Letter to the Editor

European Journal of Clinical Nutrition (2012) 66, 972; doi:10.1038/ejcn.2012.47; published online 16 May 2012

GUT bacteria and aspartame: why are we surprised?

E Pretorius1

1Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa

Correspondence: E Pretorius, E-mail: resia.pretorius@up.ac.za

The artificial sweetener aspartame (APM; L-aspartyl-L-phenylanaline methyl ester) has been the subject of many debates since its initial approval for human consumption in 1974. However, these sweeteners are frequently used as part of a weight control regime, despite research indicating the negative effects on the body. In a Science article late in 2011, Wu et al.1 discussed the fact that various dietary factors have an impact on gut bacteria, including the controversial dietary sweetener, APM. Recently, in the October 2011 Science Perspective Section, Uri Gophna2 commented on this observation, stating that it is surprising that even minor concentrations of the artificial sweetener APM, can modify bacterial communities. The observations by Wu et al., however, should not be ‘surprising’, as APM has, over the past 20 years, frequently been under vigorous scientific discussion. Currently, it is still approved by the FDA, as well as the EFSA; even though on consumption, each molecule of APM releases a molecule of methanol, which metabolizes into a molecule of formaldehyde.3 Formaldehyde (which is a highly reactive substance) is classified as a known human carcinogen, with no safe level of consumption. Therefore, it is not unexpected that very small amounts of the sweetener can modify bacterial communities, as these bacteria acts as the first line of intestinal defense and are therefore in direct contact with the sweetener and its metabolic compounds. During obesity or periods of weight management regimes, where patients might use APM (as part of their management program), it is perhaps more crucial to have optimum bacterial community functioning in the intestines. The observations of Wu et al., as well as a renewed interest in the APM debacle, spurred on by a new prepublication book released by Woodrow Monte4, entitled ‘While Science Sleeps: A Sweetener that Kills’ might urge scientists and regulatory bodies to look at APM again.


Conflict of interest

The author declares no conflict of interest.



  1. Wu GD, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA et al. Linking long-term dietary patterns with gut microbial enterotypes. Science 2011; 334: 105–108. | Article | PubMed | CAS |
  2. Gophna U. Microbiology. The guts of dietary habits. Science 2011; 334: 45–46. | Article | PubMed |
  3. Humphries P, Pretorius E, Naudé H. Direct and indirect cellular effects of aspartame on the brain. Eur J Clin Nutr 2008; 62: 451–462. | Article | PubMed | CAS |
  4. Monte WWhile Science Sleeps: A Sweetener Kills. Amazon: San Francisco, 2011.

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