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

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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.

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