Phenylalanine

[rthmjohn]

Why does my chewing gum wrapper say "PHENYLKETONURICS: CONTAINS PHENYALANINE"? Is this some harmful substance?

[jdurg]

Phenylketonurics have a genetic condition which does not allow their body to properly breakdown the amino acid phenylalanine. As a result, phenylalanine is broken down into a ketone and passed out through the urine. (Hence phenyl-keton-uria). The problem is, as a ketone the phenylalanine is a pretty nasty poison. So if the phenylketonurics eat ANYTHING with phenylalanine in it, it can cause severe problems. For someone without this genetic malady, there is no problem at all with phenylalanine.

 

(Please note that what I stated above is what I remember from my genetics class a few years ago. You may be better off posting this question in the genetics forum).

[rthmjohn]

How does one know if he/she is a phenylketonuric? Are they missing specific enzymes?

[jdurg]

Again, I'm not sure. Perhaps we can have a mod move this over to the Genetics forum as they can probably answer this a LOT better than I can.

[MulderMan]

look up the Guthrie test, its a test done on newborns in most countries for things like phenylketonuria and cystic fibrosis etc. Its caused from a defective gene not being able to produce the PAH enzyme. Its the PAH that turns phenylalanine into tyrosine. thats all i can remember.

[Dave]

Moved as requested.

[Skye]

It causes severe mental retardation for people without phenylalanine hydroxylase, which ordinarily converts about three quarters of the phenylalanine to tyrosine, the rest of the phenylalanine then goes to be made into protein. The only way to avoid the retardation is to carefully limit the amount the amount of phenylalanine that the phenylketonuronics eat, so that they get enough to live (it's an essential amino acid, which humans can't synthesise, so they still need some) but not more than enough so it builds up and causes damage. This has to be done from birth to be effective, so there are routine tests for newborns.

 

Interestingly enough, it's not known how the extra phenylalanine causes retardation.

[rthmjohn]

thanks, skye

[Nalos Surith]

This stuff is bad bad bad.

 

# Aspartame

 

After reviewing scientific studies, FDA determined in 1981 that aspartame was safe for use in foods. In 1987, the General Accounting Office investigated the process surrounding FDA's approval of aspartame and confirmed the agency had acted properly. However, FDA has continued to review complaints alleging adverse reactions to products containing aspartame. To date, FDA has not determined any consistent pattern of symptoms that can be attributed to the use of aspartame, nor is the agency aware of any recent studies that clearly show safety problems.

 

Carefully controlled clinical studies show that aspartame is not an allergen. However, certain people with the genetic disease phenylketonuria (PKU), and pregnant women with hyperphenylalanine (high levels of phenylalanine in blood) have a problem with aspartame because they do not effectively metabolize the amino acid phenylalanine, one of aspartame's components. High levels of this amino acid in body fluids can cause brain damage. Therefore, FDA has ruled that all products containing aspartame must include a warning to phenylketonurics that the sweetener contains phenylalanine.

Taken from US FDA/CFSAN

 

For more information on Aspartame, check out Aspartame and Nutrasweet Toxicity Info Center

 

Just for all to know, aspartame is genetically modified bacteria where the ammino acids are split leaving no trace of the bacteria, just the chemicals.

[ecoli]

phenylalanine turn your urine a pinkish-red, too. Am I remembering correctly?