Interpreting Food Labels
When you have a child with PKU it is particularly important to know how to interpret food labels.
This will enable you to check the protein content of foods, and work out if the food is suitable for your child’s diet without counting it as a phe exchange.
This might seem confusing and overwhelming at first, but with practice this should become easier.
To re-cap, the protein in food is counted as phe exchanges. 1 phe exchange is the amount of food that provides 1g of protein.
1g of protein = 50mg of phe
1 phe exchange = 1g protein / 50mg of phe
Most pre-packed foods have nutritional information on the back or side of the packaging.
Here is an example of the nutritional information on a Weetabix cereal packet:
This label provides information on energy content expressed as kilojoules (kJ) and calories (kcal). Information is also provided on the typical fat, carbohydrate and most importantly for PKU, protein content. All nutrition information is provided per 100 grams and sometimes per portion of the food. So, in this instance 2 biscuits of Weetabix contain 4.5g of protein.
Unless a food is a specially made 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 exchange free. If this is the case, the food can be given without contributing towards phe exchanges.
When you know the protein content of a food per 100g, you can calculate how much of that food equals 1 phe exchange.
For example this yoghurt contains:
5.1g of protein per 100g. So, 100 ÷ 5.1 = 20g
Therefore, 20g is equal to 1 phe exchange.
When you need to calculate phe exchanges quickly, use the ready reckoner below.
For example, if the protein content on the label states 0.9g per 100g, then 111g of this food is counted as 1 phe exchange.
|
Protein (per 100g) |
1 phe Exchange (g of food) |
Protein (per 100g) |
1 phe Exhange (g of food) |
Protein (per 13.500g) |
1 phe Exchnage (g of food) |
|---|---|---|---|---|---|
| 0.1 | free | 1.8 | 56 | 3.5 | 29 |
| 0.2 | free | 1.9 | 53 | 3.6 | 28 |
| 0.3 | free | 2.0 | 50 | 3.7 | 27 |
| 0.4 | free | 2.1 | 48 | 3.8 | 26 |
| 0.5 | free | 2.2 | 45 | 3.9 | 25 |
| 0.6 | 167 | 2.3 | 42 | 4.0 | 25 |
| 0.7 | 143 | 2.4 | 42 | 4.1 | 24 |
| 0.8 | 125 | 2.5 | 40 | 4.2 | 24 |
| 0.9 | 111 | 2.6 | 38 | 4.3 | 23 |
| 1.0 | 100 | 2.7 | 37 | 4.4 | 23 |
| 1.1 | 91 | 2.8 | 36 | 4.5 | 22 |
| 1.2 | 8. | 2.9 | 34 | 4.6 | 22 |
| 1.3 | 77 | 3.0 | 33 | 4.7 | 21 |
| 1.4 | 71 | 3.1 | 32 | 4.8 | 21 |
| 1.5 | 67 | 3.2 | 31 | 4.9 | 20 |
| 1.6 | 63 | 3.3 | 30 | 5.0 | 20 |
| 1.7 | 59 | 3.4 | 29 |
We have developed a small phe exchange ready reckoner to keep in your purse/wallet for when you are out
and about. Request your copy today.
Usually, it will say on the label how much protein there is in 1 portion. The table below shows how many phe exchanges are in a portion of food based on the protein content.
If a portion of food contains 0.3g protein or less, it is exchange-free. However, if your child eats more than 1 portion it will need to be counted towards their daily exchange allowance as advised by their dietitian.
Protein content (g/per portion) Number of phe exchanges
|
Protein Content (g/per portion) |
Exchanges |
|---|---|
| 0 - 0.3 | 0 - 0.3Free (1 portion only) |
| 0.4 - 0.7 | 0.5 |
| 0.8 - 1.2 | 1 |
| 1.3 - 1.7 | 1.5 |
| 1.8 - 2.2 | 2 |
If you do not have the protein content per portion available, then you can still work out the number of exchanges per portion of food using the steps below:
- Multiply the protein content of food per 100g by the amount of the food eaten.
- Divide this number by 100 to give the number of phe exchanges per portion of food.
If a child eats 20g of yoghurt:
5.1 (protein per 100g) x 20 (amount eaten)
÷ 100 = 1 phe exchange
Once your child is old enough, encourage them to interpret food labels and calculate their own phe exchanges.
Until then, at mealtimes it will be useful to get them familiar with foods that contain protein or are exchange free.
Interpreting food labels will encourage independence and help to prevent your child always relying on you to do the work! Plenty of practice will increase their ability and confidence.
We recommend you regularly refer to the NSPKU dietary information booklet on their website for the most up-to-date nutritional information.
www.NSPKU.org
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