Sugar continues to be a hot topic at the moment, especially with the impending sugar tax on high sugar drinks. There is concern about the effect of sugar on the teeth causing dental caries, as well as the calories it provides contributing to weight gain. These concerns are the same for someone with PKU who follows a low protein diet.

Dietitians are not in favour of demonising one nutrient and take a whole diet approach when it comes to a balanced diet and lifestyle. However, the bottom line is we are eating too much sugar and reducing the amount we consume can only be a good thing.

A new document, produced by the Scientific and Advisory Committee on Carbohydrates was released in 2015 advising us on the amount of sugar we should be consuming. For everybody aged 2 years and over, only 5% of dietary energy should come from added sugar. Therefore, if you are a woman consuming 2000 calories a day; no more than 100 calories should come from added sugar. This equates to about 5 teaspoons and is around 200mls of a full sugar fizzy drink. For a man consuming 2500 calories; this is around 6 teaspoons of sugar and 125 calories, equating to 300mls of a full sugar fizzy drink. Not a lot really. Big changes are needed by the population as a whole to ensure we cut down our sugar intake, including people with PKU. Following a strict low protein diet can make it hard to follow advice given to the general population. However, it is possible to make some changes to reduce your sugar consumption. Every little change will help.

Here are some of the common questions and dilemmas we may hear from people with PKU and our solutions. Please bear in mind this advice may not be suitable for children and anyone on the preconception diet and those already pregnant. Please speak with your Dietitian first before making any changes.

“Diet drinks contain aspartame so I have to have full sugar versions”
Full sugar drinks not only provide a vast amount of sugar, they also provide lots of calories. A 500ml bottle of Cola racks up a whopping 53g of sugar (around 10 teaspoons) and 210 calories. If we back track; this is double the amount of sugar recommended by the new guidelines for a woman. Bear in mind this has come from a drink and not some lovely tasty food. People with PKU can have diet and sugar free drinks, as long as they don’t have aspartame in. More drinks are now using other sweeteners such as sucralose and acesulfame K which are safe for people with PKU to take. Check the label and ask your Dietitian if you are struggling. This will be an easy way of cutting down your sugar intake.
“I eat quite a lot of sugary snacks to keep my energy levels up”

It is commonly said you can feel hungrier if you have PKU. This is thought to be due to eating less whole, natural protein, which has been shown to be the most filling nutrient, not very useful for someone with PKU. It is often easier to grab allowed sweets and both normal and low protein biscuits and cakes to keep full. These are unfortunately, the foods that contain a lot of sugar. Instead try fruit, low protein crackers and low protein cheese, low protein toast and spread, vegetable crudités and low protein dips, homemade vegetable soup and low protein bread, low protein pasta salad or see if you can adapt some low protein baking recipes to reduce the sugar content. Ask your Dietitian for some tips.


“Fruit contains sugar and this is my main snack – help!”
Fruit does contain sugar. This is true. However fruit sugars are not included in the 5% recommendation, as these are natural sugars, not “added sugars” like you would find in fizzy drinks and biscuits. Fruit also contain vitamins, antioxidants and fibre; great for bowel health. There are many health benefits so please ensure you keep your fruit intake up. It is also important, to distinguish between the whole fruit and fruit juice and smoothies. Always pick the whole fruit in favour of a juice and smoothie. Many pieces of fruit are blended to produce a drink, meaning more calories consumed; not good if you are watching your weight. Fibre can be lost in this process too.
“What do I have for breakfast? The low protein cereals are very sugary”

This is a statement we do hear quite regularly. Breakfast can be a tricky time, as in fact many normal breakfast cereals do have a lot of added sugar too. It is important to have your protein substitute in the morning to provide an initial dose of protein, vitamins and minerals. Low sugar options include: low protein toast and spread and/or tomatoes or mushrooms, low protein pancakes with fruit, exchanges of normal cereal, such a Weetabix or Shredded Wheat which is lower in sugar, with chopped fruit (banana, berries, apple, pear) and LP milk. If you have adequate exchanges, you could have weigh out some porridge oats with low protein milk and fruit for a filling start to the day.

“My Protein Substitute contains sugar – what can I do?”

Certain brands of protein substitute do contain sugar; with this amount varying between the flavours. This will be to aid the palatability of your protein substitute and help you take them regularly. It is very important you take your protein substitute as it contains all the amino acids you need, apart from phenylalanine and all your essential vitamins and minerals. However, there are new ready to drink brands that contain much less sugar. There are also powders and tablet options that contain less sugar than some of the ready to drink options. Please speak to your Dietitian for more advice on this.

It is very important to remember that the above forms a basis for a healthy diet and lifestyle and moderation is key. A sugary snack on a special occasion or for a treat is fine but it is what you do every day that makes the difference. Making reductions to the sugar you consume each day will be a great start to improving your diet and health.

Disclaimer: This article is for information, please speak to your dietitian about making changes to your diet.