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Does Aspartame Cause Lymphoma?

The approval of aspartame has a controversial history. The Commissioner of the U.S. Food and Drug Administration (FDA) concluded that “there is a reasonable certainty that human consumption of aspartame: (1) …will not pose a risk of brain damage resulting in mental retardation, endocrine [hormonal] dysfunction, or both; and (2) will not cause brain tumors.” However, the FDA’s own Public Board of Inquiry withdrew their approval over cancer concerns. “Further, several FDA scientists advised against the approval of aspartame, citing…[the aspartame company’s] own brain tumor tests…” Regardless, the Commissioner approved aspartame before he left the FDA and went on to enjoy a thousand-dollar-a-day consultancy position with the aspartame company’s PR firm. Then, the FDA actually prevented the National Toxicology Program (NTP) from doing further cancer testing. As I discuss in my video Does Aspartame Cause Cancer? we were then left with people battling over different rodent studies, some of which showed increased cancer risk, while others didn’t.

This reminds me of the saccharin story. That artificial sweetener caused bladder cancer in rats but not mice, leaving us “to determine whether humans are like the rat or like the mouse.” Clearly, we had to put the aspartame question to the test in people, but the longest human safety study lasted only 18 weeks. We needed better human data.

Since the largest rat study highlighted lymphomas and leukemias, the NIH-AARP study tracked blood cancer diagnoses and found that “[h]igher levels of aspartame intake were not associated with the risk of…cancer.” Although the NIH-AARP study was massive, it was criticized for only evaluating relatively short-term exposure. Indeed, people were only studied for five years, which is certainly better than 18 weeks, but how about 18 years?

All eyes turned to Harvard, where researchers had started following the health and diets of medical professionals before aspartame had even entered the market. “In the most comprehensive long-term [population] study…to evaluate the association between aspartame intake and cancer risk in humans,” they found a “positive association between diet soda and total aspartame intake and risks of [non-Hodgkin’s lymphoma] and multiple myeloma in men and leukemia in both men and women,” as you can see at 2:12 in my video. Why more cancer in men than women? A similar result was found for pancreatic cancer and diet soda, but not soda in general. In fact, the only sugar tied to pancreatic cancer risk was the milk sugar, lactose. The male/female discrepancy could have simply been a statistical fluke, but the researchers decided to dig a little deeper.

Aspartame is broken down into methanol, which is turned into formaldehyde, “a documented human carcinogen,” by the enzyme alcohol dehydrogenase.The same enzyme that detoxifies regular alcohol is the very same enzyme that converts methanol to formaldehyde. Is it possible men just have higher levels of this enzyme than women? Yes, which is why women get higher blood alcohol levels than men drinking the same amount of alcohol. If you look at liver samples from men and women, you can see significantly greater enzyme activity in the men, so perhaps the higher conversion rates from aspartame to formaldehyde explain the increased cancer risk in men? How do we test this?

Ethanol—regular alcohol—competes with methanol for this same enzyme’s attention. In fact, regular alcohol is actually “used as an antidote for methanol poisoning.” So, if this formaldehyde theory is correct, men who don’t drink alcohol or drink very little may have higher formaldehyde conversion rates from aspartame. And, indeed, consistent with this line of reasoning, the men who drank the least amounts of alcohol appeared to have the greatest cancer risk from aspartame.

A third cohort study has since been published and found no increased lymphoma risk associated with diet soda during a ten-year follow-up period. So, no risk was detected in the 18-week study, the 5-year study, or the 10-year study—only in the 18-year study. What should we make of all this?

Some have called for a re-evaluation of the safety of aspartame. The horse is kind of out of the barn at this point with 34 million pounds of aspartame produced annually, but that doesn’t mean we have to eat it, especially, perhaps, pregnant women and children.

For more information on the effects of aspartame, watch my videos Aspartame and the Brain and Aspartame-Induced Fibromyalgia. Interested in learning more about the effects of consuming diet soda? See, for example:

What about Splenda? Or monk fruit sweetener? I have videos on those, too—watch Effect of Sucralose (Splenda) on the Microbiome and Is Monk Fruit Sweetener Safe?.

I also do a comparison of the most popular sweeteners on the market, including stevia and xylitol, in my video A Harmless Artificial Sweetener.

Perhaps the best candidate is erythritol, which you can learn about in my video Erythritol May Be a Sweet Antioxidant. That said, it’s probably better if we get away from all intense sweeteners, artificial or not. See my video Unsweetening the Diet for more on this.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:


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.

28 responses to “Does Aspartame Cause Lymphoma?

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  1. I once used to drink litres of ice-cold Diet Pepsi during hot Australian summers. The amount of aspartame and caffeine that went down my gullet is quite frightening in retrospect. It seemed like a good idea at the time – there was no sugar after all.

    1. Tom,

      Yes, I drank liters of it, too.

      So I guess we have started the embalming process early.

      In the Poison Squad, they talked about the meat being sent to soldiers smelled like a dead body after being injected with formaldehyde.

      I was just thinking about this topic of sweeteners yesterday because of the topic of people needing to take responsibility for their own health and I think we did take responsibility based on the science over and over and over again. We went from sugary soda to diet soda to caffeine-free diet soda to different sweeteners as the science headlines changed. We went from butter to margarine to other types of “healthier” butter spreads

      We went from whole milk to 1% milk to skim milk, then on Keto and up to cream, over to plant milk, switched between coconut milk and almond milk and rice milk and soy milk and walnut milk and cashew milk and oat milk and found out there was oil in a lot of it.

      Right now, my friends are big into Stevia and Monk fruit and I will say that they don’t spike their diabetes and they can have their cake and lose weight, too, on Keto.

      1. Hi Deb,

        I love pickled veggies (carrot, daikon, burdock, radish) as in Japanese or Vietnamese style, but they use so much sugar! I refer them more piquant with less sugar. I have been making my own with unseasoned rice vinegar (on added sugar) and monkfruit/lakanto brand) sweetener. I recently took part in the Predict2 study and got to wear a continuous glucose moniter for two weeks and can attest to the fact monkfruit did not spike my blood sugar.
        I also love kombucha..but too cheap to buy it and lazy to make I do a shortcut, low waste version: 1 Tbsp unpasterized apple cider vinegar (With live cultures) and 4 drops stevia liquid and sodastream bubbly water. It is so refreshing and easy and delicious over ice. I was never one for diet sodas, so sweet!
        I also like an occasional cocktail but find the ones made with simple syrup way too cloying, even tonic water drinks too sweet for my liking. I recently tried making my own tonic water with cinchona bark and monkfruit sweetener and it worked beautifully! Once the lockdown gets relaxed I will never go back to paying $12 for a designer cocktail when you can make better at home!

    2. Mr Fumblefingers,

      I’ve rarely ever consumed diet soda — I didn’t like the taste. But then, I rarely ever drank regular soda — it was way too sweet for me. Even though I think I have a sweet tooth!! I used to wish that soda had about 1/4 the amount of sugar added to it; I thought that would be perfect.

      Instead, I drank plain carbonated water, especially when I was trying to lose weight (and I was successful! I practiced portion control and made healthier choices, more veggies and fruit, much less CRAP junk edibles), and I still drink it. I used it to dilute my morning juice, 1 part juice to about 3-4 parts fizzy water; my daughter called this drink my non-alcoholic mimosa. Now I find regular juice far too sweet.

      1. Dr J.,

        Your non-alcoholic mimosa sounds delicious. I miss juice.

        I don’t think I will try it though, because I haven’t lost much weight yet and I think it might still be too much sugar for me, but it does sound delicious.

  2. As a type 1 diabetic of over 40 years, I thought aspartame was WONDERFUL (compared to saccharin, of course). I mean, Diet Coke tastes infinitely better than Tab, its saccharin-laden predecessor in the diet soft drink world. Another huge benefit of aspartame was the sweetness it provided to baked goods. Saccharin breaks down and loses all taste in the baking process.

    Alas, science has ruined the aspartame party but the facts mustn’t be ignored. For the sake of my health I’ve pretty much laid off diet soft drinks completely and now use Stevia in my coffee and whatever other foods need a kick of non-caloric sweetness.

    1. Kent,

      Yes, science has ruined the aspartame party.

      The gut microbiome video ruined my concept of Stevia.

      And I drink my coffee with oat milk, no oil, no sweeteners.

      But I do crave sugar and I contemplate Stevia and Monk fruit. Honestly, I only contemplated it after my sweet-tooth Diabetic friend lost 90 pounds.

      I think I will do Nice cream before Stevia, but she has gotten into my head on the sweetener front because she is constantly eating desserts and lost weight, when I didn’t lose nearly as much.

      I have her eating way more vegetables.

      She would never eat potatoes or rice or grains, but she is eating vegetables now.

      And, no, I won’t just start eating Stevia. I will contemplate whether eating stevia peanut butter cups would trigger my peanut butter cup cravings or not. Sugar-free ones used to make me want the real ones more decades ago.

      I haven’t gone back there, but the cravings don’t go away.

  3. Back on aspartame, I was with a friend in Las Vegas many years ago. We went out to a nice restaurant and, though I rarely used Equal (aspartame), I had two packets that night in after dinner decaf. He awakened to find me seizing. He said I was so stiff that two people could have picked me up from each end and I’d have been like a board.

    I woke up 32 hours later in a hospital, having lost all that time and probably a few brain cells in the process! I was sent home with a week’s supply of Dilantin and instructions to see my doctor.

    At home an MRI showed there was no brain tumor, but nobody had a clue. I stayed on Dilantin for a couple of years, but wasn’t ready
    for a lifelong medication. So, I very slowly weaned myself off the Dilantin over a very long time, and eventually went a year with no problem. Then, one day at work a customer came in, found me passed out with my head on my desk and called 911. Another seizure.

    I asked myself what I’d done differently than usual – and it hit me. I’d once more used Equal in coffee two mornings in a row. My neurologist would have none of it, but I’ve assiduously avoided aspartame ever since, and been seizure and medication free for more than 27 years.

    1. Rebecca Cody, Wow, what a powerful story. I wonder how many other people get seizures from aspartame, but don’t realize it. Scary.

      1. Rebecca, Usually, “What happens in Las Vegas, stays in Las Vegas” as the old saying goes. ;-)

        But in this case, I’m glad you shared your story with us. A good warning to others.

    2. Wow, Rebecca, that is such a powerful story.

      I lost a friend who suddenly had a seizure and we never knew what caused it.

      She wasn’t epileptic.

      The seizure happened in a place where the seizure caused her to be in a life-threatening situation. They thought they had revived her in time, but she was brain dead and passed away from an infection shortly after that.

      I had seizures a few times when I was younger. Not often. I thought it was related to lack of sleep, but I have slept much less the past ten years without having any.

    3. Wow, Rebecca! When they ask us if we’re allergic to this or that, all I can think of answering is “I won’t know until I take it for the first time and the first time could kill me right then.!

      I never trusted any of those sugar substitutes with the fancy names. The only “pop” I used to drink (and only as a kid) was orange soda and root beer from our local A&W root beer stand.

    4. My grandfather was diabetic, so I grew up drinking Tab until saccharine was replaced with aspartame. As he aged, he developed Parkinson’s (presumably itself unrelated). If he consumed aspartame, he would have a freezing episode. It happened every time. Another family member began experiencing slurred speech after a few weeks of a daily Crystal Light. We all quickly gave up aspartame!

    1. Annette,

      There aren’t studies saying that yet.

      I will say to you that I used to pass out after eating at salad bars. I also passed out after eating green grapes. I threw up whenever I ate Asian foods.

      Up until coming here, I would have said “sulfites” “the chemical that elongates green grapes for shipping” and “MSG”

      I had never heard of “salad bar syndrome” or “Chinese restaurant syndrome” until last year, but I had both of them.

      But I am highly allergic to sulfur, for instance, and I am allergic to baby oil and smoke and mold and birch trees and ragweed and so many things.

      But last year, I had the organic produce at Whole Foods Salad bar and put the liquid aminos on the greens with the apple cider vinegar and I didn’t faint or throw up.

      It was a big deal. I was able to eat from a salad bar and not land on the floor. And I didn’t know hat liquid aminos had MSG in them, but they did and I wasn’t affected at all.

      Allergies are strange things.

      All I will say is that there are people who are sensitive, but the studies don’t bear witness yet to the rest of it.

      1. Deb,

        I looked at a few sources online, and they all state that liquid aminos and coconut aminos do not contain MSG. I guess these sites mean that these products do not contain added MSG:

        “FDA requires that foods containing added MSG list it in the ingredient panel on the packaging as monosodium glutamate. However, MSG occurs naturally in ingredients such as hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, as well as in tomatoes and cheeses. While FDA requires that these products be listed on the ingredient panel, the agency does not require the label to also specify that they naturally contain MSG. However, foods with any ingredient that naturally contains MSG cannot claim “No MSG” or “No added MSG” on their packaging. MSG also cannot be listed as “spices and flavoring.”“.

        Liquid aminos are made by adding hydrochloric acid to soy protein, which hydrolyzes the protein into free amino acids, then neutralizing the remaining acid by adding sodium bicarbonate, which creates sodium chloride, which is salt, giving the liquid aminos their salty taste. No kidding, because liquid aminos have high levels of salt — as much as soy sauce. Bragg’s Liquid Aminos has 350 mg sodium per tsp. (This is equivalent to about 0.15 tsp of salt, or slightly more than 1/8 tsp salt.)

        1. Wow, thanks, Dr. J.

          I read a page that mentioned it with MSG after I had eaten that salad and didn’t get sick.

          So it is liquid salt?

          I love soy sauce, but didn’t love liquid aminos on my salad.

          Trying to not eat either.

  4. This morning, I talked with my lawn man and he desperately wanted to hover around me because he hasn’t figured out how to go on unemployment yet and he told me that he is as dumb as a stone and I know that he can’t use technology or read business forms and I know that everything being so complicated seriously destroys peoples’ lives.

    No matter how thorough I try to be at everything, it gets confusing again for me and he is so lost.

    I was listening to Dr. Popper’s study logic to not wear masks and I am not sure her logic about cloth masks applies to me wearing an N99 with a procedural mask underneath at all. Particularly because I have two of them and alternate. Am I raising my risk of getting it? I feel like even just the mask making it less likely that I will touch my face would be a good thing.

  5. Try adding whole stevia leaves to stuff. Makes me wonder why this is not yet one of the Nutritionfacts green light sweeteners.

    It’s rather expensive though compared to the sweet isolated molecules.

    Any news on erythritol? Does it come with those bad metabolic changes we see in other zero calorie sweeteners? In other words, does Michael still add it to his tea? (?・・)σ

  6. In 1986, as a senior at the University of Michigan, I had a seminar class and one of the guest speakers was the former head of FDA labs who resigned when his lab was forced to certify aspartame as “safe”. I do not recall his name but I clearly remember two things he said about aspartame: 1) it is extremely latent and may stay in our bodies for up to 20 years and 2) I do not let anyone in my family or anyone I care about ingest aspartame in any form.

  7. For years while in the workforce, having many lunch and dinner meeting I would drink water with lemon and sweet and low! At the time I was thinking “good for me-drinking lemon water” now semi retired 61. At the age of 57 diagnosed with non Hoskins lymphoma. I WONDER?

  8. I understand your message that avoiding aspartame is probably best, but I did notice that the 2012 Schernhammer’s study indicates a strong positive effect of aspartame for avoiding multiple myeloma in women. So women should drink diet coke to help avoid multiple myeloma? – I don’t think so, but it makes that study more suspect as evidence of aspartame as a cancer cause. I wish there was some stronger evidence to support the aspartame causing cancer conclusion, and since we have been consuming millions of pounds over the years, wouldn’t we have found the link by now in the population surveys of cancer patients? As a side note, I don’t think implying that the FDA commissioner was corrupted because he was accused of things and took a job after leaving the FDA is responsible, unless he was convicted. I like most of your articles and videos, but this particular one is pretty shaky science and articles like this cause some people to say “ya-know that stuff causes cancer” when I happen to be drinking a diet soda.

  9. Thanks to Jamie Oliver we now have the sugar tax in England! You can’t find a single tonic water,soft drink or cordial that does not contain artificial sweetener. What a huge mistake at least before we could choose if we wanted it or not.

  10. I was diagnosed with non-Hodgkin’s lymphoma at the age of 29 in 1998. I drank aspartame sweetened diet soda all day long from 1981 to 1998 (17+ years), so this 18 year Harvard study explains what I have suspected. No aspartame or other chemical sweeteners in over 20 years since.

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