New review catalogues the myriad of ways aspartame can mess up your body and brain

Back in October I wrote about the artificial sweetener aspartame. This food ingredient is perhaps the most controversial of all: its manufacturers and official bodies claim it’s safe, but a stack of anecdotal evidence and a fair degree of science says it’s not. Tellingly, whether a study finds for or against aspartame seems to be intimately related to, err, who paid for it. In one on-line review of the evidence finds that while 100 per cent of industry-funded studies conclude aspartame is safe, 92 per cent of independently funded research and reports identified aspartame as a potential cause of harmful effects.

In October’s post I explored some of chemistry of aspartame, and provided evidence also that this food component has the capacity to harm. I focused specifically of one of aspartame’s components ” methanol ” and it’s breakdown product formaldehyde (which, by the way is used to preserve dead bodies). In a review published this month in the European Journal of Clinical Nutrition, scientists in South Africa assessed the potential effects not just of methanol, but aspartame’s other constituents (phenylalanine and aspartic acid) on the brain. The review is long and detailed, and is supported by more than 50 scientific references. In their review of the effects of phenylalanine, the authors detail the ability of this chemical to disrupt the chemistry of the brain, including its potential to lower levels of key brain chemicals such as serotonin (which may adversely influence all sorts of things including mood, behaviour, sleep and appetite). The authors note that phenylalanine also has the potential to disrupt amino acid metabolism, nerve function and hormonal balance in the body. They go on to suggest that aspartame’s ability to destroy nerve cells and this damage may mimic or even cause Alzheimer’s disease.

When the authors of this review turn their attention to aspartic acid, they highlight this chemical’s ability to stimulate or ‘excite’ the nervous system.

In their analysis of the effect of methanol in the body, the authors describe the ability of this substance to create formaldehyde, along with the cancer-causing agent diketopiperazine and a ‘number of highly toxic derivatives’.

Here are the conclusions that come at the end of this review (I’ve added some detail in brackets here and there to aid clarity and understanding):

It was seen that aspartame disturbs amino acid metabolism, protein structure and metabolism, integrity of nucleic acids (which are the building blocks of DNA), neuronal function, endocrine (hormonal) balances and changes in the brain concentrations of catecholamines (brain chemicals such as noradrenaline and dopamine that can affect, among other thing, mood).

It was also reported that aspartame and its breakdown products cause nerves to fire excessively, which indirectly causes a very high rate of neuron depolarization (which basically means aspartame has the capacity to ‘excite’ nerve cells).

The energy systems for certain required enzyme reactions become compromised, thus indirectly leading to the inability of enzymes to function optimally.

The ATP (the basic currency for energy in the body) stores in the cells are depleted, indicating that low concentrations of glucose are present in the cells, and this in turn will indirectly decrease the synthesis of acetylcholine, glutamate and GABA (chemicals that play a part in nerve and brain function).

The intracellular calcium uptake has been altered, thus the functioning of glutamate as an excitatory neurotransmitter is inhibited.

Mitochondria (the miniature ‘engines’ that generate energy in the body’s cells) are damaged, which could lead to apoptosis of cells and infertility in men and also a lowered rate of oxidative metabolism are present, thus lowering concentrations of the transmitters glutamate and production of GABA.

The cellular walls are destroyed; thus, the cells (endothelium of the capillaries) are more permeable, leading to a compromised BBB (the ‘blood brain barrier’ ” a structure which, in health, keeps certain substances from making their way from the blood stream into the brain). Thus, overall oxidative stress and neurodegeneration are present.

From all the adverse effects caused by this product, it is suggested that serious further testing and research be undertaken to eliminate any and all controversies surrounding this product.

Read this study in full (or even this short summary of it), and it’s difficult not to come away with the idea that aspartame has considerable potential for harm. The best thing, I think, is if this substance was banned from the diet. At the very least, I’d like to see the potential problems with aspartame to be widely known, so individuals can at least make a properly informed decision about whether to consume it or not. Here’s hoping that this latest review of aspartame gets the publicity it deserves.


Humphries P, et al. Direct and indirect cellular effects of aspartame on the brain
European Journal of Clinical Nutrition 2008;62:451″462

11 Responses to New review catalogues the myriad of ways aspartame can mess up your body and brain

  1. Carol Guilford 3 April 2008 at 4:23 pm #

    Check out this web site about a private experiment on aspartame. I wrote the into–so I know it is legit.


  2. helen 7 April 2008 at 1:33 am #

    good site Carol. Aspartame really is problem & not the safe alternative to sugar we are told it is, manufacturers, have a lot to answer for and so do our authorities who we trust to look after our welfare. It seems the persuit of profit trumps public care once again.

  3. Jeraldine Curran 10 April 2008 at 4:25 pm #

    My mum has been a diabete for many years and despite my objections would not listen to me only the dietican at the hospital. She began taken Aspartame and I would say is now addicted to it. Her mind has also gone and she has dementia. If you tried to take her aspartame away she is like a mad person. Is there anyway I can get this out in the open to stop other people suffering the way my mum is suffering?

  4. Liz 21 May 2008 at 10:28 pm #

    Aspartame is an ingredient in the calcium supplement treatment that those of us with Hypoparathyroidism have to take – and have taken , in many cases, for years.

    Is there an alternative?


  5. Marian Rigney 7 August 2009 at 12:07 pm #

    This is scary stuff. I used to routinely drink diet drinks sweetened with aspartane thinking they were beneficial because they helped me cut down on sugar. All I can say, over the last 7 months since I have stopped drinking them I have felt heaps better.

  6. Nicole 20 September 2010 at 2:14 am #

    Like a lot of people, i’m interested in artificial sweeteners. From my knowledge, aspartame breaks down into levels of phenylalanine, aspartic acid and methanol that are often in lower levels than every day foods. Just wondering how the effects above are possible if these levels are lower than say that in a glass of tomato juice?

  7. John Briffa 20 September 2010 at 7:35 pm #

    I’m happy to answer your question, but can you perhaps first clarify what your interest in this area is. Are you a concerned consumer, perhaps? Or do you have some other interest?

  8. Nicole 21 September 2010 at 1:13 am #

    Hi, i am a consumer, also work in the area of nutrition and I often have the question asked is it safe? I have done a bit of research through reading and always want to know both sides of the story – pro vs cons so I can give the correct advice.

  9. John Briffa 21 September 2010 at 9:41 am #


    First of all, aspartame contains levels of aspartic acid and phenylalanine at concentrations far higher than is found in natural foods. Plus, aspartame can break down into its individual constituents quite rapidly, which mean there’s potential for the body to be ‘flooded’ with aspartic acid and phenylalanine in a way that does not happen when people eat foods which contain these substances naturally.

    Interestingly, the aspartame industry appears to know this as it has conducted studies in which aspartame is administered as part of a slowly dissolving capsule, which does not mimic how aspartame is often ingested in the real World (say, as a soft drink/soda).

    Aspartame contains a methyl group which is cleaved off during digestion and converts to methanol (a known neurological toxin) which can be metabolised to other things including formaldehyde (embalming fluid). Fruits and vegetables do indeed contain methanol, but the difference is in this case it’s bound to pectin, and we do not have the capacity to split the methanol from the pectin. Still bound to pectin, the methanol is essentially harmless.

    You can learn more about this by watching this video (linke below) as well as the preceding and following parts of this film (Sweet Misery). I will warn you, though, this video is not for the faint-hearted.

    It’s interesting that you say you ‘work in the area of nutrition’ but don’t actually say what you do. And I’m intrigued by the fact that you’re often asked the question regarding is aspartame is safe or not. I’ve worked in the field in the nutrition as a practitioner, speaker and writer for years and have never been spontaneously asked about the safety of aspartame. People seem to assume its safe (after all, that’s what the industry repeatedly tells us to believe). However, once information about the genuine potential aspartame has for harm gets put in front of them, my experience is that they never knowingly consume it again.

  10. Joanna 1 November 2010 at 6:29 pm #

    I am very grateful for web sites such as Dr Briffa for providing information about artificial sweeteners that manufacturers try to hide form the public. If it were not for the information I found on the web, then I believe that my health would stil be suffering and I would not be as happy as I am today.
    Three years ago I decided to start a healthier lifestyle – cut out sugar and quit smoking. For 12 months I replaced sugary foods for sweeteners in my coffee, diet drinks, sugar free yoghurts and replaced the cigarettes with nicotine replacement lozenges(which were full of artificial sweeteners)
    Within in 6 months instead of feeling healthier, I had never felt so awful. I was moody, depressed, bloated and suffered from dizziness and headaches. Then after about 8 months, I started having seizures that started with a strange smell, then pressure and pain in my left eye. I would be absent for 1 – 3 minutes then would come to with a stong sense of de ja vous. These occrred about 3 times a week and up to 3 times a day when at the worst times. I had never experienced anything like this in my life. I had scans, electodes glued to my head and other various tests, but no reason for these episodes could be found. I googled a few of my symptoms and came across a web page about the possible dangers of artifical sweeteners when I typed in “pressure in left eye” I then went on to collect as much information as I could and couldn’t believe the similarities to how I had been feeling. I inspected the ingredients list of everything I ate or drank and ended up throwing away most of the contents of my food cupboard. I was shocked to find that even my toothpaste had sweeteners in it! I now buy a natural one from a healthfood store. Within 2 months I started feeling better and have not had had a seizure since. I started eating sugar again and actually felt slimmer and less bloated. The pressure in my left eye continued and after noticing that my vision in that eye was blurry, I went to my optictian who referred my to a consultant. I was diagnosed with secondary glaucoma and had to have an operation so that my eye could drain properly. I was only 29 and there is no history of glaucoma in my family, so I am convinced that it was damage caused by the use of artificial sweeteners. I asked all of the Doctors and specialists I saw wether they thought that artificial sweeteners could have caused my health problems. Most said that it was very unlikely and one said it was an interesting theory, but there has not been much research in that area.
    I am certain that sweeteners caused my problems and wish that I had seen web sites like this one before I made the uneducated “healthier” diet changes.
    Thank you for opening my eyes and giving me the infomation I needed to to have a REAL healthy lifestyle.

  11. Kay 8 April 2011 at 11:14 am #

    After drinking a fruit-flavored drink sweetened with aspartame I had an episode in which I was unable to read for hours. I could see the letters and I knew what they were, but I could not make the leap to knowing the words. It was as if I were illiterate. I thought I was having a stroke, but the symptom resolved. Years later I consumed aspartame by mistake and it happened again. These symptoms could be due to a temporary ischemic attack, or, according to Oliver Sacks, a migraine.

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