What is phenylalanine and phenylketonurics?

I received a request from a reader (wow I have readers!) to post about phenylalanine and phenylketonurics. Big words that I knew very little about. Well I'm all about learning new things, so let's get started.

Phenylalanine is a naturally occuring amino acid found in complete proteins and aspartame. When you consume meat or drink a diet soda containing aspartame, your body breaks it down into its individual components. The proteins are broken down into separate amino acids and aspartame is broken down into phenylalanine, aspartic acid, and methanol.

For a regular person, phenylalanine is just another building block for the body to use. People with the genetic disorder phenylketonuria (PKU) are unable to process phenylalanine because they lack a particular enzyme. Too much phenylalanine built up in the body can lead to mental retardation, muscle aches and even seizures. You can read more about this condition here - it's written in easy to understand, non-medical terms.

The reason a lot of diet or sugar-free products contain warnings about phenylalanine is because they are artificially sweetened with aspartame. Phenylalanine isn't harmful by itself. It is only those with PKU who need to watch out for it.

I'd like to go into more detail about how those with PKU have to deal with diets differently from the rest of the population. This will be a separate post later because super-long posts scare people away.