You Ask, I Answer: Phenylketoneuria/Phenylalanine

Every time I pick up a pack of gum, I see a warning that says "phenylketoneurics: contains phenylalanine"

What IS phenylalanine and why would it need to have a warning associated with it?

I'm concerned because I enjoy chewing gum while I'm working out but haven't been lately because of this additive.

Any insight you could give me on this would be really helpful

-- Leigh Simpson
Clarksboro, NJ

There is a genetic condition known as phenylketoneuria (PKU) in which people lack an enzyme called phenylalanine hydroxylase (PAH).

PAH is necessary to convert phenylalanine (an essential amino acid) into tyrosine (a non-essential amino acid).

Just to be clear: phenylalanine is NOT an artificial additive.

Without that enzyme, phenylalanine accumulates in the body and, rather than get converted into tyrosine, is metabolized into phenylpyruvate.

Adults diagnoses PKU who do not their phenylalanine intake put themselves at great risk for seizures, concentration problems, mental confusion, and impaired memory.

Pregnant women with PKU need to be particularly careful, as an improper diet will negatively effect the brain development of the fetus.

Newborn babies are screened for PKU since an inadequate diet (high in phenylalanine) causes irreversible mental disability.

The only way to treat this is through diet modification; specifically, limiting phenylalanine intake.

Food sources high in phenylalanine include whole grains, fish, dairy, soybeans, nuts, and dark green leafy vegetables. In a PKU diet, all of these foods must be completely avoided.

Although some small companies now sell low-protein breads and cookies for the PKU population, most affected individuals rely on prescribed phenylalanine-free protein mixtures and formulas that can be incorporated into their diet.

Since aspartame also contains high levels of phenylalanine, products containing the artificial sweetener (including diet sodas and sugar-free chewing gum) must carry a warning label.

The only people who should be concerned with phenylalanine are those with PKU; otherwise, you have absolutely no reason to worry.