This is a cool thing i found out.. wanted to share it with u guys:
Where Blonde Jokes Come From (a medical explanation).
Have you ever wondered where blonde jokes came from? Ever wondered why diet coke (and other sodas) say "Phenylketonurics: contains phenylalanine" on their label? You're in luck, I'm about to answer both in the same article. To do that, let me give you a little background information. Your body requires a bunch of amino acids to make up the proteins in your body (like in your muscles, your blood, etc.), to burn for energy, etc. These amino acids may sometimes be turned into other amino acids or other compounds via enzymes. Now there are certain amino acids that are called "essential" amino acids simply because you must obtain them in your diet since your body does not make them. Thus, if you're lacking that essential amino acid, you will see deficiencies in the compounds that it would have made. One such pathway I'm going to discuss is this:
Phenylalanine (an essential amino acid) --> Tyrosine (an amino acid)
Phenylalanine turns into tyrosine via the enzyme phenylalanine hydroxylase. Now there's a disease called PKU (phenylketonuria) in which this enzyme is deficient or absent. As a result, these people get a build up of phenylalanine and a lack of Tyrosine. Thus, Tyrosine now becomes an essential amino acid since your body can't make it anymore.
Now that we have the basics down, let me explain where blonde jokes came from. Tyrosine is needed for your body to make catecholamines and melanin. In PKU, the lack of tyrosine leads to a lack of catecholamines (such as dopamine and norepinephrine) and thus the person suffers from mental retardation. Also, the lack of melanin causes the person to be blue-eyed, fair-skinned, and blonde-haired. Thus, PKU causes people to be blonde-haired and mentally retarded. Sadly, before science and medicine made the discovery of PKU, the jokes had already began about those with PKU since they were blonde and mentally retarded.
Now as for Diet Coke (and other sodas), there's a warning label on the product that warns that it contains phenylalanine. Remember that in patients with PKU, there's a buildup (excess) of phenylalanine and a lack of tyrosine. Thus, the main treatment for those with PKU incorporates a limit on phenylalanine in the diet and a supplementation of tyrosine. It actually is rather effective at lessening the extent and progression of PKU's mental retardation.
Alright, there you have it.
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