How much phenylalanine can I have per day?

Individual Phe tolerance varies considerably by age, weight, PKU severity and current blood level. Reference values for classic PKU: toddlers (1–3 yrs): 100–200 mg/day; school age: 200–400 mg/day; adults: 250–600 mg/day. Maternal PKU: under 360 mg/day. Your metabolic team sets your personal daily target.

What is the relationship between protein and phenylalanine?

Protein is made up of amino acids — phenylalanine is one of them. In PKU, phenylalanine cannot be broken down. As a rule of thumb, foods high in protein are also high in phenylalanine (approximately 25–55 mg Phe per gram of protein, depending on the food source).

PKU Phenylalanine Calculator: Calculate Phe

🧮 Calculate Phe in a Food

Food name (optional)

Phe per 100 g (mg)

Serving size (g)

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mg phenylalanine in this serving

📋 Daily Phe Allowance by Age Group

Reference values for classic PKU (type I, BH4-non-responsive). Individual tolerance varies considerably — your metabolic team sets your personal target.

Infants (0–6 months)

20 – 80 mg/day

Very narrow window, strict monitoring required

Toddlers (1–3 years)

100 – 200 mg/day

Rapid growth → frequent adjustment

School age (6–12 years)

200 – 350 mg/day

School life & social situations

Teenagers (13–17 years)

250 – 450 mg/day

Puberty increases protein requirements

Adults (≥ 18 years)

250 – 600 mg/day

Wide range — highly individual

Maternal PKU (pregnancy)

120 – 360 mg/day

Target blood Phe < 360 µmol/L

⚠️ These reference values are based on international guidelines (van Spronsen et al., J Inherit Metab Dis 2017). They do not replace an individualised calculation by your metabolic team. Your actual daily target is set by your age, weight, current blood Phe level and therapy type.

📊 Phe Reference Table: Common Foods

Sources: BLS 4.0 (Max Rubner Institute) · Values per 100 g fresh weight · Variations by variety and preparation possible.

Food	Phe (mg/100 g)	Phe Level
Apple	5	✓ very low
Pear	4	✓ very low
Strawberry	14	✓ very low
Banana	34	✓ low
Tomato	22	✓ very low
Cucumber	10	✓ very low
Carrot	26	✓ very low
Potato (raw)	66	moderate
Rice (cooked)	80	moderate
Whole milk	160	elevated
Wheat bread	310	high
Pasta (regular)	480	high
Chicken breast	1 400	very high
Egg	680	very high
Tofu	740	very high
Low-protein pasta	10 – 30	✓ PKU-suitable
Low-protein bread	15 – 40	✓ PKU-suitable

❓ Frequently Asked Questions about Phenylalanine

How do I calculate the phenylalanine content of a food?

Formula: (Phe per 100 g ÷ 100) × serving size in g = Phe in the serving (mg). Example: potato contains about 66 mg Phe per 100 g. A 200 g portion therefore contains about 132 mg Phe. Use the calculator above to get the result in seconds.

Where can I find the Phe value for a food?

The BLS 4.0 database from the Max Rubner Institute (Germany) contains over 7,100 foods with amino acid profiles. PHE Buddy integrates this database directly into the app, so you don't need to look values up manually. Alternatively, check food labels (the "phenylalanine" row in the nutrition table) or specialist PKU food databases.

What is the rule of thumb between protein and phenylalanine?

A rough estimate: 1 g of protein from natural foods contains approximately 25–55 mg phenylalanine (depending on the food group). Plant sources tend to be around 30–40 mg/g protein; animal sources 40–55 mg/g. For precise meal planning, always use food-specific Phe values.

Can I use this calculator to plan my diet independently?

The calculator helps you quickly estimate Phe content and get a feel for your daily budget. However, setting your individual Phe tolerance and planning your diet should always involve your metabolic team — a dietitian and a metabolic physician at your specialist clinic.

Track daily instead of calculating manually

PHE Buddy tracks your Phe intake automatically — with AI food recognition, the BLS 4.0 database, and a real-time alert when you approach your daily budget.

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PhenylalanineCalculator for PKU