Early feeding in Maple Syrup Urine Disease (MSUD)

During the initial phases of your baby’s treatment, your specialist team will have worked to bring your baby’s Leu level down as quickly as possible into the safe range. A feeding routine will then have been established and will be adjusted under close supervision with regular blood testing.

In these early stages of feeding, the essential Leu / protein in the diet is provided by breastmilk or infant formula. Your dietitian will increase or decrease this on the basis of blood test results. Protein substitute (Leu, Iso and Val-free infant formula) is then used to provide all of the other building blocks of protein (amino acids) and key nutrients needed for optimal growth and development.

To remove Leu, Iso and Val from the protein substitute, the protein needs to be broken down into individual amino acids. The result is a slightly different smell and taste, but your baby should accept this readily and build taste acceptance from early on. Being positive and firm with the protein substitute from the very beginning is important to build a strong foundation for your baby’s treatment in the future. For more information on the Leu, Iso and Val -free infant formula provided by Nutricia Metabolics, check out the products section of the website.


Having a baby with MSUD does not need to hinder successful breastfeeding; breastfeeding provides many benefits to you and your baby. Initially it may be necessary to express regularly, then your team will guide you through the transition to breastfeeding.

In order to limit the amount of Leu / protein from breastfeeds, your dietitian will prescribe a measured volume of protein substitute to be taken before breastfeeds. Baby is then put to the breast and can feed to demand. The protein substitute should displace some of the breastmilk taken, and keep blood Leu levels under control.

It is important that the protein substitute is always offered before breastfeeds, and spread evenly throughout each day as advised by your dietitian. You will be advised on how to give extra Iso and Val supplements should they be needed.


If you choose to bottle feed your baby, your dietitian will prescribe a volume of infant formula that provides the necessary amount of Leu / protein to keep blood levels in a safe range. This will be spread over several feeds throughout the day. Protein substitute is then used to ‘top up’ feeds, your baby can drink as much of this as they need.

It is important that infant formula feeds are offered first, so that you and your dietitian can keep track of the amount of Leu / protein that your baby has taken each day. Try to give the infant formula and protein substitute in separate bottles; this also helps you to keep an accurate record of what your baby has taken, and ensures that they are used to the taste of the protein substitute. You will be advised on how to give extra Iso and Val supplements should they be needed.

Emergency regimen

Your baby will have an Emergency Regimen to use in times of illness and loss of appetite which is primarily made up of protein substitute and glucose. Become familiar with this plan, and practice making up the recipe at home before your baby becomes unwell to ensure you are comfortable preparing it. Always make sure that you have all of the ingredients to make up the Emergency Regimen, and that they are in date.

At the first sign of illness, the Emergency Regimen should be started and you should contact your specialist team immediately for further instructions. When your baby is very small, your team are likely to advise you to bring them straight to hospital rather than try to manage the Emergency Regimen at home.

Iso and Val supplements become very important when your baby is unwell, your team will advise you on how many your baby needs.

NOTE: The dietary treatment for MSUD varies for each person so all information presented here is for guidance only. Your own dietitian and/or doctor will advise you on all aspects relating to management of MSUD for you and your family