Aspartame
Aspartame is a low-calorie artificial sweetener used as a sugar substitute in foods and beverages. It is 200 times sweeter than sucrose and is commonly found under the trade names NutraSweet and Equal (North America), Canderel (Europe), and Pal Sweet (Asia).
Aspartame is most often used for
Last Updated:September 28, 2022
It's uncertain whether aspartame causes headaches due to the scarcity of blinded studies and the role of the placebo effect.
It is not known. There are many reports of headaches caused by 'aspartame', but headaches are one of the main complications that arise from the placebo effect as well. In trying to establish whether a difference exists between placebo and aspartame in regards to headaches, only one blinded study has been conducted and it was riddled with errors.
There is not enough evidence to make a final conclusion either way. Use your own judgement, as headaches are something you are aware happens and can avoid if caused by the diet.
Aspartame and Headaches
One of the most common complaints about aspartame reported to the Center for Disease Control (CDC) are headaches.[reference|url=http://www.cdc.gov/mmwr/preview/mmwrhtml/00000426.htm|title=Evaluation of Consumer Complaints Related to Aspartame Use] Specifically, "346 (67%) complainants reported neurological/behavioral symptoms, including headaches, dizziness, and mood alterations".[reference|url=http://www.cdc.gov/mmwr/preview/mmwrhtml/00000426.htm|title=Evaluation of Consumer Complaints Related to Aspartame Use]
Although a concern to the molecule itself (and some old studies hypothesizing neural effects of aspartame[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/3319565|title=Possible neurologic effects of aspartame, a widely used food additive|published=1987 Nov|authors=Maher TJ, Wurtman RJ|journal=Environ Health Perspect]), headaches are also frequently caused by the placebo effect. Due to the notoriety of aspartame, it is theoretical that many of the headaches could be induced from anxiety. The CDC report notes that:
Overall, the 517 interviewed complainants were predominantly white (96%), female (76%), and between the ages of 21 and 60 years (79%). Complainants were approximately 1.5 times more likely to be female and 2.5 times more likely to be women between the ages of 20 and 59 than expected from 1980 census estimates. Reports came from all geographic regions of the country, with a heavy concentration of cases from Arizona, where the possibility of aspartame use leading to illness received particularly extensive press coverage
Which suggests that demographics and the media may come into play due to abnormal demographic dispersion, unless there are genetic differences in Caucasian females from Arizona that are at greatly different rates than the rest of the US.
Studies into Headaches
Despite aspartame's large therapeutic window and general safety[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/1218049|title={Experiences in the expert evaluation of nucleus pulposus prolapse}|published=1975 Mar|authors=Kühn R, Graner H, Soukup P|journal=Beitr Orthop Traumatol], at least one blinded intervention, which only tested those who self-reported aspartame headaches (thus controlling for non-respondants), suggests that aspartame may be more significant than placebo in triggering headaches in some.[reference|url=http://www.neurology.org/content/44/10/1787.short|title=Aspartame ingestion and headaches] This particular study has received three official critiques after its publication[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/7644073|title=Aspartame and headache|published=1995 Aug|authors=Levy PS, Hedeker D, Sanders PG|journal=Neurology][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/7644072|title=Aspartame and headache|published=1995 Aug|authors=Roberts HJ|journal=Neurology][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/7644074|title=Aspartame and headache|published=1995 Aug|authors=Schiffman S|journal=Neurology], due to its sampling and methodology.
Said study was conducted in 1995 and no attempts have been made at replication of the study.
Beyond the above highly questioned study, a few case reports arise sporadically linking aspartame weakly to neural complications, such as increasing a migraine[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/11703479|title=Migraine MLT-down: an unusual presentation of migraine in patients with aspartame-triggered headaches|published=2001 Oct|authors=Newman LC, Lipton RB|journal=Headache] and two twins who appeared to have a genetic response linking aspartame to vestibulocochlear toxicity (hearing).[reference|url=https://pubmed.ncbi.nlm.nih.gov/20126318|title=Vestibulocochlear toxicity in a pair of siblings 15 years apart secondary to aspartame: two case reports|published=2009 Sep 15|authors=Pisarik P, Kai D|journal=Cases J|]
It does not inhibit fat loss at all, and may actually suppress appetite that could help fat loss (although it does not induce fat loss per se either). Diet soda, in regards to body fat, is a carbonated inert beverage.
Diet Soda and Fat loss
Biochemically speaking
First, let's define 'diet soda' as any drink that is sweetened with low to no calorie sweeteners (like sucralose, aspartame, acesulfame-potassium, etc.) in order to taste like regular (sugared) soda.
In short, there are no direct causative studies that show the use of artificial sweeteners slows your metabolism or promotes fat storage.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/22205311|title=Sucrose-sweetened beverages increase fat storage in the liver, muscle, and visceral fat depot: a 6-mo randomized intervention study|published=2011 Dec 28. {Epub ahead of print}di|authors=Maersk M, Belza A, Stødkilde-Jørgensen H, Ringgaard S, Chabanova E, Thomsen H, Pedersen SB, Astrup A, Richelsen B|journal=Am J Clin Nutr]
Intervention studies
The CHOICE randomized study, lasting 6 months and observing how different diet changes affect weight loss adherence, found that diet soda is an effective substitution for regular soda and had no significant differences in health or weight loss relative to water.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/22301929|title=Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial|published=2012 Mar|authors=Tate DF, Turner-McGrievy G, Lyons E, Stevens J, Erickson K, Polzien K, Diamond M, Wang X, Popkin B|journal=Am J Clin Nutr]
Data from the NHANES (03-04) study suggest that increased servings of non-caloric beverages are not related to an increase in total calories.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19349562|title=Impact of change in sweetened caloric beverage consumption on energy intake among children and adolescents|published=2009 Apr|authors=Wang YC, Ludwig DS, Sonneville K, Gortmaker SL|journal=Arch Pediatr Adolesc Med] Additionally, the PREMIER trial found that a reduction in intake of non-caloric beverage is not associated with weight loss.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19339405|title=Reduction in consumption of sugar-sweetened beverages is associated with weight loss: the PREMIER trial|published=2009 May|authors=Chen L, Appel LJ, Loria C, Lin PH, Champagne CM, Elmer PJ, Ard JD, Mitchell D, Batch BC, Svetkey LP, Caballero B|journal=Am J Clin Nutr]
What is the source of confusion?
The real problem is that people tend to under-estimate caloric intake. By thinking about the zero calories in the soda, they end up eating an excess of calories, thus increasing fat storage[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/15111986|title=A Pavlovian approach to the problem of obesity|published=2004 Jul|authors=Davidson TL, Swithers SE|journal=Int J Obes Relat Metab Disord]. This makes the well known correlation (relationship) between diet soda and obesity; one does not cause the other, but they tend to co-exist. Drinking diet soda does not make one fat, but people with obesity tend to drink diet soda.
In regards to insulin, diet soda can potentially increase insulin secretion by both an anticipatory response and the artificial sweetener aspartame can (through the amino acid, phenylalanine). However, both of these insulin spikes are too small to matter practically, and the latter mechanism doesn't seem to occur at all with many commonly ingested dosages.
Devil's advocate: Diet soda for weight loss?
As mentioned on our Aspartame and Appetite page, aspartame (via phenylalanine) might also suppress appetite.
Research suggests that diet soda is unlikely to be detrimental to metabolic health or body composition. Further controlled trial evidence is needed to explore other possible detriments.
Simply put...
Currently available research into diet soda and long-term health risks is insufficient, although there are specific areas where risks are unlikely. Contrary to popular belief, diet soda (defined as calorie free carbonated beverages sweetened with aspartame, sucralose, acesulfame-potassium, or other non-caloric or minimally caloric sweeteners) doesn't inhibit fat loss, or spike insulin levels.
Current research that attempts to link diet soda with type 2 diabetes and metabolic syndrome[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19151203|title=Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)|published=2009 Apr|authors=Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR Jr|journal=Diabetes Care][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/17646581|title=Soft drink consumption and risk of developing cardiometabolic risk factors and the metabolic syndrome in middle-aged adults in the community|published=2007 Jul 31|authors=Dhingra R, Sullivan L, Jacques PF, Wang TJ, Fox CS, Meigs JB, D'Agostino RB, Gaziano JM, Vasan RS|journal=Circulation] did not have equal caloric consumption. Excess caloric consumption has a direct correlation with many health issues, and in fact one of the studies[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19151203|title=Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)|published=2009 Apr|authors=Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR Jr|journal=Diabetes Care] distinctly states:
Consequently, the previously observed diet soda–metabolic syndrome associations are generally speculated to be the result of residual confounding by other dietary behaviors, lifestyle factors, or demographic characteristics (1,2). Biological mechanisms possibly explaining these associations are few and largely focus on artificial sweeteners in beverages/foods increasing the desire for (and consumption of) sugar-sweetened, energy-dense beverages/foods (3) or disrupting consumers' ability to accurately estimate energy intake and remaining energy needs (4). Thus, diet soda consumption may result in overconsumption, increased body weight, and consequent metabolic dysfunction.
In short, many people who have bad diets may consume diet soda in an attempt to do "less damage" - this could result in an incorrect association of diet soda consumption with health conditions.
What about those studies that I read saying diet soda was bad?
That was most likely a survey or epidemiological research. This is research that aims to find correlations (relationships) between two variables, and sets up future studies to find which variable causes what.
There are many studies that note that diet soda is frequently consumed by unhealthy people,[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19151203|title=Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)|published=2009 Apr|authors=Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR Jr|journal=Diabetes Care][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/17646581|title=Soft drink consumption and risk of developing cardiometabolic risk factors and the metabolic syndrome in middle-aged adults in the community|published=2007 Jul 31|authors=Dhingra R, Sullivan L, Jacques PF, Wang TJ, Fox CS, Meigs JB, D'Agostino RB, Gaziano JM, Vasan RS|journal=Circulation] but no studies that compare people with equivalent diets. One study (Northern Manhattan Study) was able to control a fair number of variables and found a weak correlation between diet soda and vascular events, but these differences disappeared when 'pre-existing health conditions' were considered.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/22282311|title=Diet Soft Drink Consumption is Associated with an Increased Risk of Vascular Events in the Northern Manhattan Study|published=2012 Jan 27|authors=Gardener H, Rundek T, Markert M, Wright CB, Elkind MS, Sacco RL|journal=J Gen Intern Med]
When comparing diet soda against other non-caloric beverages in an intervention study, and you control the rest of the diet, no difference in weight loss is noted. This suggests that the problem is likely the habits of people who drink diet soda, rather than the diet soda itself.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19151203|title=Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)|published=2009 Apr|authors=Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR Jr|journal=Diabetes Care] The Northern Manhattan study suggested that diet soda use may be correlated with disease as it its consumption was an attempt by (already unhealthy) individuals to reduce calories and take control of their health.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/22282311|title=Diet Soft Drink Consumption is Associated with an Increased Risk of Vascular Events in the Northern Manhattan Study|published=2012 Jan 27|authors=Gardener H, Rundek T, Markert M, Wright CB, Elkind MS, Sacco RL|journal=J Gen Intern Med]
What are the legitimate downsides to diet soda?
Soda (in general) has been linked to poor dental health numerous times, especially children.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/21922984|title=An update on the dangers of soda pop|published=2011 Jul-Aug|authors=Kaplowitz GJ|journal=Dent Assist][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19434767|title=Dental erosion and severe tooth decay related to soft drinks: a case report and literature review|published=2009 May|authors=Cheng R, Yang H, Shao MY, Hu T, Zhou XD|journal=J Zhejiang Univ Sci B] Although sucrose (sugar) plays a major role, the general acidity of diet sodas can also negatively influence dental health.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/21922984|title=An update on the dangers of soda pop|published=2011 Jul-Aug|authors=Kaplowitz GJ|journal=Dent Assist] Overconsumption of soft drinks without adequate dental intervention may result in cavities and yellowing of teeth, and this applies to both sugared and diet sodas; although sugared are worse in this regard.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/15061331|title=Soft drink consumption and caries risk in children and adolescents|published=2003 Jan-Feb|authors=Shenkin JD, Heller KE, Warren JJ, Marshall TA|journal=Gen Dent]
Like most things, overconsumption may not be a good idea, especially for your teeth. Otherwise if you want to enjoy a Diet Coke, Coke Zero, Diet Pepsi, or whatever diet soda you enjoy most, don't feel guilty about it.