Even low doses of the artificial sweetener aspartame are toxic to the brains of animals

I don’t hide the fact that I am not a fan of the artificial sweetener aspartame. It’s widespread use in processed foods and drinks gives me cause for concern, seeing as there’s a considerable body of evidence that links it with everything from weight gain to cancer. Some of the most incriminating evidence comes from studies done in animals. These are not a substitute for human studies, but when human studies have not been done they are, I believe, much better than nothing at all.

One of my major concerns about aspartame relates to its biochemical potential for ‘neurotoxicity’. Each component of aspartame (aspartic acid, phenylalanine and methanol) has the ability to damage the brain or disrupt its chemical balance. Just last week, one of my blog posts highlighted this as well as the apparent ability of aspartame to cause depression.

I was interested to read a recent study which tested the impact of aspartame on the brains of mice. The mice were subjected each day to one of three dosages of aspartame (0.625, 1.875 or 5.625 mg/kg) or placebo (saline solution) given under the skin for just two weeks. Let’s get these dosages in perspective for a moment: the acceptable daily intake of aspartame in Europe and the US is 40 mg/kg and 50 mg/kg respectively. The fact that this refers to oral dosages and in the study aspartame was given under the skin may have some relevance. However, even so, I think it’s safe to say the dosages used in the study were far from excessive.

What the results of the study showed, however, is that even at a dose of 1.875 mg/kg there was evidence in the mice brains of increased ‘oxidative stress’ (free radical damage) and lowered glucose levels. At the higher aspartame dose the situation was even worse. And at this dose, the mice suffered from memory deficits (as evidence by poorer performance on what is known as the ‘water maze’ test). Here’s the authors’ conclusions:

These findings suggest impaired memory performance and increased brain oxidative stress by repeated aspartame administration. The impaired memory performance is likely to involve increased oxidative stress as well as decreased brain glucose availability.

As I alluded to above, this is an animal study and its results may not apply directly to we humans. But in the context of all we know about the potential aspartame has for toxicity, I think this piece of research gives us yet another reason to steer clear of this stuff.


1. Abdel-Salam OM, et al. Studies on the effects of aspartame on memory and oxidative stress in brain of mice. Eur Rev Med Pharmacol Sci. 2012;16(15):2092-101.

7 Responses to Even low doses of the artificial sweetener aspartame are toxic to the brains of animals

  1. derrick 18 January 2013 at 10:18 pm #

    Does the aspartame hit the bloodstream after ingestion in the same form as which it is injected under the skin?

  2. Lorraine 18 January 2013 at 11:22 pm #

    I think all artificial sweeteners are not good for you, physically or otherwise. I personally think, if your addicted to sugar, transferring to artificial sweeteners will not help solve the addiction.

    I’ve read before that people with high phenylalanine levels in the blood (pregnant, liver disease) need to be careful with consuming aspartame products as can possibly result in brain damage. Is it true, products containing aspartame have to give a warning regarding their phenylalanine levels?

  3. Muni 18 January 2013 at 11:29 pm #

    This is so important to know. I decided some years ago not to use any kind of artificial sweetners any longer. I used to get constant headaches and migraines and was bloated and overweight. After stopping sweetners and also caffeine, my headaches greatly reduced and now I rarely get one. I don’t trust what chemicals are in these artificial sweetners and I have read that aspartame etc are known to have nasty side effects. They also never ever helped me to lose weight anyway! I would rather take a very tiny amount of unrefined demerara sugar in a drink if I really wanted it than to put something which contains chemicals. Lord know what aspartame does in the long term to our bodies.

  4. Eric Anondson 18 January 2013 at 11:41 pm #

    Have any studies been done on animals whether the neurotoxicity of artificial sweeteners like aspartame or additives like MSG affected a brains’s susceptibility to concussions or other damage?

  5. Wyn Hurst 19 January 2013 at 8:19 pm #

    I used to have painful shoulders with shooting pains down my arms at night. I thought this was caused by wear and tear (rotator cuff problem), but since reading your warnings about aspartame I’ve stopped using these sweeteners in coffee and the pain has over time gone almost completely – no more problems at night. I now use saccharin tabs – any contra-indication for these? Wasn’t saccharin considered to be a health hazard at one time? Many thanks for your vigilance on our behalf, Dr John.

  6. Mike 19 January 2013 at 11:05 pm #

    Check this out:


  7. Chloe 23 January 2013 at 6:37 pm #

    I have been using stevia if I need to sweeten something. Slight bitter after taste but it’s good in some things – I like a post gym stevia/protein/milk/cacao shake!

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