Treatment consists of avoiding phenylalanine supplements, diet products containing aspartame (which also contain phenylalanine), and phenylalanine-rich foods such as cocoa powder, gelatin, and many meat, dairy and higher protein foods.
Food dyes and colorings like tartrazine, preservatives like benzoates, BHT and BHA, flavor enhancers like monosodium glutamate (MSG), and sweeteners like aspartame have also been suspected asthma triggers.
Sugar-free foods, such as diet soda, which contain the artificial sweetener aspartame, are also prohibited foods for PKU patients because aspartame contains the amino acid phenylalanine.
Low- or no-calorie sweeteners are fine for everyone to use as a substitute for sugar, except for those with a condition known as phenylketonuria, who should not consume aspartame.
Because they are natural, many people feel sugar alcohols are healthier than artificial sweeteners, such as aspartame, sucralose, and saccharine, which are made from chemicals.
Women who are at risk of phenylketonuria (PKU) should not take aspartame because it can increase the amount of the amino acid phenylalanine, which can harm the developing baby.
Diet Coke contains aspartame and although the FDA says that it is safe to use during pregnancy, it does suggest a moderate intake of the sweetener.
Avoiding all high-protein foods is a start, but those with PKU must also avoid foods with artificial sweeteners such as aspartame.
While the caffeine isn't present in the caffeine-free diet soda, it still contains aspartame, which should be taken in moderation.
There is also some evidence that artificial sweeteners like aspartame and sucralose may still have an impact blood sugar.