Does Aspartame Spike Insulin?

sugar lipsWell we’ve looked at sucralose and insulin as well as saccharin. What about aspartame? It is one of the most commonly used artificial sweeteners and you’ll most likely find it in soda and other sweetened snacks along with acesulfame potassium. So lets take a look at aspartame and sort out what may or may not be correct.

First lets take a quick look at what aspartame is. Aspartame contains phenylalanine, an amino acid, aspartic acid and methanol. That’s right, methanol or wood alcohol. 1 Methanol gets converted into formaldehyde and formic acid, which are both toxic. Two reviews of the safety of aspartame have concluded that this isn’t a problem at the doses typically consumed by the public. 2,3  We’ll talk more about the safety in a bit. Lets now focus on insulin.

In one study of 6 males administration of aspartame had no effect on insulin levels. 4

In another study aspartame was given in meals to 16 normal individuals and they looked at several hormones after ingestion. I think this part is funny. In the study the researches claim,

Serum insulin decreased slightly and serum glucose increased slightly over the course of all test procedures; both responses were statistically significant in nearly all tests”

They then go on to say,

” We found no effect of any of the test meals on serum cortisol, GH, insulin, or glucose…” (emphasis added)

So they either had a typo or forgot that the results were signficant. It is most likely that the decrease in insulin was from the morning meal and the levels were just decreasing back to baseline, and the authors come to the same conclusion. 5

In one study of 48 people, researchers gave sucrose or aspartame over a four month period in crossover. No differences were seen in the subjects with regards to insulin. 6

In another study looking at preload meal compared sucrose, stevia, and aspartame sweetened cream chease and crackers with tea on insulin levels. Blood samples were taken post meal and found that the sucrose and aspartame samples elevated insulin the same after 30 min while the stevia group was significantly lower. This study doesn’t look strictly at aspartame vs sucrose and I think it’s useful in this case because calories were also consumed with the sweeteners as would be done in a real life situation. Aspartame didn’t raise insulin anymore than the sucrose, but it was the same. 7

In a hospital study, diabetic subjects were given aspartame and researchers looked at…you guessed it glucose and insulin, as well as triglycerides and HDL. No change was seen. 8

Another study looked at pretty much the same thing (I feel like I’m beating a dead horse here) but also compared saccharin to aspartame in a drink. No differences were noted with the exception of a small increase in the AUC (total insulin exposure) with the aspartame over saccharin. 9 The researchers claimed there was probably no clinical significance to this. Maybe not and maybe so. Who knows for sure?

Just like the last two articles discussed, these studies weren’t done over a long term (3 years or more) and to be able to make any strong conclusions about aspartame’s true effect on insulin or glucose cannot be made based on these studies. It just looks like if you have something sweetened with aspartame every once in a while, the effect on insulin and glucose in and of itself probably isn’t significant. If you’re eating carbs though with these sweeteners, which isn’t unlikely, are the results different? It’s possible but we just don’t know without the research as a whole. If you check blood glucose and notice that it went down after decreasing aspartame ingestion then you would have your answer.

Aspartame in my opinion, just like other artificial sweeteners is not all that pleasant tasting. It is very sweet, but yeah….not pleasant for me. Ice cream sweetened with aspartame is an abomination. It tastes so much better with good ol sucrose. And yes I do have ice cream from time to time because hey, it’s ice cream!  It is very often found in diet sodas. Sodas are probably the biggest sources of it followed by yogurt and powdered soft drinks, at least according to the Nutrasweet company. 10

But what about other health concerns?

According to one epidemiologic study there was no significant findings for adverse events or toxicity. 11 Another study shows that at doses of 75mg/kg/day of aspartame for 24 weeks with no adverse effects significant over placebo. 13 A quick Google search will quickly dispel those studies with anecdotal evidence. I’m not a person to discount anecdotal evidence, in fact I think it’s important, especially if the N=1 is you. But the studies are important too so I want to review a review that you can access online:

First recall that aspartame gets broken into 3 parts in the body; phenylalanine, aspartic acid, and methanol. Phenylalanine plays an important role in neurotransmission as it is a precursor for DOPA, dopamine, epinephrine and norepinephrine. It also competes for a ride on a protein called neutral amino acid transporter (NAAT). This transports not only phenylalanine but others as well. Large amounts of one amino acid will out compete the others for a spot on the NAAT and stop the balance that is normally attained. In this case with increased phenylalanine in the brain, levels of catecholamines can be increased. Tryptophan can also be displaced by too much phenylalanine and cause lack of serotonin in the brain. This can lead to sleep problems and and appetite problems. Aspartame may also bind to NMDA receptors and cause neurologic damage.

Aspartic acid may play a role as an excitatory nuerotransmitter and may play a role in the problems caused by ingesting aspartame. Additionally methanol, as discussed earlier can be converted to formaldehyde and formic acid. According to the researchers fibromyalgia, spasms, shooting pains, numbness in the legs, cramps, vertigo, dizziness, headaches, tinnitus, joint pain, depression, anxiety, slurred speech, blurred vision or memory loss have been attributed to aspartame.12

Headache's a problem? Ditch Aspartame

Headache problems? Ditch Aspartame

Much of the anecdotal evidence I’ve seen revolves around headaches. I’ve also read reports about gut problems and other neurologic problems that sound similar to fibromyalgia symptoms. I haven’t come across anything that shows there is an effect on gut bacteria. It wouldn’t surprise me if it did, but I can’t say that it does.

So should you avoid aspartame? Probably. Every once in a while probably won’t do anything if you’re otherwise healthy but I can’t recommend it regularly. The taste is gross and because of that and that companies would taint the oh so wonderful goodness of ice cream with it is enough for me…..and the possible health detriments too of course.

What are your stories? I’d love to hear about any experiences you’ve had with aspartame.


1.Humphries, P., E. Pretorius, and H. Naude. “Direct and indirect cellular effects of aspartame on the brain.” European Journal of Clinical Nutrition 62.4 (2007): 451-462.

2.Magnuson, B. A., et al. “Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies.” CRC Critical Reviews in Toxicology 37.8 (2007): 629-727.

3.Butchko, Harriett H., et al. “Aspartame: review of safety.” Regulatory Toxicology and Pharmacology 35.2 (2002): S1-S93.

4.Møller, Svend E. “Effect of Aspartame and Protein, Administered in Phenylalanine‐Equivalent Doses, on Plasma Neutral Amino Acids, Aspartate, Insulin and Glucose in Man.” Pharmacology & toxicology 68.5 (1991): 408-412.

5.Carlson, Harold E., and Jayendra H. Shah. “Aspartame and its constituent amino acids: effects on prolactin, cortisol, growth hormone, insulin, and glucose in normal humans.” The American journal of clinical nutrition 49.3 (1989): 427-432.

6.Spiers, Paul A., et al. “Aspartame: neuropsychologic and neurophysiologic evaluation of acute and chronic effects.” The American journal of clinical nutrition 68.3 (1998): 531-537.

7.Anton, Stephen D., et al. “Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels.” Appetite 55.1 (2010): 37-43.

8.Okuno, Giichi, et al. “Glucose tolerance, blood lipid, insulin and glucagon concentration after single or continuous administration of aspartame in diabetics.” Diabetes research and clinical practice 2.1 (1986): 23-27.

9.Horwitz, David L., Michael McLane, and Peter Kobe. “Response to single dose of aspartame or saccharin by NIDDM patients.” Diabetes Care 11.3 (1988): 230-234.


11.Magnuson, B. A., et al. “Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies.” CRC Critical Reviews in Toxicology 37.8 (2007): 629-727.

12.Humphries, P., E. Pretorius, and H. Naude. “Direct and indirect cellular effects of aspartame on the brain.” European Journal of Clinical Nutrition 62.4 (2007): 451-462.

13.Leon, Arthur S., et al. “Safety of long-term large doses of aspartame.” Archives of internal medicine 149.10 (1989): 2318.


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