Happy Friday, folks 🙂 Let’s get into the science. On the docket this week? The impacts of aspartame on ADHD + anxiety. It’s a doozy, but you won’t regret reading through it! I swear - the answer probably isn’t what you think it is (or is it now that I said that?).

Study #1: Aspartame and ADHD

Fun fact: There’s only one study on ADHD and aspartame (that sweetener found in many 0-sugar beverages). It’s a good thing that it was *drumroll please* the best type of study [randomized, double-blinded, + placebo-controlled]!

BUT, before we get into it, why are we concerned about aspartame in reference to ADHD? The theory goes like this:

So, let’s look at the study.

We have one knock to the study - its date. This study was conducted in 1994. Don’t worry - I’ll go over a meta-analysis of the literature as well to make sure that we cover the recent information as well. Another thing to know is that, like most older ADHD research, this was conducted with children. It’s likely that it’s generalizable to adults, but we don’t know for sure.

So the kids - diagnosed with ADHD but unmedicated - were split up into two groups: placebo and aspartame.

What did they find?

There were no behavioral or metabolic differences between the two groups (except, as expected, there was more phenylalanine and tyrosine in the aspartame group).

That’s, like, weird right? This is a common case of how common sense doesn’t exactly translate to lived, scientific outcomes. Even though it feels and definitely seems like aspartame should negatively affect ADHD, it technically doesn’t (to our current knowledge). This finding that aspartame does not impact hyperactivity has been shown again in non-ADHD children as well. In fact, in the most recent 2024 analysis of all the literature on aspartame and cognitive outcomes, they found a consistent finding in the research that aspartame, despite duration of use, is not associated with negative cognitive outcomes except under certain circumstances (such as phenylketonuria).

Of course, this does not mean liberally take aspartame. What this means is that, unless you take more than the upper limit a day (40mg/kg), you likely will not experience negative cognitive health outcomes. So, your 1 diet soda or sugar-free ice cream isn’t going to do much.

Study #2: Aspartame and Anxiety

Welcome to a case of: mice studies =/= observed health outcomes in humans. So, there are multiple studies (upwards of 20-30) essentially proving a positive effect of aspartame on anxiety in rat models, meaning aspartame can induce and exacerbate anxiety symptoms in mice.

Weirdly enough, this doesn’t currently translate to human subjects research (which, unfortunately, only contains about 2 studies I was able to find). I’ll break down one of them below, but again, just wanted to emphasize - WEIRD. After all, most anxiety research done in mice translates to humans. That being said, I do want to caution that it’s possible aspartame can impact anxiety in humans due to our lack of comprehensive human research coupled with the clear impact on mice studies. For instance, in mice, aspartame interrupts circadian rhythms and dysregulates the glutamate-GABA ratios (which, if you aren’t aware, is one of the most important physiological markers of anxiety).

Now that we got that out of the way, let’s chat about the human study.

This study was a self-report, associative study. It’s not our favorite type of study, but we do what we can with what we have. Here’s the basics:

So, anxiety scores are not associated with aspartame intake, though stress is. This means we do not currently seen an association between anxiety and aspartame intake. However, there is an association between stress and aspartame intake. It’s important to note that we don’t know which one influences the other - or even if it’s a bi-directional impact. Regarding the second study on humans, anxiety, and aspartame, we find no acute anxiety changes in people (both sensitive to aspartame and non-sensitive) who take aspartame-containing products.

Big important note on depression though:

In humans, aspartame intake can increase both depressive symptoms and irritability (this was a within-subjects design). If you have depression or are prone to depression, I would personally recommend reducing or eliminating aspartame. Again, though, we see most changes with a high-aspartame intake (approaching the upper safe guidelines).

If you are worried about aspartame and your mental health after reading through all of this, one thing to know is that protein can potentially inhibit the negative effects of aspartame. If you want your sugar-free foods, simply eat them with protein :)

Thanks for reading!

If you have any thoughts, questions, or comments, be sure to shoot me a DM on Instagram @Nutrimindcoach or simply reply to this email. I LOVE hearing from you!

Don’t forget to tune into this week’s episode of my podcast! It’s all about how food freedom impacts mental health -