Does Aspartame Cause Cancer?

Many people assume that because something is for sale, it must be safe. This is of course true for alcohol and cigarettes which have never killed anyone. Sarcasm aside, the number of substances that have been allowed to market, and subsequently shown to be detrimental to the health, is numerous and well reported. consumption of trans fats for example is now known to be a primary cause of cardiovascular disease, despite previous assurances they were safe.


Aspartame is an artificial sweetener originally used in ‘diet’ drinks. However, more recently it has started to appear more frequently in other foods, often alongside sugar. Aspartame is claimed to help weight loss because while it is very sweet, it provides negligible energy, Therefore it can be used in place of sugar for those wishing to lose weight. However, concerns over the safety of aspartame continue to simmer under the surface, despite assurances that the compound is safe.

Aspartame And Brain Function

Irrespective of the ability of aspartame to cause cancer, mounting evidence and a huge number of reported medical cases show that aspartame affects brain function is some sensitive individuals. In particular, aspartame has been linked to seizures, anxiety, panic attacks, and other neurological problems. The exact reason for these reactions are not known but may relate to the breakdown products of aspartame, one of which (phenylalanine) may alter serotonin metabolism.

Animal Studies

Animal studies show that high intakes of aspartame cause tumours in rodents. In particular, researchers have reported increases in the number of lymphomas and leukemias in rats fed aspartame. Although many claim that animals experiments are not relevant to humans and that the doses fed to rats are higher than would be consumed in the average human diet, the fact remains that aspartame does cause cancer in rodents.

So What About Humans?

Human studies are difficult to perform because if aspartame causes cancer, it likely requires many years to manifest, and studies cannot run for this long. Therefore researchers must rely on observational studies to understand the effects of aspartame. Data from such studies shows that there appears to be an increase in particular types of cancer with aspartame consumption. In particular, aspartame may increase the risk of non-Hodgkin lymphoma.

How Might Aspartame Cause Cancer?

Aspartame is a molecule made up of phenylalanine, aspartate and methanol all joined together. Upon consumption, the three components are broken up and absorbed. We have already seen that the phenylalanine component may interfere with serotonin metabolism is sensitive individuals. However, it is the methanol component that may increase the risk of cancer because it is converted in humans to formaldehyde, a known carcinogen.


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