Uniformity of Food Protein Interpretation Amongst Dietitians for Patients with Phenylketonuria (PKU): 2020 UK National Consensus Statements

In phenylketonuria (PKU), variable dietary advice provided by health professionals and social media leads to uncertainty for patients/caregivers reliant on accurate, evidence based dietary information. Over four years, 112 consensus statements concerning the allocation of foods in a low phenylalanine diet for PKU were developed by the British Inherited Metabolic Disease Dietitians Group (BIMDG-DG) from 34 PKU treatment centres, utilising 10 rounds of Delphi consultation to gain a majority (≥75%) decision. A mean of 29 UK dietitians (range: 18–40) and 18 treatment centres (range: 13–23) contributed in each round. Statements encompassed all foods/food groups divided into four categories based on defined protein/phenylalanine content: (1) foods high in protein/phenylalanine (best avoided); (2) foods allowed without restriction including fruit/vegetables containing phenylalanine ≤75 mg/100 g and most foods containing protein ≤0.5 g/100 g; (3) foods that should be calculated/weighed as an exchange food if they contain protein exchange ingredients (categorized into foods with a protein content of: >0.1 g/100 g (milk/plant milks only), >0.5 g/100 g (bread/pasta/cereal/flours), >1 g/100 g (cook-in/table-top sauces/dressings), >1.5 g/100 g (soya sauces)); and (4) fruit/vegetables containing phenylalanine >75 mg/100 g allocated as part of the protein/phenylalanine exchange system. These statements have been endorsed and translated into practical dietary management advice by the medical advisory dietitians for the National Society for PKU (NSPKU).

However, any foods with eggs as an ingredient (e.g. cakes or sweets), must be calculated/weighed as an exchange food if they contain protein >0.5g/100g.

100
Cheeses (all dairy based cheese and cheese spreads) High in protein and are best avoided.
However, any foods with cheese as an ingredient (e.g. in baby foods or sauce), must be calculated/weighed as an exchange food if they contain protein >0.5g/100g.

Nuts
High in protein and are best avoided.
Exception: whole chestnuts 82 Aspartame (E951) or neotame containing food and drinks All foods, drinks and tabletop sweeteners containing aspartame or neotame are best avoided. 100 Seeds High in protein and so are best avoided.
However, any food products with seeds as an ingredient (e.g. cereal bar) must be calculated/weighed as an exchange food if they contain protein >0.5g/100g.

100
Soya based foods High in protein and are best avoided. 100 Tofu High in protein and best avoided. 100 Quorn based foods High in protein and are best avoided. 100 Goji berries High in protein and are best avoided. 100 Yeast extract spreads High in protein and are best avoided. 90 Pork crackles/pork scratching High in protein and are best avoided. 82

Exchange-free foods
Definition: Any food given without protein measurement/restriction is referred to as an exchange-free food.

FOOD GROUPS STATEMENTS % agreement
Fresh, canned, frozen or dried fruit & vegetables ≤75mg Phe/100g Fruits and vegetables (except potatoes) containing a Phe content ≤75 mg/100g weight of fruit & vegetable are exchange-free.
The protein content appears higher than other sugars due to its processing. Treacle is made from the 'remaining' syrup after sugar is refined.

100
Fruit syrups/fruit sauces Exchange-free if they contain exchange-free ingredients only. 100 Sweet spreads e.g. Jam/marmalade/honey Exchange-free if they contain exchange-free ingredients only. 100 Artificial sweeteners e.

FOOD GROUPS STATEMENTS % agreement
Milk (animal based)-full fat, semiskimmed, skimmed, condensed, soya Any milk product (plant or animal) containing protein >0.1g /100ml must be measured/calculated as an exchange food.

80
Plant milks e.g. coconut, oat, rice, almond, hemp Includes coffee with these added e.g. dried reconstituted from sachets, frappuccino's, cappuccino, lattes, coffee pods/capsules with added milk, iced coffee, macchiato Any milk product (plant or animal) containing protein >0.1g /100ml must be measured/calculated as an exchange food.
Coffee either containing or made with animal/plant milk must be calculated/measured as an exchange drink. Exchange-free if it contains exchange-free ingredients only.

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Foods that require measuring/weighing as an exchange food if they contain protein >0.5g/100g. If they contain exchange-free ingredients only or have a protein content no more than 0.5g/100g, they are exchange-free.

General food groups
Gluten-free foods Gluten-free foods with a protein content >0.5g/100g must be calculated/weighed as exchange foods.

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Gelatine containing foods All foods containing gelatine and with a protein content >0.5g/100g must be calculated/weighed as exchange foods.

Dairy products and alternatives
Vegan, free-from or soya/plant cheese or regular cheese as an ingredient Any foods with added regular cheese as an ingredient (e.g. in baby foods or sauce), and with a protein content >0.5g/100g, must be calculated/weighed as an exchange food.
Any vegan or 'free-from' cheese is exchange-free if the protein content is ≤0.5 g/100g or if they contain exchange-free ingredients only. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

94
Soft cheese, cheese spread, cream cheese Soft, cream cheeses with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
Any vegan or free-from soft cheese is exchange-free if the protein content is ≤0.5 g/100g or if they contain exchange-free ingredients only. If they contain protein >0.5g/100g and contain exchange ingredients, they must be calculated/weighed as exchange foods.

87
Ice-lolly milk based Exchange-free if the protein content is ≤0.5g/100g of food. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

96
Ice-lolly fruit/juice based Exchange-free if the protein content is ≤ 0.5g/100 of food. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

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Cream e.g. double, single, clotted, cream alternatives, sour, spray cream Any cream with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Ice-cream (dairy and dairy-free) Any ice-cream (dairy or dairy-free) with a protein content >0.5g/100g must be calculated/ weighed as an exchange food.
Weight rather than the volume of ice-cream must be used to calculate the protein exchange amount.

100
Dairy or soya yogurt e.g. flavoured or plain, drinking, soya Any yoghurts with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
However, if they contain exchange ingredients and protein ≤0.5g/100g, it is best to limit to 1 portion/pot per day.

100
Dairy desserts e.g. fromage frais, dairy desserts, custard, mousse, instant dessert, rice pudding Any desserts with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
However, if they contain exchange ingredients and protein ≤0.5g/100g, it is best to limit to 1 portion/pot per day.

Coconut-based desserts
Any coconut desserts with a protein content >0.5g/100g must be calculated/weighed as an exchange food. If they contain ≤0.5g/100g, they are considered exchange-free.
However, if they contain exchange ingredients and protein ≤0.5g/100g, it is best to limit to 1 portion/pot per day.

97
Coconut products Dried coconut products with a protein content >0.5g/100g protein must be calculated/weighed as an exchange food.

Spreads & dips
Lemon curd All lemon curd with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Chocolate spread All chocolate spread with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Nut spread/chocolate nut spread e.g. peanut butter, Nutella All nut spreads with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

87
Hummus Hummus with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Dips -sweet and savoury Any sweet or savoury dips (e.g. sour cream, Tzatziki, nacho cheese dip) require measuring/weighing as exchange foods if they contain protein >0.5g/100g and contain exchange ingredients. If they contain exchange-free ingredients only or have a protein content no more than 0.5g/100g, they are exchange-free. 100

Gravy
Exchange-free if the protein content is ≤ 0.5 g/100 ml when prepared. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/measured as an exchange food.

100
Cheese or milk-based sauces e.g. cheese, white, parsley, carbonara All cheese sauces must be calculated/measured as part of exchange system unless dry powder ingredients are exchange-free and are made up with water or protein-free milk.

100
Herby/spicy rubs or coatings Exchange-free if the protein content is ≤0.5g per serving. Any that contain exchange ingredients with a protein content >0.5g/100g per serving must be calculated/weighed as an exchange food.
Pesto, mustard, tapenade, plant-based vegetable spreads Any pesto, mustard, tapenade or plant-based spread, including homemade, with a protein content >0.5g/100g must be calculated/weighed as an exchange food (unless it contains exchangefree ingredients only).

100
Soup If soups contain exchange ingredients and their protein content is >0.5 g/100 g, then they must be calculated/measured as an exchange food (unless they contain exchange-free ingredients only).

Pasta & rice
Regular & gluten-free pasta, rice, noodles, couscous, gnocchi, tinned pasta, pasta shapes All regular or gluten-free pasta, rice or pasta products with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Pot Noodles All pot noodles with a protein content >0.5g/100g when reconstituted, must be calculated/weighed as an exchange food. 100

Meat & Alternatives
Vegan meat e.g. vegetarian burger/sausages, Hooba mushroom sausages All pulses and beans with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
Exception: French green beans are exchange-free.

Drinks
Hot chocolate, malted milk powders, milkshake powders or liquids Flavoured milk powders, milkshake powders/liquids and hot chocolate powders/liquids with a protein content >0.5g/100g must be calculated/measured as an exchange food. These are best prepared with protein-free milk.

Sweet snacks
Biscuit/cookie Biscuits with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
Cakes and pastries, including gluten-free varieties, with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Breakfast or cereal bars Breakfast and cereal bars with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Fruit bars Any fruit bars with a protein content >0.5g/100g must be calculated/weighed as an exchange food (unless they contain exchange-free ingredients only).
All frozen pastry, pies, crumbles (including gluten-free varieties) with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

Jelly (aspartame-free)
Exchange-free if the protein content is ≤0.5g/100g. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

97
Chocolate/chocolate bars, fudge, toffee Exchange-free if the protein content is ≤0.5g/100g. All with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Gummy sweets, vegetarian gummy sweets (aspartame-free) Exchange-free if the protein content is ≤0.5g/100g. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

91
Marshmallows Exchange-free if the protein content is ≤0.5g/100g. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as exchange foods.

95
All other sweets e.g. boiled, chewy, mints, candy (aspartame-free) Exchange-free if the protein content is ≤0.5g/100g. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

91
Liquorice Liquorice with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

Savoury snacks
Potato crisps All potato crisps with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Vegetables crisps All vegetable crisps with a protein content >0.5g/100g must be calculated/weighed as an exchange food.
Exceptions: Cassava crisps are exchange-free if ingredients are all exchange-free.
Vegetable crisps containing exchange-free vegetables are calculated/weighed as exchange foods due to the concentration of protein associated with cooking methods; their protein content per 100g must be used to determine the exchange amount.

100
Corn and rice-based snacks All corn and rice-based snacks with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Popcorn All popcorn with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

Pretzels
All pretzels with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Crackers, crispbread, breadsticks Crackers, crispbreads and breadsticks with a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Rice, corn or oat cakes Rice, corn or oat cakes with a protein content >0.5g/100g must be calculated/weighed as an exchange food. 100

Sugars
Icing -e.g. Buttercream, fondant icing All icings with a protein content ≤0.5g/100g or if they contain exchange-free ingredients only, are considered exchange-free. Any with exchange ingredients and a protein content >0.5g/100g must be calculated/weighed as an exchange food.

100
Marzipan Marzipan with a protein content >0.5g/100g must be calculated/weighed as an exchange food 100 Foods that require measuring/weighing as an exchange food if they contain protein >1g/100g. If they contain exchange-free ingredients only, or have a protein content no more than 1g/100g, they are exchange-free. Require measuring/weighing as exchange foods if they contain protein >1g/100g and contain exchange ingredients. If they contain exchangefree ingredients only or have a protein content no more than 1g/100g, they are exchange-free.

80
Mayonnaise, salad cream, oil-based dressings Require measuring/weighing as exchange foods if they contain protein >1g/100g and contain exchange ingredients. If they contain exchangefree ingredients only or have a protein content no more than 1g/100g, they are exchange-free.

91
Cook-in/pour over or liquid sauces e.g. Italian, curry, sweet & sour, tomato, vegetable Require measuring/weighing as exchange foods if they contain protein >1g/100g and contain exchange ingredients. If they contain exchangefree ingredients only or have a protein content no more than 1g/100g, they are exchange-free.

Cake decorations
All cake decorations are exchange-free if they contain exchange-free ingredients only or if the protein content is ≤1g/100g. If they contain >1g/100g and contain exchange ingredients, they must be calculated/weighed as exchange foods.

97
Foods that require measuring/weighing as an exchange food if they contain protein >1.5g/100g. If they contain exchange-free ingredients only or have a protein content no more than 1.5g/100g, they are exchange-free.

Soya sauce
Exchange-free if it contains protein ≤1.5g/100g. Any with a protein content >1.5g/100g must be calculated/measured as an exchange food 79
If low protein special prescribed foods contain exchange ingredients but contain Phe ≤25mg Phe/100g of prepared product, they are exchange-free. If they contain exchange ingredients and contain Phe ≥26/100g of prepared product, they are an exchange food.

FOOD GROUPS STATEMENTS % agreement
Low protein milks replacements (available on prescription) Any low protein special milk that provides a Phe intake of >5mg/100ml must be calculated/measured as an exchange food. However, if they contain added ingredients that are protein containing (e.g. milk or wheat), they are calculated/weighed as exchange foods.

Potato and potato products
Potato -boiled, mashed (no milk), jacket, baked 80g = 1 exchange of protein, based on phenylalanine analysis.
Fresh/frozen potatoes are calculated/weighed as exchange foods. If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.

96
Canned potato 100g = 1 exchange of protein, based on phenylalanine analysis.
If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.
If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.
If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.

96
Instant mashed potato 10g (dry weight) = 1 exchange of protein based on phenylalanine analysis.
If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.

96
Processed potatoes -waffles, croquettes, wedges, Alphabites, hash browns, Smiley faces, potato salad Fresh/frozen potato products are calculated/weighed as exchange foods. If Phe analysis is unavailable, the protein content is used to calculate exchange amounts. If potato products contain additional exchange ingredients (e.g. wheat flour, or milk), the protein analysis on the packet is used to determine its exchange amount.

STATEMENTS
Rounding values up or down if protein is <0.5g or >0.5g/100g Definition: 1g protein exchange = the amount of food that is calculated/measured to provide 1g protein from the protein food analysis.
Food 'exchange' amounts for food portions must be rounded up or down based on the 'rule of maths' (Table 1* below for guidance).
General guidance Patients/caregivers are advised to read ingredient lists as well as the protein content per 100g on food labels.
As guidance: -If ingredients are protein containing (but the protein analysis appears very low), it is important to establish more accurate protein analysis before consuming. -If ingredients are 'clearly' exchange-free, then it is appropriate to give as an exchange-free food even if the protein analysis is unavailable on the label. -If there is no nutritional analysis on the product but it contains ingredients that are exchange foods, then further food protein analysis must be obtained before consuming. -If a label states protein content is 0 g but one or more ingredients is a protein source (e.g. gelatine), then an accurate food protein analysis must be obtained before consuming.