The top 10 worst foods listed at planetgreen.com elects diet soda as the number one worst food/beverage, even worse than regular soda. However, I find it a little hard to believe, since the number of calories is much lower and the sugar content is null. Is it preferable to drink regular soda?

Diet soda is my choice for the Worst Food of All Time. Not only does diet soda contain most of the problems of regular soda, it contains aspartame, now called AminoSweet. According to research by Lynne Melcombe, author of Health Hazards of White Sugar, aspartame is linked to the following health conditions: anxiety attacks; binge-eating and sugar cravings; birth defects; blindness; brain tumors; chest pain; depression; dizziness; epilepsy; fatigue; headaches and migraines; hearing loss; heart palpitations; hyperactivity; insomnia; joint pain; learning disabilities; PMS; muscle cramps; reproductive problems; and even death. Aspartame’s effects can be mistaken for Alzheimer’s disease, chronic fatigue syndrome, epilepsy, Epstein-Barr virus, Huntington’s chorea, hypothyroidism, Lou Gehrig’s disease; Lyme disease, Ménière’s disease, multiple sclerosis, and postpolio syndrome. That’s why I give Diet Soda the Worst Food of All Time award.

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    Aspertame may be linked to more serious illnesses than sugar, but to really compare diet soda to regular, a comparison of the quantities found in soda must be made. I'll be curious to see if such a study has been made. In the mean time, I try to avoid all soda. – Flimzy Nov 18 '11 at 18:12
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    If you want to take the question seriously then you needy to find some way to account for the general health problems caused by excess calories. A disturbing number of people in many western countries are too fat and surgery drinks add extra calories to diet wit no compensating health benefits at all. All this before taking a serious view of the possible effects of aspartame (though it is worth noting that, given the number of people who take aspartame regularly, its effects should be strongly visible is epidemiology stats and it isn't.) – matt_black Nov 18 '11 at 19:21
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    Oh, and if any of the answers are going to be taken seriously they will need to quote better sources than planetgreen.com which seems to be an advocacy site for the idea that everything man-made is bad; everything natural is good. – matt_black Nov 18 '11 at 19:27
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    @SamIAm I Am: Yes, and that study shows the point: People who drink diet soda are more likely to be obese, but that's not because diet soda causes this, but because of all the associations. I would contend that diet soda by itself is not bad for your health at all, except for the unproven claims associated with Aspartame and the acidity against your teeth. If you drink diet soda instead of regular soda and because of that grant yourself another Donut, you're doing it wrong. (With you I don't mean you specifically ;) ). – Pascal Nov 19 '11 at 0:34
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    @Pascal, the article points out another possibility, "Fowler points to a recent study in which feeding artificial sweeteners to rat pups made them crave more calories than animals fed real sugar." I was just trying to point out a different source than planetgreen.com and that this is a very vaild question and should be taken seriously. I wasn't trying to make any conclusions. – Sam I Am Nov 19 '11 at 2:47

Hysteria around the aspartame in diet drinks is not justified by the evidence

It is quite hard to prove a negative but the simple observation that hundreds of millions of people take aspartame containing drinks every day without apparently causing any notable epidemiological evidence of all the effects should be of some significance. As far as I can tell no such evidence has ever been presented and most of the "evidence" is merely anecdotal.

Here is what a 2004 BMJ editorial said about the evidence:

Evidence does not support links between aspartame and cancer, hair loss, depression, dementia, behavioural disturbances, or any of the other conditions appearing in websites. Agencies such as the Food Standards Agency, European Food Standards Authority, and the Food and Drug Administration have a duty to monitor relations between foodstuffs and health and to commission research when reasonable doubt emerges. Aspartame's safety was convincing to the European Scientific Committee on Food in 1988, but proving negatives is difficult, and it is even harder to persuade vocal sectors of the public whose opinions are fuelled more by anecdote than by evidence. The Food Standards Agency takes public concerns very seriously and thus pressed the European Scientific Committee on Food to conduct a further review, encompassing over 500 reports, in 2002. It concluded from biochemical, clinical, and behavioural research that the acceptable daily intake of 40 mg/kg/day of aspartame remained entirely safe—except for people with phenylketonuria.

For those who argue that aspartame releases toxic substances in the body when metabolised (though it is hard to see how natural amino acids are toxic) it is worth bearing in mind the doses involved in typical diet drinks. This lucid explanation and summary of actual evidence appeared in the BMJ in response to some of the more hysterical critics of aspartame who criticised the editorial quoted above (my emphasis):

Mercola talks about “flooding the brain” with amino acids, presupposing that aspartame causes excessive rises in plasma concentrations of phenylalanine that then cross the blood-brain barrier. Plasma phenylalanine rises to 80-120 mmol/l after a protein meal such as a glass of the “natural substance” milk, about the same as after a dose of 34 mg aspartame per kg body weight (about 28 canned drinks sweetened with aspartame consumed at once); current consumption data show that average daily intake is less than 1% of this and maximum intake less than 10%.

Briffa thinks that aspartame metabolism produces methanol toxicity. According to the US Food and Drug Administration, to cause toxicity in humans, 200-500 mg methanol per kg body weight is needed to produce sufficient amounts of its metabolite, formate (federal register 1984). This corresponds to drinking 600-1700 cans of diet soft drink at once, an amount not achieved after a dose of 200 mg aspartame per kg body weight.

It is also worth noting that studies in children show that sugary drinks make them fatter than artificially sweetened drinks, though the evidence in adults is mixed (perhaps because of confounding as people already concerned about weight may tend to drink lower calorie drinks confusing the direction of cause and effect).

So, overall, there is no convincing reason to suppose that diet drinks sweetened with aspartame are bad for you, especially when compared to the empty calories of sugary drinks which have plenty of bad effects, especially in children.

Update There have been several low quality studies suggesting that aspartame containing drinks don't have the expected effects on obesity (they don't have any calories, so you might think they ought to help compared to sugary drinks).

But a better quality recent study (link is to pdf of paper) has looked at some of the implications of sugary drinks on long term health and has found a significant association with Type 2 diabetes.

The summary of the paper claims:

Results In adjusted models, one 336 g (12 oz) daily increment in sugar-sweetened and artificially sweetened soft drink consumption was associated with HRs for type 2 diabetes of 1.22 (95% CI 1.09, 1.38) and 1.52 (95% CI 1.26, 1.83), respectively. After further adjustment for energy intake and BMI, the association of sugar-sweetened soft drinks with type 2 diabetes persisted (HR 1.18, 95% CI 1.06, 1.32), but the association of artificially sweetened soft drinks became statistically not significant (HR 1.11, 95% CI 0.95, 1.31). Juice and nectar consumption was not associated with type 2 diabetes incidence.

Conclusions/interpretation This study corroborates the association between increased incidence of type 2 diabetes and high consumption of sugar-sweetened soft drinks in European adults.

The lack of significance of the effect in artificially sweetened drinks after adjustment is noteworthy as it suggests that one reason why other studies have not seen the effect on weight is that they did suffer from confounding caused, probably, because the already fat are more likely to take diet drinks. This study concludes that, for a given group, taking too much sugary drink is clearly bad for you.

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    I think the "innocent until proven guilty" approach to nutrition is dangerous. For example, for many years people thought that margarine was a healthy alternative to butter, but now we know that trans fats are actually very unhealthy. – Muhd Feb 15 '12 at 23:35
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    Also, you are leaving out a very important more recent study, which I have provided in my answer. – Muhd Feb 15 '12 at 23:35
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    @Muhd That paper reports a very weak effect that doesn't persuade me that what they observe is not just the result of confounding (e.g. because some people start taking diet drinks after they are warned about weight or health). – matt_black Nov 18 '12 at 16:45
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    @jwenting Most "diet" drinks (coke, pepsi, other lemonade-like drinks) don't contain any other calories. I suppose there are some fruit juice like drinks that do, but I'm not sure they are the problem. – matt_black Apr 26 '13 at 11:46
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    @jwenting True, but the actual amounts matter. Diet drinks contain between 0.1% and 1% of the amount (even if you measure in calorific content) of sweetener as sugary drinks, so you have have to take a very very large volume to consume the same number of calories. – matt_black Apr 26 '13 at 23:01

In a recent study, diet soda consumption was linked with greater incidence of vascular events:

Controlling for age, sex, race/ethnicity, education, smoking, physical activity, alcohol consumption, BMI, daily calories, consumption of protein, carbohydrates, total fat, saturated fat, and sodium, those who drank diet soft drinks daily (vs. none) had an increased risk of vascular events, and this persisted after controlling further for the metabolic syndrome, peripheral vascular disease, diabetes, cardiac disease, hypertension, and hypercholesterolemia (HR = 1.43, 95% CI = 1.06–1.94). There was no increased risk of vascular events associated with regular soft drinks or light diet soft drink consumption.

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    You omitted " Further research is needed before any conclusions can be made regarding the potential health consequences of diet soft drink consumption." – RedGrittyBrick Jun 20 '13 at 9:58
  • "greater incidence of vascular events" and "is worse for you than regular soda" are not the same thing. – Shane Apr 1 '18 at 0:14

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