The speculations on the carcinogenic action of sweeteners have been vivid for many years. There are many interesting articles, interviews and appeals on the Internet which warn against the negative consequences caused by replacing sugar with artificial sweeteners. The truth is, it's worth thinking if worries concerning the carcinogenic potential of aspartame, potassium acesulfame or sucralose are confirmed in research.
In order to understand the influence of a particular substance on the human body, multiple examinations are needed. Some trials are done in the test-tubes (in vitro), some are done on living organisms like fruit flies, mice or rats, and then the next step is research done with people, which can be designed with the use of various methods (randomisation, blank material, double-blind study). Actually, there is no other possibility of checking long-term effects (such as cancer formation, which needs time to grow), caused by using particular compound than doing well-prepared research.
Therefore, as it's easy to conclude, wondering about the carcinogenic action of a particular compound should be supported by the results of research, which would verify such properties in a direct or indirect way. The problem with stories on the carcinogenic potential of aspartame or other sweeteners is that their authors assure that regular intake of such substances leads to cancer formation, however, they have no proof to support their thesis. Indeed, you can find information in such articles that “scientific research prove” the carcinogenic potential of artificial sweeteners, but it's impossible to find such research, just as if it didn't exist. In other words, it's usually impossible to verify the authenticity of information found in such pseudo-scientific works, and their content is similar to the quality of horoscopes.
The truth is, that potential carcinogenic properties of aspartame, acesulphame-K, sucralose and other sweeteners have been verified many times. Taking under consideration the results of research, it should be stated that there is no proof which would support the thesis, according to which using artificial sweeteners would cause cancer. However, it does not mean that these compounds are uncontroversial among the authors of research, or that you can consume them in unlimited amount. The fact of scaring with the “carcinogenic aspartame” is unjustified in the context of available literature and it should be perceived in the category of science-fiction. I encourage people who are more interested in this subject to read the literature mentioned below.