Have you ever noticed the line, “Phenylketonurics: Contains Phenylalanine” at the bottom of the ingredients list on various beverages and processed foods? Were you curious about this ingredient? Well, I was, too!

I first noticed this warning listed on Crystal Light and on some of the beverages that I researched in the grocery store for a previous article . I also received a comment by Mashell suggesting this as a topic for an article, which was a great suggestion. I’ve done some research on phenylalanine to find out more about it, and why we see that warning on ingredient labels. Here is what I learned:

  • Phenylalanine (PHE) is a powerful amino acid, one of two that makes up aspartame (Nutra Sweet and Equal). The other amino acid that composes aspartame is aspartic acid. You will notice the warning on foods and beverages that are sweetened with Nutra Sweet or Equal.
  • The reason for the warning on foods containing aspartame is for those with the genetic disorder PKU (phenylketonuria), which prevents them from metabolizing phenylalanine. People with this disorder must avoid not only aspartame, but also all foods that contain the amino acid phenylalanine naturally, i.e.: dairy, eggs, bananas, nuts, and protein in general.
  • Others at risk from ingesting phenylalanine through aspartame are people with advanced liver disease and pregnant women who have high levels of phenylalanine in their blood.
  • PHE is an essential amino acid for your body, however there is a difference between getting it through aspartame vs. naturally in foods. In aspartame, it is isolated, but when you eat foods that contain it, you are also getting other essential amino acids at the same time. Amino acids are provided in combination in nature. It is only through man-made processing where you will find them in isolation, such as in the example of aspartame.

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  • This site that is run by Coca Cola (see the footer of the page, otherwise the name “The Beverage Institute for Health & Wellness” is rather deceiving) gives you a chart of the levels of PHE that occur in foods naturally, and then states that the FDA has approved the levels of phenylalanine that you ingest in aspartame.
    It seems that they are trying to convince you that aspartame is safe, which makes sense since so many of their products contain it. They do not mention the fact that you are ingesting phenylalanine as an isolated amino acid in the artificially processed sweeteners Nutra Sweet and Equal, and that you cannot compare this ingestion to the ingestion of PHE through natural foods. Additionally, I haven’t read anything about health hazards of getting phenylalanine through natural foods (unless of course you have PKE), or the levels of phenylalanine in natural foods being dangerous, but instead the problem is when you get it in aspartame. So their comparison of the levels in each isn’t ringing true for me.
  • When you upset the delicate balance of amino acids in your body through artificial, processed aspartame, there can be serious issues that develop in the brain, not only in infants, but also in adults. Phenylalanine reduces the serotonin levels in your brain, while the amino acid aspartic acid (the other half of aspartame) stimulates the brain. These two amino acids that were isolated to create aspartame can cause seizures in the brain through the reactions that each of them they create in the body.
    So, it is not necessarily the high levels of PHE that cause the health hazards, but the combination of both of the amino acids that make up aspartame that is hazardous to your health. This issue is separate from the genetic disorder of PKE since anyone with PKE cannot use phenylalanine at all.

To sum up, the warning “Phenylketonurics: Contains Phenylalanine” is placed on food and beverages that contain aspartame for those with the genetic disorder PKE, however based on what I’ve learned, it can have a negative effect on anyone’s health. It sounds to me like it’s better to avoid aspartame all together, something that I don’t use today. When I used to drink diet sodas that contained Nutra Sweet, I would wake up every morning with a strange fuzzy feeling (not from caffeine, I drink tea and don’t have that result) on the top of my head. I had to drink more of the soda in order for that feeling to go away (strange, huh?).

In addition to the links I have referenced above, I also gained some of this information from the book by Carol Simontacchi, The Crazy Makers (How the Food Industry Is Destroying Our Brains and Harming Our Children). This book is fascinating, covering the upsurge of mental illnesses that parallels the rise of the processed food industry. I highly recommend it.

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