mechanism by which diet soda could increase the risk of stroke. They were unable to suggest that the culprit is any specific substance used in diet soda, since their subjects drank the whole gamut of diet sodas, and therefore were exposed to aspartame, saccharin, and sucralose, all three. So the investigators (and other experts interviewed by the media), have been at a complete loss to offer a plausible mechanism for these findings.
Whenever an unexpected association is discovered in an observational study such as this, the possibility that the association is "real" is always highly suspect. When that association cannot be tied to any theory to explain why the finding might be real, it should be even more suspect. (To further illustrate this point, at the very same ASA meeting, investigators from UCLA reported that strokes are very prevalent, and take an "enormous toll," among Oscar nominees. )
Finally, it is important to realize that this study was presented only in "abstract" form, and has not been published. Therefore, it has not yet been peer-reviewed. Until it is actually accepted for publication - if it ever is - it is impossible to derive any firm conclusions about the likelihood that the study reflects some semblance of reality. And based on what I have seen, I will be a little surprised if this study ever makes it to print.
So I see very little reason to be overly concerned at this point about the consumption of diet soda giving you a stroke. While it is obviously a possibility, the evidence we have right now is quite weak. This study made the news based on its sensationalism, rather than its scientific merit.
At present, from my standpoint at least, the most likely way for diet soda to give you a stroke is to be struck in the head by a full can, like that jogger in the Super Bowl commercial.
Thanks for the good article. You’ve made some valid points about the flaws in the study (overweight folks gravitating to diet sodas, variety of diet sodas involved). This study did not include the energy drinks, did it? That’s a different can of worms and news story.
If diet soda can cause strokes with its low calories, what conditions can sugar sweetened drinks cause? I don’t have enough room in this comment to list them all. However, I would say larger clothing sizes is probably the least of them.
I would also assume that those who drink diet soda or any kind of soda do not have a good diet to begin with.
Drinking diet drinks is sometimes a toss up between having a diet drink or actually having a drink with sugar in it. Some people say it’s better to have the drink with sugar, but not have so many.
When somebody is thirsty, all that is needed is water, preferably mineral and at room temperature. One does not need the ASA to be told that diet soda is no use to anybody.
I don’t think you are getting what the basis of the matter regarding diet soda consumption is about. It’s about ASPARTAME, which is an EXCITOTOXIN. Google Dr. Russel Blaylock (a board certified neurosurgeon and author) and aspartame dangers. Aspartame was never going to be approved by the FDA until Rumsfeld pushed it through.
Thank you so much for clearing this up.I have been drinking diet sodas for years and this study caused a great alarm for me. Thank you for easing my mind.
As a scientist, let me say that you should be worrying about the phosphoric acid base that is used in drinks like Coke, an industrial chemical that is used in plastics manufacture, degreasing etc. Only a person with no respect for their body would consume these drinks, but, it does show the power of advertising….
Kathy Ridge: re-read the article. The drinks in the study were sweetened with ALL THREE common artificial sweeteners, NOT just aspartame.
Michael Manicone: You’ve made a very important observation. Until a well-designed study – which this was not – compares the stroke-causing potential of regular soda to diet soda, whether DIET soda per se is or is not the culprit is a moot point.
Dr. Sayer: another excellent point. We must remember that even carbonated water, carbon dioxide dissolved in water under pressure, produces carbonic acid so although colas with phosphoric acid are unusually nasty, ALL sodas are acidic. I bought some no-name diet cola, tried one can, hated it and set the other cans aside in an old enameled fridge drawer, unable to discard something I just paid $$ for. I re-discovered the drawer several years later. The cans were empty because the cola had turned the cans into Swiss cheese. An uncle used cola to clean his car radiator and windshield because it dissolved dead bugs and other debris better than any commercial cleaner. Words to the wise as I grab a rum, diet cola and a squeeze of lime!
Kathy Ridge: I took your advice and Googled Blaylock. Some hits identify him as a quack, others are more circumspect and state that his views run counter to scientific evidence on a variety of topics on which he expresses opinions. Having an MD and having formerly practiced as a neurosurgeon does not mean that everything that falls out of his mouth is God-given gospel.
Try putting a little vinegar into a can, seal it, and come back in a few years. Suspect there won’t be much left of the can either. We ingest lots of acidic things without harm. In fact, stomach acid is a much stronger acid than any of them. Didn’t the article also say that there was no added stroke risk among those who drank BOTH diet and sugar pop? So if you slug down a few hundred calories of sugar pop with your diet Coke, you’re Ok?
what is the cause of not undergoing erection early morning when one wakes up from bed.
I really wanted to say something about this. Columbia University is a very religious college, and also homophobic. Many gay people drink diet sodas, and I have a sneaking suspicion this study was done in light of the events happening among the gay community. I dont trust Christian research, as it is very biased and innacurate information.