Even though you have lived with PKU your whole life, now you are in your teens you will be starting to take more of an active role in managing your diet and will continue to do so as you get older.
You might be at high school, university, working, living at home or perhaps moving out of the family home. These are exciting times and requires you to make decisions and manage your PKU yourself. You are not alone so don’t worry. There are patient support groups and the metabolic team are there to help and support you.
Here are some practical tips for managing your PKU and if you have any specific questions about your low protein diet, your dietitian will always be happy to help.
Managing the diet well involves;
1. Knowing what your phe level is by taking good quality blood spots regularly as advised by your dietitian. This involves understanding how to take a blood spot, remembering to do it and ensure you get the result!
2. Eating within your protein allowance, understanding the protein content of foods and how to calculate this, meal planning, food shopping and cooking including using specifically manufactured low protein foods. Also understanding how to make food choices to suit your diet when eating outside of the home, whether at friends houses, being out and about or eating takeaway or out at café’s and restaurants.
3. Taking your protein substitute in the amounts prescribed daily, and asking for help or alternatives if you are struggling with it.
Dried blood spots
Providing dried blood spots for Phenylalanine (Phe) monitoring is essential in PKU, as this enables your dietitian to check your phe levels are within a target range and make any amendments needed to your diet. Your dietitian will advise you on how often blood spots need to be provided for testing.
It is important that you become used to providing good quality blood spots. If poor quality blood spots are received at the lab, they may not be accepted and you will need to do them again!
What are blood spot samples?
Blood spot samples are a drop of blood, about a centimetre in width, that are placed onto a specially made testing card.
This testing card takes 2-4 blood spot samples and is sent back to a lab where the phe level in the blood is tested.
How do I complete a blood spot card?
Before taking the blood spot sample, check the date on the testing card to make sure it has not expired and that all sections are completed.
These cards may already have a label on them with all your details (it’s still always useful to double check these are correct).
If not, you will need to add them to the card.
Providing a good quality blood spot sample
You will have completed a blood spot sample hundreds of times in your life but just in case you need a refresher on how to do it, here is a step-by-step guide to providing a good quality blood spot sample:
Important points to remember
When you have PKU it is particularly important to know how to read food labels.
This might seem confusing and overwhelming at first, but with practice this will become easier.
The protein in food is counted in grams of protein. 1g of protein equals 50mg of phe in most foods.
1g of protein = 50mg of phe
When feeding your child commercially available, packaged food, it is important to know how to interpret the food label.
This enables you to -
1) Decide if the food needs to be counted
2) Decide how much can be included in your child’s diet if it is to be counted.
It is also important to compare the
declared serving size of the packaged food to the amount that your child would eat. This will allow you to consider the amount of protein your child would eat from that food, which helps to plan
Protein values for foods without a
nutrition information table ie. fresh fruit and vegetables, can be obtained from your dietitian or the PKU Handbook (ASIEM).
Always check labels for the added sweetener ASPARTAME (E951 or E962) which is not permitted as it is a source of phenylalanine.
Most pre-packed foods have nutritional information on the packaging or on supermarket websites.
Here is an example of the nutritional information on a Weetabix cereal packet:
Serving Size: 33g (2 bsicuits)
|Fat, Toal (g)
This label provides information on the energy content shown as calories (kcal). Information is also provided on the typical fat, carbohydrate and most importantly for PKU, protein content. All nutritional information is provided per 100 grams and sometimes per portion of the food. So, in this instance 2 biscuits of Weetabix contain 4.1g of protein.
Unless a food is a specially manufactured low protein food, then it is extremely unlikely that the phe content will be provided on a food label.
Sometimes food labels will state that the product contains protein. However, the ingredients list may be made up of foods which you know are protein-free. If this is the case, the food can be eaten without contributing towards your protein allowance.
To work out if a food needs to be counted towards your protein allowance look at the protein content on the label. If the protein is 0.5g or less per 100g, then this food is classed as protein free (please note, this does not apply to plant-based alternatives to milk, please speak to your dietitian about this). However, if it is over 0.5g per 100g, then you will need to calculate the total number of grams of protein in the amount of food that you eat. The protein content will be listed per 100g of the food, and also per serve. Check what the serve size is and compare this to the serve size that you would eat. Your dietitian will tell you how many grams of protein you are allowed to eat each day.
The PKU Handbook (ASIEM) provides a comprehensive list of products which are protein free and has further information on reading food labels.
Calculating Protein in Foods
Knowing a food’s protein content per 100g, enables you to calculate how much of that food provides ONE gram of protein.
For example, look at the yoghurt nutritional panel below –
Nutrition Information (Average) 720g tub of Boysenberry Yoghurt (Serving Size: 90g, Servings per pack: 8)
per Serve (90g)
|of which are saturates (g)
|of which are sugars (g)
This yoghurt contains 5.9g of protein per 100g. So, 100 ÷ 5.9 = 17g
Therefore, 17g is equal to 1 gram of protein.
The nutrition panel also tells you that one serve contains 5.3g, one serve being 90g of yoghurt.
The next example, is another yoghurt, nutritional panel below –
Nutrition Information (Average) 600g tub of dairy free Coconut Yoghurt (Serving Size:125g, Servings per pack: 4)
per Serve (125g)
|of which are saturates (g)
|of which are sugars (g)
This yoghurt contains 0.9g of protein per 100g. So, 100 ÷ 0.9 = 111g
Therefore, 111g is equal to 1 gram of protein.
The nutrition panel also tells you that one serve contains 1.2g, one serve being 125g of yoghurt.
A nutrition information panel will also state the amount of protein per serve/portion. The table below shows how many grams of protein are in ONE portion of food.
If ONE portion of food contains 0.3g protein or less, then the amount of protein ONE portion provides, is considered protein- free. However, if your child eats more than ONE portion, this amount of food will contain greater than 0.3g protein, and so it will be counted towards the daily protein allowance.
If you do not have the protein content per portion available, then you can still work out the amount of protein per portion of food that your child eats using the protein content for 100g.
See steps below:
If a child eats 20g of yoghurt:
5.9 (protein per 100g) x 20 (amount eaten) ÷ 100 = 1.2 gram of protein
Remember practice makes perfect and will increase your confidence in working out what you can incorporate into your low protein diet.
We recommend you regularly refer to the PKU Handbook (ASIEM), food labels or your dietitian for the most up-to-date nutritional information.
We recommend you regularly refer to the NSPKU dietary information booklet on their website for the most up-to-date nutritional information.
As you get older you may start to get interested in cooking, heatlh and recipes. Helping with food planning and preparation will allow you to develop skills and gain confidence in the kitchen. This may help to increase variety and enjoyment of your meals. Specially manufactured low protein foods will likely become staples of your diet, if they aren’t already, and act as a great base to build a meal around. Here are a few helpful hints and tips for cooking with specially manufactured low protein foods:
Low protein pasta
Low protein rice
To bake low protein bread
To bake low protein cakes
Additional useful tips: