Beyond Blue

Beyond Blue

Does Diet Coke Make You Depressed?


When you are a recovering drunk, you don’t have a ton of options at parties. I used to be an avid Diet Coke drinker. But last summer my sister scared the well you know out of me when she started talking about what aspartame can do to your system. I am chemically sensitive as it is, and many of you are, too, probably–which is why I don’t drink alcohol and gave up smoking.

But I was curious if Diet Coke was really that dangerous. I did some research, and as you well know, every paranoia will be confirmed eventually by some article on the web.

I found an article about Diet Coke on John McManamy’s very reputable website (which you can get to by clicking here). What was particularly interesting to me was the relationship between aspartame and depression and bipolar disorder. Says John:


In 1993, Dr Walton, who is a psychiatrist, conducted a study of 40 patients with unipolar depression and a similar number without a psychiatric history. The subjects were given 30 mgs per kg of body weight a day of aspartame or a placebo for 20 days (about equal to daily consumption if it completely replaced sugar).

Thirteen individuals completed the study, then an institutional review board called the project to a halt “because of the severity of reactions within the group of patients with a history of depression.” In a smaller, shorter crossover design, “again there was a significant difference between aspartame and placebo in number and severity of symptoms for patients with a history of depression, whereas for individuals without such a history there was not.”


Accordingly, the author concluded that “individuals with mood disorders are particularly sensitive to this artificial sweetener and its use in this population should be discouraged.”

As to further particulars of the study, based on the eight depressed subjects and five healthy subjects who completed it:

Three quarters of the patients with a history of depression taking aspartame reported feeling depressed vs none of the healthy subjects taking aspartame and about 40 percent of both groups taking a placebo. The 40 percent is probably a statistical aberration owing to the small numbers who completed the study.

Nevertheless, the figures consistently show the depressed/aspartame group experiencing an array of symptoms in far greater numbers and severity, including: fatigue, nausea, headache, trouble remembering, insomnia, and other symptoms.


The depressed/placebo group showed almost none of these symptoms, along with the healthy/aspartame and healthy/placebo groups Dr Walton told this writer he believes aspartame inhibits serotonin synthesis by decreasing the availability of the precursor L-tryptophan, a finding borne out in another research team’s 1987 experiment on rats.

Remarkably, Dr Walton’s study is the only one we have related to both mood and aspartame. It would be helpful to get a second opinion, but no one else since, apparently, has tried to either replicate or refute his results. This may be due to the political and funding climate. “The NutraSweet company,” Dr Walton told this writer, “clearly tried to block our study.”


So we are left contemplating the fridge, where our Diet Coke is being chilled, with but one aging study to either guide us or confuse us. Once again, like the trial and error of our meds, we find ourselves human guinea pigs, this time experimenting with our diet. For many, aspartame may turn out to be a life-saving alternative to that well-documented sweet poison, sugar. Others who continue to experience depression, fatigue, and other symptoms, however, may want to moderate their aspartame consumption and see what happens.

I decided to give up Diet Coke like every other bloody drink I’ve given up. So now I’m back to my boring sparkling water and lime again. Snore.

Click here to subscribe to Beyond Blue and click here to follow Therese on Twitter and click here to join Group Beyond Blue, a depression support group. Now stop clicking.

  • http://AddaURLtothiscomment Sam Gyura

    Diet coke is revolting.

  • Pingback: Does Diet Coke Make You Depressed? – Beyond Blue |

  • http://AddaURLtothiscomment Wildstar

    I clicked on the link in your article and got a 404- page not found. Can you check the url again?? Thanks!

  • http://AddaURLtothiscomment Wildstar

    You could also hit the health food/farmer’s markets (like Whole Foods)and see if there are any drinks made with agave, which is a natural, low glycemic sweetener made from cactus, I believe. You could probably just call them and ask before even going down there. Whoever is in charge of the grocery department would know.

  • http://AddaURLtothiscomment kenneth

    I think it’s a good idea to use some prudence in consuming aspartame, or for that matter, soda of any kind. Aspartame could use some closer evaluation for a number of reasons, but would caution against getting sucked in by the hysteria that many of these websites are about. Most that I’ve seen are very fringe-science conspiracy theory oriented and link aspartame to almost every disorder in the medical texts. They have, as noted here, very little evidence to back that, but as conspiracy theorists do, they cite that lack of evidence as evidence itself. “This stuff is so dangerous that THEY prevented the studies.”

    Time to take a few deep breaths and do the science. A 40-patient study is pitiful from a statistical standpoint, and there may be design flaws as well. It’s an ok place to jump off from but conclusively tells us nothing. One of the founders of my own line of bacteria genetics famously said “the plural of anecdote is not data.”

  • http://AddaURLtothiscomment Allen

    I suffer from depression/anxiety disorder and am also borderline diabetic and obese. Some years ago I was drinking 4 to 6 cans of diet pepsi a day. I heard somewhere that aspartame could contribute to depression so as an experiment I stop drinking diet drinks cold turkey and felt better almost immediately. After having been off of it for a while I don’t even like to smell the stuff. Not scientific I know but I avoid it and advise others to as well.
    thanks for all you do.

  • Eli

    A very pro Post.
    Really like it thanks

  • Theimexpert

    Aspartame has a lot to answer for. It is not just depression but it has been know to increase appetite and therefore can actually make those people seeking to use to decrease calorie intake, want to eat more!

    It has many other medical side effects too. Best left alone. If you must drink sodas, just go for the sugar kind. The lesser of two evils!

  • http://AddaURLtothiscomment pam munro

    My husband & I have both switched to homemade ice tea (from blk teabags) – unsweetened! Very refreshing year round – & you might have an iced coffee occasionally….

  • http://AddaURLtothiscomment Jesse

    I never thought that Diet Coke could mess with my head. I gave up caffeinated drinks because it was damaging my heart, so I took up caffeine free drinks like 7-up/Sprite/Sierra Mist, and caffeine free Diet Coke.

    This is kinda scary. All those years of pills and doctor visits could have been avoided had I known this……

  • http://AddaURLtothiscomment Sam Gyura

    Have you ever tried Ribena and soda water? I really like it even though Ribena is loaded with sugar.

  • http://AddaURLtothiscomment tutelstar

    Ooooooooh. Thanks for the info.

  • http://AddaURLtothiscomment Anne

    This is interesting… I am a diet coke addict but have switched to caffeine-free because it was the CAFFEINE ( a drug) not the aspertame that was interfering with my medications for depression. This study is way too small to make any conclusions and they need to control for the caffeine, as well.

  • http://AddaURLtothiscomment L

    My mom’s friend long ago suggested Tab as the preferred drink…….it has sacharin (sp?) which she believes is the better choice to aspartame when drinking sodas. Maybe an occasional Tab could be a treat?

  • http://AddaURLtothiscomment Mary

    I suffer from deep depression. I did not know that aspartame could affect mood. However, I am allergic to it. I was working for a company that had employees in groups. Everyone in my group drank diet Coke. I tried it one day, two sips and I had a massive headache and passed out on the floor. When I woke up in the hospital, they told me had I drank any more, I probably would have had a stroke. My doctor told me he had many patients that had problems with aspartame and the company that made it would not listen to the doctors’ findings.

  • http://AddaURLtothiscomment Anonymous

    I have a history of depression and used to drink WAY more diet coke than I do now (once or twice a week, and I prefer Coke Zero now in the little itty bitty cans.) Frankly, I don’t see a connection with mood at all–but on the other hand, if I have too much aspartame it DOES give me a headache.

    I tend to sweeten with either Splenda, which is kind of neutral because it substitutes chlorine for one of the other atoms in the sugar molecule so your body can’t absorb it–unlike aspartame, which digests as two amino acids which might alter brain chemistry–and I also like stevia based sweeteners now that there are commercial ones (the original ones were way too sweet.)

  • http://AddaURLtothiscomment SpiderMom

    I’m having the same problem; the URL doesn’t work for me.

  • http://AddaURLtothiscomment CCGD

    Ditto the url prob.

  • http://AddaURLtothiscomment laike

    I read a book on aspartame sensitivity when I first began treating for my chronic fatigue. The awareness of how it was impacting my body caused enough concern that, although I am currently having it in moderate amounts, for years I chose to use either acesulfame or – more often – stevia (herbal sweetener). I have NEIDS (the scientific name of the diagnosis for multiple chemical sensitivities). I do better with as little sweetener and chemicals as possible. I am also allergic to corn and stay as far away from corn syrup and malto-dextrin as possible.

    Why do we expose our children to sweets so much? Most professionals agree that if we didn’t give our kids so many sweet things, they wouldn’t develop such a taste for them.

  • http://AddaURLtothiscomment Ginger

    This is anecdotal, but the author of this article determined it was diet coke that triggered a period of mood instability that got labeled bipolar.

    From the article:

    “In my reading, I also came across some information about the artificial sweetener Aspartame being implicated in mood disorders. When I thought back over my own history, I realized that my mood swings had started in college, soon after I’d turned to diet soda as a study aid. I’d never liked coffee or tea, and didn’t want the calories in regular soda, so Diet Coke became my drug of choice. More importantly, those mood swings had stopped when I’d stopped drinking Diet Coke.”

    she reports being symptom free now

  • http://AddaURLtothiscomment FB

    Hi Therese – I read this article with interest, as I have been somewhat concerned about aspartame for a long time. When it was first put on the market, I had a college friend who was a dietician working with diabetics. She was trying it out on her patients and told me she thought I ought to avoid it, as she was seeing some strange side effects on some of the patients who had switched to it. For myself, I’ve mostly avoided it because I often found I had a similar reaction to the way I feel with some antihistamines – jumpy! Lately I have been using water flavorings with it just because in the heat we have been experiencing here in Texas it made it easier for me to drink enough liquids if they had some taste. I have found a new alternative though. Crystal Light has come out with a line called “Pure” that uses stevia (made from a plant in the mint family) instead of aspartame, and I have switched to those now. So far only about three flavors available, but perhaps if these gain popularity they will expand. The lemonade is very good. I have used stevia for years, used to grow it in my garden, so I know this is a safe alternative. Not calorie-free, but only 15 calories. It at least gives you another option than aspartame!

  • http://AddaURLtothiscomment barb

    i drink diet coke regularly. i think it is the caffeine i look for in the morning, as opposed to coffee. i like a cold drink in the morning.
    i don’t seem to be affected by the aspartame, but i could try a test and buy the coke zero and see how that works. i would have to keep a diary, because my brain cells short term memory are lousy. thanks theres. hope you are recovered from your appendectomy.

  • http://AddaURLtothiscomment Caroline R

    Dr. Russell Blaylock, MD, a neurologist, has written an excellent book entitled Excitotoxins which includes extensive info on this subject. It is worth the read. I gave a copy to my psychiatrist and he handed out info from it to his other patients. Aspartame affects brain function in general.

  • Sage Norbury LAc

    I’ve been advising people to stop drinking diet drinks since the early ’90s. I believe they are poison to our bodies. There’s an interesting book, Excitotoxins, about this very issue. Thanks for posting this.

  • http://AddaURLtothiscomment Tony

    Therese, I looked over the study you refered to. The amount of aspartame they used was quite large: the equivalent of substituting all sugar someone would normally consume with the equivalent of apsartame (I think 35mg/kg/day). That amounts to a lot more than drinking a can or two of Diet Coke. Maybe in moderation aspartame is fine? Hard to say from this study.

  • Melanie Sees

    It’s called Coke Zero! You won’t be giving anything up because it’s better than diet coke, no side effects, and Sonic has replaced diet coke with coke zero. (can u tell, my favorite drink).

  • http://AddaURLtothiscomment G

    Well I have severe depression and used to drink tons of Diet Coke as well as use aspartame for everything. How much? Averaged 15-20 packs of the sweetener daily as well as drinking diet coke. I was on high doses of anti-depressants (usually the max).

    Since those days I have given up all of that, and eat all organic foods, and use organic Stevia. I have Organic no sugar added Dark Chocolate. I didn’t drink alchohol for years, and used a lot of coffee and then went extended periods without coffee. I exercise regularly and do ‘everything’ I am supposed to do. Bottom line: Still have major depression, fight suicidal thoughts on a daily basis.
    Contributing factors: No health insurance/no meds for depression.
    Lost all family of origin members (except brother) to death within the last 20 years.

    Fired from job due to false allegations thus losing all benefits and retirement as well as a moderatly high paying job and am now reduced to several part time jobs with no benefits averaging 17-20 thousand a year Adj.Gross income. This down from about 60,000 a year I was making before being fired. My wife had an affair with a 24 year old man and left (I am 59)

    In other words, none of this food related stuff has any effect on me. It is all the result of living life on the edge, many losses, and no hope for a future, given the economy and the ideological civil war going on in govt. that is threatening to prevent me from any medical help or support network as I age.

    Just daily fear, and extreme anxiety, = major depression.
    If I drink wine, or coffee or a diet coke, I get a few minutes of a ‘high’ (that is feeling normal and not like I am being crushed) So those few simple pleasures actually help keep me alive!

  • http://AddaURLtothiscomment Steve

    In the mid-90s, after Diet Coke became very popular, I went to my doctor of 15 years, complaining of terrible headaches. Before examining me, he said, “Do you drink Diet Coke?” I looked at him like he had three heads. “Of course I do,” I replied. “How much?” “A few cans a day.” “That’s it,” he said. “Stop drinking it. You’re allergic to Aspertame.” He told me of all these tests that the makers of Aspertame and Coke suppressed, and said that about 20 percent of the country had this allergy. Since then, it has not been easy, but I have not had any Aspertame. Lots of seltzer and water. And all those symptoms are gone. So, yes, Aspertame appears to be dangerous. Who knows what the long term effects are?

  • http://AddaURLtothiscomment Dee

    I have suffered from mild depression for many years, but never heard of the association with Aspartame. However, in the last few years I began having serious bowel distress, which led to the removal of my gall bladder. Unfortunately that did not ease my symptoms so I was sent to a “Digestive Disease Clinic” and the Doctor asked me pre-exam if I consumed artificial sugars. I answered yes, as I drank Diet Coke for years, but had switched to Coke Zero recently for the taste. He suggested I quit drinking them as a test, and within two days my bowel function became normal again. I switched back to regular Coke, but try to limit myself to 2 or 3 a day, as I realize the extra calories aren’t good for me either. I also eliminated dairy as they suggested, and now feel “cured”.

  • http://AddaURLtothiscomment Debra Rincon Lopez

    I have been drinking DIET COKE since I have been in RECOVERY from alcohol about 6-7yrs now? I wished I would have learned this sooner? I AM DISCUSTED cause I have been taking ANTI-DEPRESSANTS along with COUNSELING for the past 4yrs because of the DEPRESSION, it’s still lingering, NOW I KNOW WHY???

  • http://AddaURLtothiscomment georgie moore

    Oh my, you told my story. i don’t drink alcohol, smoke cigarettes and now after years of diet coke drinking (24/7) I have been off it since May 6th. 2011. I do sleep 100% better. I used to have to take a benadryl to sleep. The only problem is that I too a drinking boring water.

  • http://AddaURLtothiscomment Betsy

    I recall reading recently that diet sodas with aspartame was found as a possible culprit in weight gain, because blood sugar and cortisone levels reacted the same way to the fake sugar as it did to real sugar. It’s amazing how many people (myself included) love Diet Coke despite the realization that there is absolutely nothing healthy about it. We ingest a concoction of toxic chemicals and think nothing about it. Crazy.

  • http://AddaURLtothiscomment Athena

    Wow, I’ve read before about the bad things about aspartame, and this is the first study I’ve heard about linking it with depression. I drink some diet Coke almost daily. When I stop I have caffeine withdrawal headaches. I also right now have S.A.D. which lasts for me six months. Whether the diet Coke makes it worse I’m not sure. I use nutrasweet in my coffee each day and truvia sometimes. I’ve been wanting to give up diet Coke because of the link between diet drinks and stroke. Water is really boring, as you say. It, tea, and decaf. coffee may be what I’ll have to switch completely to, though. Thanks for this article.

  • http://AddaURLtothiscomment gwendolyn

    My mother drinks diet coke faithfully…in the past she would drink 4-6 a day…has slowed down, she doesn’t buy to keep in fridge..she gets it out of vending machine where we live..she has mood disorder..depression also..she drinks over ice, and feels it’s okay..water it down she says..ha ha..when she gets nervous she says it calms her down..thank you

  • http://AddaURLtothiscomment kathie chiu

    Could this be because of the link to hypoglycaemia
    that they’ve found with Diet Coke? It can present like depression, among other things. All those symptoms are like it.


    Coke ZERO -ZERO Calories with SPLENDA same with Black Cherry Coke Zero- yay!!! also waist watchers all flavors have splenda for those with blood pressure meds do buy citrus waist watchers may interfere with your meds

  • http://oops!!meant=DoNOTBUYCitrusFlavorsifonBloodpressuremeds!!Editerror*FIXED Pat Francis

    * Correction: Waist Watchers uses citric acid in it’s frosted citrus flavors-great taste by the way!! BUT do not buy the green lime citrus as it may effect Blood pressure meds

  • http://AddaURLtothiscomment sandra austin

    Was diagnosed as bipolar over 24 years ago and was not drinking diet drinks @ that time!!!!! My depression is treated w/ meds and I find myself in and out of the “black hole” but now I do drink diet drinks. Not surprised Nutra Sweet did not want a study done…………
    Antioxidants are important 2 me @ this stage of my life-67 years old and still wanting something safe 2 drink.

  • S Davis

    I can honestly say that I am 57 years old and have *never* been depressed over anything enough to put me in the hospital and I have been drinking diet coke and other name brand soda’s in that same range and there’s never been depression due to drinking a soda that is diet. I have to say that I do feel that someone is trying to make another ‘break-through problem’ that just is not there! I have been drinking diet sodas and other diet drinks since they’ve come out and there is no problem with me.

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