Ask The Nutritionist


Hi Rick, I am drinking a naturally flavored sparkling water beverage. It is sugar free, caffeine free, sodium free, no calories, no sugar, but it contains phenylalanine. Is phenylalanine a bad thing for me or not?


Phenylalanine is an essential amino acid. What this means is that you have to eat it because your body needs it and cannot make it in sufficient quantities. According to our phenylalanine page, it is found naturally in dairy, almonds, avocados, lima beans, peanuts, and seeds. If you are eating it from these natural sources - you probably do not need additional phenylalanine from a commercial drink. Will it harm you in reasonable quantities? Doubtfully.... unless you suffer from the genetic disorder phenylketonuria (PKU).