Phenylalanine source: What this note means for foods

The statement “contains a source of phenylalanine” indicates that a food contains the protein phenylalanine. Some people are allergic to it.

The statement “contains a source of phenylalanine” on products is only actually relevant for very few people – those affected by the rare hereditary disease phenylketonuria (PKU). In this disease, the body cannot properly break down the protein phenylalanine. Affected people must follow a strict diet low in phenylalanine.

What is Phenylalanine?

Phenylalanine belongs to the chemical group of essential amino acids, which are actually very important for the body. Amino acids are the basic building blocks for proteins. Our body, in turn, needs proteins for a variety of tasks: They give cells and tissues structure, enable movement, store and transport substances, protect the body from diseases, regulate processes as hormones and accelerate chemical reactions as enzymes. For example, phenylalanine is involved in the construction of important proteins and in the production of hormones.

However, the body cannot (completely) produce essential amino acids such as phenylalanine itself. You therefore have to get them through food. The required daily dose is around one to two grams.

According to the, phenylalanine occurs naturally primarily in these foods:

• Meat, especially pork and poultry
• dairy products
• Eggs
• Grain
• legumes
• soy

Manufacturers must label products if they contain a source of phenylalanine. This is the case, for example, with certain artificial sweeteners such as aspartame.

The indication of a source of phenylalanine

Normally, phenylalanine does not pose a threat to the body, but is actually essential for survival. However, there are people who have an inborn error of metabolism called phenylketonuria (PKU). This disease is the result of a genetic mutation and is hereditary. So if both parents have the disease or at least the altered genes, then the child also has the inborn error of metabolism. According to Netdoktor, around one in 10,000 newborns in Europe is affected.

People with phenylketonuria cannot break down phenylalanine. If left untreated, phenylalanine accumulates in the blood and, according to Netdoktor, leads to severe damage to the brain, which can cause intellectual disability.

Doctors usually diagnose PKU shortly after birth. According to Onmeda, symptoms of untreated PKU first appear after two to four months: developmental disorders and hyperexcitability occur.

The only treatment method so far is a strict diet in which those affected strictly adhere to not consuming any or only extremely little phenylalanine. That’s why pointing out a source of phenylalanine is so important for you: Depending on the severity of the disease, even small amounts of phenylalanine can be harmful to your body.

A low-phenylalanine diet is largely plant-based and low in protein because it excludes meat, milk, and eggs. It should also be as free of soy and legumes as possible. Suitable recipes can be:

• Oven vegetable recipe with potatoes and seasonal vegetables
• Turnip stew: recipe for the hearty, regional dish
• Sweet Potato Brownies: A quick recipe
• Jägerpfanne: A vegetarian recipe

Read more on Utopia:

• Short- and long-chain carbohydrates: occurrence and utilization in the body
• Tannins: Vegetable tannins really are that (un)healthy
• Fiber in the diet: what are the best suppliers?

Edited by Annika Reketat

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