Chemistry Question #79

Sébastien Morin, a 18 year old male from the Internet asks on October 11, 1999,

How is aspartame synthesized (theoretically and within industrial processes)?

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The answer

Barry Shell answered on October 11, 1999

The Merck Index (available in any library) gives the patent number for aspartame as Patent #665591. Using this information, I looked it up in at the US Patent Office website. This is a very handy service for any invention you can imagine and very informative as every page of the 6 or so million US patents is available. I found two processes. Here is the summary for one of them: "A process for the preparation of the N-L-.alpha.-aspartyl-L-phenylalanine 1-methyl ester (aspartame) which is characterized by adding phosphoric acid and a lower alkyl alcohol to the reaction mixture containing N-formyl .alpha.-L-aspartyl- and ß-L-aspartyl-L-phenyl-alanine methyl ester and only one of the resultant deformylated isomers, i.e. aspartame phosphate precipitates. The .alpha.-isomer phosphate is collected by filtration and converted to free aspartame by treatment with a base."

Nancy Haase answered on December 7, 2004

Nancy asks: Are there any specific tests that can be done to test for Aspartame poisoning? When I found that I had it, Aug 3, 2002 there was not, with the exception that phenylalanine levels could be checked in the blood stream, however my HMO wouldn't do that test because I was not born PKU, and current medical thinking (I think) is that if you weren't born with it, nothing could change it. What about the multiple transformations that Aspartame goes through in the system... could it possibly do more than they want to admit. With the FDA, the ADA and other low carb nutritionists and the terribly amout of diet products out there I imagine that fighting Searle, or Nutra Sweet would be difficult at best. Can you let me know what's going on in this area?

Barry Shell answers:

There are no tests for aspartame "poisoning". The solution for this is simple. Stop eating Aspartame. The best way to fight the big companies that make these questionable products is with your wallet. Don't buy anything with aspartame in it, or sucralose, or olestra, for that matter. This is not that hard to do. That is what I do. I prefer sugar--in moderation.

As far as the metabolic products of aspartame, scientifically I don't think there are any worries. A good site that truthfully explains the chemistry and metabolism of aspartame is the Finch University of Health Sciences, The Chicago Medical School. As far as I can tell there are no "multiple transformations" or mysteries about what happens to aspartame inside your body. The products: aspartic acid, phenylalanine, and methanol are all very common naturally occurring molecules that a normal human body can handle very easily. You get these in many other foods. The first two are amino acids and the second one is essential for life. In other words, you cannot live without it and the human body needs pheylalanine, so is well adapted to use it. The amount of methanol produced is small and can be handled by the body. As far as I can tell, the products of aspartame do not "build up" in your body. You can easily get rid of them quickly, so any "poisoning" should be short lived.

WARNING: there are a huge number of quasi-scientific websites about the dangers of aspartame with tons of misinformation about its chemistry and metabolic pathways in the body. Be careful if you read these. I agree: aspartame is not desirable and should be avoided if possible. As a scientist, I find some of the explanations and reasoning given on the many anti-aspartame websites to be questionable.

Finally, if you are having a medical problem you suspect is due to eating aspartame, go see a doctor. Websites are no substitute for medical attention.

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