Aspartame and the Brain

Image Credit: Mike Mozart / Flickr. This image has been modified.

Side-Effects of Aspartame on the Brain

The National Institutes of Health AARP study of hundreds of thousands of Americans followed for years found that frequent consumption of sweetened beverages, especially diet drinks, may increase depression risk among older adults. Whether soda, fruit-flavored drinks, or iced tea, those artificially sweetened drinks appeared to carry higher risk. There was a benefit in coffee drinkers compared to non-drinkers, but if they added sugar, much of the benefits appeared to disappear, and if they added Equal or Sweet-and-Low, the risk appeared to go up.

Various effects of artificial sweeteners, including neurological effects, have been suspected. For example, aspartame—the chemical in Equal and Nutrasweet—may modulate brain neurotransmitters such as dopamine and serotonin, although data have been controversial and inconsistent. Scientific opinions range from “safe under all conditions” to “unsafe at any dose.” The controversy started in the 80’s soon after aspartame was approved. Researchers at the Mass College of Pharmacy and MIT noted:

“given the very large number of Americans routinely exposed, if only 1% of the 100,000,000 Americans thought to consume aspartame ever exceed the sweetener’s acceptable daily intake, and if only 1% of this group happen coincidentally to have an underlying disease that makes their brains vulnerable to the effects, then the number of people who might manifest adverse brain reactions attributable to aspartame could still be about 10,000, a number on the same order as the number of brain and nerve-related consumer complaints already registered with the FDA before they stopped accepting further reports on adverse reactions to the sweetener.”

Those with a history of depression might be especially vulnerable. Researchers at Case Western designed a study I highlighted in my video Aspartame and the Brain to ascertain whether individuals with mood disorders are particularly vulnerable to adverse effects of aspartame. Although they had planned on recruiting 40 patients with depression and 40 controls, the project was halted early by the Institutional Review Board for safety reasons because of the severity of reactions to aspartame within the group of patients with a history of depression.

It was decided that it was unethical to continue to expose people to the stuff.

Normally, when we study a drug or a food, the company donates the product to the researchers because they’re proud of the benefits or safety of their product. But the Nutrasweet company refused to even sell it to these researchers. The researchers managed to get their hands on some, and within a week, there were significantly more adverse effects reported in the aspartame group than in the placebo group. They concluded that individuals with mood disorders may be particularly sensitive to aspartame, and therefore, its use in this population should be discouraged.

In a review of the direct and indirect cellular effects of aspartame on the brain, it was noted that there are reports of aspartame causing neurological and behavioral disturbances in sensitive individuals, such as headaches, insomnia, and seizures. The researchers go even further and propose that excessive aspartame ingestion might be involved in the development of certain mental disorders and also in compromised learning and emotional functioning. They conclude that “due to all the adverse effects caused by aspartame, it is suggested that serious further testing and research be undertaken to eliminate any and all controversies,” to which someone responded in the journal that “there really is no controversy,” arguing that aspartame was conclusively toxic.

But what do they mean by excessive ingestion? The latest study on the neuro-behavioral effects of aspartame consumption put people on a high aspartame diet compared to a low aspartame diet. But even the high dose at 25 mg/kg was only half the adequate daily intake set by the FDA. The FDA says one can safely consume 50mg a day, but after just eight days on half of that, participants had more irritable mood, exhibited more depression, and performed worse on certain brain function tests. And these weren’t people with a pre-existing history of mental illness; these were just regular people. The researchers concluded that “given that the higher intake level tested here was well below the maximum acceptable daily intake level [40mg in Europe, 50mg here] careful consideration is warranted when consuming food products that may affect neurobehavioral health.”

Easier said than done, since it’s found in more than 6,000 foods, apparently making artificial sweeteners “impossible to completely eradicate from daily exposure.” While that may be true for the great majority of Americans, it’s only because they elect to eat processed foods. If we stick to whole foods, we don’t even have to read the ingredients lists, because the healthiest foods in the supermarket are label-free, they don’t even have ingredients lists—produce!

I’ve previously touched on artificial sweeteners before:

The healthiest caloric sweeteners are blackstrap molasses and date sugar (whole dried powdered dates). The least toxic low-calorie sweetener is probably erythritol (Erythritol May Be a Sweet Antioxidant).

Coffee may decrease suicide and cancer risk (Preventing Liver Cancer with Coffee? and Coffee and Cancer) but may impair blood flow to the heart (Coffee and Artery Function).

Other ways to improve mood include:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2013: Uprooting the Leading Causes of DeathMore Than an Apple a Day2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

46 responses to “Side-Effects of Aspartame on the Brain

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  1. Back in the late ’80s when Aspartame hit the market, I loved the idea of “free sugar”. Then after eating a lot of Nutra Sweet I had an excruciating migrane, by far the worst headache I’ve ever experienced. I remember walking outside in the middle of the night, staring at the stars and praying for the pain to end. Years later my daughter, after drinking a couple cans of diet soda, experienced a strange tingling hot then cold sensation in her legs and feet. Yeah, Aspartame definitely has dangerous neurological effects.

  2. Back in the late ’80s when Aspartame hit the market, I loved the idea of “free sugar”. Then after eating a lot of Nutra Sweet I had an excruciating migrane, by far the worst headache I’ve ever experienced. I remember walking outside in the middle of the night, staring at the stars and praying for the pain to end. Years later my daughter, after drinking a couple cans of diet soda, experienced a strange tingling hot then cold sensation in her legs and feet. Yeah, Aspartame definitely has dangerous neurological effects.

  3. I had a friend who moved to France for a total immersion language experience. He drank sugar-free Kool-Aid by the quart. He had terrible problems trying to learn French, couldn’t remember a sentence long enough to translate it. Then he ran out of Kool-Aid and it wasn’t available in France so he had to wait for his father to ship it from the U.S. During the time he was aspartame free his memory returned to normal and he excelled in his language courses. Once the Kool-Aid was received and he started drinking it again, his memory deteriorated and he struggled to learn. Nevertheless, he continued to drink that poisonous glop and it took him three years to complete one year of classes. I never understood why he kept drinking that stuff when he had irrefutable proof of the damage it did. He’s gone now, pancreatic cancer, caused I’m sure by his meat-heavy, chemical-laden processed food diet. RIP Rick.

  4. The last sentence in the above article is a classic! “If we stick to whole foods, we don’t even have to read the ingredients lists, because the healthiest foods in the supermarket are label-free, they don’t even have ingredients lists—produce!”

    I don’t even bother with trying to make sure I get the MDR of the Gov’t recommended ingredients. My personal “MDR” is what ever is contained in the “Daily Dozen” and the other Whole Plant Foods I eat :-) So refreshingly simple to not have to do all that reductionist ingredient counting, thanks to T. Colin Campbell, Dr G and the other WFPB Docs.

    (Note: I do take the B12 and the other nutrients that Dr G recommends!)

    1. EXCELLENT…!

      I am always confounded when I read so many people on this forum buying and eating so much packaged and processed food. It’s like, what part of WFPB are they not getting.

      ‘Dear Dr. Greger, is it okay if I buy my canned beans and preserved artichokes from Trader Joe’s?’

      1. LG King: Dr. Greger eats canned beans and NutrtionFacts looks on canned beans favorably. For example:
        Equating canned beans with processed foods is not consistent with how the term ‘processed’ is used by most people. Nor is it helpful in helping people to understand what is healthy vs unhealthy. (Deriding people for eating canned beans and other whole foods which come in packages is counter productive.) It’s fine if you want to go the route of never buying anything from a can or jar. But that doesn’t mean that all canned and jarred food can not be part of a WFPB diet for most people.
        There’s plenty of other examples besides beans too. For example, nut butters come in containers, but when purchased without added ingredients are as much part of a WFPB diet as a whole apple.
        If you want to learn more about what foods count as WFPB, I recommend reading Dr. Greger’s book, How Not To Die. Part 2 of the book goes into great detail on which foods are part of Dr. Greger’s recommended diet of the “Daily Dozen”.

        1. Many years ago a friend introduced me to the concept of whole foods and I was skeptical because of all the exceptions, e.g. tomato paste (and she ate things like cheese and was partial to candy and diet soda). But she was/is a smart woman (though I wish she didn’t eat cheese and candy) and now I see the wisdom of the whole foods approach as well as the wisdom of not being absolutist about it. My example of tomato paste being a case in point – it’s very healthful and I’ve found a brand that is organic and packaged in glass jars. I already spend a good deal of time in the kitchen and I can’t see myself making my own tomato paste from scratch.

          1. Prepared beans like “pork and beans” or “BBQ beans” have a lot of added sugar, but if you just buy a can of pintos or black beans, you’ll find no added sugar under the ingredients. You may see the nutritional information as showing sugar, but that is not the same.

  5. I am sorry but aspartame is poison. Nothing less. Everyone that I know whom have used it for as little as one time, had dramatic bad effects, to their body, feeling ill, terrible headaches. In my most humble opinion no one should ever ingest it !

  6. It makes me angry when I read about how big food companies knowingly harm us with their products like aspartame. And let’s not forget the FDA that foists poisonous medicines onto unaware masses of people.
    Surely, the law of Karma must eventually right these nefarious wrongs that have been forced upon struggling people around the world. It’s hard enough to survive in a basically “good” environment, but then when food companies and government agencies slowly poison us with their additives and so-called “medicines” it makes survival even more difficult. May these political and business entities reap what they sew.

  7. I don’t know whether any artificial sweeteners definitely cause harm to health, but it doesn’t matter: they taste bad, at least to me. I’ve never fully understood why people accept them as a taste substitute for good old fashioned sucrose (or other sugars), but then again, “there’s no accounting for taste” (which would explain much about music trends, too).

  8. Finally people are speaking out about this. One thing that was not mentioned and of utmost importance is that there is evidence that Aspartame upsets the gut microbiome, which is another pathway to ill health (and explains the mood disorders since there are more neurotransmitters in the gut)— particularly diabetes, the very thing patients with diabetes are told to consume. I also don’t know anyone who drinks this stuff regularly that isn’t addicted to aspartame…just watch what happens when they try to stop–massive migraines and withdrawal.

  9. I was on migraine Rx for decades and accepted that I had inherited them from my grandpa and my mom. About 2 yrs ago, in my 40’s my migraines simply got out of control in severity, frequency and rebounding….etc. My replax wasn’t cutting it and even caused one of my eyeballs to shake (literally). After 2 appts with the ophthalmologist & several tests later, he concluded it’s the replax. That was my breaking point.
    Thanks to Dr. Greger I learned about these sweeteners and connections to headaches. Since the 80’s I’ve been only using them and sugar free products, that’s what my mom bought and I always used sugar free since. I was shocked when I raided my frig and food pantry to discover the #1 ingredient I was consuming was aspartame. So, I stripped them ALL from my diet and as Drl. Greger recommended I switched to stevia and later added erythritol to my diet a year later.
    I can honestly say, within 30 days I simply felt different a general overall wellbeing of feeling ‘better’. As the months passed from 6 months, 1yr, 18 months, my migraine’s have DRAMATICALLY reduced in intensity, frequency and no rebounds. It has been a slow change, not over night, but obvious for me.
    Three months ago I ran out of maxalt and decided to try Dr. Greger’s cayenne pepper in the nostril and now combo it with advil.
    Over a year ago, I told my neurologist about what I did and Dr. Greger’s research on aspartame…..and she said “Oh yes! It’s a neurotoxin!” I was so upset my doctor knew this, yet NEVER asked me about my diet!
    Thank you Dr. Greger!

  10. I read about the dangers of aspartame before it was even allowed on the market and was shocked that it went into the food supply, and that so many people were ingesting it every day. Over the years, though, while I didn’t use it regularly, I did use the one in the pink package, and if Equal was the only artificial sweetener available, I would occasionally use it in coffee, which I only like when it’s sweet.

    Fast forward to 1995. I was in Las Vegas with a friend. Dinner that night was followed by coffee and I used Equal in one cup.

    During the night my friend awakened to find me “so stiff that if two people had tried to pick me up, one at my head, the other at my feet, they could have.” I woke up 32 hours after that seizure in a hospital.

    Over the next couple of years I had another, lesser, seizure or two, and went on Dilantin. I wasn’t using aspartame regularly, but would again occasionally have coffee with it in a restaurant, or take a packet of it home just in case I ran out of my regular toxic sweetener. I don’t like taking drugs, so I had scan of some kind, which showed normal brain activity, so I weaned myself off Dilantin. Then, a few months later, I once more I had coffee with Equal two mornings in a row. That day at work I had another seizure and whacked my face into my desk. I worked alone and when a client came in and found me passed out he called the medics. I recovered shortly after they arrived.

    Finally, thinking about all that had happened, the nickel dropped. It HAD to be those occasional cups of coffee with aspartame! It HAD to be! My neurologist disagreed, but I knew I was right. So, I took six full months to slowly and methodically wean myself off Dilantin. I have since scrupulously avoided aspartame. I put it in all my medical records as an allergen, because it is in some medications and hospitals may use it.

    It’s been 20 years now and I’ve never had another seizure.

      1. Yes. I gave up sugar totally in 2010 (coffee too) and now many things taste far too sweet to me. Our home grown green beans were so sweet this summer! Now I’m working on salt. It was never a problem because my blood pressure was quite low, but lately I’ve seen it creep up a bit.

  11. OK, can anyone offer clarification on this part of the study: “self-reported depression diagnosis”? Could it be those consuming artificial sweeteners were overweight and/or diabetic? Couldn’t that make one “self report” depression? And I’m guessing those that didn’t use artificial sweeteners might just be thin, or “fat and happy”, as they say.

      1. Thank you! Even though that was from a group of chemists, I wouldn’t go so far as to say artificial sweeteners are healthy. Again, I keep going back to the dosage over time logic. As one expert Harvard grad in nutrition said, self reported studies are not considered scientificly reliable, and technically shouldn’t be called studies. The doc has other videos on artificial sweeteners, I assume with better study references than this one.

  12. After having parathyroid cancer, I take two Calcichew D3 tablets a day for my calcium. I’m an avid whole food plant based eater so I was shocked to discover my tablets contain aspartame. Why does medicine have to contain this stuff? And are any calcium tablets available without it?

    1. Perhaps one of the site nutritionists should weigh in on this one, but I was under the impression that calcium supplements may be problematic. Something about a bolus effect and deposition of calcium on the interior of artery walls

      What do you know, Dr. Greger did a video on it:

      I would try to eat as much green leafy vegetables as possible; combining them with alliums (garlic, onion, leeks) is supposed to help with mineral absorption (*). If you are not opposed to soy, tofu is a good source of both calcium and magnesium, though the amounts can be variable from batch to batch due to variations in nigari. Some people think magnesium is very important for bone health; my top sources for magnesium are tofu, natto, white beans, almonds/almond butter, pumpkin seeds and green leafy veg (kale and spinach).

      mentions iron and zinc, not calcium, but it tastes good to cook greens with alliums so why not

      Dr. Greger has also done videos on prunes and almonds for osteoporosis prevention:

    2. Leslie – Forget Calcium supplements and eat a whole foods plant based diet, with lots of green leafy veggies. You will get the magnesium and other minerals that your body needs from the greens. I love all greens, but especially my wife and i eat lots of kale, especially in the fall, winter and spring. I grow them organically in our garden. But a farmers market or store bought is always an option.

    1. clarksss: See if this helps: Think of it as having an implied word at the end : Prematurely. Another way to think of the title is understanding where the stress is: It’s *how* not to die. So chapter 1 is *how* not to die of heart disease. Chapter 2 is *how* not to die of lung disease. Etc. The title is not meant to imply that you will never die. It’s how to prevent dying early as that’s not *how* most people want to die.

      1. Or it could even mean don’t die sick. We all die but wouldn’t it be better to die but live a life with a clear mind and fit body. (Don’t die at 70 having been an invalid for 15 years)

    2. Since it seems no-one dies of ‘old age’ but rather of specific ailment/s, the book’s title applies perfectly to Part I, how not to die of the 15 leading causes of US deaths, as Thea explained.
      You might die next year of one of the lesser causes not part of this first edition, so dying ‘slower’ won’t cut it.

  13. I developed severe fibromyalgia, diagnosed in 1988 by a rheumatologist. Prior to that, I had tried to lose weight by drinking diet soda hoping it would make me feel full and curb my appetite. I’ve always thought the two could be connected, since the time line intersected. I haven’t drunk any soda for years, eat a WFPB diet, and have also checked any labels before eating anything packaged, for artificial ingredients. Unfortunately I still have the fibromyalgia, and am willing to try most anything to get ride of it. Any suggestions?

    1. A friend who suffered for years with debilitating fibromyalgia started taking a certain preparation of glutathione and her life is completely different now. Because it worked so well, she began selling it. If you request, I can give you contact info on the brand that worked for her.

    2. Aspartame is cumulative The reason its addictive is methanol is classified as a narcotic. It causes chronic methanol poisoning which affects the dopamine system of the brain and causes addiction. In the movie, “Sweet Misery: A Poisoned Word” on U-Tube you will see Cheryl Kempter who had fibromyalgia. Dr. Ross Hauser who does prolotherapy in Oak Park, Illinois wrote a paper on how it will treat to remove the pain. She insisted on the operation and Dr. James Bowen explained how the operation would interact. Aspartame causes chemical hypersensitization . I told Cheryl at least put aspartame on her records hospital records so they wouldn’t give it to her as she did. However, in the movie you will hear a dietitian gave her some lemonade with aspartame and she became a Code Blue. They had to resuscitate her to save her life. She then had prolotheraphy and it cured the pain but the operation messed her up. Aspartame hardens the synovial fluids and its the whole chemical mess. See for more information on aspartame. Dr. Betty Martini, D.Hum, Founder, Mission Possible Worlds Health Intl, warning the world off the chemical poison aspartame. Now they have approved Advantame, be warned.

  14. One of the videos talked about artificial sweeteners and its impact on gut flora and, indirectly I suppose, digestion…so I wanted to hop in here and ask what other vegan foods might disrupt proper digestion (and all that that implies). I’ve been vegan for 3 years and have focused increasingly on WFPB meals over the last year. I came to this lifestyle to treat my IBS but I still can’t seem to shake it entirely and I was wondering what others on this site might have to say on the matter. For reference, my diet consists mainly of fresh, whole fruits for breakfast and lunch, whole medjool dates as snacks, and greens/veggies/beans/nuts(raw)/brown rice for dinners (I currently do not eat any grains other than red/brown/black rice). I drink 3L of water a day, rarely consume tea or coffee (TMI: I only drink coffee to quickly alleviate IBS symptoms) and only add raw cane sugar as a sweetener, and use it sparingly. I’m light on salt, take B12 and D, and probiotics every once in a while if the IBS starts REALLY getting out of hand (more than 3 days a week). I’ve also started adding some flax (2tbs) to my routine. I exercise almost every day, including running, biking and yoga. I feel like I’m living this lifestyle ‘to a T’ and yet I still struggle with ongoing IBS issues.

    The only think I can think is that maybe soy is the culprit (despite the evidence referenced on this website)? Sometimes I also use soy milk (in the coffee) and tamari (GF soy sauce). Note: I feel best eating raw vegan (digestion-wise) but I find it to be less than satisfying if I stick to it for more than a few days at a time and I end up craving cooked food. Can anyone provide any feedback? I’ve tried visiting probably 10 different doctors (both domestically and abroad when I was living there) and naturally not one of them saw my IBS as abnormal, but for me to not have regular bowl function is incredibly painful and really, truly disrupts my mood and quality of life.

    I love this community and the intelligent, well-crafted comments of the readers, viewers and moderators. Thanks in advance for any help.

    1. Caveat, I am not an expert but I think would be easier to get answers if you clarify type or tendency, IBS -D or IBS -C.

      If your tendency is D (as it’s most common) you might want to cut down the flax seeds, and an excess of soluble fiber might accentuate symptoms.

      1. Hi Thule, thanks for replying, and you’re right that’s an important distinction to make. I trend in the opposite direction to most then, and am very much IBS-C.

  15. half the adequate daily intake

    Adequate intakes mean something else entirely, so this bugged me. Surely you meant “acceptable daily intake”.

  16. What is the relation between Type 1 diabetic using Aspartame and other side effects?
    Apart from the long list already with Aspartame, many Dieticians and Doctors still say its safe and is good for Type 1 Diabetics.
    Are there any papers that show that this is really bad for diabetics or not?

    1. Hello Scott,

      I searched through Pubmed for research on Type I Diabetes and Aspartame use; however, I could not find much data. I did however, find a meta-analysis which showed no benefits in metabolic factors from choosing aspartame-based sweeteners. What I could find consistently is that there is a major lack of data on long-term risks of consumption for people with diabetes.

      This is something you should speak with your doctor about and come to a conclusion regarding your health.

      I hope this helps,

      Matt, Health Support

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